Note: Descriptions are shown in the official language in which they were submitted.
3 193
BACKG~OUND OF lHE INVENTION
2 Field of the Invention
3 This invention relates to a catalyst composi-
4 tion and its use in catalytic cracking processes. More
particularly, the invention is concerned with a fluid
6 cracking catalyst which has improved activity and selec-
7 tivity for producing high octane gasoline fractions from
8 petroleum gas oil feedstocks.
9 DescriPtion of the Prior Art
As is well known, the catalytic cracking of
11 heavy petroleum fractions is one of the msjor refining
12 operations employed in the conversion of crude petroleum
13 oils to desirable fuel products such as heating oils and
14 high octane gasoline. Illustrative of "fluid" catalytic
conversion processes is the fluid catalytic cracking pro-
16 cess wherein suitably preheated high molecular weight
17 hydrocarbon liquids and vapors are contacted with hot,
18 finely-divided, solid catalyst particles, either in a
19 fluidized bed reactor or in an elongated riser reactor,
and maintained at an elevated temperature in a fluidized
21 or dispersed state for a period of time sufficient to ef-
22 fect the desired degree of cracking to lower molecular weight
23 hydrocarbons suitable as gasoline fractions.
24 A wide variety of petroleum cracking catalysts
are described in the literature and are commercially avail-
26 able for use in fluidized cracking processes. Commercial
27 cracking catalysts currently in use generally comprise a
28 crystalline aluminosilicate zeolite cracking component in
29 combination with an inorganic oxide matrix component.
Typical zeolites combined with the inorganic oxide matrix
31 include hydrogen and/or rare earth metal-exchanged synthetic
32 faujasite of the X or Y-type. The matrix materials gen-
33 erally include amorphous silica-alumina gel and/or a clay
34 material such as, for example, kaolin.
Cracking catalysts which are commercially used
36 for the production of gasoline must exhibit good activity
37 and selectivity. The activity of a catalyst is generally
38 referred to as the ability of the catalyst to convert heavy
. .
petroleum fractions to lower molecular weight fractions.
2 Under a given set of operating conditions, the degree to
3 which the catalyst converts the Eeed to lower molecular
4 weight materials is a measure of the catalyst activity.
5 Thus two or more catalysts can have their activities com-
6 pared by the level of cracked products msde by each cata-
7 lyst under the same process conditions. The selectivity
8 of a catalyst refers to the fraction of the cracked products
9 in a particular boiling or molecular weight range; e.g.,
C5/430F. naphtha, C3- dry gas, carbon, etc. A more speclal
11 measure of selectivity is the octane rating of the C5/430F.
12 naphtha hereafter referred to as octane producibility.
13 Hence it is most desirable for a preferred cracking cata-
14 lyst to exhibit both high cracking activity, a high selec-
lS tivity to gasoline (C5/430F.) boiling range material, and
16 of high octane number producibility, that is the ability
17 to produce gasoline boiling range material with a high oc-
18 tane rating. Unfortunately, catalysts having the highest
19 activity do not produce the highest octane naphtha products
and vice versa. As an example, the amorphous silica-
21 alumina cracking catalyst used prior to the advent of the
22 present day zeolite cracking catalyst is less active than
23 the present day zeolite cracking catalysts for cracking
24 the gas oil feedstock, is less selective in the yield of
C5/430F. naphtha, but produces a higher octane number
26 naphtha than conventional zeolite cracking catalysts.
27 The individual components of the catalyst composi-
28 tion of this invention are described in the literature.
29 The specific combination of the components of the invention
to produce a highly active and selective catalyst for the
31 production of high octane gasoline is not believed to be
32 shown in the prior art. For example, U.S. Patent No.
33 3,312,615 describes a three component catalyst system
34 comprising a crystalline aluminosilicate, substantially
inert fines and an inorganic oxide matrix therefor. The
36 crystalline aluminosilicate includes a wide variety of
37 zeolites such as zeolites X, Y, A, L, D, R, S, T, Z, E,
38 F, Q, B, ZR-4, ZK-5 as well as naturally occurring zeolites
39 including chabazite, faujasite, mordenite, and the like.
~1~1193
-- 3 --
1 The substantially inert fines include alpha-alumina,
2 barytes, zircon, zirconia, kyanite, and rutile fines.
