Note: Descriptions are shown in the official language in which they were submitted.
BAC KGROUND OF THE I NVE NTI ON
___ _ _ _ ~_ _
1. Field of the Invention
This invention relates to porous amor.phous alumino-
silicate powders having uniform pore sizes and uniform
particl~ size aluminosilicate aquasols. More specifically,
this invention relates to porous amorphous aluminosilicate
powders having a uniform pore size,precursor aluminosilicate
aquasols with uniform particle size and their preparation
by drying said aquasols to a powder without gelling.
2. Prior Art
Silica gels which are dried to porous silica
powd~rs are considered to be masses of spheres of SiO2
ranging from a few Angstroms up t~ several hundred ~n~stroms
in diameter, which are aggregated together in a three-
dimensional mass. Vysotskii ["Adsorption and ~dsorbents"
(No. 1), John t1iley & Sons, N.Y., 1973, p. 101] states that
globular particles of silica form the skeleton of gels and
that the cavities between the spherical particles consti-
tute the pores in silica gels. This structure of silica
gels is further d2scribed in detail by R. K. Iler, "The
Colloid Chemistry of Silica and Silicates", Cornell Uni-
~crsity Prcss, Ithaca, N.Y., 1955, p. 129. The pore size
nnd pore uniformity of silica is related to the particle
si7e and particle uniformity.
.S, Patent 3,782,075 disclos~s a silica packin~
.ltcrial for chromato~raphic columns havin~ uniform-sized
porou~ mi.crosphereS havin~ su~stantially all of the micro-
r.plleres ln the ran~e of from 0.5D to 1.5D whel-e D is the
n~era~Je di.~m~ter.
.
3~14
It is known to react sodium silicate, sodium
aluminate, and an acid, or sodium silicate, aluminum sul-
fate, and an acid to form a gel or precipitate of alumino-
silicate directly However, the prior art does not teach
any method for controlling the ultimate size of alumino-
silicate particles which eventually aggregate to form the
gel structure or the preparation of the ultimate particles
of uniform si7.e. The control of the pore size aistribution,
namely the size distribution of spaces between these pri-
mary globules or aluminosilicate particles is likewise
not known.
The difficulty of making aluminosilicate solparticles from which uniformly porous gels and powders can
be formed is exemplified by Kontorovich, et al., J. of
Colloid Chemistry, USSR (English translation), Vol. 35,
p. 864, 1973 (Kolloyd, zhur, p. 935). Aluminosilicate
particles,made simply by mixing sodium silicate, sulfuric
acid, and aluminosulfate,showed a wide distribution of
radii such that, for example, where the commonest particle
radius was 20 A, a large fraction of the particles were
also as large as 60 ~ radius. He further points out that
even when the gels are aged for growth, the particles grow
only to about 35 A, even after long exposure in water at
70C. He states definitely that the presence of aluminum
in the globules hinders the increase in the size of the
particles. This puts a limit in the ~1 contcnt for certain
particle sizes.
The nonuniformit~ of porcs of amorphous alumino-
sili.cates is exemplified in U.S. Patcnt 3,346,509 which dis-
closcs the prcparation of silica-~lumina compositions with
- 4 -
1:~23~:14
a preponderance of the pore volume in pores of small radii.
The pore radii are disclosed as ranging from above 200 A
to less than 10 A with up to about 60% in the range of
O O
10 A to 20 A.
U.S. Patent 3,766,057 discloses an alumino-silica
gel dried to a powder having a mean pore radius of 40 A to
100 A and 15~ of the pore volume in a 10 A section with a
wide distribution of particles in the adjacent particle
sizes.
Making aluminosilicate sols of particles of 3 to
150 millimicrons in diameter which are uniform in chemical
CQmposition was described by G. B. Alexander in U.S. Patent
2,974,108, issued March 7, 1961. In U.S. Patent 2,913,419,
issued November 17, 1959, Alexander discloses the prepara-
tion of gels and particles having a skin or outer surface
of alumi~osilicate composition. The gels have a coarse
structure to permit coating with aluminosilicate without
closing the pores in the gel. There is no disclosure of
the need for uniform pores or for the preparation of uni-
form pore sizes or the control of the pH at a constant
value between 9 and 12. Alexander's particles are used as
filters while his gels are used as catalysts.
In porous catalyst powders, the uniformity in
pore size is a definite advantage in affording specificity
of reaction by avoiding side reactions and preventing the
deposition of carbonaceous residues. Heretofore, it has
not been possible to produce amorphous aluminosilicatc
catalysts Wit]l a uniform pore size.
SI~MJ~ R~' OE TIIE IN~7EN'rION
Now it has bcen found that aluminosilicatc porous
powders witll uniform porc sizc distribution comprisi
-- 5 --
~2~38~L4
spheroidal colloidal partieles of uniform size ean be pre-
pared by first growing uniform size particles at a con-
stant pH to prepare a uniform partiele size amorphous
aluminosilicate sol and then drying said uniform particle
size sol to a powder without gelling the sol.
The eompositionsof this invention, which are
particularly useful as a eatalyst, consist essentially of
uniformly porous powders comprising spheroidal colloidal
particles of uniform size packed into porous aggre~ates
10. having a uniform pore diameter between the particles, a
bulk density of 0.5 g/cc or more, preferably from 0.5 to
D.9 g/ce and a specific surface area of 30 to 750 m2/g of
said particles having a surface of amorphous aluminosilicate.
The uniform spheroidal discrete eolloidal particles
of the sol to be dried have particle diameters which range
from 3 to 90 nanometers.
The spheroidal particles have a coating that con-
sists of an amorphous aluminosilicate. Said aluminosilicate
is coated or deposited on a pre-formed core of more or less
spheroidal colloidal particles which may or may not have the
same composition as the deposited aluminosilicate. For
eatalytie activity it is only essential that the required
eolloidal particles have a coating or surface of cataly-
tieally active amorphous aluminosilicate. This coating
eomposition extends witnin the surface to a depth of at
least 0.5 nanometer, preferably 0.5 to 1.5 nanometers.
~lthough tllis composition can extend to a depth o~ ~reater
than 1.5 nanomcters, ~epths ~rcater than 1.5 nanometers are
seldom req~lired.
The spheroidal particles are coatcd with an amor-
phous hydrous alumino~ilicatc compound compri.siny onc or
-- 6 --
more cations selected from the group consisting of sodium,
potassium, hydrogen, ammonium and Group I to;VIII metals
selected from the group consisting of Cs, Li, Mg, Ca, Sr,
Ra, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc,
Ru, Rh, Pd, Ag, La, Ce, rare earth metals, Hf, Ta, W, Re,
Os, Ir, Pt, Au, Sn, Cd, Bi and Sb. The interior of the
spheroidal particles is also composed of said aluminosili~
cate except to the extent that the nuclei or core may be a
refractory metal oxide or silica.
The aluminosilicate chemical composition may be
defined by the following formula:
x ~(A102)X(siO2)y]n~wH2o
v
where x and y are the number of moles of A102 and SiO~
r~specti~tely, the molar ratio of y:x being from 1:1 to 19:1
~f Si:Al, and ~ is the moles of bound water, M is one or
m6re metal cations selected from the group consisting of Li,
Na, K, H, ~H4, ~s, Ru, Mg, Ca, Sr, Ba, Sc, Ti, V, Cr, Mn,
Fe, Co, Ni, Cu, ~, zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, La, Ce,
~0 r~re ea~th metals, ~f, Ta, W, Re, Os, Ir, Pt, Au, Sn, Cd,
Bi and Sb; and v is the valence of M. It is understood
that where there are, e.g., three metals, the term Mx would
v
include each metal and its valence. The cations represented
~y M are preferably selected from one or more of the group
consisting of amm~nium, hydrogen, Cs, Li, Mg, Ca, Sr, Ba,
Sc, ~i, V, Cr, Mn, Fe, Co, Ni, Cu, Yl Zr, Nb, Mo, Tc, Ru, I~h,
Pd, Ag, La, Ce, rare earth metals, l~f, Ta, W, Re, Os, Ir,
Pt, ~u, Sn, Cd, Bi and Sb. Wllat is meant by one or more is
3~ that in the replacemellt o~ sodium or potassium with one or
~Z38i~
more mctal cations listed, there will be replaceme~nt to the
extent the sodium or potassium is replaceable with one or
more metal cations. Thus in addition to the one or more
metal cations, some unreplaced sodium or potassium will
remain.
Cenerally the aluminosilicate of this invention
is produced in the form where M is sodium or potassium.
The sodium or potassium aluminosilicate is ion exchanged
so that it is largely ammonium aluminosilicate although
L0 some sodium or potassium aluminosilicate still remains.
The ammonium aluminosilicate can be heated to drive off the
ammonium to give hydrogen aluminosilicate. The final form
of the powder is generally ammonium or hydrogen alumino-
silicate. However, where it is desired to replace the
ammonium or hydrogen with one or more metals indicated above
for M, t~e sol before drying may be ion exchanged to yield
the aluminosilicate with the desired metal or metals. In
such a case, a small amount of ammonium and/or hydrogen
aluminosilicate also remains.
The powder compositions of this invention may
also have a surface layer over the aforesaid aluminosilicate
coating of one or more of the following metal or metal
oxides which may be in the cationic form, partially replac-
ing M: Li, Cs, Rb, Mg, Ca, Sr, Ba, Sc, Ti, V, Cr, Mn, Fe,
Co, Ni, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, La, Ce, the rare
eath metals, Hf, Ta, W, Re, Os, Ir, Pt, Cu, ~g and Au. The
most prt-~ferred aluminosilicate chemical composition is whcre
M is ammonium or hydrot3cn or mixtures thereof.
Thus, in accordance witll thc invcntion, a uni~
3n formly porous powtlcr composition has becn found which com-
priscs porous ag~l-c~atcs of spllcroida] particlcs which are
-- 8 --
3 to 90 nanometers in size and nonporous to nitrogen and
contain:
(a) a core of silica, aluminosilicate or one or
more refractory metal oxides selected from alumina, zir-
conia, titania, thoria and rare earth oxides
(b) a coating around said core of at least 0.5
na~ometer in depth of an amorphous hydrous aluminosilicate
- compound having a molar ratio of Si:Al of from 1:1 to 19:1
and comprising one or more cations selected from sodium,
potassium, ammonium, hydrogen and Groups I to VIII metals
selected from Cs, Li, Mg, Ca, Sr, Ba, Sc, Ti, V, Cr, Mn,
~e, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, La, Ce,
rare earth metals, Hf, Ta, W, Re, Os, Ir, Pt, Au, Sn, Cd,
Bi and Sb; and
(c) a surface layer over said coating of 0 to
15~ by weight of a metal or metal oxide selected from Cs,
Li, Mg, Ca, Sr, Ba, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y,
Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, La, Ce, rare earth metals,
Hf, Ta, W, Re, Os, Ir, Pt, Au, Sn, Cd, Bi and Sb; said
powder composition having a specific surface area of 30 to
750 m2~g, a bulk density of 0.5 g/cc or more and substan~
tially uniform size pore diameters of from 20 A to 250 A,
O O
with pore diameters of 20 A to 45 A having a uniformity such
that at least 90% of the pore volume is made up of pores
of from 0.6D to 1.4D and pore diameters of 45 A to 250 A
having a uniformity such that at least 80% o the pore
volume is made up of pores of from 0.6D to 1.4D, where D
is the median pore diameter. A particularly useful powder
is one with pore diameters of 20A to 150 A with a uniformity
such that at least 90~ of the pore volume is made up of
pores of from 0.6D to 1.4D. An even more uniform powder
within the scope of the aluminosilicate powders of this
invention is one with pore diameters of 20 A to 150 A with
a uniformity such that at least 90% of the pore volume is
made up of pores of from 0. 7D to 1.3D. The porous aggre-
gates of this invention may range in size from 2 to 500
microns.
The aluminosilicates of this invention are pre-
pared by a process comprising:
(a) preparing a heel sol of discrete colloidal
particles selected from sodium, potassium or ammonium
aluminosilicate, silica and one or more refractory metal
oxides selected from the group consisting of titania,
alumina, zirconia, lanthana, thoria and rare earth metal
oxides, said heel sol comprising `particles o~ a substantially
uniform diameter within the range of 2 to about 85 nano-
meters, the initial concentration in the heel sol of sodium,
potassium, ammonium aluminosilicate or total refractory
metal oxide being at least 0.2.~ by weight with the particles
stabilized against aggregation in the pH range 9 to 12;
~ b) addin~ to said heel, separately but simul-
taneously, two feed solutions, one being a solution of
sodium or potassium silicate having from 1 to 36 grams of
silica per 100 cc, or a sol of silicic acid containing from
1 to 12% silica, the other being a solution of sodium or
potassium aluminate containing from 1 to 15Q~ alumina, said
feed solutions being added in rclati~e rates and proportions
to maintain a constant molar ratio of Si:~l in the feed streams
of from 1:1 to 19:1 with the rate of addition of silica not
3~ to exceed 10 grams of SiO2 per 1000 squarc mc~ers o~ total
surface area of particlcs in thc hccl sol per hour;
-- 10 --
~.Z3~
~ c) maintaining the pl~ of the heel sol at a
constant value between 9 and 12 by adding a cation exchange
resin in the hydrogen or ammonium form until the particles
in the heel sol have attained an increase in diameter of at
least 1 nanometer and a maximum size of 90 nanometers;
(d) filtering the sol from (c) to remove the
cation exchange resin and optionally adjusting the concen-
tration of the resulting aluminosilicate sol to a solids
content of uo to 60% by weiqht: an~
(e) drying the resulting substantially gel-free
sol of particles having an aluminosilicate surface to a
powder by removing water at a rate at which no gelling will
occur.
Accordingly, the uniform size amorphous alumino-
silicate particle sols of this invention are produced by
steps a, b and c of the aforesaid process followed by re-
moval of the exchange resin. The uniformity of said parti-
cles is such that the maximum standard deviation of the
particle size is 0.37d where d isweighted avera~e particle
size diameter.
Thus, the amorphous aluminosilicate sols of this
invention have uniform particles of from 3 to 90 nanometers
in diameter with a molar ratio of Si/Al of 1:1 to 19:1,
said uniformity defined by particles having a maximum stan-
dard deviation of 0.37d, where d is the weighted average
particle size diameter.
The sol from (d) may be ion exchanged to remove
the sodium or potassium ions by contacting it with a strong
acid type of cation exchange resin in the ammonium form,
after which the solids concentration may be adjusted to the
-- 11 --
31~L4
range of 10 to 60% by wei~ht before drying the substantially
gel-free aluminosilicate sol to a powder by removing the
water at a rate at which no gelling will occur.
