Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates to the catalytic crackiny
of hydrocarbonaceous feeds containing metals and in particular
to the cracking of these feeds with fluid catalysts which have
improved metals tolerant characteristics.
There is a continually increasing demand for gasolines,
coupled with shrinking supplies of normally used cracking stocks~
such as gas oils. As a result, more attention has recently ~een
directed to the catalytic cracking of heavier charge stocks such
as residuals. One of the primary problems with these stocks is
their high metals content which tends to deposit on the catalyst
and decrease its desirable cracking characteristics. The term
"metals" in this application refers to free metals or relatively
non-volatile metal compounds. Many petroleum charge stocks con-
tain at least traces of many metals and in addition to the metals
which are naturally pre~ent, petroleum stocks have a tendency to
pick up iron because of transportation, storage and processing
in iron equipment. Substantially all of the metals are present in
an organo-metallo form, suCh as, for example, in a porphin ring or
as a naphthenate. The metals in the petroleum charge stock tend
to deposit in a relatively non-volatile form onto the catalyst
during the cracking process, and regeneration of the catalyst to
remove coke does not remove these contaminants which have an
adverse effect on cracking resuljs when using convent-onal
-- , , : ~, . .
- . . . . - . ~
' ' : : : . . , , .
- : , . '
.,., :~ , ~ '
:. , ' . . : , '
,: . ' . ';
'' , . ~ ` , ,,
, ~ : ', ` . ' ` : ', ' : '
.. ::.' ` ' ' ,` ` . ' : ' ~ . ,
o~
cracking catalysts. Examples of typical metals which can be
present include: nickel, vanadium, copper, chromium, and iron.
Further, the use of æeolitic cracking catalysts has become of
increased importance due to the higher activity characteristics
of these materials (see "Recycle Rates Reflect FCC Advances", by
J. ~. Montgomery, Oil & Gaq Journal, Dec. 11, 1972, pp. 81-86).
Unfortunately, these zeolitic cataly~ts are also susceptible to
metals poisoning.
of course, a number of methods have been proposed in
the past to overcome the problems associated with the cracking
of metals contaminated feedstocks. Suggestions have been made
to pretreat the contaminated feed to reduce the content of
metals to bel~w about 1 to 4 parts per million by volume. Feeds
have also been carefully fractionated to exclude the heavier gas
oils and residue materials where the major metal contaminants are
concentrated. Still other techniqueY are directed to removing
the metal contaminants once they have been deposited on the
catalyst. Most of these techniques, however, require expensive
additional equipment and chemicals which are not justified from
an economic standpoint.
i The above problems are overcome in accordance with the
present lnvention by providing an improved metals tolerant crack-
ing catalyst which incorporates in part the desirable higher
activity characteristics of zeolites.
In accordance with the in~ention, an improved process
for the catalytic cracking of a high metals content feedYtock
is achieved by cracking the feedstock in the absence of added
hydrogen and in the presence of a catalyst comprising from 1 to 40
weight percent of a zeolite having cracking characteristics dis-
persed in a refractory metal oxide matrix having a pore size dis-
tribution such that less than 20 volume percent of the pores have a
pore diameter of less th2n 50 A, and the average pore diameter
, .
2 ~
, :. . .. . .
IS at least about 100 ~ . The new ~etals tolerant catalyst can
be used in pellet form for a fixed-bed operation; powder form
for fluid bed operation; or in bead form for a moving bed opera-
tion. The fluid bed operation is preferred. The improved metals
tolerant catalyst composition of this invention comprises as one
component a crystalline aluminosilicate , preferably exchanged
with rare earth metal cations. This crystalline aluminosilicate,
sometimes referred to as the "rare earth zeolite", is dispersed
in a large pore refractory metal oxide materix. Catalysts compris-
ing a crystalline aluminosilicate zeolite dispersed ln a refractorymetal oxide matrix are disclosed, for example, in U. S. Patents
3,140,249 and 3tl40,253 to C. J. Plank and E. J. Rosinski.
Typical zeolites or molecular sieves having cracking ~ -
activity which can be suitably dispersed in a matrix for use as -
a catalytic cracking catalyst are well known in the art. Suitable
zeolites are described, for example, in U. S. Patent 3,660,274
to James J. Blazek et al. Synthetically prepared zeolites are
are initially in the form of alkali metal aluminosilicates.
~ The alkali metal ions are exchanged with rare earth metal ions
i 20 to impart cracking characteristics to the zeolites. The zeolites
are, of course, crystalline, three-dimensional, stable structures
containing a large number of uniform openings or cavities inter-
connected by smaller, relatively uniform holes or channels. The
effective pore size of synthetic zeolites is suitably between
six and 15 A in diameter. The overall formula for the zeolites
can be represented as follows:
XM2/no:Al2o3:l-5-6-5 SiO2 YH2O
where M is a metal cation and n its valence and x varies from
0 to 1 and y is a function of the degree of dehydration and
' `" . .