3 U.S. Patent No. 3,542,670 describes a cracking
4 catalyst made by combining a silica-alumina hydrogel with
a boehmite amorphous hydrous alumina, and a crystalline
6 aluminosilicate having pores in the 8 - 15~ range and
7 a silica-to-alumina mol ratio greater than 3:1. The
8 crystalline aluminosilicate includes a variety of zeolites
9 which are exchanged with various ions including hydrogen,
and nonpoisoning metals such as rare earth metals.
11 U.S. Patent No. 3,816,342 is directed to a
12 process for preparing a fluid catalytic cracking catalyst
13 containing a highly act$ve crystalline aluminosilicate
14 and a relatively less active matrix material. The patentee
claims the crystalline aluminosilicate materials having
16 the general formula:
17 M2/nO A1203 YSiO2 ZH20
18 in the salt form, wherein n is the valence of the metal
19 cation M, Y is the number of moles of silica, and ZH20 is
the water of hydration. Zeolites Y and X are described
21 as being among the most suitable synthetic crystalline
22 aluminosilicates. The matrix materials are described as
23 inorganic oxide gels, such as those of silica-zirconia,
24 alumina, magnesia, and combinations thereof with one
another, clays, alumina, metals and refractory materials.
26 U.S. Patent No. 3,930,987 describes a cracking
27 catalyst comprising a composite of crystalline alumino-
28 silicates containing rare earth metal cations dispersed
29 in an inorganic oxide matrix wherein at least 50 wt. %
of the inorganic oxide is silica and/or alumina. The
31 matrix preferably is made up of silica-alumina, silica-
32 zirconia, or silica-zirconia alumina, desirably along
33 with a weighting agent preferably clay and/or alumina.
34 Alpha alumina is preferred in the event alumina is em-
ployed.
36 U.S. Patent No. 3,717,587 describes the prepara-
37 tion of a cracking catalyst composition containing 8 wide
38 variety of crystalline aluminosilicates dispersed in an
39 inorganic oxide gel matrix containing a weighting agent.
11;~3
The patent specifies that the most preferred weiyhting agent
is kaolin clay. Other suitable weighting agents include
zirconia, alpha alumina, mullite, alumina monohydrate, alumina
trihydrate, halloysite, sand, metals such as aluminum and
titanium, etc.
U.S. Patent No. 3,788,977 relates to a cracking catalyst
for increasing the amount of aromatic gasoline fractions from
gas oil feedstocks. The cracking catalyst is described as a
composition comprising a number of zeolite components in
combination with minor amounts of a reforming-like additive
which consists of uranium oxide and/or platinum metal impregnated
upon an inorganic oxide support. The zeolites contemplated by
patentee include hydrogen and/or rare earth metal exchanged
synthetic faujasites which have silica to alumina ratios on the
order of 2.5 up to about 6, including type X or Y faujasties.
In addition to rare earth metal exchanged faujasites, patentee
contemplates the use of low soda content zeolites.
SVMMARY OF THE INVENTION
A cracking catalyst which has improved activity and
selectivity for the conversion of hydrocarbon feedstocks to
high octane gasoline fractions, which comprises (a) the ultra-
stable variety of Y zeolite, (b) alumina, and (c) an inorganic
porous oxide matrix material.
DETAILED DESCRIPTION OF THE INVENTION
The zeolitic component of the catalyst of the invention
comprises a crystalline aluminosilicate zeolite which is com-
monly known as "stabilized" or "ultra-stable" Y-type faujasite.
These types of zeolites are well known. They are described,
for example, in U.S. Patent Nos. 3,293,192 and 3,402,996 and
in the publication, Society of Chemical Engineering (London)
Monograph Molecular Sieves, pp. 186 (1968) by C.V. McDaniel
and P.K. Maher. As used herein, "ultra-stable" refers to a
Y zeolite which is highly resistant to degradation of
crystallinity by high temperatures and steam treatment and
is characterized by an R2O content (where R is Na, K,
~L~ 9~
1 or any other alkali metal ion) of less than about 4 weight
2 %, preferably less than about 1 weight %, and a unit cell
3 size less than about 24.50 angstrom units (A) and an
4 SiO2/A1203 mol ratio in the range of 3.5-7 or higher.
In a preferred embodiment of the invention, the unit cell
6 size of the ultra-stable Y zeolite will be }ess than 24.40
7 ~. The ultra-stable form of the Y zeolite is obtained
8 primarily by the substantial reduction of the alkali metal
9 ion content and the unit cell size reduction subsequent
to the alkali metal removal steps. In other words, the
11 ultra-stable zeolite is identified both by the smaller
12 unit cell and the low alkali metal content in the crystal
13 structure.