In the process of making the sol of this invention,
the silica reacting with the aluminate ions is either largely
monomeric or polymeric. When the silica is monomeric, most
of the individual silicon atoms become associated directly
with the A102 ions forming SiA104 ions in the colloidal
particles r accompanied in the colloidal particle by the alkali
ion present in the reaction such as Na+. On the other hand,
in conventional gel processes, substantially more of the
silica is polymerized before it can be linked to alumina,
therefore less silica units are directly associated with
alumina. For these reasons the aluminosilicate compositions
of this invention are believed to have a more uniform SiO2
to A102 distribution than the conventional silica-alumina
gels. This kind of uniformity at a submicron range scale
combined with narrow pore size distribution is of great
importance in determining the performance of this composition
as catalysts and catalyst supports, for example when mixed
with active zeolite catalysts.
It will be understood that even when the heel sol
is a refractory oxide or silica or aluminosilicate, the
particles in the final sol product will have a coating of
alùminosilicate and are referred to herein as an al,umino-
silicate sol.
The powders of this invention have substantially
uniform pore sizes becausc the particles in,tne alumino-
silicate sol beforc dryin~ are substantially uniform in
diametc?r. The uniform p~rticle size of thc sol rcsults
11~38:~L4
because the two individual species, the aluminat~ ions and
silica or silicate ions, are not allowe~ to react to form
new particles or precipitate. The aluminate ions and
silica or silicate ions are converted to.soluble forms of
alumina and silica or silicate which are deposi~ed on the
substantially uniform sized nuclei or initial particles in
- the heel. When the alkaline solutions of silicate and
aluminate are added, the plI of the mixture, but for the addi-
tion of ion exchange resin,would rise. The addition of ion
exchange resin is regulated to maintain the pI~ constant
in the range of 9 to 12. This control of pH and the maxi-
mum addition rate of silicate and aluminate de~cribed herein
after (10 g of SiO2 per 1000 sq. meters of surface area per
hour) results in the aluminosilicate particles being of
- 13 -
~ ~3~
The powders of this invention have an average
pore size which dep~nds on the average particle size of
the precursor aluminosilicate aquasol. The aquasol is in
turn obtained by deposition of sodium or potassium alumino-
silicate on colloidal nuclei particles in the heel sol.
For these reasons the selection of the heel sol has to be
made on the basis of what properties are required in the
final powder and on the amount of aluminosilicate that is
-. to be deposited.
In the process of the present invention what is
meant by constant pH is maintaining the pH within ~ 0.2.
The addition of a cation exchange resin in the hydrogen or
ammonium form removes sodium ions and prevents the accumu-
lation of sodium salt in the reaction medium that would
cause coagulation of the colloidal particles.
Once the required spheroidal particles have been
formed containing cations of sodium or potassium, there
are the following ways in which the final powder of the in-
vention can be made, depending on what cations are desired
in the final product:
(a) The sodium or potassium ions in the sol may
be ion exchanged, e.g., by hydrogen or ammonium ions and
then the sol converted to powder by removing water.
(b) One or more cations of metals describcd herein
to enhance catalytic activity may ~e added in limited amounts
to the sol to partially replace hydrogen or ammonium ions
be~ore formillg th~ powder.
(c) The sol containinc3 thc ori~inal sodium or
potassium ions may be convert~d to powder and then the
sodium or potassium iOIl cxchanged for ammonium or one or
- 14 -
~ ~38~
more of thc metal cations described herein. In this in-
stance, removal of all sodium or potassium from thc powder
is substantially attained only ~here the pores of the pow-
der ~re large and only the outer surface of the ~pheroidal
particles consists of aluminosilicate.
(d) In carrying out alternative (b) and (c), more
cation metal may be used than required for ion exchange if
it is desired to leave a thin film of metal on the alumino-
silicate surface. Said metal deposited on the aluminosilicate
is converted to hydroxide and oxide when the aluminosilicate
is dried and calcined.
The metal cations of Groups I to VIII of the
Periodic Table referred to herein include Group 1~ except
for Fr, (;roup lB, Group 2A, Group 2B, except for Hg, Group
3B, exceljt actinium, Group 4B, Group 5B, Group 6B, Group 7B,
Group 8 and Sn, Sb and Bi.
The aluminosilicate powders of the present in-
vention are made by drying sols of spheroidal discrete
colloidal uniform sized particles to obtain dried aggre-
gates of said particles in which the spheroidal particlesare closely packed to~ethcr. The narrow pore size distri-
bution of the powder of this invention is attainable with
porous aggregates ranging in size from 2 to 500 microns,
preferably 10 to 200 microns, althougll considerably larger
powdcr grains can be obtained, depcndin~ on the method of
drying. The uniform individual particlcs that compactly
ag~lomcrate to form the powdcrs of this invention ~re
selectecl from thc rang2 from 3 to 90 nanomcters in diamctcr,
depcndi~l~ on the dcsi1-cd rcsulting porc siæe.
- 15 -
3~
It is most important that loose a~gregation of the
particles or formation of gel networks of linked particles
does not occur before water is removed. Otherwise, par-
ticles become linked together in open three-dimensional
networks in the sol. These open networks do not completely
collapse upon removal of water and drying, thus leaving
some pores appreciably wider than those remaining when the
spheroidal particles are closely packed together upon being
dried.
Most simply stated, drying should occur ~efore
aggregation or gellin~ occurs in the sol. One way to obtain
a mass of close-packed colloidal particles is to force the
water under pressure out of a sol through microporous
membrane against which the silica particles become packed,
and then drying the water fro~ the wet solid ~iltercake.
~owever, the most convenient way is to concentrate the sol
as much as possible, such as to a solids content of 10 to
60% by weight, without aggregating the particles and then
to dry suddenly as ~y spray drying. In this case, the sol
is concentrated rapidly in spheroidal droplets and the sur-
face tension of the water compresses the mass of particles,
orcing them together in spite of the mutualrepulsion due
to the ionic charge on the surface, until they are randomly
closely packed.
Fi~ure 1 is an illustration of the dried particle
structure of the aquasol o~ this invention in contrast to
structures after ~elation, coagulation or flocculation.
Figurc 2 is a drawing of a spray dricd porous
a~gregatc of this invcntion.
~ ~igurc 3 is a cross sectioll of a particlc rna!ci ng
~.~.23~4
up the aggregate where the particle is homogeneous and
where there is a core of a refractory o~ide.
Figure 4 illustrates the pore volume formed by
the spheroidal particles of this invention.
Referring now to Figure 1, the gel s-tructure
formed after drying is shown after (a) gelation or (b)
coagulation or flocculation of the a~uasol of this in-
vention. The dried structure of this invention with uniform
- pore size distribution is also shown after drying without
gelation.
Referring now to Figure 2, the spray dried
aggregates of Particles of this invention is shown in a
spheroidal shape to illustrate the uniform packing of -the
particles to form the aggregate. The individual particles
ma~ing up the aggregate may be homogeneously an amorphous
aluminosilicate or may have a core of silica, aluminosilicate
or one or more refractory metal oxides with a coating of
said aluminosilicate as illustrated by Figure 3.
Figure 4 was merely included to illustrate the
pore volume of this invention and its formation by the
particles.
The theory of the shrinkage orces in dryin~
water from wet masses or ~els of colloidal silica has been
described by R.K. Iler in "Colloid Chemistry of Silica
and Silicates" (Cornel University Press) 1955, pages 140
to 143. The nature of the resulting ~el or aggregate masses
has been discussed by R.K. Iler in a monograph on "Colloidal
Silica" in Surface and Colloid Science, Vol. 6, edited by
F. Matijevic (John Wiley & Sons, Inc.) 1973, pages 65 to
70. The principles relating to colloidal silica also apply
to the present sols which are converted to powders.
-17-
~ .,
3~314
The colloidal particles which bear the highest
ionic charge and which exert the greatest mutual repulsion
in the end, form the most clos~ly packed aggregates. The
reason is that as the sol becomes concentrated the particles
still repel each other and do not join together even when
they are ~uchcloser to each other than their own diameter.
Thus, the uniform spheroids remain uniformly distributed as
further water is removed, un~il the concentration reaches
the point where all the particles are ~orced into ~ontact
at about the same time so that the spaces or pores be~ween
them are uniform in size.
" If, however, the particies in the soi begi'n 'to
form open three-dimensional aggregates, or i'gei phasei' as
described by Iler in "Colloidal Siiicai', 'page 45, the'n these
particles are no longer freè to move toge'the'r 'ù'nifor'ml'y as
the sol l~ecomes very concentrated and 'when d'ried sùch
particles are not fully closely packed and la'rger ~r`regular
pores then remain in the powder.
Since aggregation of the particles i`n a sol to
form a gel is not an instantaneous process bù't generally
occurs over a period of hours or dàys, thè sol o'f t'his i'n-
vention must be dried as rapidly as possible or bè'fo're
gelling at as low a temperature as consistent'w`i`th `ra`p'i~
drying. Generally speaXing, the sols suitable 'for d`ry:in~
do not ~el in less than about an hoùr so that d'ry`ing 'w'ithin
one hour is desirable.
Spray drying is a prc~errcd procedu'r~ `not o'nly
because drying is rai~id, but bccausc thc powdcr `product is
obtaincd as porous spllercs typically 5 to 200'mi`crons iil
diamctcr which arc cspccially useful as catalysts.
- 18 -
~P~3~
Thc surface of the powder consists of an alumino-
silicate at least to the dcpth of about 0.5 nanometer of
the formula indicated above or it may contain a surface
layer of the metal cations described in the following par-
agraph and amounting to 0 to 15% by weight.
In the general formula, the hydrogen or ammonium
ions may be wholly or in part substituted by cesium, rubidium,
lithium or metal cations selected from the group magnesium,
ealcium, strontium, barium, scandium, titanium, vanadium,
chromium, manganese, iron, niekel, cobalt, copper, yttrium,
zirconium, niobium, molybdenum, technetium, ruthenium,
rhodium, palladium, silver, lanthanum and elements of the
rare earth lanthanide series numbers 58 to 71 in the
periodic system, thorium, uranium, hafnium, tantalum,
tungsten, rhenium, osmium, iridium, platinum, gold, bismuth,
eadmium, tin and antimony.
The core of the spheroidal particles eonsists
of the pre-formed colloidal particles on whi~h the alumino-
silicate is deposited. The chemical nature of the interior
of the particles plays no direct role in catalysis, since
the particles are nonporous to or~anic molecules. Ho~ever,
the pre-formed particles must be thermally stable and pro-
vide a suitable physical substrate for the aluminosilicate
on the sur ace. Thus, the core may consist of aluminosili-
cate,of any ratio of Si:~l from 1:1 to 99:1, and prefcrably
1:1 to 19:1, silica or one or more refractory o~ides having
a meltin~ point over 1600C, which can be prc-~ormcd as an
aqueous sol o~ rclatively uniform, morc or lcss sphcroi~al
colloical particlcs from ~ to ~7 nanometcrs in diametcr.
Ty~ical re~ractory oxidcs arc alumina, zirconia, titania,
-- 19 --
~2~4
lanthana, thoria and rare earth oxides. ~lowever, such pre-
formed particles must be of such uniform size that after
the aluminosilicate has becn dcposited, the final particles
will meet the above requirement of uniformity. It will be
noted that even if the pre~formed colloidal particles are
cubic crystals of a refractory oxide, the shape becomes
more rounded as amorphous aluminosilicate is deposited as
an increasingly thick coating. If ~he pre-formed particles
are the same as the aluminosilicate being deposited, then
the particles are homogeneous and are simply grown in size.
The core material is supplied in the form of an
aquasol, the preparatlon of which is known in ~he art~ The
size of the particles in the aquasol comprising the heel
or core of the particles making up the powders of this in-
vention can vary rather widely in view of the particle size
range of 2 to 87 nanometers. The powder of this invention
with large pores, would have, for example, large colloidal
particles of 50 nanometers in diameter. These large
particles may have an aluminosilicate surface or coating
as little as 0.5 nanometer in thic~ness. Thus 83-~- of the
volume of such particles may consist of a core material
which may be a refractory oxide such as silica or alumina.
Thus in this case, aluminosilicate comprises only a minor
part of the weight of the powder. On the otllcr hand, the
ultimate colloidal spheroidal particles ma~ing up the
powder grains may consist throughout of aluminosilicate.
The powders of this invention with cores of a
very stable rcfractory are more rcsistant to sintexin(3
than when they consist entircly of ~]uminosilicate. T}-us,
whell tho cores o~ spll~roidal particles of this inv~ntion
- 20
3~1~
comprise more than 50~ of the volume of ~ractory par-
tieles, the powders of this invention are more resistant
to sintering which would close the pores thereof. The
aluminosilicate surface may sinter and flow to some ext~nt,
but the thermally stable cores prevent collapse of th~
structure and closing of the pores. Thus, high surface
area can be retained and by suitable partial rehydration of
the aluminosilicate surface catalytic activity can be
restored.
The colloidal particles in the heel or starting
sol whieh constitute the core on which aluminosilicate is
to be deposited must meet a number of requirements:
- (a) The particles must be of generally spheroidal
or equidimensional in width, thickness and breadth, with an
average diameter of 2 to about 87 nanometers. Thus in
making aluminosilic~te-coated particles 3 nanometers in
diameter, if the thickness of the aluminosilicate coating
is 0.5 nanometer and the diameter of the heel sol particle
is 2 nanometers, the final diameter will be 3 nanometers.
If it is l.5 nanometers in thic~ness ~nd the heel particles
are 87 nanometers in diameter, the final particles will
be 90 nanometers in diameter. As will be explained, the
thic~ness of the deposited aluminosilicate should be greater
when the particles of the heel sol are of a different com-
position from the coating.
(b) The heel sol particlcs must be physically
and chcn1ically stablc at high tempcrature. The rcfractory
mctal particles of the hcel are charactcrize~ c~s having a
melting point in e~cess of 3600C.
~ (c) Tl~e hcel sol particlcs must bc Or a subst.~ncc?
- 21 -
38~4
that ean be made in the form of an aqueous sol of colloidal
partieles of uniform size.
The heel sol partieles eonstitutinq thc eore of
the partieles making up the powders of this invention are
seleeted from siliea, a sodium or potassium aluminosilieate
having a ~i:Al molar ratio of from 1:1 to 99:1, preferably
1:1 to 19:1 and one or more refraetory metal oxides seleeted
from the group consisting of alumina, zireonia, titania,
thoria and rare earth oxides~ The preferred refraetory
metal oxide is seleeted from alumina, zireonia and titania.
The preferred heel particles are selected from siliea,
- sodium or potassium aluminosilieate having a Si:Al molar
ratio of from 1:1 to 19:1, alumina, zireonia and titania.
- The preparation of sueh heel sol particles in
the form of an aqueous sol is known in the art. Colloidal
siliea of uniform size has been deseribed by R. K. Iler
in "Colloidal Silica", in Surface and Colloid Seienee,
Volume 6, E. Ilatijevie Editor (John Wiley & Sons, Ine.)