. . - . : ~ : . .
1C~4i(~
varies from 0 to 9. M is preferably a rare earth ~etal cation
such as lanthanum, cerium, praseodymium, neodymium or mixtures of
these.
Zeolites which can be employed in accordance with this
invention include both natural and synthetic zeolites. These
zeolite~ include gmelinite, chabazite, dachiardite, clinoptilolite,
faujasite, heulandite, analcite, levynite, erionite, sodalite,
cancrinite, nepheline, lazurite, scolecite, natrolite, offretite,
mesolite, mordenite, brewsterite, ferrierite, and the like. The
fau~asites are preferred. Suitable synthetic zeolites which can
be treated in accordance with this invention include zeolites X,
Y, A, L, ZK-4, B, E F, H J, M, Q? T, W, Z, alpha and beta,
ZSM-types and omega, The term "zeolites" as used herein contem-
plates not only aluminosilicates but substances in which the
aluminum is replaced by gallium and substances in which the silicon
is replaced by germanium
The preferred zeolites for this invention are the syn-
thetic faujasites of the types Y and X or mixtures thereof.
It is also well known in the art that to obtain good
cracking activity the zeolites have to be in a proper form. In
most cases this involves reducing the alkali metal content of the
zeolite to a~ low a level a~ po~sible. Further, a high alkali
metal content reduces the thermal structural stability, and the
effective lifetime of the catalyst will be impaired as a conse-
quence thereof. Procedures for removing alkali metals and putting
the zeolite in the proper form are well known in the art as
described in U. S. Patent 3,537,816.
. .
The cryqtalline alumino~ilicate zeolite~, such as
~ynthetic faujasite, will under normal conditions cry~tallize
as regularly shaped, discrete particles of approximately one
,.
~4~
1(~4~
to ten microns in size, and, accordingly, this is the size
range normally used in commercial catalysts. Preferably the
particle size of the zeolites is from 0.5 to lO~micronR and
more preferably is from 1 to 2 micron~ or leas Crystalline
zeolites exhibit both an interior and an exterior surface area,
with the largest portion of the total surface area being internal.
Blockage of the internal channels by, for example, coke forma-
tion and contamination by metals poisoning will greatly reduce
the total surface area. Therefore, to minimize the effect of
contamination and pore blockage, crystals larger than the normal
size cited above are preferably not used in the catalysts of
thi8 invention
It has now been discovered that when the above described
zeolites are dispersed in a matrix material having defined large
pore size characteristics, the resulting catalyst has unu~ually
improved metals tolerant characteristics and can be utilized
much more effectively in the catalytic cracking of high metals
content hydrocarbonaceous feedstocks, such as residues or full
crudes. While it is not certain, it is believed the metals from
20 the charge stock deposit themselves in the large pores of the
matrix rather than on the zeolitic catalyst sites, and thus the
matrix sacrifices itself and prolongs the useful life of the
catalytically active zeolitic material. The matrix material can
suitably be formed from any refractory metal oxide or clay and
is preferably formed from at leaet a portion of alumina. By a
"portion" is meant greater than 25% by weight of alumina. Most
preferably the matrix contains over 50/O by weight of alumina.
The remainder of the matrix material can be any other well known
refractory metal oxide such as silica, magnesia, zirconia or
30 mixtures of these materials or suita~le large pore clays.
--5--
,
It is preferred that the matrix material be a substan-
tially homogeneous refractory metal oxide or mixture of metal
oxides which can be made in situ or made separately and thoroughly
blended. The refractory metal oxides making up the matrix can
be crystalline or amorphous or partially crystalline. It is
within the ambit of this invention to include matrices of discrete
portions of several refractory metal oxides, and in these instances
it is preferred that each discrete portion of the matric have the
pore size distribution characteristics set forth herein. It is
possible, of course, to incorporate small amounts of inert low
average pore size refractory oxides in the matrix. The pore size
distribution characteristics of the total matrix must, of course,
conform to the limits set forth herein.
The particular method of forming the catalyst matrix
does not form a part of this invention. Any method which produces
the desired large pore size characteristics can suitably be
employed~ Large pored refractory metal oxide materials suitable -
for use as a matrix can be obtained as articles of commerce from
catalyst manufacturers or they can be prepared in ways well known
in the art such as described, for example,in U.S.Patent 2,890,162.
