Note: Descriptions are shown in the official language in which they were submitted.
~F~ ! 7~ q~
--1--
PHOSPHORUS MODIFIED MAGNESIUM SILICATE
The present invention concerns to novel phos-
phorus modi*ied, porous magnesium silicates. More par-
ticularly the present invention concerns such phosphorus
modified porous magnesium silicates having ca'alytic
properties that are usefully employed in the alkylation
of aromatic compounds.
Porous aluminosilicates, i.e., zeolites,
especially highly siliceous forms thereof, such as ZSM-5,
silicalite, ZSM-35, and others, are well-known in the
art. Typically such compounds are porous crystalline
frameworks based on an extended three-dimensional net-
work of SiO4 and greater or lesser amounts of A104
tetrahedra linked to each other by shared oxygens. u. s.
Patent 4,049,573 discloses that zeolites such as ZSM-5,
ZSM-11, ZSM-12, ZSM-35, ZSM-38, and others, could be
beneficially treated by impregnation with modifying sub-
stances including phosphorus compounds thereby preparing
zeolitic catalysts having deposited or occluded modifying
31,372A-F -1-
~7~ qt
--2
species. These modifiers are believed to affect the
acid sites of the zeolites and were found tc be useful
catalysts in hydrocarbon converslon processes.
U.S. Patent 4,002,698 describes phosphorws
modified aluminosilicates that are particularly suited
for the alkylation of toluene. Preferred compounds
possessed a silica/alumina ratio of at least about 12
and were modified by the addition thereto o~ at least
0.5 percent by weight phosphorus
Numerous additional references teach -that
alumino~ilicate zeolites may op-tionally further contain
modifying substances including phosphorus. The phos~
phorus may be added by contacting the zeolite with an
organic phosphorus compound or an inorganic phosphorus
compound such as quaternary ammonium phosphate salts.
Illustrative of such references are U.S. Patents
4,140,726; 4,276,437; 4,276,438; 4,275,256; 4,278,827;
4,259,537; 4,230,894; 4,250,345; 3,962,364 and 4,270,017.
In 1972, U.S. Patent 3,702,886 issued directed
to a synthetic zeolite termed ZSM-5 and method for
making it. This patent discloses a zeolite having a
SiO2/A12O3 molar ratio from about 5 to 100. The main
claim characterized ZSM~5 by reference to a table of
X-ray diffraction lines (see Table I following) and the
following composltion in terms of mole ratios of oxides
0.9~0.2 M2~nO:Al2o3:ysio2 2H2
31,372A-F -2-
~ ~'7~
--3-
wherein M ls at leas-t one ca-tion having a valance n, Y,
is a-t least 5 and z is between 0 and 40.
TABLE I
ZSM-5, Interplanar Spacing d(A)
.
11.1~0.2 6.30~0.1 5.01~0.1 3.71~0.05
lO.o~Q.2 6.04~0.1 . 4.60~0.08 3.04~0.03
7.4~0.15 5. 97IO . 1 4.25iO.08 2.99~0.02
7.1~0.15 5.56~0.1 3.~5~0.07 2.94~0.02
According to Mobil scientists, the ZSM-5
aluminosilicate is prepared by including nitrogenous
organic molecules such as tetrapropyl ammonium bromide
in the reaction mixtures. For very high SiO2/Al2O3
preparations, no aluminum need be deliberately added
since it is present as an impurity in the reactants.
The organic molecules are incorporated into the frame-
work structure as it forms and-these as-synthesized
materials are termed "nitrogenous zeolltesi'. Appli-
cation of high temperatures will free high SiO2/Al203
materials of these organic components without altering
the basic framework structure, D. M. Olson et al.,
"Chemical and Physical Properties of the ZSM-5 Sub-
stitutional Series", J. Catal., 61, 390 396 at 391
(1980).