14 The ultra-stable form of the Y zeolite can be
prepared, for example, by successively base-exchanging a
16 Y zeolite, i.e., Y-type faujasite, with an aqueous solution
17 of an ammonium salt, such as ammonium nitrate, until the
18 alkali metal content of the Y zeolite is reduced to less
19 than about 4 wt. %, R20 (where R refers to an alkali
metal such as sodium). The base-exchanged zeolite is
21 then calcined at a temperature of 1000F. to 1500F. over
22 a period of time ranging, for example, from 0.5 to 5 hours,
23 to produce an ultra-stable Y zeolite. If desired, steam
24 may be added to the system during the calcination.
Preferably, the ultra-stable Y zeolite is thereafter again
26 successively base-exchanged with an aqueous solution of
27 an ammonium salt until the alkali metal content is re-
28 duced to less than 1 wt. % R20. More preferably, the
29 ultra-stable Y zeolite is then again calcined at a temp-
erature of 1000 to 1500F. with added steam, if desired,
31 to produce an ultra-stable Y zeolite having a unit cell
32 size less than about 24.40 A. This sequence of ion ex-
33 change and heat treatment results in the substantial reduc-
34 tion of the alkali metal content of the original zeolite
and results in unit cell shrinkage which are believed to
36 lead to the ultra high stability of the resultant Y zeo-
37 lite. The particle size of these zeolites is usually in
38 the range of 0.1 - 10 microns, more typically in the
39 range 0.5 - 3 microns.
1193
In a preferred embodiment, the ultra-stable Y-type
zeolite component of the invention will be substantially free
of rare earth metals such as, for example, cerium, lanthanum,
praseodymium, neodymium, promethium, samarium, europium, gado-
linium, terbium, dysprosium, holmium, erbium, yttrium, thulium,
scandium, lutecium and mixtures thereof. By substantially free
is meant that the rare earth metal content of the zeolite will
be less than about 1 wt. ~ as metal oxide (~e2O3). Similarly,
up to about 1 wt. ~ of other metal ions such as magnesium or
calcium may be base exchanged into the zeolite.
The alumina component of the catalyst of the invention
comprises discrete particles of various aluminas which are known
and, in many instances, commercially available. These aluminas
include the anhydrous and/or the hydrated forms. A rather
comprehensive description of aluminas is given in "Encyclopedia
of Chemical Technology", Kirk-Othmer, Second Edition, Volume 2
(Interscience Publishers) at pages 41-55.
Among the aluminas useful in preparing the catalyst
of this invention are discrete alumina particles having a total
surface area (B.E.T. method - Brunauer, Emmett and Teller;
The Van Nostrand Chemist's Dictionary (1953 Edition)) greater
than 20 square meters per gram (m2/g), preferably greater than
145 m2/g, for example, 145 - 300 m2/g. Preferably the pore
volume (B.E.T. method) of the alumina will be greater than
0.35 cc/g. The average particle size of the alumina will
generally be less than 10 microns, more preferably less than
3 microns. These discrete alumina particles used in preparing
the catalyst are sometimes designated as "bulk" alumina.
The term "bulk" is intended herein to designate an alumina
which has been preformed and placed in a physical form such
that its surface area and pore structure is stabilized so
that when it is added to an impure inorganic gel containing
considerable amounts of residual soluble salts, the salts will
not alter the surface and pore characteristics measurably nor
will they promote more than minimal chemical
,,
1 attack on the preformed alumina which could then under-
2 go change. For example, addition of "bulki' alumina will
3 mean a material which has been formed by suitable chemical
4 xeaction, the slurry aged, filtered, dried, washed free
of residual salts and then dried to reduce its volatile
6 contents to less than about 25 wt. %.
7 In addition to the above described bulk,
8 porous, preformed aluminas, it is also envisioned to pre-
9 pare the catalyst by using hydrous slurries of diverse
hydrated aluminas which may be a particular crystalline
11 form, or amorphous, or mixtures. These hydrates include
12 alpha-monohydrate, alpha-trihydrate, beta-trihydrate, and
13 to a lesser de~ree, beta-monohydrate forms of alumina.