1973, page 1. U.S. Patent 3,370,017 diseloses the prepara-
tion of aluminasols of man~ types. U.. S. Patent 2,974,108
diseloses aluminosilicate sols. U.S. Patents3,111,681
and 2,984,628 diselose zireonia sols. U.~. Patent
3,024,199 discloses sols of the rare earth oxides. Most
refraetory oxides ean be made in the form of a stable
aqucous sol cxeept those such as ealeium oxide, barium
oxide or magnesium oxidc, which tend to hydrate or dissolve
to an undesirable extcnt in water. It should be understood
that eolloidal hyclrous oxidcs, in which tlle oxide in the
eolloidal particle is el-cmically hydrated with some bound
watcr that e.-nnot bc remo~c?d by vacuum at ordinary tempcr~~
turc, is satisf.~ctory for thc prcsellt purposc, unlcss thc
- 22 -
.238~L~
.
loss of water at elevated tem~erature results in a gross
shrinkage of the core within the aluminosilicate particle.
Even if the small heel particles initially have
a cubic or other approximately equidimensional shape, they
become rounded when enough aluminosilicate coatin~ has been
deposited to form the spheroidal shape of the final sol
particles.
~ f the available refractory oxide sol is not of
sufficient uniform particle size, a fraction of suitable
uniformity must be isolated by means known to those skilled
in the art of colloid chemistry, such as fractional sedi-
mentation or centrifugation.
The refractory oxide sols must be so constituted
that the particles remain nonaggregated in a pH range
wider than that at which the aluminosilicate is deposited,
namely g to 12. Many refractory oxides including alumina,
~irconia and thoria are stable by virtue of a positive
charge on the particles with nitrate or chloride counter-
ions at a pH below 5 or 6. Ordinarily, when the pH of such
~0 a sol is raised to 7 or 8 or higher, the particles coagu-
late or gel.
To stabilize such sols at pH above 7, those
skilled in the art are familiar with tèchniques for re-
~ersing the charge on the particles by adding an excess of
~ultivalent ions that are strongly adsorbed on the oxide
particles at low pll and put a negative charge on the
- particles. Then the pH can be raised to the alkaline side
with ammonia or sodium hydroxidc. Citric or tartaric acid
is often uscd ~or this purposc. Enough of said acid is
added, to thc o~idc sol which is bclow pll 6, to furnisl
- 23 -
~J23~3~4
one or two acid moleculcs per square nanometer of colloid
~xide surface, before the pl~ is raised to the desired range.
In some instances, the charge of a positive oxide sol can
be reversed by adding it in a thin stream at a point of in-
tense agitation in a solution of sodium polym~taphosphate
or sodium silicate. When the aluminosilicate deposition of
this invention begins,it can displace the organic cations
from the oxide particles, but generally not polymetaphos-
phat~, which remains in the product. For this reason, the
phosphate is less preferred.
Where very small particles are required in the
heel, e.g., an aluminosilicate sol of particles less than
5 or 10 nanometers in diameter, it is preferable to pre-
pare the particles as a heel just before the aluminosili-
cate is deposited. Where very small silica particles are
wanted as nuclei, sodium silicate is added to water to
obtain a silica concentration of 0.5 to 1.0% and the pH
is adjusted to 8 to 10.5 with ion exchange resin at a
temperature of 30 to 50C. Initially, colloidal particles
as small as 1 nanometer are formed an~ these grow in size
spontaneously while diminishillg in numbers. When the
desired size is reached, the temperature is raised to at
least 50~C and deposition of the aluminosilicate according
to the process of the invention is begun.
Similarly, small particles of sodium aluminosili-
cate can be attained in the heel by adding to watcr sodium
silicate and sodium aluminate solutions to acllicve the de--
sired ratio of Si:~l and thc combined conccntration of
SiO2 plus ~12O3 of 0.2 to 0.5~. The pll is adjusted to ~ to
12, and the solution warmed to 50~C bcfor~ the dcpositio
- 24 -
38~
of aluminosilicate according to the process o~ the in-
vention is begun.
Initially in sueh heel solutions, polym~rization
of the oxide occurs with initial equilibrium formation of
elusters containing various numbers of molecules. Clusters
that are smaller than a certain critieal size have a ten-
dency to redissolve, while elusters that are larger than
this critical si~e will have a tendency to grow. Such
eritical size clusters of moleeules are referred to in the
art and herein as nuclei. In general, the term nuelei im-
plies elusters of molecules or very small eolloidal partieles
which are not in equilibrium with the dispersing medium and
have a strong tendeney to grow into larger particles.
Thus to ma~e the smallest aluminosilicate particles
the heel in the process of the invention can consist of
wat~r dispersions of nuclei of silica or aluminosilicate,
said nuclei being ~reshly formed clusters of small particles
having a tendency to grow and form larger particles. For
some~hat larger particl~s, the heel can eonsist of a water
dispersion of silica or aluminosilicate particles rather than
nuelci, in equilibrium with the ~ater.
For very small nuclei of refractory oxide around
2 nanometers in diameter, certain basic salts may be used
providinc3 they are suitably converted to stable negativel~
eharged particles. Thus, basie aluminum ehloride having
the cmpirical formula ~12(O~I)5Cl actually consists of
hydrated alumina units eontaining about 13 aluminum atoms
bearinc~ positivc eharges, surroundcd by ehloride ions in
solution, as discloscd by Gcorg Johansson, ~cta Chonlica
Scandinavica, Volume 14, pa(~c 771, 19G0. By addincJ a dilu~e
- 25
.23i314
.
s~lu-tion of the basic aluminum chloride, containin~, ~or
ex~mple, 0.3% by weight of equivalent A1203, to a very
strongly agitated solution of ammonium citrate so as to
have present at least one citrate ion per chloride ion, a
negativ~ly charged complex is obtained. To this a dilute
s~d-iùm silicate solution can then be added in an amount
such that there are several silicate ions present per alumi-
~- ae-om. When the sodium is removed by exchange with a
~tion ex-change resin in ammonium form and the solution
he~ted to 50C, there is obtained a sol of silica coated
~lumina nuclei on which aluminosilicate may then be de-
posited by the process of this invention until a particle
~i~e o 3 or 4 nanometers has been attained suitable for
mak:ing a powder having very fine uniform pores.
C~mmercially available ~quasols with particle
dl~metèrs from about 4 to 60 nanometers may be used as a
~eel i~ the process of the present invention. Silica
~quas-~ls are used as nuclei where the silica composition
~f th~ core is not déleterious to the properties, most
notably the thermal stability and the catalytic activity,
of the final product.
As a general statement about forming very small
particles of refractory oxides by hydrolysis of salts,
the process of nucleation is influenced by several factors,
especially those.that affect the solubility of the nùcléi.
The rate of formation of nuclei of a solid in water dèpends
on the degree of supersaturation. The less soluble the
su~stance formed, the hi~her will be the supcrsaturation,
~nd thus there will be present more and smaller iluclei.
Sir.ce solubility in ~vater increases with tempcratul-e, the
- 26 -
~L23~
~upe~saturation levcl decrcascs with incxeasing temperature.
Thus, the lower the temperature, the more nuclei present
ahd ~he smaller the nuclei for a given heel and the higher
the temperature the fewer nuclei and the larger the nuclei
for a given heel.
Generally, the range of temperature at which sil-
ica nuclei àre formed by deionization of sodium silicate
~s ~0 to ioooC. In this case silica nuclei of about 1 to
6 naiiometers in diameter are obtained. In the case of
~10 a-iuminosilicate sols the nuclei are formed at temperatures
between 3bo and about 50C. At higher temperatures there
may be some forma~ion of coarse precipitates instead of
aiscrete particies. However, although it is necessary in
the casê of the aluminosilicate to effect the deionization
o the added soluble silicate and soluble aluminate at a
~elatively low temperature to obtain very small but discre.e
aiuminosilicate nuclei, once a sufficiently large number
of nuciei of said aluminosilicate have been formed, the
tem`peratùre can be increased to as much as 10~C to accel-
~0 érate the build-up or growth of the particles,
~ he desired final particle size of the sol is
de`penàent on the initial particle size nuclei o~ the heel
ahd the amount of aluminosilicate to bc deposited. When
the final powder pore size desired requires small final
`pa`rticles of alùminosilicate, the initial hcel should con-
tain smaller particles. When small particles are used in
~he initial heel and the reactants build-up the nuclei
to a lar~er particlc, the corc that constitutcs the ori~lnal
nuclei has a ne~ iblc efcct on thc catalytically active
surfacc of the ~inal par1:ic]cs or powder. Thus, whcrc thc
- 27 -
Z38~L~
nuclei are silica and the build-up or deposit constitutes a
substantial part of the final particle, the product i5 essen-
tially a homogeneous aluminosilicate particle. In such
cases the volume of original silica of the nuclei is ne~li-
gible compared to the volume of the final particle and this
small amount of silica has very little effect on the pro-
perties of the final aluminosilicate solution.
When the nuclei are larger, relatively smaller
~mounts of aluminosilicate may be built up around the
nuclei, depending on the finally desired particle size and
pore diameter. When these larger nuclei are alumina, some
overall physical properties of the final product will be
somewhat different from those where the ~articles are
homogeneous aluminosilicate, for example, density, refractive
index and thermal properties will be different. However,
the surface properties will be the same.
Particle size and concentration of the nuclei in
- the heel have an effect on the desired or practical build-up
ratio. Build-up ratio (BR) is the ratio between the total
weight of solids in the product sol and the total weight
of the nuclei in the heel, assuming all the added ~lumina
and silica has been deposited upon the nuclei.
It is possible to calculate the build-up ratio
on the basis of rclative volumes, assumin~ densities for
the h~el nuclei and the deposited aluminosilicate. When
the ratio is calculatcd as total volume of solids in the
final sol particles divided by the total volume of solids
in the hccl sol, it is possibl~ to calculatc the average
particle c1iamcter in thc fin~ sol from thc bui]d-up ratio
3~ and the particlc sizc of thc hcel sol.
- 28 -
38~
As an example of build-up ratio by weight, if we
start with a one-liter heel with a concentration of
1 g/100 ml of aluminosilicate (total mass of nuclei 10 g)
and during the process we add a total of one liter of
sodium silicate solution with a concentration of 20 g
SiO2/100 ml and one liter of sodium/~luminate solution with
a concentration of 5 g NaAlO2/100 ml (total mass of
SiO2 NaAlO2 250 g), the result is about 3 liters of a sol
containing 260 g of solids. The build-up ration in this
case will be 260/10, or 26.
Assuming that all the silica and aluminate accrete
or are deposited uniformly on the aluminosilicate nuclei,
there will be a relationship between the build-up ratio
MF/Mi (where MF is the mass of solids in the final product
and Mi is the mass of particles or nuclei initially) and
the cube of the ratio between the particle di~meter of the
product DF and the nuclei diameter Di:
BR = F =( DF )
When the layers of new material formed on the nuclei are
not porous to liquid nitrogen, the relationship between
build-up ratio and specific surface area of the product
(SF) and the nuclei (Si) as measured by nitrogen adsorption,
will be
MF ~Si~3
Mi ~ SF J
However, it is pointed out that these formulac apply only
when thc dcnsity of the dcpositcd aluMinosilicatc is the
samc as that of the nuclci particles. Where thc dcllsities
are different, suitable corrcctions must be made.
- 2'~ -
~ Z3~
Thus having selectcd the particle size or speci~ic
~urface area of the final aluminosilicate sol, the formulae
relating build-up ratio to particle sizes or surface areas
and total masses or concentrations can be used to select
the particle size and concentration of the required heel.
The nuclei or particles in the heel are caused to
grow into a uniform particle size by the simultaneous but
separate addition of a silica sol or a sodium or potassium
. -silicate and sodium or potassium aluminate into a heel in
the presence of a cationic exchange resin in the hydrogen
- or ammonium form for pH contro~. The nuclei or particles
in the heel grow by an accretion process. The cationic
exchange resin in the hydrogen or ammonium form may be
added to the heel prior to the simultaneous but separate
addition of the silica sol or the silicate and aluminate
solutions, or it may be added at the time the addition
starts or shortly thereafter. Thereafter said resin is
added to maintain a constant pH + 0.2.
It is required that the rate o~ addition of silica
or silicate and aluminate is not permitted to reach that
point where the silicate and aluminate will react in solu-
tion and form new particles or a precipitate. The aluminate
and silicate must bc hydrolyzed and deposited as completely
as possible on the nuclei. The build-up or growth of the
nuclei in the hee,l is thus limited by the rate that will
permit the moleculcs of silicate and aluminate to deposit
on said nuclei. Generally, the silicate and aluminate must
not be add~d at a ratc greater than that by W]liCIl 10 g of
SiO2 per 1000 square meters of surfacc area is ac~ded to thc
system pcr hour. Gcnerally, thc addition of rc3ct~nts
- 30 -
~1~.238~4
will be such that 5 to 10 g of SiO2 arc added per 1000
square meters of surface area available in the system per
hour. Rates of addition above the maximum specified
above are undesirable because they will permit new nuclei
to form which will result in nonuniform particle slze in
the final sol.
The procedure of the present invention involves
adding the solutions supplyin~ the silica and alumina simul-
taneously, but separately to the heel sol in which the
particles are growing. Premixing the reactants results in
the formation of a precipitate and therefore must be
avoided. The heel is vigorously stirred during the deposi-
tion process to permit almost constant dispersion of the
reactant solutions. The use o~ very thin feed tubes or
jets for ihe introduction of reactants assists in the
dispersion of the reactants. Generally, the discharge of
the feed tubes is inside the liquid of the heel immediately
above the agitation blades. The heel sol may be circulated
from a reaction vessel through a centrifugal pump, through
a mass of weak base ion exchange resin in ammonium form,
and then bac~ to the vessel while the feed solution is fed
in at à point close to the pump impeller.
The pH' of the heel must be controlled to remove
the sodium or potassium of the reactants and control the
solubility of the particles. The pll is held constant within
+ 0.2 units, preferably + 0.1 at a value betwc~n 9 and 12,
preferably 10 to 10.5. The addition of the reactants at
a lowcr pll such as 8 would rcsult in the formation of
additional nuclci, and lcss complet~ dcposition of thc
aluminosilicate on thc nuclci. This is bccause thc maximum
ratc at which dcposition call occur is lowcr at lower pll.
~ Z3~314
Generally, the temperature during particle ~rowth
is from 50 to 100~C. Particle growth below 50C may be
achieved but relatively slowly. The higher the temperature,
the faster the rate of growth, but in any case, the speci-
fied rate of addition of reactants should not be exceedcd.
Temperatures above 100C may also be used provided care is
taken to avoid evaporation by using greater than atmos-
pheric pressure. However, at sufficiently high temperature
- under pressure certain compositions of aluminosilicate,
particularly sodium aluminosilicate with a Si:Al ratio of
around 1:1, tends to crystallize and the desired amorphous
layer on the nuclei is not deposited. Instead crystalline
nuclei tend to form in suspension. The formation of such
crystalline æeolite compositions should be avoided. On
the other hand, aluminosilicate compositions with Si:Al
ratios of 10:1 or 19:1 are less likely to crystallize and
temperatures of up to 150C might be used if an economic
advantage resulted.