Whatever matrix material is chosen and whatever method
of preparation is employed, the resulting matrix material must
contain relatively large pores. A suitable pore size distribution
would be such that less than 20 volume percent of the pores have
o ~ ~
a pore diameter less than 50 A . In one preferred form, less than ~ -
five volume percent of the pores have a pore diameter above 600 A.
In addition, the matrix material must have an average pore dia-
meter of at least 90 A and preferably the average pore diameter -~
o
is at least 100 A. The upper limit for the average pore diameter
is suitably about 350 A, although usually an upper limit of
275 A is satisfactory.
,~
3 ~ 3
lQ-~O~l
A suitable method of determining the average pore
radius of a matrix material is by the BET method, described,
for example, in S. Brunauer, "The Adsorption of Gases and
Vapors", Vol. l, Princeton University Press, 1943. The average
pore diameter is, of course, a numerical value of twice the
average pore radius.
For purposes of this invention, the determination of
the average pore radii of the matrix matbrial occurs after the
fresh dried matrix material is calcined at 1000F. in air for
10 hours. No other pretreatment should occur prior to
determination of the average pore radii and the determina-
- tion of the pore size distribution as defined above. It is
recognized that other pretreatment# or post-treatment~ such
- as steaming, the presence of a particular type of zeolite, and
the amount of zeolite, will affect the average pore diameter of
the matrix and the average pore diameter of the total composited
material, Since average pore diameter is an additive function,
the average pore diameter of a composited material made up of ;
a large-pored matrix and a relatively small-pored zeolite will
be adjusted according to the amounts and types of the zeolite
. .
and large-pored matrix portions. A proper correlation can be
obtained by one having ordinary skill in the art between the
amount and type of zeolite admixed with the large-pored matrix
and the average pore radius of the final catalyst. Thus it is
possible through routine exper1ments to correlate the decroase
in the average pore radius of a final composited catalyst with
the amount and type of zeolite incorporated therein. For
example, for every l weight percent of a synthetic faujasite
composited with a large-pored silica alumina matrix, a 1.3
percent decrease in average pore diameter of the finished cata-
lyst was experienced. With such a correlation, back calculation
of the average pore radius of the matrix can be obtained.
-7-
~' . : .
The amount of the zeolitic material to disperse in the
matrix can suitably be from 1 to 40 weight percent, preferably
2 to 30 weight percent, and most preferably from 5 to 25 weight
percent of the final catalyst. The method of forming the final
composited catalyst also forms no part of this invention, and any
method well known to those skilled in this art is acceptable. For
example, finely divided zeolite can be admixed with the finely
divided matric material, and the mixture spray dried to form the
final catalyst. Other suitable methods are described in U. S.
Patents 3,271,418; 3,717,587; 3,657,154; and 3,676,330. The
zeolite can also be grown on the matrix material if desired.
The above described composite catalysts have a high
tolerance to metals and thus the catalyst compositions are par-
ticularly useful in the cracking of high metals content charge
stocks. Suitable charge stocks include crude oil, residuums or
other petroleum fractions which are suitable catalytic cracking
charge stocks except for the high metals contents. A high metals
content charge stock for purposes of the process of this invention
is defined as one having a total metals concentration equivalent
to or greater than a value of ten as calculated in accordance with
the following relationship:
Equation I
; 10[Ni] + [V] + [Fe] - 10
where [Ni], [V] and [Fe]are the concentrations of nickel, vanadium
and iron, respectively, in parts per million by weight. It is
to be understood that the catalyst compositions described above
:
- 8 -
~ , :, . , ~ ,: ,
1(~4~0~
can be used in the catalytic cracking of any hydrocarbon charge
stock containing metals, but is particularly useful for the treat-
ment of high metals content charge stocks since the useful life
of the catalyst is increased. The charge stocks can also be
derived from coal, shale or tar sands. Thus charge stocks which
have a metals content value of at least 10 in accordance with
Equation I cannot be treated economically in commercial processes
today due to high catalyst make-up rates, but can now be treated
utilizing the catalyst compositions described above. Typical
feed~tocks are heavy gas oils or the heavier fractions of crude
oil in which the metal contaminants are concentrated Usually
the charge stocks have a metals value of less than 5000 by Equa-
tion I although charge stocks having higher values can be used.
Particularly preferred charge stocks for treatment by the process
of this invention include deasphalted oils boiling above 900F.(482C.?
at atmospheric pressure: heavy gas oils boiling from 650F. to
1100F. (343C. to 593C.) at atmospheric pressure; atmospheric
or vacuum tower bottoms boiling above 650F.