According to the present invention, there
are provided novel porous, crystalline magnesium sili-
cates modified by the addition thereto of phosphorus
in the amount from about 0.25 percent by weight to
about 30 percent by weight.
31,372A-F -3-
The porous crystal:line magnesium silicate may
be further described as follows. The amount of magnesium
present 1n this silica-te may vary. However, for all com-
positions of the present invention, it is essential that
some magnesium which is not ion-exchangeable by conven-
tional techniques be presen-t i~ the silica-te. Conven-
tional techniqlles of ion-exchange are presented in Breck,
Zeolite Molecular Sieves, John Wiley & Sons (1~74). Other
elemen-ts may be present in porous magnesium silicates as
impurities such as aluminum, germanium, or gallium or
chemlcals may be delib~rately added either to modify or
improve the properties of the magnesium silicate or for
other advantageous reasons, for example, to ameliorate
process parameters. Suitable additional chemicals
include primarily chromium, iron, copper, barium and
boron.
These porous magnesium silicates have a com-
position which may be expressed according to the follow
ing formula in terms of the molar ratios of oxides on a
dry basis:
(M2~n)p(Mg3)X(R23 )y(si~)2 )Z
wherein M is at least one ion-exchangeable cation having
a valence of n; R is at least one element (with valence
3 ) which is not ion-exchangeable by conventional means;
x/z>0; y/z~0; p/n~y; and p, x, z are positive numbers and
y is a positive number or zero. By dry basis is meant
material which has been heated in air at about 500C for a
period of one hour or more. The invention is not limited
to use only of such dried material or said oxide forms,
31,372A-F -4-
_ ) _
ra-ther the composi-tion of the porous magnesium silicates
employed herein may be presented in terms of oxides and
on a dry basis (as in the above formula) in order -to pro-
vide a means for identifying such compositions.
The porous magnesium silicates modlfied by
addition of phosphorus accorclin~ to the present inven-
tion are prepared by hydro~hermal me-thods from a variety
of silicate and magnesium sources leading to produc~s,
all of which incorporate magnesium into the struc-ture of
the resul-ting porous crystalline magnesium silicate.
Incorporation of phosphorus may be performed
by any suitable technique. Advantageously, the previously
prepared porous magnesium silicate is physically contac-ted
with a suitable phosphorus compound optionally in a solvent.
Removal of the solvent as, for example, by evaporation,
results in isolation of the phosphorus modified porous
magnesium silicate. Once prepared, the phosphorus modi-
fied porous crystalline magnesium silicates may be han-
dled like previously known alkylation catalysts. The
composition may be mixed with binders such as clays and
compressed into pellets, pulverized or otherwise machined
prior -to use and calcined. The phosphorus modified por-
ous crystalline magnesium silicates of the invention are
useful catalysts in the alkylation of aromatic compounds
such as benzene, toluene, etc., with a variety of alkyl-
ating agents including olefins, primary alcohols, and
others.
The term crystalline when used herein
refers to materials which are recognized by those
skilled in the art as having a highly ordered structure.
31,372A~F -5-
f9[)~ 3
--6~
Three dimensional periodicity is characteristic of a
highly ordered structure. The skilled artisan recognizes
that evidence of such periodicity may be presented by cata-
lytic reactivity, infrared spectroscopy or other means of
analysis as well as by the commonplace X-ray diffraction
analysis. Porous magnesium silicates employed in the
present 1nvention are "crystalline" as that term is char-
acterized above even if said silicates appear amorphous
to X-ray diffraction analysis if a skilled artisan recog-
nizes a highly ordered structure by other evidence. Ar~cent article by P. A . Jacobs et al., "Evidence of X-ray
Amorphous Zeolites", ~ s~ C~:c~ ro~ , 591, 1981, is
useful on this point.
By the term "porous" are meant those sili-
cates having a framework structure con-taining cavities
capable of allowing the entrance or absorbance of mole-
cules such as water, nitrogen or toluene.