14 These are generally made from solutions of aluminum salts
or of alkaline aluminates. Depending on reaction condi-
16 tions, the product aluminas can have a wide range of
17 physical properties. In addition to the foregoing, the
18 alumina slurry can be a gel. Alumina gels generally have
19 a dried solids content of about 2 - 12% by weight. On
drying, the alumina gels lose water progressively and
21 with increasing temperatures the first transision phase
22 (nonhydrated) can be either eta- or gamma- alumina.
23 The presence of discrete particles of crystalline
24 alumina in the catalyst of this invention can be observed
by x-ray diffraction in accordance with well known tech-
26 niques such as described in Advances in X-Ray Diffractometry
27 and X-Ray Spectrographyedited by William Parrish (1962),
28 Centrex Published Company - Eindhoven.
29 The inorganic porous oxide which is used as
the matrix in the catalyst composition of the invention
31 may include any of the readily available porous materials
32 such as alumina, silica, boria, chromia, magnesia, zir-
33 conia, titania, silica-alumina, and the like, and mixtures
34 thereof. These materials may also include one or more of
the various well known clays such as montmorillonite,
36 kaolin, halloysite, bentonite, and the like. Preferably,
37 the inorganic porous oxide will be one or more of the
38 conventional siliceous varieties containing a major amount
39 of silica and a minor amount of an oxide of at least one
-- 8 --
1 metal in Croups II-A, III-A and IV-B of the Periodic
2 Table (Handbook of Chemistry and Physics, 38th Ed., 1957).
3 Representative silica-containing matrix materials include
4 silica-alumina, silica-magnesia, silica-zirconia, silica-
thoria, silica-titania, silica-fllumina-zirconia, silica-
6 alumina-magnesia, etc.
7 In a more preferred embodiment of the invention,
8 the inorganic porous oxide matrix material will be an
9 amorphous silica-alumina gel. As is generally known,
these materials are typically prepared from silica hydro-
11 gel or hydrosol, which is mixed with an alumina source,
12 generally an aluminum salt solution, to secure the desired
13 silica-alumina composition. The alumina content of the
14 silica-alumina matrix will typically range from about 5
to 40 wt. % with the preferred composition having an alumina
16 content of about 10 to 35 wt. %. Various procedures are
17 described in the literature for making silica-alumina,
18 e.g., U.S. Patent Nos. 2,908,635 and 2,844,523.
19 The catalyst composition of the invention will
comprise 5 - 40 wt. %, preferably 10 - 30 wt. %, of the
21 aforedescribed ultra-stable Y zeolite; 5 - 40 wt. %,
22 preferably 10 - 30 wt. %, of alumina; and 40 - 90 wt. %,
23 prefersbly 50 - 80 wt. %, of the porous oxide matrix. It
24 is also within the scope of this invention to lncorporate
in the catalyst other materials commonly employed in
26 cracking catalysts such as various zeolites, clays, metal
27 C0 oxidation promoters, etc.
28 In a preferred embodiment, the catalyst of the inven-
29 - . Wei~ht % Na 0 on total catalyst
tion will have the ratlo Weight % ze~lite in total catalyst
31 equal to or less than 0.013.
32 The catalysts of the present invention may be
33 prepared in accordance with well known techniques. For
34 example, a preferred method of preparing a catalyst of
the invention is to react sodium silicate with a solution
36 of aluminum sulfate to form a silica-alumina hydrogel
37 slurry which is then aged under controlled conditions to
38 give the desired pore properties, filtered to remove a
39 considerable amount of the extraneous and undesired sodium
- 9 -
and sulfate ions and then reslurried in water. Separately,
2 a bulk alumins is made, for example, by reacting solu-
3 tions of sodium aluminate and aluminum sulfate, under
4 suitable conditions, aging the slurry to give the desired
5 pore properties of the alumina, filtering, drying, re-
6 slurrying in water to remove sodium and sulfate ions and
7 drying to reduce volatile matter content to less than 25
8 weight percent. The alumina is then slurried in water and
9 blended, in proper amount, with the slurry of impure
10 silica-alumina hydrogel.