The feed solution of sodium or potassium silicate
may contain from 1 to 36R by t~ei~ht of silica, preferably
15 to 25~ silica. The most prefer-ed concentration is 20~
silica. Generally a feed solution of sodium silicate with
a ratio of SiO2:~a2O of from 2.6 to 3.8 is preferred, while
about 3.3 is most prefcrred.
The soclium or potassium aluminate solutions used
in this invention may be purchased commercially, or thcy
may be preparcd from commcrcially available solid sodium
or potassium aluminate. In prcparin~ a solution o the
aluminatc, it is sometimcs dcsirablc to add cxecss al~ali,
e.~., NaOII or ~OII or LiOII, in.ordcr to dccrcasc thc cxtellt
3~ 4
of hydrolysis of the aluminate, but the amount should be
minimized so as to reduce the amount of ion exchange resin
that is needed.
Freshly prepared or commercially stabîlized solu-
tions free from precipitate should be used in any case.
The aluminosilicate surface that results from the
accretion of the sodium or potassium silicate and sodium or
potassium aluminate onto the nuclei must have a Si:~l mole
ratio of from 1:1 to 19:1. The concentrations and volumes
of the added silicate and aluminate solutions must be such
that they are ~Jithin the above final ratio. This often
places a restriction on the concentrations that can be used.
The aluminate solution may be as concentrated as 15~ by
weight aluminate, but at that concentration the addition
would have to be very slow to pre~ent local precipitation of
aluminosilicate. Generally, a solution containing 5%
aluminate is very convenient.
In the process of this invention the desixed con-
centrations of silicate and of aluminate being added must
be held constant, unless compensating changes in the flow
rate are made. Once the ratio of Si:Al desired is deter-
mined, and the rate of silicate addition is selected, the
correspondin~ aluminate solution feed is set. The maximum
addition rate of 10 g of SiO2 per 1000 square meters of
surface area of the solids in the mixture per hour will thus
limit the feed rate of both reactants.
Solllble electrolytes, such as sodium chloride,
lithium carbonate or potassiUnl nitrate, tend to coa~ulate
the aluminosilicatc particles. For this reason the hecl
and fecd solutions sl-ould be essentially ~ree OI extrancous
- 33 -
;3~J.~
electrolytes such as those indicated. Salts liberatlng
polyvalent catlons should specifically be avoided during
the build-up operation.
The build-up or growth is continued until the
desired particle size is reached. At this point, the
aluminosilicate particles contain sodium or potassium
cations.
The uniform particle size a~uasols of this in-
vention have ion-exehange properties. Although the parti-
cles have ion-exehange properties they are nonporous to
organie moleeules. This indleates that the Al in this
eomposition is in the 4-fold eoordination state as M A102
rather than in the 6-fold eoordination state as A12O3. Eaeh
aluminum in the 4-fold eoordination is aeeompanied by a
Na or X ion. For this reason, the maximum total exchange
eapaeity ean be ealeulated on the basis of the Si/Al mole
ratio.
The aetual exchange capacity for the various
metal ions that ean replaee Na or K in the aluminosilicate
a~uasol ean be measured by saturating the partieles in
the sol or powder with the speeifie ion, and either analyz-
ing the amount of metal in the sGlution after separating
the aluminosilicate solids or by removing the excess of
added salts and analyzing the solid phase for the specific
metal ion.
The aluminosilicate sol may be treated with
various ion exchange resins to remove the sodium or potas-
sium ions. In some cases with aluminosilicate of high Si:Al
ratio the resin in hydrogen ion form may be used, but the
ammonium form is preferred. Dowex* 50W-X8, an ion exchange
* denotes trade mark
- 34 -
,~,l
238~
resin, is a strong acid cation exchan~e resin o sulfon~tc~
polystyrene-divinyl bcnzene type and is commercially avail-
able from Dow Chemical Co. The sodium or potassium alumino-
silicate solution is converted to the ammonium form by
passing the solution through an ion exchan~e column packed
with wet Dowex 50W-X8 previously converted to the ammonium
form.
The aluminosilicate solution may be adjusted in
concentration by dilution with water or concentration to
the range of 5 to 40% by weight solids content before ion
exchanging.
When the aquasols are converted from the sodium
or potassium form to the ammonium form the sols are less
stable. For example, an aquasol of 3.7 nanometers particle
size with a concentration of 8 weight percent at pH 7 is
stable in the Na form for at least 9 months at room
temperature (R.T.) but the NH4 form of the same sol forms
a gel after about one month.
It is important to notice that since the aquasols
are only precursors to the powder compositions, it is
not required that they are stable for lon~er than the period
of elapsed time between sol preparation and drying.
In ~eneral, the sols of the present invention
before drying are at least temporarily stable at a pll in
the range from 4 to 12. The lower pl~ limit depends on the
Si/~l ratio: the higher the Si/~l ratio, the lower the pI~
limit of chcmical stability or tlle sol. For example, a
sol of Si/~l ratio of 1/1, when freshly made, is in equili-
brium w~th 200 mg/l o~ ~1 expressed as A].O2 in thc solution
at pll 4 and R.T., but a~tcr 18 l~ours the ~12 in the solu-
~ion increascs to morc thall 300 m~/l. On the othcr hand,
- 35
~.Z38~
a sol of Si/Al ratio of 6/1 when freshly made is in equili-
brium with 15 mg/l of Al in the solution expressed as ~12
at pH 4 and R.T. and the equilibrium is maintained ~or at
least 18 hours.
The aluminosilicate sols of this invention are
made up of uniform particles of aluminosilicate having a
uniformity such that the maximum standard deviation is
0.37d where d is the weight average particle diameter.
The aforesaid sols are especially useful when the maximum
standard deviation is 0.30d. The uniformity of the particles
in the sols of this invention can also be expressed in a
form based on the number average of particles rather than
weight average. The uniformity based on particle number
average is a maximum standard deviation of 0.43d where d is
the number average particle diameter.
The aluminosilicate sols of this invention may be
modified with various metals defined herein by replacing
some of the a~monium ions with metallic ions. The metal
desired in the final powder may be introduced by replacing
the ammonium ion in the aluminosilicate sol by addition of
a soluble salt of the metal. In this case a salt is selected
with an anion such as nitrate or formate that can be elimin-
ated by heating the powder at relatively low temperature,
or one that does not interfere with the use of the powder
as ~ catalyst.
The metal desired in the final powder can also be
introduced in the aluminosilicate sol in some cases by re-
placing the replaceable ammonium in the aluminosilicate sol
using an ion exchange resin containing the desired metal
ion prior to the drying step. The ion e~change step can
be made by either the batch method or the column method.
- 36 -
~L f Z~
~ Iydrogen can also be substituted for the replace-
able ions by heating the ammonium aluminosilicate in the
powder form to eliminate ammonia.
Some dilute sols with Si:Al ratios of 10:1 or
more having sodium or potassium ions may be exchanged
directly with hydrogen ions, providing the particles are
not allowed to aggrec3ate before drying.
- Metal cations that may replace the sodium,
potassium or ammonium in the aluminosilicate solution be-
fore drying may be Cs, Li, Rb,. Mg, Ca, Sr, Ba, rare earth
metals, transition metals, electron donor metals and
Bi, Sn, Cd, and Sb.
What is meant by transition metals is Sc, Ti, V,
Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Mo, Tc, Rn, Rh, Pd, Hf, Ta,
W, Re, ~s, Ir and Pt.
What is meant by rare earth metals is La, Ce, Pr,
Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.
What is meant by electron donor metals is Cu, Ag
and Au.
The preferred cations to replace the sodium or
potassium of the aluminosilicate are NH4, H, Ca, Mg, Mn, Ru,
Rh, Pd, La, W, Re, Ir, Pt, Ce and mixed rare earth metals.
In all cases where metals are exchanged in the
sol, conditions must be such as to avoid any aggregation or
gelling of the sol particles.
~eplaceable ions can al:,o be replaced in the po~7der
after drying by adding a metal soluble salt to a suspension
of the powder in water and drying or separating the powder
by filtration or centrifugation, washing and drying.
The final concentration of the aluminosilicate
- 37 -
.~^3.Z3~3~4
sol is limited by the finAl particle size of the sol.
This is because the maximum concentration at which a sol
is still stable with respect to gelation is a function
of its particle size. Larger particle size sols can be
concentrated to stable sols of higher concentrations than
smaller particle size sols.
Table 1 illustrates the maximum stable concen-
tration limits of aluminosilicate sol where the particles
consist entirely of aluminosilicate:
- 10 Table 1
Particle Dia.Max. Conc. Alumino-
(d) nanometersilicate, % by weight
12
53
The maximum stable concentration, cm of inter-
mediate particle sizes appears to follow the equation
Cm = 5.1d'56
whcre d is the diameter of the particles.
The heel concentration likewise is limited by the
particle size of th~ sol but may vary generally from 0.2
to 55~ by weight of the aluminosilicate or silica. The
uppper concentration level depends on the composition and
particle diameter of the heel particles. Discrete silica
particles are in general less solvated than aluminosilicate
particles Silica sols are stable toward gelation or
flocculation at higher concentration than corresponding
~lumillosilicAte sols of the same particle size. Thus, the
3Q uppcr limit of heel concentration is higher for silica than
- 38 -
.Z~
for aluminosilicate. However, as soon as deposition o~
aluminosilicate has started the sol of silica or other re-
fractory oxide takes on the colloid characteristics o~ an
aluminosilicate sol.
Low concentrations of heel sol are generally em-
ployed when the heel particles are very small or the build-up
ratio is to be high. Concentrated heel sols are used only
when the heel particles are large and only a low or moderate
build-up ratio is anticipated. In any case, it is advan-
tageous to start with as conccntrated a heel sol as ispractical so as to provide as much surface as possihlc ~or
deposition of aluminosilicate and thus permit the coating
process to operate at ma~imum allowable speed.
The particle size and particle size distribution
of the colloidal particles of the aquasol can be determined
by photomicroscopic counting techniques involving micro-
graphs obtained with the electron microscope by transmission
or scanning electron micrography. The electron micrographs
show that the ultimate particles of the sol are essentially
discrete or unag~regated. The micrograph is used to
- 39 -
3~
determine the particle size and particle size distribution
of the colloidal pa~ticles of the aquasol by employing a
photomicroscopic counting technique utilizing a Zeiss
Particle Size Analyzer TGZ3 to assist in the counting. The
technique is described in the literature as, for example,
"Semiautomatic Particle Size Analysis", Ceramic Age,
December, 1967, and "Applications of Pho~omicroscopic
Technique to the Particle Analysis of a Sample from a
Nuclear Cratering Cloud", by G. F. Rynders, IMS Proceedings,
313 (1969).
The following table illustrates results of particle
size distribution determinations of homogeneous aluminosili-
cate aquasols of this invention obtained by electron micro-
graph counting techniques.~
- 40 -
1~ ~3l3~
Z
OOOOOO
-- 41 -
~.Z3~1~
~ he sols prcpared by the proc~ss of this invcntion
m~y contain 3 to 70~ solids depending on th~ir composition
and particle size~ The sols are stable, that is th~ir vis-
cosity does not increase substantially when stor~d at room
temperature (20 to 35C) over a ten-month period.
The amorphous aluminosilicate sols having uniform
particle sizes, prepared by the process of this invention,
are dried to achieve a powdered amorphous aluminosilicate
with uniform pore si2e dis~ribution. In order to attain
10 the uniform pore si~e, the particles must pack themselves
uniformly into a porous a~regate sa that the final mass
or aggregate is not bridged by particles leaving lar~er
voids internally.
The ~ols o ~his invention consisting of uni~orm-
sized particles have the cha~acteri~tic tha~ as water is
removed and the percent solid in~xeases, the viscosity does
~ot change drastically until a certain rather na~row concen-
tratian ran~e is reached, a~t~r ~hich ~urther increase in
~oncentratian causes a sharp increasc in the viscosity o
the soi~ ~his paL-ticular concentra~ion ~ange depends to a
la~ge ~xt~nt an ~he ~l~imate pa~icle si2e of the sol~ I~
the so~ is concentrated up to this more o~ less critical
cohcehtr~tion, ~, so ~h-at it becomes viscous, it becomes
unstable i~ ~hc sénse ~hat the ~iscosity of tlle sol will
then spontaneously incr~ase with time ~ven thouqh no more
- water is remo~ed. I~ this spontaneous increase in vis~osity
is pcrmitted to occurr the sol is convert~d to a solid mass
of hydrated ~el containin~ all the ~ater ~hat was present
in the so]. ~hcn a gel of ~his typc is th~ ro~cn up and
furthcr dried to a powder, it is folllld that t11e pore dia-
mctcr in ~hc dricd ~cl is not uniorm.
- 42 -
~L~.Z3~314
On the other hand, if the sol is rapidly and con-
tinuously concentrated beyond W by further rapid removal of
water, the viscosity increases until the mass becomes rigid.
When this is further dried it is found the pores are uniform.
Thus, if the sol has been concentrated to some
point less than 1~, and then it is dried very rapidly as by
spray drying, the water is removed and the ultimate particles
move closely together to form a closely packed nnass, In
such ~ powder the pores between the particles are relatively
uniform. In order for this to occur the water must be re-
moved relatively quick1y so that the particles do not have
time to form the chain networks that occur during the gelling
process.
Accordingly, drying must be sufficiently rapid
that once the critical total solids concentration W is
reached, water is removed fast enough to prevent bridging
of the sol particles and consequently gelling. An example
of too slow water removal is where the sol was allowecl to
stand at elevated temperature in a humid atmosphere. How-
ever, it is usually most economical to dry usincJ processes
where the sol is fed in drops or thin streams of liquid or
~atomized" in a fine mist so that water is removed from the
sol particles in a matter of seconds. If, howevcr, freeze
drying techniques are used, the sublimation or water re-
moval can bc extremely slow but still no c3elling wil] occur.
However, other forms of drying will r~sult in gclling if
sufficiently slow.
Once tl-e sol has bcen prcparecl, it may bc neccs-
sary to further conccntratc it in order to minimizc the
amount of water that must bc rcmoved W11c1l it is dricd ro
- 43 -
~ 38~
the sol to a 9~1 powder. In some instances, this concen-
tratic)n may be so high that the sol is only tcmporarily
stable, as evidenced by the fact that the viscosity in-
creases with age due to the incipient formation of gel.
It is important that if the sol has to be conccn-
trated to the pc)int where experience shows that it is only
temporarily stable, the sol should be dried at once before
the viscosity has increased appreciably.
Examples of suitable drying processes include tray
dryers, sheeting dryers, rotary dryers, spray dryers,
through-circulation dryers, cylinder dryers, drum dryers,
screw conveyor dryers, agitated pan dryers, freeze dryers,
vacuum dryers, etc.
Adding alcohol or electrolytes to precipitate the
aluminosilic~te to separate by filtration or centrifugation
the solid particles from the bulk of the water and drying
the wet residue, will cause bridging of the particles,
forming a precipitate, a coagulum or a gel with nonuniform
pore size.