Due to the differences in ionic radii of
Si (0.41 A) and Al (0.50 A) replacement of Si by
Al in TO4 sites will cause a unit cell volume expansion
in most zeolites. The degree of unit cell volume expan-
sion will depend on the amount of Al substitution for Si
in the TO~ sites. If -the substitution is low, as in some
ZSM-5 and silicalite zeolites, high resolution, calibrated
X-ray diffraction techniques must be utili7ed to detect
the expansion.
Similarly, in the present invention, it is
believed -that nonion-exchangeable Mg is contained in
the magnesium silicate lattice. Replacement of Si
I~ o
30 (0.41 A) by Mg (0.65 A) in T04 sites will also cause
31,372A~F -6-
~ ~ . 7 { ~ 3
--7--
a un:it cell expansion. Once again, the amount of Mg
- subs-titution for Si, will influence the degree of cell
volume expansion.
Evidencing element loca-tion in a framework
lattice struc-ture by de-termining cell volume expansion
~con-traction) has been done by others skilled in making
silicates. See, e.g., M. Taramasso, G. Perego and
B. Notari, "Molecular Sieve Borosilicates", Proceedings
of the Fifth International Conference on Zeolites, 40-48
10 at 44 (Heyden ~ Sons Ltd.) (1980).
High resolution X-ray powder diffraction data
were obtained from Huber-Guinier powder diffraction cam-
eras equipped with Ge and quartz monochromators for pro~
viding-CuK~l and FeK~1 radiation, respectively. The
films were calibrated, with well-known internal stan~ards
such as NBS Si (NBS Circular 539 Vol._9, p. 3~ or As2O3,
scanned with a densitometer and the re~ulting data profile
fit by techniques described in: J. W. Edmonds and W. WO
Henslee, Adv. in X-ray Anal., 22, 143 (1978) and J. W.
Edmonds, "Precision Guinier X-ray Powder Diffraction Data",
NBS Special Publication 567, Proceedin~s of Symposium on
Accuracy in Powder Diffraction Held at NBS, Gaithersburg,
MD, June 11-15, 1979 (Issued February 1980~. The cali-
brated data were least-squares refined and fitted to
-obtain accurate cell dimensions and volumes.
Using data from the method described above
and using single crystal X-ray crystallographic data from
the literature, the cell volume for porous magnesium sili-
cates employed in the present invention where Mg I is
believed to replace SiIV, can be compared to the cell
31,372A-F -7-
volume of silicalite which has SiIV in all the T04 sites.
Typical data are shown in Table II, for ei-ther anhydxous
zeoli-tes or calcined zeolites. (Minimum calcination of
50GC for 1 hour.)
TABLE II
Cell Volumes
Compound Volume (A3) Reference
Silicali-te 5306
Silicalite 5305 2
10 Magnesium Silicate 5347 2
Magnesium Silicate 5349 2
Cell volumes were obtained from the lattice param-
eters given in an article by E. M. Flanigen, J. M.
Bennett, R. W. Grose, J. P. Cohen, R. L~ Patton,
15 R. M. Kirchner and J. V. Smith, Nature, 271, 512
(1978~.
2Cell volumes were calculated using the National
Bureau of Standards - Geological Survey Lattice
Parameter Refinement Program written by Dan
Appleman (available through NTIS~ on XRD data
obtained on samples made either according to the
process explained herein or according to the sili-
calite patent.
The above values are typical examples of cell
volumes of porous magnesium silicates employed in -the
invention and a highly siliceous zeolite such as silica~
lite. The difference between these volumes shows a cell
volume expansion. The exact amount of expansion will be
composition dependent. The porous magnesium silicate
compounds employed in -the present invention will exhibi-t
31,372A~F -8-
unit cell volume expansion when compared to silicalite,
but expansion is not limited to that derived from the
data shown ln Table II. I-t is believed -that the above-
mentioned uni-t cell expansion evidences the placemen-t
of maynesium as a part of the lattice framework struc-
ture. It is believed that altering the SiO2~MgO ratio
varies the pore size and volume, framework density and
refractive inde~ of the resulting magnesium silicates.