11 The ultra-stable Y zeolite of the invention may
12 then be added to this blend, with a sufficient amount of
13 each component of the catalyst being utilized to give the
14 desired final composition. If desired, the resulting mix-
ture is filtered to remove a portion of the rem~ining ex-
16 traneous soluble salts therefrom and to reduce the amount
17 of liquid present in the slurry. The filtered mixture is
18 then dried to produce dried solids. The dried solids are
19 subsequently reslurried in water and washed substantially
free of the undesired soluble salts using a pH controlled
21 ammonium sulfate solution followed by a water rinse. The
22 catalyst may then be dried to a residual water content of
23 less than about 15 wt. %. Other methods for compositing
24 the components of the invention are known to those skilled
in the art and are meant to be included within the scope
26 of this invention.
27 The feedstocks suitable for conversion in accor-
28 dance with the invention include any of the well known
29 feeds conventionally employed in catalytic cracking pro-
cesses. Usually, they will be petroleum derived, although
31 other sources such as shale oil, tar sands oil, and coal
32 are not to be excluded. Typical of such feeds are heavy
33 and light virgin gas oils, heavy and light virgin naphthas,
34 solvent extracted gas oils, coker gas oils, steam-cracked
gas oils, cycle oils, residua, deasphalted residua, hydro-
36 treated residua, topped crudes, etc. and mixtures thereof.
37 The catalyst of the invention may be employed
38 for the catalytic cracking of the aforementioned feedstocks
39 in accordance with well known techniques. In general, the
g3
- 10 -
1 cracking conditions will include a temperature in the
2 range of about 850 to 1050F., l pressure of O to 50
3 psig. and a feed rate of 1 to 200 W/Hr/W. The catalyst
4 may be regenerated at conditions which include a tempera-
ture in the range of 1100 to 1500F., preferably 1175
6 to 1350F.
7 BRIEF DESCRIPTION OF THE DRAWING
8 The Figure is a graph illustrating the activity
9 and selectivity characteristics of various cracking cata-
lysts which are compared and described in detail in the
11 examples hereinafter.
12 DESCRIPTION OF THE PREFERRED EMBODrMENTS
13 The following examples further illustrate the
14 present invention. Unless otherwise stated, all percentages
refer to weight percentages.
16 Example 1
17 A catalyst of the invention was prepared as
18 follows:
19 A dilute sodium silicate solution containing
20 about 50 g. silica/liter was contacted with C02 to effect
21 gelation, the impure silica hydrosol aged and then blended
22 with a stream of aluminum sulfate. After filtering the
23 impure silica/alumina to remove some of the extraneous
24 soluble salts, the material had a dry solids content of
15.7% and the dry solids analyzed 57.3% SiO2 and 20.2%
26 A1203.
27 In a mixing tank, 35 pounds water were blended
28 with 98. 75 pounds of the above impure silica/alumina
29 hydrogel. In a second mixing tank, 15 pounds of water
were blended with 1824 grams (dry basis) alumina (sold
p~31 under the trade ~ Catapal HP grade by Conoco Chemical
32 Division of Continental Oil Company) and then with stirring
33 1824 grams (dry basis) of low soda content faujasite (sold
34 under the trade ~ Linde 33-200 grade by Union Carbide
Corporation) blended therein. The composite slurry was
36 added to the gel slurry, homogenized by colloid milling
3 7 twice, and then spray dried.
38 The impure material was slurried in warm water
39 to about an 18 wt. % solids content and then filtered.
~ 9 3
1 The filter cake was treated with a 3 wt. % ammonium
2 sulfate solution brought to a pH of 8 with ammonia and
3 finally rinsed with ammoniated water (about 5 lb. solution
4 per lb. catalyst) to remove residual soluble salts and
finally rinsed with water. The resultant catalyst had
6 an Na20 content of 0.17 wt. % and contained about 20%
7 ultra-stable Y zeolite,20% A1203 and 60% (SiO2/A1203)
8 and is designated "A" in subsequent examples.
9 Example 2
The catalyst of Example 1 was compared in activity
11 and selectivity for the production of high octane cat
12 naphthas with various cracking catalysts designated as
13 "B", "C" and "D" which are commercially avsilable or which
14 are representative of cracking catalysts presently employed
in the petroleum industry.