~he preferrcd drying method is spray drying. Spray
drying involves the "atomization" of the sol into a mist
made of ~inedrops which dry almost instantaneously in con- -
tact with hot air. Spray drying produces a regular hollow,
sph~roidal, porous aggrecJate with a uniform pore size dis-
tribution where the average pore diameter as measured by
nitrogcn adsorption-desorption techniques is roughly half
the diameter of the particles forminc3 the closely pac~cd,
porous agCJrcgate. The ~veragc diameter of the aggregates
~nd the agcJL-egate size distribution c~n be controllcd ~y
controlling the conditions of sprtly dL-ying. For examl~le,
- 44 -
:~L3.23~ 4
the type of atomizer used in spr~y dryin~ influences the
microspheroidal aggregate size distribution of the p~oduct.
Rotating discs produce more uniform aggregat~ size distri-
bution than pressure nozzles. In the case of two-fluid
pressure nozzles or pneumatic atomization, the lower the
concentration oE the aquasol fed into the spray dryer, the
higher the atomizing force (feed pressure in the spraying
nozzle), and feed rate, and the lower the inlet drying
t~ perature, the smaller the aggregate size.
When the sol is drum dried the aggregates tend
to be irregularly shaped and the product shows a very broad
aggregate size distribution. However, within the aggre-
gates, the original aluminosilicate particles are very
closely packed, and since they are spheroidal, the pores
that they create within the assembly have a very uniform
-size distribution and the average size is approximately
half the diameter of the uniformly sized particles con-
stituting the assembly.
The powders having pore diameters between 45 A
and 250 A with a uniformity such that at least 80% of the
pore volume is made up of pores of from 0.6D to 1.4D, where
D is the median pore diameter are also especially useful even
though they are not as uniform as the powder with 20A to
150 A pores.
To obtain such a close packing of particles and
therefore such a uniform pore size distribution, the aquasol
has to be dried without substantial gelling or coagulation.
When the particles are allowed to remain
- 45 -
~.Z3~314
unaggr~gatcd until most of the water between the partic~es
evaporates, the surface tension of the water film around
the particles, and especially in crevices around points o
contact between particles, creates a force equivalent to
compressing the assembly particles at high pressure. As
a consequence, each sol droplet forms an aggregate or more
of closely packed spherical particles. In this case, the
pores are fairly regular in shape throughout the aggregate,
and the size of the pores is very uniform.
The composition of this invention can be charac-
terized by their chemical analysis, X-ray analysis, speci-
fic surface area measurement, pore size and pore size dis-
tribution determination, appearance under the electron
microscope by transmission electron microscopy (TE~) and
scanning electron microscopy (SEM), aggregate size measure-
ment with Coulter counter, surface acidity measurement by
titration with adsorbed indicator in nonaqueous liquid
phase, ion exchange capacity, infrared analysis, differential
thermal analysis (DTA), thermogravimetric analysis (TGA)
and measurement of bulk density.
The chemical composition of the powders of this
invention can be determincd by analytical techniques con-
ventional in the art. Broadly, the powders comprise chemi-
cally combined silicon, aluminum, hydrogcn, oxygen and a
metal ion, and physically or chemically combined water.
Water associatcd with the aluminosilicate can be
analyzed by infrared, DTA and TG~ techniques conventional
in the art.
Watcr can be in thc form o~ ~hysically adsorbcd
1~2O,ci~cmisorbcd 1~2O and Oll structural groups. Chcmisorbcd
46 -
~.23~14
H2O includes water of hydration of Na iOIls and }I-bound
water on the surface of the particles. Physically adsorbcd
H2Q is released at atmospheric pressure at 100C and
chemisorbed ~12 between about 100 and 200C. Thcre is
more than one kind of 0~ structural group. Most Ol-~ groups
stay on the surlace of the aluminosilicate particles only
up to temperatures in the order of 600 to 700C.
Thermogravimetric analysis of said compositions
- in the Na form shows a gradual weight loss up to about 800C
and very little weight loss at higher temperatures. The
total weight loss of the spray dried powders is about 20%.
The structure of said compositions is shown to
be amorphous by X-ray diffraction analysis.
Specific surface area o. the powders of this in-
vention can be measured by the well known BET method in-
volving nitrogen adsorption ~Brunauer, S.; Etnmett, P. H.;
and Teller, E. J.; J. ~n. Chem. Soc. 60, 309 (1938)~ or by
a nitrogen adsorption method involving continuous-flow
equipment based on principles of gas phase chromatography
[Nelson, F. M., and Eggertsen, F. T., Anal. Chem., 30,
1387 (1958)]. Results of surface area measurements and
electron micrograph observation of the precursor sol and the
resultant powder can be combined and show that the powders
of this invention are constituted by closely packed dense
spherical or sph~roidal part~cles nonporous to nitrogen
with a uniform particle diameter in tl~e range of 3 to 90
nanometcrs forming porous aggregates with an aggregate size
lar~er than 1 micron.
. Spccific surfacc area of the powdcrs of this in-
velltion ran~3e bctwccll 30 an~ 750 m2jg~ Diamctcr of thc
- ~7 -
nonPorous spherical particles making up the aggregates can
be calculated by the formula:
Particle Diameter [nanometerJ =
6000
Specific Surface Area [m /g] x Density of the Particles [g/cc]
The density of the particles can be measured by
techniques well known in the art. The density varies wi-th
the chemical composi-tion (Si/Al ratio) of the particles.
The shape and si~e of the aggregates are estimated
from electron micrographs taken by TEM or SEM. For aggregates
smaller than 100 ~m, it is convenient to use micrographs made
by transmission electron microscopy or by scanning electron
microscopy.
Micrographs of powders of this invention made by
spray drying show hollow spheres ranging in diameter between
l and 200 microns. The aggregate size and aggregate size
distribution of these spheres is a function of the conditions
used for spray drying and whether a rotary disk or a spraying
nozzle is utilized. Aggregates obtained by drum drying are
irregular in shape and have an irregular size in the micron
range.
Aggregate size and aggregate size distribution can
also be obtained by a well known technique using the Coulter
counter ("Particle Size Measurement", T. Allen, 2nd Edition,
Chapter 13, Chapman and Hall, London, 1975). The Coulter
technique is a method of determining the number and size of
particles or aggregates by suspending the powder in an
electrolyte and causing the particles or aggregates to pass
through a small orifice on either side of which is immersed
an electrode. The changes in resistance as particles pass
-48-
~.Z38 3L~
through the orifice gcnerate volta~e pulses whose amplitudes
are proportional to the volumes of the particles. The
pulses are amplified, sizcd and countecl and from the derived
data the size distribution of the suspended phase may be
determined.
Pore volume, average and median pore diameter and
pore size distribution can be calculated using data on nitro-
gen adsorption and desorp.ion obtained on a Model 2100 D
Orr Surface-~rea Pore-Volume Analyzer. This instrument is
available from Micromeritics Instrument Corporation of
Norcross, Georgia.
; Pore volume distribution analysis can be made
based on the method proposed by B. F. Roberts, J. Colloid
and Interface Science 23, 266 ~1967). This method provides
a consistent method of pore volume distribution analysis
allowing to estimate the distribution of the pore volùme and
area of a porous material as a function of pore size. The
limitations are very few. The range of pore diameters is
O O
20 A < pore diameter < 600 A. Other limitations are common
to all procedures which use the capillary condensation
approach including the fact that the pore model may not be
representative of the pore structure.
Results are computed using a PORDIS-PORPTL com-
puter program which generates BET surface area calculation,
nitrogen dcsorption isotherm, plots of pore volume distri-
bution, surfacc area distribution usin~ the assumcd pore
model (cylindcrs) and plot of cumulativc perccnt of both
the po~e volume distributioll and surface arca distrib~ltion.
Spccific surface area is dctermincd by thc B~T mcthod.
~vcraqc cxpcrimental porc diam~ter is ca]culatcd by thc
- 49 -
~ 23~
ratio pore volume at saturation to the BET surface area.
A plot of the cumulative percent o the pore volume dis-
tribution permits median pore and maximum and minimum dia-
meter of pores constituting 90~ of the pore volume to be
determined.
The especially use-ful powders within the scope
of this invention as measured by the method mentioned above
O O
showed median pore diameters between 20 A and 150 A with
at least 90~ of the pores in the approximate range -~ 40%
of the median pore size. Thus said pores are of such
uniformity that at least 90% of the pore volume is made up
of pores that are from 0.6D to 1.4D in diameter, where D
is the median pore diameter.
The powders of this invention have a "tapped"
bulk density of at least 0.5 gram per cubic centimeter.
"Tapped" density is measured by placing a weighed quantity
of sample in a graduated cylinder, and tapping the cylinder
until the volume is essentially constant. If the bulk
density is less than about 0.2 g/cc, it will be found that
the powders are e~tremely difficult to compact uniformly,
and will give catalyst pellets or compacts having internal
strains and in which stratification of the solids will be
present.
When the bulk density of the powder as dried is
~oo low as it may be in the case of some dryin~ techniques,
the bul~ density can be increascd by pressiny the powdcr
at low prcssures into a compact and brea~ing up the compact
to scrccn it or to use it in thc form of small granulcs or
particles.
Thc amorphous aluminosilicatc powdcrs of t]liS
invcntion arc ef~ectivc catalysts. Thcir uniform porc
- 5~ ~
~.Z3~i4
opcnin(~s permit them to discriminate on the basis of size
and configuration o~ molecules in a system. For example,
the narrow pore size distribution of the powdcrs of this
invention enable them to be more effective catalysts in
petroleum rcfining and catalyst cracking processes by thelr
improved selectivity. The narrow pore size distribution of
the powder permits the selection of a pore size for the
catalytic operations ~ithout the accompanying of widely
varying selectivity based on wide pore size ranges. Thus,
the powders of this invention give an optimum catalyst
selectivity in cat cracking operations wherehy the desired
isomers are obtained through narrow control of the pore
slze .
The compositions of this invention are amorphous
aluminosilicates. Crystalline aluminosilicate zeolites are
known to possess among other properties catalytic activity.
However, crystalline aluminosilicate zeolites are so highly
active âS catalysts that, when used in the pure state, com-
mercial catalytic crac~ing units cannot easily control the
reaction involved to ~ive desirable rcsults. The present
trend in the petroleum industry with re~ard to such zeolites
favors the use of Y-type synthetic aujasite crystalline
zeolites of silica/alumina ratios of 4.5 to 5.5/1 because
they are thermally and hydrothermally more stable than X-type
synthetic faujasite crystalline zeolites of silica/alumina
râtios o~ 2.5/1.
The powders of this invention can be used together
with crystalline aluminosi]icate zeolites. The uniform
distribution of crystalline zcolitcs within said powders as
a matrix substalltially improvcs thc pcrformancc of the
- 51 -
~ 23~
zeolites in catalytic crackin~ by dilutin~ the active zco-
lite and modcrating its activity while taking advantagc of
the bcnefits of the powders of this invention The amor-
phous aluminosilicates of this invention are specially suited
for this purpose because (1) they provide a matrix cataly-
tically active itself (instead of inactive), (2) they pro-
vide access of reactants to the zeolite crystals through
pores of controlled size and controlled size distribution
. and therefore controlled selectivity, (3) they are stable
to the high temperature hydrothermal treatment received in
commercial re~enerators, and (4) the~ form zggre~ates or
grains hard enough to survive interparticle and reactox wall
collisions without excessive breakage or attrition. However,
the use of the amorphous aluminosilicates as a matrix and
co-catalyst is not limited to one type of crystalline
zeolite. The choice of crystalline zeolite to be incorpor-
ated in the amorphous aluminosilicate of this invention is
based on the type of reaction involved and the type of
reactor unit available.
Another advantagc of the amorphous aluminosilicates
as matrices or co-catalysts with crystalline zeolites is
that preferred ions, as for example the mixed rare earth ions
in the case of catalytic crackin~ catalysts, can be uniformly
and intimately distributed in the matrix by ion exchange
techniques described herein for the parent amorphous alum-
inosilicate aquasol or the powder o~tained by drying the
aguasol.
The crystalline aluminosilicate zeolitcs are well
known in the art and dcscril~cd in dctail, for exampl~, in
Donald t~. ~reck's book on "Zco.litc Molecular Sievcs", Wilcy-
Intcrscicllcc, ~cw York, 197~.
- 52 -
~: z38~
Compositions involvin~ known crystalline alumino-
silicate zeoli~s and the amorphous aluminosilicates of this
invention can be made by using the mixing, compoundin~, etc.,
techniques disclosed in the art to make zeolite-amorphous
aluminosilicate catalysts (see for example, "Preparation
and Performance of Zeolite Cracking Catalysts", by J. J.
Magee and J. J. Blazek, Chapter 11 of ACS Monograph 171,
"Zeolite Chemistry and Catalysis", edited by J. ~. Rabo, ACS,
W~sh. D.C. 1976) or by othèr techniques specially suited
to the characteristic properties of our compositions. For
example, one way of intimately and uniformly distributing
crystalline aluminosilicate zeolite crystals in the amorphous
aluminosilicate matrix is to disperse the zeolite crystals
of microscopic size in the amorphous aluminosilicate aqua-
sols of the present invention, followed by drying of the
aqueous dispersion in the manner described herein.
The amount of crystalline aluminosilicate zeolite
that is advanta~eously incorporated in the amorphous silicate
powders of this invention ~enerally is from 5 to 50~ by
wei~ht. Thus, catalyst crac~ing compositions can consist
of 5 to 50~ by weight (preferably 10 to 25~) of crystalline
aluminosilicate 7.eolites and 95 to 50% by weight (preferably
90 to 75~) of the amorphous aluminosilicates of this
invention.
The following examples further illustrate the
compositions of this invention and the metho~s for their
preparation. In the examples that followf all parts are
by wei~ht unless otherwise notcd.
EX~MrLE 1
This is an example of thc preparation of ~ hydrous
~.Z38~L~
amorphous aluminosilicate powder of the invention where a
heel of silica 501 is used to form the core of the particles
making up the powders.
A heel solution was prepared in a reactor vessel
fitted with stirrer paddles in the following manner: 2000
ml of water were heated to 50C and 20 ml of sodium sili-
cate JM* diluted to a concentration of 20 g SiO2/100 ml were
added. Sodium silicate JM is an aqueous solution of sodium
silicate with SiO2/Na2O weight ratio of 3.25 and a con-
centration of 29.6 weight percent silica (41.9 g SiO2/100 ml).Ten grams of cationic ion exchange resin, Amberlite* IRC-84-S,
in the H+ form were then added and the pH of the solution
dropped from 10.2 to 9. At this point a dilute sol
(0.2 g SiO2/100 ml) of extremely small silica particles is
formed. Amberlite IRC-84-S is a weak-acid carboxylic
methacrylate cation exchange resin available from Rohm
& Haas Company of Philadelphia, Pa. This resin has a
total exchange capacity of 3.5 meq/ml wet, an approximate
pK value of 5.3 with respect to sodium in a 1 molar solu-
tion, an apparent wet density of 0.75 g/cc, an effectiveparticle size of 0.38 to 0.46 mm and a pH range 4 to 14,
maximum operating temperature for this resin is about 120C.