If small ranges of the SiO2/MgO ratios are utilized,
the ability to detect volume, pore size and density
differences will be dependent on the resolution capa-
bilities of the analytical technigue used.
Samples of compositions of the present inven-
tion whose crystallite size is appropriate to produce a
distinct X-ray powder diffrac-tion trace, have a pattern
which includes at least the interplanar d spacings
listed in Table III.
31,372A-F -9-
't~ 3
-L0
TABLE III
Ma~nesium silicate, interplanar spacings d(A)
11.2 +0.2
10.1 ~0.2
10.0 ~0.2
9.8 ~0.2
6.0 ~0.2
5.8 +0.2
5.6 +0.2
4.26*0.1
3.85_0.05
3.81+0.05
3.74+0.03
3.72+0.03
3.64+0.03
The range cited is due to unit cell volume
expansion with decreasing SiO2/MgO ratio. Magnesium
silicates with low Mg content in the TO4 sites will be
near the low d spacing limit and those with high Mg
content in TO4 sites will be near the high d spacing
limit.
The magnesi.um silicates employed in the pre-
sent invention are further characterized by a minimum
of two reflections at 10.1+0.3 A and a minimum of four
reflections between 3.72 and 3.gO A.
31,372A-F -10-
t
These values were obtained by Huber-Guinier
techniques (preferred method) mentioned previously or
by a Philips Electronics X-ray powder diffraction unit
equipped with scintillation-counter detector, yraphite
monochromator, and a strip char-t recorder. The recorded
reflections were identified by their two thçta locations,
after these locations were calibrated with an internal
standard. The-standar~ used wa~ either Nss Si (Nss Cir-
cular 539, Vol. 9, p. 3) or As2O3. The maynesium sili-
cate diffraction peaks at approximately 10.0 and 3.81 Acan often be obscured in poorly crystalline samples or
ln low~resolution X-ray diffraction data.
X-ray analyses of magnesium silicates
employed in the present invention reveal distinct differ-
ences in the diffraction patterns as a result of specifictreatments given to these magnesium silicates. Intensity
changes are observed and lines may appear, disappear or
merge depending on the exact calcination procedure uti-
lized. Ion-exchange of these silicates may also cause
changes in certain cases. Several authors have made
similar observations on related materials like zeolite
ZSM-5. See H. Nakamoto and H. Tarahashi, Chem. Lett.,
1013-1016 (1981). Regardless of the causes of the above-
-mentioned changes, they are expected by those people
skilled in the art of analyzing porous crystalline sili-
cates.
The magnesium silicates employed in this
invention are characterized also by infrared analysis.
The use of infrared analysis is recognized as a standard
method in the characterization of inorganic and organic
materials and has been used in the study of both natural
and synthetic zeolites. See for example, E M. Flanigen
31,372A-F -11-
1~7(~3~t
et al., Adv._Chem. Series, Vol. 101, p. 201-229, 1971.
See also P. A. Jacobs, supra. For examples from the
patent literature pertaining to the use of inf'rared
analysis in zeolite characterization, see U.S. Patent
4,257,885.
Poro~s magnesium silicates employed in the
present invention exhibit unique features in the 1300-
400 cm~1 region. Many compositions employed in this
invention exhibit at least two distinct bands in the
1200-980 cm~1 region. Preferred compositions employed
in the present invention exhibit these two distinct
~ands and al~o characteristic infrared bands at 1225+10
cm~1, 800+20 cm~1 ~20+10 cm~1, 550+20 cm~1 and 450+20
cm~1.