16 Catalyst "B" is a widely used commercial catalyst
17 and contains about 14 - 16% faujasite (Y-type), about 28 -
18 30% kaolin clay and about 55 - 60% silica/alumina gel
19 matrix. The total catalyst contains about 2.8 - 3.5%
rare earths (as oxides). Catalyst "C" is a commercial
21 catalyst and consists of about 5% faujasite (Y-type) and
22 about 95% silica/alumina gel. The faujasite in "C" was
23 exchanged with mixed rare earths and calcined before
24 compositing with the matrix gel. Catalyst "C" contains
about 1.0 - 1.2% rare earths (as oxides). Catalyst "D"
26 contains about 8 - 9% faujasite (Y-type) and about 91 -
27 92% silica/alumina gel matrix. It is believed to contain
28 faujasite pre-exchanged with rare earths and calcined
29 before mixing with the matrix. Catalyst "D" analyzes
about 1.8 - 2.2% rare earths (as oxides). Thus the
31 catalysts of comparison in the following example contain
32 from 5 - 16% faujasite (Y-type), from 1.0 - 3.5% rare
33 earths (as oxides), and a matrix of silica/alumina gel
34 with or without added bulk kaolin. These catalysts are
compared in cracking performance with the catalyst of the
36 invention "A" in Example 3 hereof. Each of these catalysts
37 compared in Example 3 were steamed for 16 hours at 1400F.
38 and 0 psig. to simulate commercial deactivation before
39 testing.
11~1193
- 12 -
1 Example 3
2 Each of the catalysts described in the previous
3 two examples were tested under conditions listed below in
4 a circulating, fluidized bed cat,alytic cracking unit with
reactor and regenerator vessels. The feed used for these
6 experiments is described in Table I. The results of these
7 experiments are listed in Table II.
8 TABLE I
9 Feed
Gravity 27.5 API
11 Sulfur .812 wt. 70
12 Nitrogen 618 ppm
13 Conradson Carbon 0.27 wt. %
14 Aniline Point 171F.
Distillation Range*, C.
16 rBP/5% 249/263
17 10/20% 276/298
18 30/40% 317/341
19 50/60% 366/382
70/80% 416/441
21 90/95% 475/504
22 FBP 513
23 * Atmospheric Pressure
. .
3 -
I~ ~ ~ _~ `J O ~ `D U~ _~ O O u~
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` ~ O O 'D 1~ ~ o
..... ....... ..
,l ~ o o ~ ~ ~ ~ a~
a~
I~ _1 0~1 u~ ~ O ~ 0~ ~ O ~1
I~ O a~O O ~ C~ I ~ O
¢~u~o o ~i~ ~_io u~
a~ oo oo r~
a~
~ C~
¢ u ~ z
E-' 3
~- ~ C
0
0
u
~ O ~ 0 ~ ~ ,i ,~
o ~ o ~ O E3
.C~ ~ ~ +
~o~ ~ o ~ C C~ ~¢
D, ~ ~ ^~ ~ O ~ t~ C C~ ~C
0 bO :~ ~0 1 ~3 ~ ~ 0 oZ ~ o
0 E
o ~ ~ ~ ~ o ~ U
E~ :1 ~ C ~ ^ C ~ 1~ + ~ ~ ~1 ~
O ~: O ~ 0 ~ ~ o ~ ~ o ~ 3
J0~ C ~ J~ ~0 ~ ,~ o a~ J~ z O
~ 0 ~ ~C ~ CO ~ ~ ~ 0~ 0 P' ~ ~ ~; ~ ~;t C
JJ ~ 0 4 0 ~ C ~ ~ P~
g ~ g g
.,
:'
- 14 -
1 The relative activities and octane producibilities
2 of the catalysts tested in this example are shown in the
3 figure wherein octane producibil:ity as measured by 1/2
4 (RONC + MONC) is plotted against catalyst activity as mea-
sured by volume percent conversion at the same cracking
6 conditions. In general, it is seen from the figure that
7 catalyst octane producibility is greater for state of the
8 art catalysts having lower actlvity and vice versa. Un-
9 expectedly, however, the catalyst of this invention was
found to have much higher octane producibility for its
11 activity than prior art catalysts. At the same time, its
12 selectivity for naphtha as measured by volume percent
13 naphtha as a fraction of 430F. conversion yield was found
14 to be equivalent to the prior art catalysts. In fact,
when the potential aLkylate (i.e., propylenes and butylenes
16 yields) produced by all catalysts was considered, the
17 potential gssoline selectivity (cat naphtha plus potential
18 alkylate per unit of conversion) of catalyst A was somewhat
19 better than the state of the art catalysts. This is shown
by Table III.