To this heel two feed solutions were added simul-
taneously and separately with vigorous agitation of the
heel. One solution was an aqueous solution of sodium sili-
cate with aSiO2/Na2O weight ratio 3.25, with a silica
concentration of 20 g/100 ml and the other was an aqueous
solution of sodium aluminate, with a concentration of
NaA102 of 5 g/100 ml. The sodium aluminate solution was
prepared by dissolving 67.61 g of Nalco* 680 grade sodium
aluminate in enough 0.lN NaOH to make 1 liter of solution.
* denotes trade mark
- 54 -
,. ~
81'~
Nalco 680 is the Nalco Chemical Company, Chicago, Illinois,
trademark for a white granular sodium aluminate trihydrate.
Maximum solubility of Nalco 680 a-t 22C is 80 parts in 100
parts of water Nalco 680 has a Na2O/A12O3 molecular ratio
of 1.12 to 1, A1203 content is 46~, and Na2O cont~nt 31.0~.
This analysis corresponds to 73.95~ NaAlO2. The sodium
silicate solution was prepared by mixing 1351 g of JM grade
sodium silicate with enough tap water ~o make 2 liters of
solution. The two feed solutions were fed through capillary
tubes into the heel solution just above the stirrer paddles
at a rate of 4.3 ml/min for the silicate and 5.9 ml/min for
the aluminate. Throughout the run the pH of the heel was
kept constant at pH 9.1 + 0.2 units by periodically ~dding
- measured amounts of the IRC~84-S ion exchange resin and
temperature was kept constant at 50C ~ l~C. Measurement
of pH was done continuously at room temperature with ~
glass electrode by circulating part of the heel ~hrough
a cooler.
A total of 1265 ml of sodium silicate salu~ion,
1650 ml of sodium aluminate solution and 610 g of resin
were used. At the end of the addition, the product was
filtered first through cloth and then through fil~er paper
to separate the resin from tlle aquasol. The pH of the
product was 9Ø
The resultin~ product was 3.9 liters of a sta~le
sodium aluminosilicate sol having a pll of 8.9. Solids
concentration was det~rmined by evaporating a wei~hed
s~m~le to dryness and calcinin~ to ~linlinate 1l2O. The
solids concentration was 8.1 ~ p~r lnO ml. Ch~mical
~l~a]ysis of the res~lltill~ sol illdicatcd that it ~ontained
- 55
~.Z3~14
~.50 g SiO~/100 ml, 1.45 g ~1O2/100 ml, and 0.~7 g Na/100 ml.
Thus the resulting product was an aluminosilicate sol hav-
inq the approximate cmpirical formula of NaAlO2 3.75 SiO2 n
H2O. An electron micrograph of the sol sho~ed very small
particles in the order of 5 nanometers diameter or less.
To determine the d~gree of aggregation which is an
indication of the closeness to gelling, the percent hydrated
colioid solids or percent S value was calculated from a
. measurement of viscosity in an Ostwald pipette and found to
be 40. Calculation of percent S was made using the ~looney
equation as described in J. Colloid Sci. 6, 162 (1951).
The value of 40 indicates there is no extensive aggregation.
The sodium aluminosilicate sol was converted to
the ammonium form by passing it through an ion exchange
column pac~ed with wet ~owex 50~ 8 ion exchange resin in
the NH4 form. Dowex 50W-X8 is the trademark of the Dow
Chemical Co. for a strong-acid cation e~change resin of
the sulfonated polystyrene-divinylbenzene polymer type.
Dowcx 50W-X8 has a total exchange capacity of 1.7 meq/ml
wet resin. Mesh size of the wet resin is 20 to 50, density
is 50 to 53 lb/ft3 and moisture content as shipped by the
manufacturer in the H form is 53%. Effective pH range of
Dowex 50W-X8 is 0 to 14~ and the resin is stable up to
150C. When the sol was thus treated, NH4+ ions replaced
most of the Na+ i,ons attached to ~12 sites and chemical
analysis showed that only 0.017 g Na/100 ml (3Qo of the
original Na content) remained in the aquasol.
The ammonium aluminosilicate thus formed had a
pll of 9 and it was spray dricd in a Bowen Engineering f Inc.
No. l Ccramic Dryer usin~ a two-~luid nozzle typc 59-BS.
- 56 -
~Z3~1~
Operating conditions for spray drying were the following:
Feed Weight % solids: 8
Total feed: 2000 ml
Feed rate: 120-125 ml/min
Inlet temp.: 300-310C
Outlet temp.: 140-148C
Atomizing pressure: 20 psig
Powder samples were collected in the cyclone and
chamber collectors. Total product collected was 128 g for
80~ recovery on a wet basis.
Electron micrographs of the spray dried powder
showed that it was constituted by spheroidal aggregates
with an average diameter o about 15 microns.
Chemical analysis of the powder gave the follow-
ing Si/Al ratio and A12O3 content:
Si/Al ratio 3.75:1
A123 17~ by weight.
Surface area and pore volume, pore diameter and
pore size distribution analysis of the spray dried powder
were made hy a nitrogen absorption-desorption method using
a Micromeritics 2100-D apparatus. Micromeritics 2100-D
is the trademark o Micromeritics Instrument Corporation
of Norcross, Georgia, for an Orr Surface-Area Pore-Volume
Analyzer.
Results were obtained as follows:
Specific Surface Area 590 m2/g
Experiment~l average pore 22 A
diametcr
Pore volumc 0.330 ml/g
Pore volumc distribution analysis was maclc bascd
on the B. F. ~o~erts met:]lod [J. Colloid and Intcr~ace
- 57 -
~L~.Z3~
Science 23, 2G6 (1967)] and thc rcsults computed a~d plottcd
using the PO~DIS-PORTI computer program.
The arithmetic probability plot of the pore dia~
mete~ versus pore volume data computed by the PORDIS program
~howed a median pore diameter of 28 ~. Ninety percent of
the volume of the pores w~s constituted of pores ranging in
diameter from the smallest measurable by the method (20 A)
- up to 39.5 A (416 above the median pore diameter). Seventy
percent of the volume of the pores was constituted of
pores ranging in diameter from 20 A, the smallest measurable
by the method, up to 32.5 A (16% above the median pore
diameter).
EXAMPLE 2
The usefulness of the product of this invention in
catalyst cracking of petroleum is illustrated by this example.
Using the procedures well kno~m in the art, 200
parts of the dried product obtained above is intimately
mixed with 800 parts of an acid-activated halloysite clay,
blending in sufficient water to produce a thin paste. The
paste is prcpared to the consistency required for extrusion
and is converted by extrusion to 1/8' x 1/8'l cylinders.
It should he noted that if a more abrasion resistant mater-
ial is requircd, the product can be pilled on a typical
phaL~maceutical pil]in~ machine to obtain harder and much
stronger material than th~t obtained by ~xtrusion.
After formin~ into the cylinders, the catalyst is
impre~nated with 0.5~ Pd ~y ion cxchange from an aqueous
solution o~ palladium tetraaminc chloride. Thc dri~d cata-
lyst is then rcduccd and char~ed to a typical small scale
hydrocracXill~ test unit whcre thc followin~ conditions per
taincd an~ ~csults o~taillcd.
- 58 -
~.Z3~
Chargc: Catalyt.ically crackcd gas oll
Tem~erature ,650~F
Pressure, psi~ 1,600
Liquid space velocity 2.50
H2/oil ratio scf/barrel 8000 -
,~ Product; Jet Fuel
Wei~ht percent based on
- feed .65.2
Specific gravity 0.802
Sulfur contcnt ppm 950.0
Freezing point _-76F
H2 consumption scf/bbl 2?50,0
EXAMPLE 3
ThiSwas an example of the preparation of a hydrous
amorphous aluminosilicate powder of the invention where a
heel of silica sol prepared in situ was used in the apparatus
described in Example 1 to form the core of ~he par.ticles of
this invention.
A 1% silica sol heel was prepared in situ at 70C
and pH of 9 by diluting 160 ml o 20R SiO2 sodlum silicate
JM (SiO2/Na2O weight ratio 3.25) t~ a total ~olume of 3000
ml with hot tap water to ma~e 3 litcrs of 1. 06o SiO2 heel
(32 g SiO2 in 3000 ml of solution), The he.el was heated to
70~C and then deionized to pH 9 ~ 0,1 ,with 80 g of ion
exchange resin ~mberlite IRC-84-S. ,A .sample of .the solution
was extracted at this point to measure speciflc surface arca
of the silica thus formed. Spccific surface area of the
silica as measured by the titration method o G. W. Sears
ih ~nal. Chcm. 2~, 19~1 (1961) w~s 675 m2/g. ~ssumin~ that
the silica is ;.n the orm of spherical particles o~ amor-
phous SiO2 of dcnsity 2.2 ~/cc t~lC avcra~c partic}.e di.amc~cr
- 59 -
of the silica calculated on the basis of the specific surface
area value obtained is 4 nanometers. Feed solutions were
added in the manner explained in Example 1 to build-up with
sodium silicate and sodium aluminate, each at a rate of
12 ml/min while simultaneously heating the heel to 100C.
Heating from 70C to 100C took about 30 minutes. The two
feed solutions of Example 1, aqueous sodium silicate solu-
tion 20 g SiO2/lO0 ml and aqueous sodium aluminate solution
5 g NaA102/100 ml were used. In 10 minutes the pH of the
heel rose to 10.3 due to the alkalinity of the feed solu-
tions being added. From this point on the heel was kept
at 10.4 + 0.1 by periodic additions of IRC-84-S resin.
A total of 3958 ml of sodium silicate solution,
3950 ml of sodium aluminate solution and 1440 g of resin
were used. At the end of the addition the hot colloidal
solution obtained was filtered first through cloth and
then through filter paper to separate the ion exchange resin
from the aquasol.
The resulting product was 9050 ml of a stable
20 sodium aluminosilicate sol of pH 10.7 containing 10.72 g/lO0
ml solution. Solids concentration was determined as disclosed
in Example l. Chemical analysis of the resulting sol indi-
cated that it contained 10.4 g SiO2/100 ml, 1.44 g
A102/100 ml and 0.854 g ~a/100 ml. Thus the resulting product
was an aluminosilicate sol having the empirical formula
NaA102.7SiO2.n~2O. The specific surface area of the sol
was determined after the sol was drled by measuring the sur-
face area by nitrogen adsorption using the flow method.
5pecific surface area thus measured was 135 m2/g.
-60-
~ ~,
.
3~
An e]ectrOn micrograph of the sol showed discrete
spheres of uniform diameter. Weight average diameter was
18 nanometers and number average diameter was 16 nanometers.
The standard deviation in both cases was 3 nanometers.
The sol was converted to the ammonium form by
ion exchange in the manner described in Example 1.
The ammonium aluminosilicate thus formed was dried
in vacuum in a Hoffman* drum dryer at 100C. A Buflovak*
laboratory size vacuum double drum dryer manufactured by
the Buffalo Foundry & Machine Co. was used. It had two
- 18x18 Type 304 stainless steel drums, 6" diameter x 8" face,
designed for 150C steam or 100C water. The casing was
designed for full vacuum and provided with doors for access
into the drums. Drum spacing was adjustable from the out-
side shell. The sol was allowed to drip into the cavity
formed by the two hot rotating metal cylinders. The cylin-
ders were under vacuum and heated internally with steam at
100C, therefore a very fast rate of evaporation was
achieved. The dried material was scraped with a Type 410
hardened chrome steel cutting knife. Drying conditions were
as follows:
Steam Temperature 100-103C
Vacuum 8-15 mm
Drum Speed 7 rpm
The drum dried powder was analyzed for specific
surface area, pore volume, pore diameter and pore size
distribution as in Example 1. The resul~s obtained were as
follows:
Specific surface area 250 m2/g
Experimental average O
pore diameter 40 A
Pore volume 0.256 ml/g
* denotes trade mark
- 61 -
.238~
Th~ data showed a median pore diameter of ~3
The upper (52.1 ~) and lower (27.9 A) limits for 90~ of
th~ pore volume were within the medi.an pore diameter.
Chemical analysis of the powder.-showed that Si/Al
ratio was 3~75 and A1203 content 18~ by weight.
E~lPLE ~
The usefulness of the product of.the:.~'nvention
for Fluid Catalytic Cracking Operations (FCC)-coùld be
. .illustrated by the example~
Using the procedures well known:.in-.the~~.rt, 200
parts of the dried product obtained above is:intimatèly
mixed with 800 parts of an acid-activated halloysite:'clay,
blending in sufficient water to produce a:thin pSste. ~'The
paste i5 prepared to the consistency required'for'spray
drying and then the spray drying operation ~s per~o-rmed,
and a microspheroidal product is ~btained.
The catalyst thus obtained is-evàluated:i'n a
typical bench scale fluid catalytic cracking~con~erter
equipped so that the catalyst can be .tr.eate`d be'fore`:t'e-s`t
with steam at 1100F and 20 psig for 10.hours. ~Ther'eafter,
the fluidized catalyst is treated with:H2~ 'or-2:h'ours-also
at 1100F but at only 10 psig.
A feed of Lybian gas oil of '6'50 to 1120F boil'ing
range is processed at temperatures of 880 ~o :1020F-to
produce the following products at the low, mi~-point 'and
top of the reactor tempexature ranges.
- 62
23~3~4
~r
~J ~O O ~ ~- ~ O O
o
a~
a~ u) o ~3
. ~ o ~r ~r o u~ ~D CO
'' a ~r
.
~I o
o rl
U~ ~ ~ ~ ~ ~ ~1 0. 0
ta-,~
~ ~ ~ ~ CO CD ~ ~I r~
.C o
.
~ ~ C -C
~ U V
~ U ~ .
~ ~ ~ Z O O
0,~ u) o o o m ~
h ,, ~ h h u~ I ~ m c~ ~) o
Pl ~ p, P, H æ m a ~ ;c o
~ 63 --
238~4
The eatalyst can be shown to be equally directive
with other feed types and other operating conditions. The
eatalyst ean be used without the clay matrix or it can be
mixed with other clays or binders as economically pref~r-
able. The proportion of clay to catalyst can be varied also
to achieve the optimum.
The liquid space velocity can be varied from th~
2.0 employed above to as low as 0.5 or as high as 6.5 with
. appropriate modifications in the operating temperature cind
eonditions.
The used eatalyst becomes deaetivated by coke
(earbon) deposition, but it is readily regenerable by
eontrolled oxidation of the deposit with a controlled at-
mosphere of low percentages of oxygen in steam or in
nitrogen. Beeause of the uniform pores of the produet of
the invention, regeneration is more uniformly and completely
possible. Consequently the catalyst is regenerated essen-
tially to its original selectivity and activity.
Further modifications of the eatalyst may be
aeeomplished by utilizing the ion exehange properties of
the product of the invention. Manganese, magnesium, rare
earths, especially lanthanum, and mixed rare earths are
introdueed into the strueture in place of alkali by ion
exehange.