; The preferred method of operating the process of this
invention is by fluid catalytic cracking. Hydrogen is not added
to the reaction. A suitable reactor-regenerator system for per-
forming this aspect of the invention is shown in ~he attached
Figure 1. The cracking occurs in the presence of a fluidized
- composited catalyst described above in an elongated reactor tube 10
which is referred to as a riser. The riser has a length to dia-
meter ratio of above 20 or above 25. The charge stock to be
cracked is passed through preheater 2 to heat it to about 600F.
(315.6C.) and is then charged into the bottom of riser 10 to
the end of line 14. Steam is introduced into oil inlet line 14
through line 18. Steam is also introduced independently to the
bottom of riser 10 through line 22 to help carry upwardly into
the riser regenerated catalyst which flows to the bottom of the
_9_
.
1031
- riser through transfer line 26.
The oil charge to be cracked in the riser is, for
example, a heavy gas oil having a boiling range of about 650F.
to 1100F. The steam added to the riser can amount to about
10 weight percent based on the oil charge, but the amount of steam
can vary widely. The catalyst employed is a composite zeolite -
large pore matrix material in a fluid form and is added to the
bottom of the riser. The riser temperature range is suitably
about 900F. to 1100F. (482C. to 5~3C.) and is controlled by
10 measuring the temperature of the product from the riser and then ~-
adjusting the opening of valve 40 by means of temperature controller
42 which regulates the inflow of hot regenerated catalyst to the
; bot~om of riser 10. The temperature of the regenerated catalyst
is above the control temperature in the riser so that the incoming
catalyst contributes heat to the cracking reaction. The riser
pressure is between about 10 and-35 psig. Between about 0 and 5
percent of the oil charge to the riser can be recycled. The
residence time of both hydrocarbon and catalyst in the riser is
;. : . . .
: very small and ranges from 0.5 to 5 seconds. The velocity through
the riser is about 35 to 55 feet per second and is sufficiently
high so that there is little or no slippage between the hydrocarbon
and the catalyst flowing through the riser. Therefore no bed of
catalyst is permitted to build up within the riser whereby the
density within the riser is very low. The den~ity within the riser
is a maximum of about 4 pounds per cubic foot at the bottom of the
ri~er and decreases to about 2 pounds per cubic foot at the top
of the riser. Since no dense bed of catalyst is permitted to
build up within the riser, the space velocity through the riser
is unusually high and will have a range between 100 or 120 and
600 weight of hydrocarbon per hour per ins~antaneous weight of
catalyst in the reactor. No significant catalyst buildup within
the reactor is permitted to occur, and the instantaneous catalyst
~:
--10--
. .. ~ ~, .
:
- : ., : . :-
: . ~
i~4~Q3~L
inventory within the riser is due to a flowing catalyst to oil
weight ratio between about 4:1 and 15:1, the weight ratio corres-
ponding to the feed ratio.
The hydrocarbon and catalyst exiting from the top of
each riser is passed into a disengaging vessel 44. The top of
the riser is capped at 46 so that discharge occurs through lateral
- slots S0 for proper dispersion. An instantaneous separation between
hydrocarbon and catalyst occurs in the disengaging vessel. The
hydrocarbon which separates from the catalyst is primarily gasoline
together with some heavier components and some lighter gaseous
components. The hydrocarbon effluent passes through cyclone system
54 to separate catalyst fines contained therein and is discharged
to a fractionator through line 56. The catalyst separated from
hydrocarbon in disengager 44 immediately drops below the outlets
of the riser so that there is no catalyst level in the di~engager
but only in a lower stripper section 58. -Steam is introduced into
catalyst stripper section 58 through sparger 60 to remove any
entrained hydrocarbon in the catalyst,
Catalyst leaving stripper 58 passes through transfer
line 62 to a regenerator 64. This catalyst contains carbon deposits
which tend to lower its cracking activity and as much carbon as
possible-must be burned from the surface of the catalyst. This
burning is accomplished by introduction to the regenerator through
line 66 of approximately the stoichiometrically required amount of
air for combustion of the carbon deposits. The catalyst from the
stripper enters the bottom section of the regenerator in a radial
and downward direction through transfer line 62. Flue gas leaving
the dense catalyst bed in regenerator 64 flows through cyclones 72
wherein catalyst fines are separated from flue gas permitting the
flue gas to leave the regenerator through line 74 and pass through
a turbine 76 before leaving for a waste heat boiler wherein any
carbon monoxide contained in the flue gas is burned to carbon
104~)31
dioxide to accomplish heat recovery. Turbine 76 compresses
atmospheric air in air compressor 78 and this air is charged to
the bottom of the regenerator through line 66.