21 TABLE III
22 Catalyst A B C D
23 C /430F. Naphtha .89 .89 .90 .88
24 5Selectivity
C /430F. Naphtha + 1.21 1.18 1.20 1.18
26 5Alkylate Selectivity
27 ExamPle 4
28 Another catalyst of this invention was prepared
29 as follows:
(a) 22 pounds of faujasite (sold under the trade
31 name Linde T7-Y52 grade by Union Carbide Corporation) were
32 slurried into 100 pounds of water at 135F. In a
33 separate vessel, 9 pounds of ammonium sulfate were dis-
34 solved in 50 pounds of water, followed by the addition of
200 cc H2S04. The acidified ammonium sulfate solution
36 was then added to the faujasite slurry and the mixture
37 heated to 135F. and stirred for 2 hours. The slurry,
38 which had a pH of 4.5, was then filtered, rinsed with
1 hot water and oven dried at about 225F. for 16 hours.
2 (b) The oven dried material from step (a) was
3 placed in shallow trays and heated in a furnace preheated
4 at 1250F. in an atmosphere of flowing steam. The faujasite
was calcined 1 hour at 1250F. and the furnace cooled to
6 500F. in flowing steam before removing. The calcined
7 material had a Na20 content of 5.7% and a unit cell size
8 of 24.62A.
9 (c) The calcined faujasite zeolite from step (b)
was re-treated as described above in step (a). After
11 oven drying, the faujasite was calcined 1 hour at 900F.
12 in ambient air. After cooling, the resultant faujasite
13 had a Na20 content of 2.15% and a unit cell size of 24.50A.
14 It is a stabilized low soda content faujasite (zeolite Y).
(d) In a mixing tank, 40 pounds of water were
16 slurried with 80 pounds of impure silica-alumina hydrogel
17 prepared in the manner of Example 1 (11.3% catalytic solids
18 dry basis). In a second mixing tank, 25 pounds of water
19 were slurried with 1850 grams (1360 grams dry basis) of
a commercial grade alumina. A portion of the alumina was
21 previously calcined at 1000F. for 6 hours and had a sur-
22 face area (BET) of 523 M2/g and a pore volume of 1.08
23 cc/gram with a pore volume of 0.21 cc/gram in pores having
24 diameters in the range of 90 - 200A. To this alumina
slurry was added 1648 grams (1360 grams dry basis) of
26 the calcined stabilized faujasite from step (c) above
27 after ball milling in ambient air. The slurries were
28 combined and then spray dried at about 250F. The com-
29 posite material was washed free of extraneous soluble
salts, filtered, rinsed and dried as described hereinabove
31 in Example 1. The resultant catalyst contained 0.24%
32 Na20 and comprised about 20% ultra-stable Y zeolite, 20%
33 alumina, and 60% silica-alumina gel. It is designated as
34 catalyst "E" in subsequent examples.
Example 5
36 This example illustrates the preparation of a
37 preferred catalyst of the invention.
38 (a) A portion of the stabilized zeolite Y from
39 step (c) of Example 4 above was placed in a dish and
~131~'93
- 16 -
1 charged to a furnace at 1000F. The temperature was2 raised to 1500F., held there for 1 hour, and then allowed
3 to cool. The material analyzed 2.15V/o Na20 and had a unit
4 cell size of 24.38A. The heat treatment reduced the cell
size from 24.50A to 24.38A.
6 (b) 3.0 pounds (dry basis) of the calcined,
7 stabilized faujasite from step (a) of this Example were
8 then slurried in 20 pounds of water. This was followed
9 by the addition of 3.0 pounds (dry basis) of the alumina
from Example 4. The mixed slurry was then blended with
11 9.0 pounds (dry catalytic solids basis) of the impure
12 silica-alumina hydrogel of Example 4, spray dried, and
13 washed free of extraneous soluble salts in the manner of
14 Example 4. The total composite catalyst, designated "F",
had a composition of about 20% precalcined ultra-stable
16 Y zeolite, 20% A1203, and 60% silica-alumina gel. It
17 analyzed 0.23% Na20 and 0.46% sulfate.