The eatalyst of the invention ean be modified
(promoted) with one or more metals to derive a catalyst
useful for catalytie reformillcJ. The spray dried product
derived in the first paragrap}l of the deseription of the
prepar~tion of the FCC (fluid craekincJ catalyst) is further
treated by methods ~nown in the art so as to imprec~nate or
- 6~ -
3814
ion exchange the catalyst with platinum, for example, as
platinum a~line chloride. The treatment is effected in such
a way as to attain a 0.56 platinum content. l~he platinum-
containing catalyst is dried and reduced in a hydrogen
atmosphere at 200C (392~F). The reduced catalyst is then
coated with sufficient perrhenic acid solution to attain
a level of 0.3% Re in and on the catalyst. To reduce the
salts to the metallic form, the salt-impre~nated catalyst
is heated to 250 to 300C in a hydrogen flow. The metals
in and on th~ catalyst now comprise 0.5% Pt and 0.3% Re
in reduced form. The catalyst at this point is suitable
for use in the reforming operation and is evaluated in
equipment well known in the art as follows:
- 65 -
~.Z;383~
U~
O ~ O --1 N ~ 7 CC)
.,1
Q, ~r o ~ co ~ ~r o o
O ~ ~1 ~ r~ ~ ~ ~ 1`
o , ,~
o
O ''l
Ul
o -
`~O o ~ ~ ~ ~ ~t7 ~ 1~- ~
o ~ ~ ~ ~ a) aJ h U
u u a
ul ~ u u ~) u
U ~ ~ ~ ~ ~ 0
- O "
0 0 ~U 3 3 ~; 3
.Y rl O (d ~ N ~ ~ `7C.) U ~7 ~7
o .~ t) U U rl ~ C~ U
O O ~ h
u) m u ~ ~
,~ Ul
QJ Q~
a~ . h
-- 66 --
38~L~
The used catalyst can bc r~generated by rcmoval
of coke and the activity is restored to that of fresh cata-
lyst. The use and rc~cneration can bc repeated with the same
results of high activity and selectivity because of the
high thermal stability of the catalyst of the invention.
Space velocities that the catalyst will effectively permit
are in the range 0.5 to 4.6 liquid/vol cat/hour.
EX~MPLE 5
Thiswas an example of the preparation of a hydrous
-10 amorphous aluminosilicate powder of the invention where a
heel of sodium aluminosilicatewas used as the core for the
particles making up the powder.
A heel was made by diluting 1166 ml of the aquasol
product of Example 3 (specific surface area 135 m2/g) in the
Na form (pH 10.4) containing 10.7~% solids, with hot water
to complete a total volume of 3 l~ters. Thus the heel was
4.16~ solids and contained 125 g of sodium aluminosillcate.
The heel was heated t~ 100C and the pH was measured (pH 10).
When the heel reache~ 100C, the feed solutions of E~ample 1
were added each at a rate of 12 ml/min in the manner des-
cribed in Example 1 while keeping the temperature of the
heel at 100C + 1C and the pE~ at 10.4 + 0.1. The pH was
kept constant by periodically adding IRC-84-S ion exchange
resin. A total of 3980 ml of each of the feed solutions
and 1360 g of resin were used. The build-up ratio (BR) for
this first build-up step was there~ore 8.96. Bui]d-up ratio
is calculated by dividin~ the total amount of soli~s in thc
feed solutions added during the process by the amount o
solids prcsent in thc heel beforc startin~ thc additionO
Thc build Up ratio c~lculatcd above and the S
- 67 -
~.Z~38~L~
~speeiic surface area initially) determined indepcndently
by measurement were used to calculate the final specifie
surfaee ar~a (SF) with the followin~ formula:
3 r 3 r 2
SF = Si ~ 1 = 135 ~ 1 = 65 m /g
Using the formula d = 600
DxS
where d is the diameter of the particles in
nanometers
where D is the density of the particles g/cc
where S is the speeifie surfaee area in m /g of
the partieles.
The diameter of the final partieles was ealeulated
as follows:
d = 2626~ = 4~ nanometers.
At the end of the addition the slurry was filtered
first through eloth and then through filter paper to
separate the ion exehange resin from the aquasol.
The volume of the produet reeovered was ~700 ml.
The concentration was 11.76 g solids per 100 ml. This coneen
tration was determined by evaporating a weighed sample to
dryness, caleining the residue and reweighing.
Chemieal analysis of the sol ~ave the following
results: 10.5 g SiO2/100 ml, 1.64 g AlO2~100 ml and 0.854 g
Na/100 ml. A sample was dried on steam and the speeifie
surfaee area as measured by the Flow Method of nitro~en
adsorption ~as 70 m /~. An eleetron micro~raph of the sol
showed discrete, dcnse spherieal partieles with a uni~orm
particle size distribution, a weicJht avera~e diamcter of
38 nanometers and a numbcr avc?.ra~e diamet~r of 36 nallometcrs.
Standard cleviatlon in both CaSc!s was 5 nanomcters.
- 68 -
38~
Because of limitations in the size of the vessel
and the feed concentration, the above particle build up was
continued in a second step. sased on an initial surface
- area of 70 m /g, it was calculated that a build-up ratio
(BR) of about 5 would be needed to attain a specific surface
area of about 40 m2/g. The particle size calculated from
SF = 40 was 65 nanometers.
A heel for the second step of the build up was
prepared by diluting 850 ml of the sol of concentration
- 10 11.76 g solids/100 ml just described with hot tap water to
a total volume of 5 liters. The heel was therefore 2~
solids and contained a total of 100 g of sodium aluminosilicate.
The heel was heated to 100C and feed solutions
were added each at a rate of 6 ml/min while keeping the pH
constant at 10.3 ~ 0.2 with the periodic addition of ion
exchange resin IRC-84-S. The two feed solutions were the
same used in the first build-up step, aqueous silicate solu-
tion 20 g SiO2/100 ml and aqueous aluminate solution 5 g
NaAlO2/100 ml.
A total of 1640 ml of each of the feed solutions
and 560 g of ion exchange resin were used. At the end of
the addition, the slurry was filtered first throu~h cloth
and then through filter paper to separate the ion exchange
resin from the aquasol.
The volume of the product recovered was 7600 ml.
Analysis of the product gave the followinc3 results:
Concentration = 6.96 g solicls/100 ml
sio2 = 5.31 ~100 ml
~lO~ = 0.87 ~J/100 ml
Na = 0.~6G (J/100 ml
Speci~ic Sur~ace ~re.l = 4G m2/c3.
_ ~9 _
An el~ctron microgr~ph of the sol showed discrete,
dense sphcrical particles with a uniform particle size dis-
tribution, a weight average diameter of 65 nanometers
(standard deviation = 5 nanometers) and a number average
diameter of 64 nanometers (standard deviation = 6 nanometers).
The sodium aluminosilicate aquasol was converted
to the ammonium form by passing it through an ion exchange
column packed with wet Dowex SOW-X8 ion exchange resin in
the NH~ form. pH of the NH4 sol thus formed was 9.5
The sol was vacuum drum dried under the same con-
ditions given in Example 2 and the dry power obtained was
analyzed for pore size distribution and pore volume by
nitrogen adsorption-desorption as described in Example 1.
The results obtained are as follot~s:
Experimental average pore diameter = 150 A
~ore Volume = 0.306 ml/g.
The powder had a narrow pore size distribution:
both the upper t229 A) and the lower limit (110 A) o pore
size for ~0% of the pore volume were within 40~ of the
median pore diameter (180 Al.
Ex~rlpL-E 6
The powder of Example 5 was tested for its ability
to catalyze the synthesis of methylamines. A continuous
flow reactor was used in which NH3 and methanol were pumped
continuously throu~h a 1" tube containing 50 ~ of powder.
Feed rate used for liquid methanol was 1.50 cc/min, feed
rate for ammonia gas, 1100 cc/min. The tube was kept at a
constant tcmpcrature o~ 450~C and at a constant pressure
of 1 atm. The cxit and inle~t strcams of thc tube wcr~
analyzecl with a ~as chromato~rapll and thc yiclds of mcthyl-
amines and tllc conversion o~ mcthallol dctermincldO
- 70 -
~3.~:3~
The operation was repeated using commercial
Davison silica-alumina gel Clrade 970, a trademark of the
Davison Ch~mical Division of W. R. Grace & Co., with about
the same alumina content of our sample. The results ob-
tained with both catalysts are as follows:
- 71 -
3~
U~ o
,~
Oa~
~ a~ o ~
~a a~
~1 h
a
.~
o
t-- N ~ O Q~
U~ H a~ --1 ~I N ~J
Q, t
0~ ~
C~ ~ O
~0 O
O
~ O
o ~1 ~1 a) s~
~ ~ >1
a)
o ,t ~ ~ a
Id
o
o ~ ~ ~
-- 72
3~
Thus, the r~sul~s show that a composition of this
invention gave hicJher methanol conversion, higher desirable
monomethylamine production and more favorable product dis-
txibution than standard commercial silica-alumina gel.
EXAMPLE 7
This was an example of the preparation of an
amorphous aluminosilicate powd~r of the invention using a
freshly pr~pared sol of silicic acid and a solution of
. sodium aluminate as reactants and a heel of water.
A heel of 1.5 liters of water was heated to re-
flux at 100C. To this heel, simultaneously and separately,
was added (a) 1200 ml of 2~ silicic acid solution prepared
from "F" grade sodium silicate, which contained 28.6~
SiC2 content, then passed through a column of Dowex 50~X8
cation exchange resin in the hydrogen form, the resulting
silicic acid effluent contained 2~. SiO2 and had a pH of
about 3.2 and (b) 1200 ml of a sodium aluminate solution
(2.7 g NaAlO2 per 100 ml) prepared by dissolving 42 g of
NaAlO2 (74% reagent) in water and diluting to volume. The
rate of addition of each was 200 ml per hour. During the
addition of th~ two feed solutions, the temperature was
maintained at 100C and the p~ at 11.3 ~ 0.2 by adding
IRC-84-S ion exchange resin. The resulting sol was cooled,
deionized with ~mberlite IRC-84-S in the hydrogen form by
stirring this resin with the sol until the pH reached 7.6.
The resulting 3800 ml of product was a stable
sodium aluminosilicate sol containing 1.08 g so].ids per
100 ml. Chemical analysis of the resulting sol indicated
that it containecl 0.~7 C3 SiO2~100 ml, 0.39 g ~1O2/].00 ml
and 0.24 g Na/100 ml~ Thus, the rcsu].ting procluct was t~n
~.238~
aluminosilicate sol having the empirical formula NaAlO2-SiO2,
An electron micrograph of the sol showed discrete spheres of
uniform diameter. The weight average diameter is 13 nano~
meters (standard deviation 4 nanometers) and the number
average diameter is ll nanometers (standard deviation 3
nanometers),
The sol was converted to the ammonium form and
spray dried in the manner described in Example 1. The
powder obtained was analyzed as in Example l.
The results obtained were as follows:
Specific surface area: 280 m2/g
Experimental average pore diameter: 57 A
Pore volume: 0.3995 ml/g.
Median pore diameter was 51 A. Ninety percent of
the volume of the pores was constituted of pores ranging
in diameter from 32 A to 68 A (within ~ 40% of the median
pore diameter).
EXAMPLE 8
The usefulness of the product of Example 7 for
the isomerization operation is shown by this example.
The procedure of Example 4 is followed with the
product of EXample 7, except that a paste is made to a
consistency for extrusion. The paste is extruded into l/8"
x l/8" cylinders. The cylinders are impregnated with pro-
moters, 0.5~ Pt and 0.2% Re and the impregnated catalyst is
reduced to form the respective metals. The catalyst is
then given a typical isomerization test in small scale
equipment as follows:
- 74 -
Charge: Pentanes and Hexanes - HDS treated.
Conditions:
Tempera-ture 300 to 400 F
Pressure 300 psig
Space velocity 3.0 LVH
H2 to oil, mole ratio 0.1 to 0.5:1
Components, wt percentFeed Product
C4 and lighter 0.2 1.0
Isopentane 24.8 39.9
n-Pentane 21.4 10.8
2,2-dimethylbutane1.0 16.3
2,3-dimethylbutane2.9 4.5
Cyclopentane 1.5 1.1
2-methylpentane 14.0 12.5
3-methylpentane 12.3 6.9
n-Hexane 13.1 4.2
Benzene 1~6
Methyl cyclopentane 1.8 1.3
Cyclohexane 0.0 1.0
Research Octane No. 72.0 85.0
The catalyst shows excellent stability and con-
tinued selectivity.
EX~MPLE 9
This is an example of the preparation of an amor-
phous aluminosilicate powd~r of this invention with silica
as the particle nucleus or core.
Three thousand grams of a 50% by weight, 60 nano-
meters particle size silica sol heel is heated to 100C and
the pH is adjusted to 10.3 with sodium hydroxide. The silica
sol used is com~ercially available under the trade mark of
~ - 75 -
23c~3~L4
NalcoacJ 1060 Erom the Nalco Chemical Company o~ O~k Brook,
~llinois. ~eed solutions`and ion exchange resin are added
in the manner described in Example 1 and sodium silicate
~nd sodium aluminate, each added at a rate of 6 ml/min while
~eeping the heel at 100C. The two feed solutions of
EXample 1, aqueous sodium silicate solution 20 g SiO2/100
~1 ahd aqueous sodium aluminate solution 5 g Na~102/100 ml,
a~e used. The heel is kept at pH 10.3 ~ 0.1 by periodic
adclitions of IRC-84-S resin.
A total of 340 ml of sodium silicate solution,
340 ml of sodium aluminate solution and 117 g of resin are
usec~. At the ehd of the addition, the hot colloidal solution
ôbtained is filtered first through cloth and then through
f;lte~ paper to separate the ion exchange resin from the
aquasol.
The resulting product is 3010 ml of a stable sol
made o~ siiica particles coated with sodium aluminosilicate,
of pH 10.7 containing 43 g of solids per 100 ml solution.
Soiids concèhtration is determined as explained in Example 1.
Dry powder is obtained by drying the sol. The sur~ace area
o~ the powder is measured by nitrogen adsorption using the
flow method. The specific surface area thus measured is
O -m2/
Ah eiectron micrograph of the sol shows discrete
sphe~es of ùniform diameter. Average diameter is about
65 nanometers.
~ he sol obtained is converted to the ammonium form
by passillcJ it throucJh an ion exchancJe column packed with w~t
Dowex 501~-X~ ion exchanc~e rcsin in the N1l4 ~orm as ex-
plail-ecl in ~xamplc? 1.
- 76 -
~! Z3~3~1L4
The aquasol in t~le ammonium form thus formcd is
spray dried as described in ~xample 1 using the samc spray
drying conditions, Powder samples ~re collected in the
cyclone and chamber collectors. Total product collected
is 1035 g.
Electron micrographs of th~ spray dried powder
showed spheroidal aggregates with an average diameter of
about 21 microns.