The temperature throughout the dense catalyst bed in
the regenerator is about 1250F (676,7C.). The temperature
of the flue gas leaving the top of the catalyst bed in the
regenerator can rise due to afterburning of carbon monoxide to
carbon dioxide. Approximately a stoichiometric amount of oxygen
is charged to the regenerator,and the reason for this is to
minimize afterburning of carbon monoxide to carbon dioxide above
the catalyst bed to avoid in~ury to the equipment, since at the
temperature of the regenerator flue gas some afterburning does
occur. In order to prevent exce~sively high temperatures in
the regenerator flue gas due to afterburning, the temperature
of the regenerator flue gas is controlled by measuring the tem-
perature of the flue gas entering the cyclones and then venting
some of the pressurized air otherwise destined to be charged to
the bottom of the regenerator through vent line 80 in response
to this measurement. The regenerator reduces the carbon content
20 of the catalyst from 1 + 0.5 weight percent to 0.2 weight percent
or less. If required, steam is available through line 82 for
cooling the regenerator. Makeup catalyst is added to the bottom
of the regenerator through line 84. Hopper 86 i9 disposed at
the bottom of the regenerator for receiving regenerated catalyst
to be pa~sed to the bottom o the reactor riser through transfer
line 26. ;~
The reaction temperature in accordance with the above
described process i5 at least about 900F. (482.2C.). The upper
limit can be about 1100F. (593.3C.) or more. The preferred
30 temperature range is 950F. to 1050F. (510C. to 565.6C.). ~
The reaction total pressure can vary widely and can be, for -
example, 5 to S0 psig (0.34 to 3.4 atmospheres), or preferably,
-12-
, -
1~41V~
20 to 30 psig (1.36 to 2.04 atmosphereg) The maximum residence
time is 5 seconds, and for most charge stocks the residence time
will be about 1.5 or 2.5 seconds or, le88 commonly, 3 or 4
seconds. ~or high molecular weight charge stocks, which are
rich in aromatics, residence times of 0.5 to 1.5 seconds are
suitable in order to crack mono- and di-aromatics and naphthenes
which are the aromatics which crack most easily and which produce
the highest gasoline yield, but to terminate the operation before
appreciable cracking o polyaromatics occurs because these mate-
rial~ produce high yields of coke and C2 and lighter ga~es. Thelength to diameter ratio of the reactor can vary widely, but
the reactor should be elongated to provide a high linear velocity,
such as 25 to 75 feet per second; and to this end a length to
diameter ratio above 20 or 25 is suitable. The reactor can have
a uniform diameter or can be provided with a continuous taper or
a stepwise increa~e in diameter along the reaction path to main-
tain a nearly constant velocity along the flow path. The amount
of diluent can vary depending upon the ratio of hydrocarbon to
diluent desired for control purposes. If ~team is the diluent
: ;
employed, a typical amount to be charged can be about 10 percent
by volume, which is about 1 percent by weight, based on hydrocarbon
charge. A suitable but non-limiting proportion of diluent gas,
such as steam or nitrogen, to fresh hydrocarbon feed can be 0.5
-~ to 10 percent by weight.
The catalyst particle size must render it capable of
fluidization as a disperse phase in the reactor. Typical and
non-limiting fluid catalyst particle size characteristics are
as follows:
Size (Micron~) 0-20 20-45 45-75 >75
Weight percent 0-5 20-30 35-55 20-40
These particle sizes are u~ual and are not peculiar to this inven-
tion. A suitable weight ratio of catalyst to total oil charge
-13-
1~411~3~
is about 4:1 to about 12:1 to 15:1 or even 25:1, generally,
or 6:1 to 10:1 preferably. The fresh hydrocarbon feed is
generally preheated to a temperature of about 600F. to 700F.
(316C. to 371C.) but is generally not vaporized during preheat,
and the additional heat required to achieve the desired reactor
temperature is imparted by hot, regenerated catalyst.
~ he weight ratio of catalyst to hydrocarbon in the feed
is varied to affect variations in reactor temperature. Further-
more, the higher the temperature of the regenerated catalyst
10 the less catalyst is reguired to achieve a given reaction tempera-
ture. Therefore, a high regenerated catalyst temperature will
permit the very low reactor density level set forth below and
thereby help to avoid backmixing in the reactor. Generally
cataly~t regeneration can occur at an elevated temperature of
about 1240F. or 1250F. ~671.1C. or 676.6C.) or more to
reduce the level of carbon on the regenerated catalyst from
about 0.6 to 1.5 to about 0.05 to 0.3 percent by weight. At
usual catalyst to oil ratios in the feed, the quantity of cata-
lyst is more than ample to achieve the desired catalytic effect
20 and therefore if the temperature of the catalyst is high, the
- ratio can be safely decreased without impairing conversion. Since
- zeolitic catalysts are particularly sensitive to the carbon level
on the cataly~t, regeneration advantageously occurs at elevated
temperatures in order to lower the carbon level on the catalyst
to the stated range or lower. Moreover, since a prime function
of the catalyst is to contribute heat to the reactor, for any
given desired reactor temperature the higher the temperature of
the catalyst charge, the less catalyst is required. The lower
the catalyst charge rate, the lower the density of the material
30 in the reactor. As stated, low reactor densities help to avoid
backmixing.