It should be recognized that bands located
between 1200-980 cm~1 may be due to asymmetric stretch
of T04 units in zeolites and silicates, see, e.g.,
20 Flanigen et al., "Molecular Sieve Zeolites-1," Adv. !
Chem. Series, 101, 201 A.C.S. (1971). It is believed
- that the band found nearest to 980 cm~1 in the magnesium
silicates employed in the present invention is due to
silanol groups of the form -Si(OH)3, >Si(OH)2, >SiOH,
or to their corresponding silicate forms.
Differential thermal analysis (DTA) is one of
the thermal methods used in the literature as an aid in
zeolite characterization. See D. W. Breck, Zeolites
Molecular Sieves, John Wiley, 1974.
31,372A-F -12-
-13-
Compcsitlons employed in the present invention
may be analyzed by DTA methods. When using a Dupont~ 990
thermal analysis unit e~uipped with a 1200C furnace, a
10-mg sample is tested against alumina as a reference mate-
rial (both contained in platinum crucibles). The heatingrate for the system is 20C per minute in air with an air
flow rate of S0 cm3 per minute. Under these conditions,
one obser-~es a distinGt exotherm at 870+30~C. X-ray dif-
Eraction (XRD) analysis of the sample both before and
after the exotherm yields at least the interplanar d
spacings listed in Table III, suPra.
The magnesium silicate materials employed in
this invention have ion-exchange properties. The ion-
-exchange capacity of traditional zeolites is associated
with their aluminum content. The ion-exchange properties
of the magnesium silicates employed in this invention are
not necessarily dependent upon any one of its particular
components. Indeed it is believed, without wishing to be
bound to this belief, that the ion-exchange capacity of
the present invention is due to a combination of factors.
Among them are: the magnesium content, the trivalent
metal ion content and also to the presence of internal
silanol moieties within the silicate framework which
under appropriate conditions can participate in the
ion-exchange process.
.
Even though a relationship among the compo-
sition and the ion-exchange capacity of these solids
is recognized, the magnesium silicates employed in the
present invention is not restricted by the traditional
"linear relationship" between composition and ion-ex-
change capacity, characteristic of traditional zeolites.
31,372A-F -13-
~.~'7(3~
-14-
The exchangeable cations in zeolite composi-
tions often play a critical role in their synthesis by
hydrothermal methods. In certain cases, a particular
cation is required to obtain a given zeolite, for exam-
ple, sodium is said to be re~uired to produce zeolite Xfrom aluminosilicate gels. Apparently the cation plays
a template role in the formation of certain structures
and/or acts as a crystallization promoter. The magne-
sium silicates employed in this invention do not appear
to require a particular alkali metal cation for their
formation. Magnesium silicates employed in the present
invention may be obtained from magnesium silicate gels
in the presence of several alkaline metal salts includ-
ing sodium or potassium salts. The presence of sodium
or potassium ions during and/or after the synthesis may
affect certain properties o the final product in appli-
cations which are susceptible to drastic changes by sub-
tle differences such as catalysis and adsorption. Salts
other than sodium and potassium may have similar effects.
In the synthesis of traditional zeolites the
source of silica may be a critical factor in the prepa-
ration of certain zeolites. In the case of the present
invention, the source of silica appears to have an effect
in the morphology of the crystalline product. There are
many examples in the literature relating morphology to a
variety of useful properties of porous crystalline sili-
cates like, for example, catalytic applications, ion-
-exchange, and adsorption.
Typically, the porous magnesium silicates
employed in the present invention are made by hydro-
thermal methods using one of many sources of silicon
31,372A-F -14-
~, 7~3(~'3
--15--
such as one of the commercially available soluble sili-
cates or water glass solutions, amorphous silica,
colloidal silica, silica gels. fumed silica or an
organosilicate like ~Eto)4Si. Advantageously employed
are two commercially available sources: a colloidal
silica sold by the du-Pont de Nemours C~mpany under the
trademark Ludox SM~ and a sodium silicate sold by the
Philadelphia Quartz Company under the trademark Phila-
delphia Quartz Sodium Silicate N~.