- Surface area and pore volume, pore diamater and
pore size distribution analysis of the spray dried powder
are made by th~ nitrogen absorption-desorption method used
in Example 1.
Results obtained were as follows:
Specific Surface Area 40 m2/g
Experimental Average Pore Diameter 155 A.
The arithmetic proba~ilit:y plot of the pore dia-
meter versus pore volume data computed by the PORDIS program
shows a median pore diameter of 150 A. Ninety percent of
the volume of the pores is constituted of pores ranging in
diameter from 108 A to 20~ A. Only 5~ of the pores are
larger than 202 A. This pore fraction is smaller than 280 A.
EX~IPLE 10
This is an example of the preparation of an amor-
phous aluminosilicate catalyst of the invention with a
zirconia heel as t,he particle nucleus.
One thousan~ grams of 10~ weight, 25 nanometers
particle size zirconia aquasol is used as a heel. The sol
is made of spherica]. particles with a uniform particle size
distribution. ~rhe pll of ~he sol is 3.5. Onc hundred milli-
liters of a sodium citratc solution containing 2.8 g of
- 77 -
~lZ~
sodium citratc are addcd to thc sol at a r~tc of about
12 ml/min with stron~ a~it~tion. The resulting sol is
2.8 g of sodium citrate/100 g ZrO2. The p~l of the sol is
raised to 10.3 with NaOEI.
The two feed solutions of Example l, aqueous
sodium silicate solution 20 g SiO2/100 ml and aqueous sod-
ium aluminate solution 5 g NaAlO2/100 ml and ion exchange
resins are added as described in Example l at a rate of
. 4.3 ml/min for the silicate and 5.9 ml/min for the aluminate
while keeping the heel at 100C. The heel is kept at pH
10.3 + 0.1 by periodic additions of IRC-84-S resin.
A total of 205 ml of sodium silicate solution,
286 ml of sodium aluminate solution and 70 g of resin are
used. At the end of the addition the hot colloidal solu-
tion obtained is filtered first through cloth and then
through filter paper to separate the ion exchange resin from
the aquasol.
The resulting product is 1010 ml of stable sol
made of zirconia particles coated with sodium aluminosilicate,
of pH 10.7 containing 11.5 g solids/100 ml solution. Solids
concentration is determined as ex21ained in Example l.
A sample of this sol is dried and the dry powder
obtained is used for measurement of surface area by nitrogen
adsorption using the flow method. Specific surface area
thus mcasured is 37 m2/g. An electron micrograph of the
sol s]lOws discre~c splleres of uni~orm diameter. Average
diameter is about 30 nanometers.
The sol obtaincd is convertcd to the amrnonium form
by passing it through an ion c.Ychange column packed with wet
3~ DOW~X 50W-x~ iOIl exchan~c resi~ in the Nll~ rorm as dcs-
c~ibcd in ~xamll~ l. Thc aqllasol in thc ammoni~lm fo~m thus
- 78 -
~.231~4
ormcd is spray dried as d~scrib~d in Example 1 using the
same spray drying conditions. Powder samples are collected
in the cyclone and chamber collectors. Total product col-
lected is 81 g.
Electron micro~raphs of the spray dried powder
showed spheroidal aggregates with an average diameter of
about 10 micrometers.
Surface area and pore volume, pore diameter and
. pore size distribution analysis of the spray dried powder
are made by the nitrogen absorption-desorption method of
Example 1.
The specific surface area is 35 m2/g and the~ex-
perimental average pore diameter is 120 A.
The arithmetic probability plot of the pore dia-
meter versus pore volume data com?uted by the PORDIS pro-
gram shows a median pore diameter of 110 A. Ninety percènt
of the volume of the pores is constituted of pores ranging
o O
in diameter from 77 A to 143 A. Only 5~ o the pores are
lar~er than 1~3 ~. This pore fraction is smaller than 210 Ao
EXAMPLE 11
This is an example of the preparation of an amor-
phous aluminosilicate catalyst of this invention with an eta
alumina heel as the particle nucleus.
One thousand grams of 10~ weight, 50 nanometer
particle size eta alumina aquasol is used as a heel. The
sol is made o~ spherical particles with a uniform particle
size distribution. The L~l of the sol is 3.5. One hundrcd
millilitcrs o~ a sodium citrate solution containing 5 ~ of
sQdi~m citratc are ~dded to th~ sol at a rat~ oE about
3a 12 ml/min with stro~ gitat:ion to yield a sol with 0.55 g
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~.23~
sodium citrate/100 g ~12O3. The pH of the sol is raised
to 10.3 with N~OH.
The two feed solutions of Example 1, aqueous
sodium silicate solution 20 g SiO2/100 ml and aqueous
sodium aluminate solution 5 g NaAlO2/100 ml and ion ex-
change resins are added as described in Example 1 at a xate
of 4.3 ml/min for the silicate and 5~9 ml/min for the
aluminate while keeping the heel at 100C. The heel is
kept at pH 10.3 + 0.1 by periodic additions of IRC-84-S
resin.
A total of 97 ml of sodium silicate solution,
133 ml of sodium aluminate solution and 50 g of resin are
used. At the end of the addition, the hot colloidal solu-
tion obtained is filtered first through cloth and then
through filter paper to separate the ion exchange resin
from the aquasol.
The resulting product is 950 ml of stable sol
made of alumina particles coated with sodium aluminosilicate,
of pH 10.7 containing 9.9 g solids/100 ml solution. Solids
concentration is determined as in Example 1.
A sample of this sol is dried and the dry powder
obtained is used for measurement of surface area by nitrogen
adsorption using the flow method. Specific surface area
thus measured is 34 m2/g. An electron micrograph of the
sol shows discrete spheres of uniform diameter. Average
diameter is about 55 nanometers.
The sol obtained is converted to the ammonium form
by passing it through an ion exchc~nge column packed with wet
Dowex 50W-X8 ion e~change resin in the Nli4 form as in
Ex~mple 1.
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38~4
The aquasol in the ammonium form thus formed-is
spray dricd as described in Example 1 using the samc spray
drying conditions. Powder samples are collected:in-the
cyclone and chamber collectors. Total product coll~cted
is 76 g. Electron micrographs of the spray dried po~der
showed spheroidal aggregates with an average diameter:of
about 11 micrometers.
Surface area and pore volume, pore diameter-and
. pore size distribution analysis of the spray dried powder
are made by the nitrogen absorption-desorption method used
in Example 1.
The specific surface area was 30 m2/g and-the
experimental average pore diameter was 130 A.
The arithmetic probability plot of the pore dia-
meter versus pore volume data computed by the POR~IS pro-
gram shows a median pore diameter of 145 ~. Ninety -percent
of the volume of the pores is constituted of pores ranging
c~ O
in diameter from 102 A to 189 A. Only 540 of the pores are
larqer than 189 A. This pore fraction is smaller than
260 A
EXAMPLE 12
This is an example of the preparation of an amor~
phous aluminosilicate catalyst of the invention with a ti-tania
heel as the particle nucleus.
One tl~Qusand grams of 10~ weight, 10 nanometers
particle size titania aquasol is used as a heel. The sol
is made of spherical particles with a uniform particle size
distribution. The pll of the sol is 3.5. One hundred milli-
liters o~ a sodium citratc solution containing 135 g of
sodium citrate are addcd to tl~e sol at ~ rate o~ abou~
1~238~L~
12 ml/min with stron~ agitation to yield a sol with 13 7 5 g
s~dium citrate/100 g Tio2; The pll of the sol is rais~d to
10.3 with N~OH.
The two feed solutions of Example 1, aqueous
sodium silicate solution 20 g SiO2/100 ml and aqueous
sodium aluminate solution 5 9 NaAlO2/100 ml and ion exchange
resins are added as described in Example 1 at a rate of
4.3 ml/min for the silicate and 5.9 ml/min for the aluminate
while keeping the heel at 100C. The heel is kept at pH
10.3 + 0.1 by periodic additions of IRC-84-S.
A total of 641 ml of sodium silicate solution,
894 ml of sodium aluminate solution and 220 g of resin are
used. At the end of the addition, the hot colloidal solu-
tion obtained is filtered first tllrough cloth and then
through filter paper to separate _he ion exchange resin from
the aquasol.
The resuling product is 1980 ml of stable sol
made of titania particles coated with sodium aluminosilicate,
of pH 10.7 containing 10.5 ~ solids/100 ml solution. Solids
concentration is detcrmined as in E~ample 1.
A sample of this sol is dried and the dry powder
obtained is used for measurement of surface area by nitrogen
adsorption using the Flow Method. Specific surface area
thus measured is 94 m /g. An electron micrograph of the sol
shows discrete spheres of uniform diam~ter. Avera~e dia-
meter is about 15 nanometers.
The sol obtained is converted to the ammonium form
by passing it through an ion exchange column packed with wet
Dowex 50W-X8 ion cxchange rcsin in the N~14+ form as dcs-
cribcd in Example 1. ~hc ~quasol in thc ammonium form thus
~ormcd is spray drie~ as d~scribed in ~xamplc 1 using the
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3~1~
same spray dryin~ conditions. Powder samples are collected
in the cyclone and chamb~r cOllcctors. Total product col-
lected is 165 g.
Electron microyraphs of the spray dried powder
showed spheroidal ag~regates with an average diameter of
about 8 micrometers.
Surface area and pore volume, pore diameter and
pore size distribution analysis of the spray dried powder
are made by the nitrogen absorption-desorption method used
lQ in Example 1.
The specific surface area was 95 m /g and the ex-
perimental average pore diameter was 75 A.
The arithmetic probability plot of the pore dia-
meter versus pore volume data computed by the POR~IS pro-
gram shows a median pore diameter of 70 A. Ninety percent
of the vclume of the pores is constituted of pores ranging
in diameter from 49 A to 91 A. Only 5~ of the pores are
larger than 91 A. This pore fraction is smaller than 170 A.
Thus, the porous powder compositions of this in-
vention may be used for the hydrocracking of petroleum dis-
tillates by contacting said compositions with said distillates,
under conditions well known in the art.
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~L~31~
EXAMPLE 13
This was an example of the preparation oE a
hydrous amorphous aluminosilicate powder of the invention
where a heel of silica sol prepared in situ was used in
the apparatus described in Example 1 to form the core of
the particles of this invention.
A 1% silica sol heel was prepared in situ at
70C and pH of 9 by diluting 127 ml of 20% SiO2 sodium
silicate JM (SiO2/Na2O weight ratio 3.25) to a total volume
of 3000 ml with hot tap water to make 1.270 liters of
1~ SiO2 heel (12.7 g SiO2 in 1270 ml of solution). The
heel was heated to 70C and then deionized to pH 9 + 0.1
with 80 g of ion exchange resin Amberlite~ IRC-84-S.
Feed solutions were added in the manner explained
in Example 1 to buildup with sodium silicate and sodium
al~lminate, the sodium silicate solution at a rate of
12 ml/min and the sodium aluminate solution at a rate of
27 ml/min while simultaneously heating the heel to 100C.
Heating from 70 to 100C took about 48 minutes. The two
feed solutions of Example 1, aqueous sodium silicate solu-
tion 20 g SiO2/100 ml and aqueous sodium aluminate solution
5 g NaAlO2/100 ml were used. In 4 minutes the pH of the
heel rose to 11.3 due to the alkalinity of the feed solu-
tions being added. From this point on the heel was kept
at 11.3 + 0.1 by periodic additions of IRC-84-S resin.
A total of 3770 ml of sodium silicate solution,
8420 m~ of sodium aluminate solution and 1450 g of resin
were used. At the end of the addition the hot colloidal
solution obtained was filtered first through cloth and then
through filter paper to separate the ion exchange resin
from the aquasol.
~ 84 -
1~231~
The resulting product was 11.8 litersof a stable
sodium aluminosilicate sol containing 10 g/100 ml solution.
Solids concentration was determined as disclosed in
Example 1. ~hemical analysis of the resulting sol indi-
cated that it contained 4.98 g SiO2/100 ml, 2.47 g
AlO2/100 ml and 1.01 g Na/100 ml. Thus the resulting
product was an aluminosilicate sol having the empirical
formula NaAlO2-1.98SiO2 nH2O. The specific surface area
of the sol was determined after the sol was dried by
measuring the surface area by nitrogen adsorption using
the flow method. Specific surface area thus measured was
122 m2/
An electron micrograph of the sol showed discrete
spheres of uniform diameter. Weight average diameter was
26.6 nanometers. The standard deviation was 4.7 nanometers.
The sol was converted to the ammonium form by
ion exchange in the manner described in Example 1.
The ammonium aluminosilicate thus formed had a
pH of 9 and it was spray dried in a Bowen Engineering, Inc.
No. 1 Ceramic Dryer using a two-fluid nozzle type 59-BS.
Operating conditions for spray drying were the
fol,owing:
Feed Weight % solids10
Total feed 3000 ml
Feed rate 100 ml/min
Inlet temp. 350C
Outlet temp. 190C
Atomizing pressure5 psig
Powder samples were collected in the cyclone and
cham~er collectors. Total product collected was 117 g for
39% recovery on a wet basis.
- 85 -
~3~
Ninety-four g of the cyclone product were sus-
pended in 1 liter of saturated ammonium carbonate solution
at room temperature and stirred gently for 5 hours. The
slurry was centrifuged and the cake obtained was reslurried
in a 50:50 mixture of concentrated ammonium and H2O. The
washing operation was repeated four times and the cake
obtained was dried in vacuum oven at 80C overnight. The
dry powder was analyzed for sodium and it contained 0.27%
Na by weight. The extraction operation was then repeated
and the dry powder obtained was analyzed again for Na and
gave 0.12% Na by weight.
Surface area and pore volume, pore diameter and
pore size distribution analysis of the spray dried powder
were made by a nitrogen absorption-desorption method using
a Micromeritic~ 2100-D apparatus. Micromeritics~ 2100-D
is the trademark of Micromeritics Instrument Corporation
of Norcross, Georgia, for an Orr Surface-Area Poxe-Volume
Analyzer.
Results were obtained as follows:
Specific surface area 122 m2/g
Median pore diameter 61 A
Pore volume 0.325 ml/g
~ ore volume distribution analysis was made based
on the B. F. Roberts method [J. Colloid and Inter~ace
Science 23, 266 (1967)] and the results computed and plotted
using the PORDIS~PORTL computer program.
Eighty-four percent of the volume of the pores
was constituted of pores ranging in diameter from 0.6 to
1.4 of the median pore diameter.
The powder was mixed with a rare earth zeolite
and pro~-ed in testing to be an excellent catalyst for the
cat-cracking of petroleum.
- 86 -
~.23~314
It is to be understood that any oE the components
and conditions men-tioned as suitable herein can be sub-
stituted for its counterpart in the foregoing examples and
that although the invention has been described in consider-
able detail in the foregoing, such detail is solely for the
purpose of illustration. Variations can be made in the
invention by those skilled in the art without departing from
the spirit and scope of the invention except as set forth in
the claims.
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