-14-
The reactor linear velocity, while not being 80 high
that it induces turbulence and exces3ive backmixing, must be
sufficiently high that substantially no catalyst accumulation
or buildup occurs in the reactor because such accumulation itself
leads to backmixing. (Therefore, the catalyst to oil weight
ratio at any position throughout the reactor i9 about the same
as the catalyst to oil weight ratio in the charge.) Stated
another way, catalyst and hydrocarbon at any linear position
along the reaction path both flow concurrently at about the same
linear velocity, thereby avoiding significant slippage of cata-
lyst relative to hydrocarbon. A buildup of catalyst in the
reactor leads to a dense bed and backmixing, which in turn
increases the residence time in the reactor for at least a por-
tion of the charge hydrocarbon induces aftercracking. Avoiding
a catalyst buildup in the reactor results in a very low catalyst
inventory in the reactor, which in turn results in a high space
velocity. ~herefore, a space velocity of over 100 to 120 weight
of hydrocarbon per hour per weight of catalyst inventory is
highly desirable. The space velocity should not be below 35
and can be as high as 500. Due to the low catalyst inventory
and low charge ratio of catalyst to hydrocarbon, the density of
the material at the inlet of the reactor in the zone where the
feed is charged can be only about 1 to less than 5 pounds per
cubic foot, although these ranges are nonlimiting. An inlet
density in the zone where the low molecular weight feed and
catalyst is charged below 4 or 4.5 pounds per aubic foot is
desirable since this density range is too low to encompass dense
bed systems which induce backmixing. Although conversion falls
off with a decrease in inlet density to very low levels, it has
been found the extent of aftercracking to be a more limiting
feature than total conversion of fresh feed, even at an inlet
density of less than 4 pounds per cubic foot. At the outlet
-15-
- '
~(3~031
of the reactor the density will be about half of the density
at the inlet because the cracking operation produces about a
four-fold increase in mols of hydrocarbon. The decrease in
density through the reactor can be a measure of conversion.
The above conditions and description of operation are
for the preferred fluid bed riser cracking operation. For
cracking in the older conventional fluid bed operation or in
a fixed-bed operation, the particular reaction conditions are
well known in the art and form no part of this invention.
The invention will be further described with reference
to the foilowing experimental work.
The fresh catalysts which were evaluated for metals
tolerance in accordance with the proce9s of this invention were
heat shocked at 1100F. for one hour, contaminated with nickel
and vanadium by impregnation with nickel and vanadium naphthenates,
followed by a calcination at 1000F. (537.8~.) for 10 hours
and a steam treatment at 1350F. (732 2C,) for 10 hours. As
noted earlier, the average pore radii were determined after
calcination but before the steam treatment. In the Tables below,
the contaminated catalysts are defined as containing a given
amount of "Ni Equivalents, ppm", and thls term means the total
ppm of nickel plus one-fifth of the total ppm of vanadium by
weight deposited on the catalyst by impregnation with the nickel
; and vanadium naphthenates. Fresh catalysts synthetically con-
taminated by this technique were found to display activity
characteristics very similar to those of equilibrium catalysts
contaminated by on-stream usage. The excellent activity correla-
tion of "in situ" and synthetically contaminated cracking catalysts
is shown on Figure 2 attached.
Referring to Figure 2, all of the data were obtained
using a standard commercially available cracking catalyst whose
as received properties are shown in Table I below:
,.~
-16-
4:~31
TABLE I
. _
Catalyst: Fresh standard composite cracking
catalyst consisting of about 10
weight percent zeolite having
cracking characteristicc disper~ed
in an halloysite matrix
. ~
MAT Activity: 62%
Total Pore Volume: 0.27 cc/g
Surface Area:221 m2/g
.
The "MAT Activity" was obtained by the use of a micro-
activity test (MAT) unit similar to the standard Davison M~T
Isee Ciapetta, F.C. and Henderson, D.S., Oil & Gas Journal, 65,
- 88 (1967). All cataly~t samples were tested at 900F. (482.2C.)
reaction temperature; 15 weight- hourly space velocity; 80 seconds
of catalyst contact time; and a catalyst to oil ratio of 2.9.