18 Example 6
l9 The catalyst of this example is a catalyst of
this invention. It was made as follows:
21 (a) Commercially available stabilized low soda
22 content faujasite (sold under the trade ~ e of Linde LZ-
23 Y82 grade by Union Carbide Corporation) having a dry solids
24 content of 80.3%, a soda content of 0.12% as Na20, a
SiO2/A1203 mol ratio of 5.5 and a unit cell size of 24.5L~
26 was ball milled and 3.0 pounds ~dry basis) thereof slurried
27 in 20 pounds of water. To this slurry were added 3.0
28 pounds (dry basis) of the alumina described in Example 4
29 above.
(b) In a separate mixing tank, 40 pounds of water
31 were slurried with 71.0 pounds of the impure silica-alumina
32 hydrogel described in Example 1 (equivalent to 9.0 lbs.
33 catalytic solids). The slurry prepared in step (a) of
34 this Example was then added with mixing to the slurry of
silica-alumina hydrogel. The composite slurry was then
36 colloid milled, spray dried, washed free of extraneous
37 soluble salts, and dried in the manner of Example 1. The
38 catalyst analyzed 0.08% Na20 and 0.11% S04 and had a
39 composition of about 20% ultra-stable Y zeolite, 20%
1131~93
- 17 -
1 alumina, and 60% silica-alumina gel. It is designated
2 "G" in subsequent examples.
3 Example 7
4 The catalyst of this example is another catalyst
of the inventlon. It was made as follows:
6 (a) The stabilized, low soda content Y zeolite
7 as described in Example 6 above was placed in a dish and
8 charged to a furnace at 1000F. The temperature was
9 raised to 1500F. and held for 1 hour and then allowed to
cool. The material was discharged from the furnace below
11 1000F. This precalcined ultra-stable faujasite had a
12 unit cell size of 24.34~ compared to 24.5LA before this
13 calcination step.
14 (b) In a mixing tank, 40 pounds of water were
slurried with 71.0 pounds of the impure silica-alumina
16 hydrogel (equivalent to 9.0 pounds catalytic solids)
17 described in Example 1 above. In a second mixing tank,
18 20 pounds of water were slurried with 1400 grams of ball
19 milled precalcined faujasite (3.0 pounds dry basis) from
step (a) of this Example. To this slurry were added 3.0
21 pounds (dry basis) of the ball milled alumina of Example
22 4.
23 (c) The slurries from step ~b) of this Example
24 were combined, colloid milled, spray dried, washed free
of extraneous salts, and dried in the manner of Example 1.
26 The resultant catalyst is designated "H" and contains
27 0.07% Na20 and 0.40% S04. Catalyst "H" has a composition
28 of 20% precalcined ultra-stable zeolite Y, 20% alumina
29 and 60% silica-alumina gel.
Example 8
31 Catalysts "B", "E", "F", "G" and "H" were each
32 calcined 6 hours at 1000F. and then steamed at 1400F.
33 for 16 hours and 0 psig steam pressure to simulate commer-
34 cial equilibrium cracking catalyst performance. The
catalysts were then each evaluated for cracking performance
36 in a full cycle cracking operation. The unit employed is
37 a circulating, fluidized cat cracking unit with a regen-
38 erator and reactor/stripper vessels. The temperatures in
39 the reactor and regenerator were 925F. and 1105F.,
1131193
- 18 -
1 respectively. The feed stock was a 450/1100F. vacuum
2 g8S oil described below in Table IV. The unit was oper-
3 ated at a catalyst to oil weight ratio of 4.0, a pressure
4 of 0 psig. The results given below in Table V compare
the catalysts at constant 70 vol.ume % conversion.
6 TABLE IV
Feed
8 Gravity 22.9 API
9 Sulfur 1.245 wt. %
Nitrogen 705 ppm
11 Conradson Carbon 0.43 wt. %
12 Aniline Point 183.5F.
13 Distillation Ran~e*, C.
14 IBP/5% 298i334
10/20% 349/378
16 30/40% 395/412
17 50/60% 432/457
18 70/80% 482/499
19 90/95% 523/543
FBP 565
21 * Atmospheric pressure
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- 20 -
1 The data show that catalysts E, F, G and H all
2 show significant increases in octane nu~bers of the
3 cracked naphtha over reference catalyst B. Catalysts F
4 and H of this invention show increased octanes over
catalysts E and G, due to the precalcining treatment
6 given the ultra-stable Y zeolite to reduce the unit cell
7 size to 24.38~ and lower.