The source of magnesium usually is one of its
water-soluble salts, magnesium chloride, acetate,
sulfate, ~itrate, or others, or a complex ion like
Mg(NH3)62 or Mg(EDTA)2 , or a slightly soluble compound
like Mg(OH)2 or MgF2. A magnesium chloride salt is a
preferred source of mag~lesium.
Besides these components the reaction mixture
will contain a solvent such as water, along with alkali
metal ion salts such as, chlorides, sulfates or hydrox-
ides of sodium, potassium, rubidium or cesium. The
solvent may be added separately to the reaction mixture
or may already be present with one of the reactants
such as the silica source. Water is the preferred
solvent.
- A material which is believed to act as a
crystallization promoter and is hereinafter termed a
"crystallization promoter" is utilized in the process
of making the porous crystalline magnesium silicates
employed in the present invention. Typically, this
crystallization promoter is (or is formed from) an
organic nitrogen compound such as quaternary ammonium
ion salts, or hexamethylene diamine, but may also be
31,372~-F -15-
~'s'~ 3
-16-
other compounds such as seed crystals typically of
compositions similar to those cxystals sought from the
process. In particular, tetrapropyl ammonium ion salts
are often used with tetrapropyl ammonlum brcmide and
tetrapropyl ammonium hydroxide being preferred.
.
In a typical method of making these magnesium
silicates, a magnesium source, a crystallization promoter,
an alkali metal ion salt and a solvent are combined.
The pH of this combination of chemicals is usually
adjusted and the combination is further combined with a
mixture of a silica source and a solvent to gi~e a
reaction mixture typically having a pH of about 11.
The pH may advantageously be adjusted either above or
below a pH o~ 11 to modify certain crystallization or
process parameters such as the solubility of magnesium
in the mixture, formation of precipitates, rates of
crystallization, etc. The pH is adjusted as desired
using acids or bases such as H2SO4 or NaOH and may be
adjusted before, after and/or during t~e mixing step of
the reactants.
The reaction mixture is vigorously mixed at
room temperature for a sufficient time to produce an
apparently homogeneous gel. Typically the rate of mix-
ing is sufficiently vigorous to produce a satisfactory
slurry or gel within one minute.
The mixture resulting from the above proce-
dure is allowed to crystallize into compositions
employed in the present invention. Preferably, crys-tal-
lization takes place at temperatures above room temper-
ature to increase the rate of crystal growth. Usually
31,372A-F -16-
~_~a 79 ~t)~3
-17-
about 150C is used with autogeneous pressure. ~igher
or lower temperatures may be advantageously employ~d
depending upon the process or product parameters desired,
e.g., larger crystals are generally formed with lower
temperatures and the rate of crystallization increases
with higher temperatures. When quaternary ammonium ion
salts are used as crystallization promoters, temperatures
above 200C are avoided to prevent the,ir decomposition.
Suitable time periods for the crystallization
may be determined by analysis of reaction mixture
samples at intervals. The crystalllzation time will
vary depending upon the reactants or the particular
process parameters chosen. Crystallization times of
one to five days are not uncommon.
During the crystallization step, stirring may
be advantageously employed to facilitate product forma-
tion. The rate and type of stirring may affect crystal-
lization parameters such as the rate of crystallization,
uniformity of the product and crystal size. The effect
of this parameter and optimum adjustment is dependent
upon other parameters and is believed to be within the
skill of the art to determine without undue experimen-
- tation.
Following crystallization it is often desir-
able to filter the 'crystallized mixture using a water
wash to remove the mother li~uor and then to heat the
crystals to about 110C to remove water and thereby
produce a convenient free-flowing powder.
31,372A-F -17-
0~3
-18-
The compositions as made by the above pro-
cedure may contain organic moieties which, if desired,
may be removed by known methods such as calcination in
an oxygen-containing atmosphere at a temperature suffi-
cient to decompose the organic moie-ties. Calcination
at about 500C-600C for approximately an hour is suffi-
cient -to remove commonly present organi-c moieties.