The charge stock was a Kuwait gas oil having a boiling range
of 500F. to 800F. (260C. to 426.7C.). Inspections of this
Kuwait gas oil are shown on Table II below.
- ' : -
- '
--17--
-
(~4~V~
.
T~BLE II
KUWAIT GAS OIL INSPECTIONS
~ .
Stock MAT
Identification Feedstocks
Inspections:
Gravity, API, D-287 23.5
Viscosity, SUS D2161, 130F 94.7
"150F. 70.5
" " " 210F.50.8
Pour Point, D97, F. +80
Nitrogen, wt % 0.074
Sulfurj wt % 2.76
Carbon, Res., D524, wt % 0.23
Bromine No., D1159 5.71
Aniline Point, F. ~ 176.5
~ickel, ppm ~ 0.1 ~ -
Vanadium, ppm < 0.1
Distillation, D1160 at 760 mm
End Point, F. 800
5 Pct. Cond. 505
Approx. Hydrocarbon
Type Analysis: Vol %
Carbon as Aromatics 23.1
" " ~aphthenes 10.5
" " Paraffins 66.3
The curves in Figure 2 designated U, U', U" and U"'
refer to the data obtained using a series of standard commercially
available cracking catalysts which had been contaminated to metal
level~ of 600, 850, 1,200 and 1,912 nickel equivalents either by
30 actual use in a commercial FCC unit or by prolonged teqting in a
pilot plant charging gas oils. The curves designated S, S', S"
and S "' refer to the data obtained using a synthetically con-
taminated series of the same commercial catalyst. The metal
level~ used in this series and for the data shown in Figures 3-10
are presented in Table III below.
'~ .
-18-
, . , . ' . ~ . ~ . ' .. . :, .
.. . . ~ : -.. . . .
1(341()31
TABLE III
. ~ .
Levelæ of Nickel and Vanadium
Deposited on the Fresh Cracking
Catalyst Sh~wn in Table ~ above
_ .
Level Wt, % Wt. % Nickel
No. Nickel Vanadium Equivalents
. . . ~ . .................... .
1 0.045 0.075 600
2 0.06 0.125 850
3 0.075 0.225 1200
4 0.17 0.106 1912
` 5 0.24 0.30 3000
:, .
Since an excellent activity correlation is shown, the
ynthetic method of metals contamination was u~ed in the data
to follow using various pore size matrices.
Several different types of matrix materials were employed
in the Examples to follow, and the characteristics of these matrices
are shown in-Tables rv and V below.
TABLE IV
Matrix ~roperties After
Heat Treatment at 1000F.
~or 10 Hours
~i . . .
Matrix Matrix Avg.Pore Total Surface
Letter Material Diameter Pore Vol. Area
A cc/g m2/g
_ ..
Al Halloysite
aluminum 61.4 0.22 144
8 ilicate
clay)
~2 Silica alumina
(75% Si02: 81.8 0.89 487.4
25% A123 )
cl A123 63.8 0.36 403
Dl Treaied 113.6 0.36 151
~60~fi sio~: -
40% A12~3)
ESilica alumina
(72% SiO2: 253.8 0 87 - 242
~ 128% Al2o3~ .
- F A123 100.6 0.56 223.3
-Gl A123 186.0 0.63 180.7
___________________________ ____ __________ .
tl) crystalline
(2) amorphous ;
.
- ' --19--
~,., ~ . ;. ., , ~ ,
L03~
TABLE V
Matrix .