The magnesium silicates employed in the inven-
tion may be beneficially modified by techniques well~known
in the art which treat said silicates with acids, salts or
other ions or molecules. Acid treatment is especially
valued to produce a stable, catalytically active form of
porous crystalline magnesium silicate.
As mentioned before, certain compositions
employed in the invention may be expressed according
to a formula in terms of the molar ratios of oxides
on a dry basis, for example,
2/n)p~Mg)X(R203)y(sio2)
wherein M is at least one ion-exchangeable cation having
a valence of n; R is at least one element with valence
3+ which is not ion-exchangeable by conventional means
x/z>0; y/z>0; p/n>y; and p, x, z are positive numbers
- and y is a positive number or zero. The statement x/z>0
is essential to all compositions employed in the present
invention since it defines a magnesium silicate. A11
compositions employed in the present invention must con-
tain magnesium.
31,372A-F -18-
--19--
The statement y/z~0 indicates that this is a
nonessential term. Typical nonion-exchangeable elements
which may advantageously be present include by way of
example, aluminum, iron, chromium, boron and gallium.
Also the above-mentioned formula could be
modified to include other elements optionally present
which are not ion-exchangeable by conventional means
having a valence other than 3+ such as 2+ or 4+. Ger-
manium is an example of such an element.
Preferred embodiments of magnesium silicates
employed in the present invention expressed in terms of
the above formula are those wherein p is from about 0.1
to about 20; x is from about 0.1 to about 12; y is from
about 0 to about 3 and z is from about 84 to about 96.
It is especially preferred that the term y of the above
formula be from 0 to about 1Ø
Typically, the ion-exchangeable cations M (of
both the magnesium silicates represented by the above for-
mula and similar magnesium silicates employed in the pres-
ent invention) are alkali metals, hydrogen, group VIIImetals or rare earth elements, or ammonium ions, but may
be any element or moiety capable of exchange into the mag-
nesium silicates of the present invention. Preferred are
hydrogen, the alkali metals and the rare earth elements.
Methods of ion-exchange are well-known in the art, e.g.,
hydrogen may be exchanged into a silicate by simply treat-
ing with acid.
31,372A-F -19-
~,7~
-20-
Modification of -the porous magnesium silicate
- by adding ~hosphorus thereto is accomplished by contact-
ing the ma~neslum silicate with a phosphorus compound.
Sultable phosphorus compounds may be either organic or
inorganic. Representative compounds include, for
example, those of the formula PX3, RPX2, R2PX, X3PY,
( ) 2~ R2P(Y)X, P205 or R2PO2, wherein R is C1 6
alkyl, phenyl, Cl 6 alkoxy or phenoxy, X is halo or
hydrogen and Y is oxygen or sulfur. Additional suit-
able examples include salts of phosphorus acids, par-
ticularly ammonium, phosphonium, or hydrogen ammonium
salts of phosphorlc acid. An especially preferred
phosphorus compound is ammonium hydrogen phosphate.
The phosphorus compound is employed neat or
as a solution in an organic or inorganic solvent thereby
simplifying contacting with the magnesium silicate and
separation thereof. After contacting with the phos-
phorus compound the modified porous magnesium silicates
of the invention are prepared by drying and calcining
thereby converting the phosphorus compound to the oxide
for catalytic use. Calcining may be accomplished by
heating to elevated temperatures of at least about
300C and preferably at least about 400QC in the pre-
sence of oxygen for a time sufficient to convert sub-
stantially all of the phosphorus to the oxide. Sui-t-
able calcination times are from about 1 hour to several
hours or even days.
The phosphorus modified porous magnesium sil-
icates of the present invention preferably contain from
about 0.5 percent to about 20 percent by weight of an
oxide of phosphorus calculated as phosphorus. Preferred
31,372A-E -20-
-21-
modified compounds contain from about 1 percent to
about 6 percent by weight phosphorus. A unique feature
of the present compounds lies in the particular alkyl-
ation of toluene by reaction with ethylene, where
amounts of phosphorus greater than about 6.0 percent
lead -to catalyst inac~ivation, whereas amounts of
phosphorus from about 2 percent to about 5.9 percent by
- weight, and preferably from abQut 4.5 percent to 5.5
percent by weight are very effective in suppressing the
formation of ortho- and meta-ethyl toluene during the
reaction. The result (at least about 90 percent para-
-ethyl toluene formation) is considered surprising since
phosphorus contents in phosphorus modified aluminosili-
cates such as ZSM-5 are not as effective in suppressing
the formation of ortho- and meta- isomers, and increasing
phosphorus content in such compounds does not appear to
lead to catalyst deactivation. -
The above description and following examplesare given -to illustrate the invention, but these examples
should not be taken as limiting the scope of the inven-
tion to the particular embodiments or parameters demon-
strated since obvious modifications of these teachings
will be apparent to those skilled in the art.
Example 1
. .
A solution _ is made by combining 106 g of
commercially available Philadelphia Quartz Sodium Sili-
cate N~ type (trademark of Philadelphia Quartz Company)
(8.90 weight percent Na2O, 28.7 weight percent SiO2)
with 132 g of H2O. A second solution B is made by
combining 180 g of H2O, 40 g of NaCl, 26 g of (C3H7)4NBr,
31,372A-F -21-
~, ~'f't~
22 -
1 0 . 2 g MgC12 6H2O and 8 g of concentrated H2SO4 (96
weigh-t percent) to form a clear solution.
Solution A is transferred to a Waring~ blender
and the blender is s-tarted at the lihigh" setting.
Solution B is added at once and the mixture is stirred
vigorously for 1 minute. The resulting slurry is then
placed inside a stainless steel autoclave, heated to
about 150~C under autogenous pressure and stirred.
After 24 hours, the autoclave is cooled to room tem-
perature and the solid product is isolated by filtra-
tion. The filter cake is washed several times with
much water and then air dried at about 110C into a
free flowing powder.
The above prepared porous magnesium silicate
is calcined for 15 hours at 550C in air to remove the
quaternary ammonium salt from the internal pores.
Next, the material is slurried with l.ON NH4NO3 solution,
at a temperature of at least 80C overnight. The
resulting material is filtered, washed with deionized
water and dried at 110C.
Ten grams of this material is spread into a
thin layer in a large petri dish and sufficient (N~4)HPO4
solution (25 weight percent concentration) is added
dropwise to the powder with a syringe to provide 4.7
percent phosphorous based on dry catalyst weight. The
moistened powder is then mixed well with a spatula.
The powder is first dried at room temperature and then
at 110C. The dried catalyst is mixed with kaolin
clay, 1/2 part clay per part catalyst, and enough water
is added to form a moist cake. The cake is dried, first
31,372A-F -22-
-23-
at room -temperature, then at 110C, and then calcined
at 550C for 5 hours in air.
The calcined catalyst is crushed and tested
in the alkylation of toluene with ethylene. Eight
grams of catalyst are loaded in a 1/2-inch (1.3 cm~
diameter stainless steel reactor tube. The operating
conditions of the reaction are: tem~erature 41DC,
pressure 100 psi (690 mPa), toluene flow rate 104.7 g/hr,
ethylene flow rate 60 cm3/min, H2 flow rate 140 cm3/min,
WHSV = 13, molar ratio toluene/ethylene = 7.6, molar
ratio ethylene/hydrogen = 2.3. Data are obtained
during a continuous run lasting four days. At the end
of two days, the temperature is increased to 440C.
The initial ethylene conversion is about 80 percent
falling to a level of about 60 percent prior to increase
in reaction temperature. Selectivity to para ethyl-
toluene is at least 96 percent during the entire
reaction period.
31,372A-E -23-