Mater~
from A B C D E F G
Tablerv . . _
PoreDia, Vol Vol Vol Vol Vol Vol Vol
A % _ . o/o % % % %
600-500 3.8 0.6 0.4 6.0 8.0 1.9 1.0
500-400 6.1 1.0 0.7 9.3 14.3 4.6 2.3
400-300 7.5 1.7 1.2 12.6 17.9 10.6 7.6
. 300-200 11.2 2.7 2.4 19.1 21.7 26.3 32.9
200-180 3.3 0.8 0.8 4.Q 4.4 5.9 8.2
. 180-1603.7 1.2 1.3 6.0 5.1 6.5 9.7
160-1404.3 1.6 1.6 5.5 4.6 5.1 8.9
140-1205.6 4,7 2.3 6.9 4.4 5.4 7.8
120-1004.6 8.3 4.1 5.5 4.2 4.9 6.3
100-90 3,4 7.3 4.1 4.1 2.0 2.1 ~
. 90-80 3.4 9.2 6.0 3.0 2.4 2.4 J6.1
80-70 3.5 10.5 10.1 3.7 2.2 2.7 ~
70-60 4.4 11.2 12.8 3.3 2.0 2.6 J5.1
: 60-50 5.5 13.0 14.5 4.1 2.5 4.7 ~4 2
50-40 7.3 12.3 16.8 3.3 2.5 6.9 J
40-30 9.6 12.2 16.7 3.6 1.7 7.4 ~
30-20 12.1 1.6 4.4 0.0 0.0 0.0 ~0,0
20-14 0.5 0.0 0.0 0.0 0.0 0.0 0.0
29.9* 26.1*37.9* 6.9* 4.2* 14.3* 4.2
________ __________ ____ ______ _____ ____ __ _ . ---- .
(*) Volume % of pOores having pore diameter of
. less than 50 A. _ ,_
.
For a comparison testing of the matrix materials whose
characteristics are shown in Tables IV and V above, a rare earth -~
exchanged zeolite was dispersed throughout a given matrix prior
to impregnation of the metal contaminants. The zeolite was a
rare earth exchanged Y-type zeolite which was prepared by exchang-
ing a commercially available Y-type zeolite (SK-40 obtained from
Union Carbide Corporation~ with a natural mixture of rare earth
chlorides until the residual sodium content of the zeolite was
0.7 weight percent or less The zeolite had an effective pore
diameter of about 8 to 10 A and an average particle size of 1 to 2
20-
.. . .
1~4~031
microns. The zeolite was dispersed in the matrix by a 24-hour
mechanical mixing of finely divided portions of zeolite and
matrix followed by forming in a press and sieving to 10-20 mesh
5ize graIlUle8.
The zeolite content in the composited catalysts made
from matrices A, B, D, E and G was 12 weight percent in order for
the final composited catalyst to compare in its initial activity
with the commercially available catalyst shown in Table I.
The composited catalyst using alumina matrix C required
22 weigh~ percent zeolite to obtain comparable cracXing activity
since the alumina matrix per se is ess~ntially devoid of cracking
activity.
Composited catalysts using alumina matrix F were prepared
containing both 12 and 22 weight percent zeolite, the lower zeo-
lite content producing, of course, a final catalyst having lower
initial cracking activity.
The metals tolerance of the~e composited catalysts was
compared to the metals tolerance of a commercially available
zeolite-matrix composited catalyst whose properties are shown in
Table I. The data are summarized in a series of Figures 3 through
9 which contain the data plotted as curves labeled S or various
primed S's using composited catalysts prepared from matrices A
through G, respectively. In Figure 8, the curves labeled S repre-
sent the data for the 12% zeolite catalyst, and the curves labeled
SS represent the data for the 22% zeolite catalyst. In addition,
each of the Figures contains reference curves labeled U or various
primed U's which represent data using the commercially available
zeolite-matrix composited catalyst whose properties are shown in
Table I above and which were synthetically contaminated.
Referring to Figures 3, 4 and 5, it is evident the metals
tolerance of these catalysts using relatively small pore matrices
is no better than the standard catalyst. On the other hand, the
use of matrix materials D,E, F and G (defined as large pore materials)
.
definitely results in improved metals tolerance as shown in
Figures 6, 7, 8 and 9.
Referring to Figures 6,7,8 and9, the results show that
with large pore matrices, the rate of deactivation with metals
.i
deposition is significantly reduced such that conversion and
gasoline yields are essentially unaffected over the time period
studied. In addition, a compari~on of Figures 6, 7, 8 and 9 shows
that a preferred large pore matrix should contain a high alumina
content to minimize coke and hydrogen production. Further,
Figure 8 shows that improved metals tolerance is not due to an
increase in the zeolite content becau~e the conversion lineq out
in both the use of the 12 and 22 weight percent zeolite catalysts
but at different levels depending on the zeolite content.
In Figure 10, the metals tolerance of matrix D (see
Tables IV and V above) promoted with 12% rare earth exchanged
Y-zeolite (SK-40 obtained from Union Carbide Corporation) is com-
pared to the metals tolerance of the pure matrix. In Figure 10,
the curves de~ignated "a" and " a' " are for the matrix D promoted
with 12% rare earth exchanged Y-zeolite; the curves marked "b"
and " b' " are for the pure matrix D. Figure 10 shows that, by
itself, matrix D is very susceptible to deactivation by metal
deposition but when promoted with the zeolite, the composited
cataly~t is only slightly affected by an increasing metals content
in the charge stock. These resuIts quggest that the role of the
large pored matrix is to behave as a "sink" for the metal con-
taminants, thereby prolonging the useful life of the more active
zeolite component.
Resort may be had to such variations and modifications
as fall within the spirit of the invention and the scope of the
appended claims.
, ~
-22-
- ~ :
