Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PHYSICAL MIXTURE OF CATALYSTS
Background of the_Invention
This invention relates to an improved cracking catalyst.
More particularly, this invention relates to a composite
of a zeolite-containing cracking catalyst and a fluorided
reforming catalyst.
Cracking reactionc are used to convert heavier hydro-
carbons into products having a lower average molecular
weight useful in the production of motor fuels. Cracked
products generally have a lower octane number than that
, desir~d for gasoline blending components. Catalytic
reforming is a process which increases the octane number
of cracked products by converting low octane hydrocarbons,
such as paraffins and naphthenes, into aromatic-rich
products. To minimize further processing, such as
catalytic reforming operations, it is desirable that the
gasoline componènts of ~he products of the cracking
operation have as high an octane number as possible.
It is known in the art that catalytic activity of solid
contact catalysts may be enhanced by incorporating into
the catalyst acid activators, such as fluorine. See
generally Choudhary, Ind. Eng. Chem., Prod. Res. Div~,
16, 12 (1977). Prior to the advent of zeolite cracking
catalysts, amorphous-type catalysts, for example, alumina
and silica-alumina catalysts, were enhanced by treatment
with various fluorine compounds under anhydrous or
aqueous conditions. For example, U.S. Patent Nos.
2,336,165 (Connolly), 2,483,131 (Garrison), 2,694,674
tStarr et al.), and 2,848,380 (Thomas) all describe the
preparation of improved alumina and silica-alumina crack-
ing catalysts by treatment with various fluorine compounds.
,
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More recent patents disclose fluorided reforming and
dual-function catalysts. Some of these catalysts contain
a zeolite component. For example, U.S. Patent No.
4,191,638 (Plank et al.) describes a reforming catalyst
which comprises a mixture of a zeolite and a conventional
reforming catalyst, such as a metallic reforming catalyst.
Both the zeolite component and the metallic reforming
catalyst contain a halogen component, ~uch as chloride or
fluoride. The patent does not disclose a method for
fluoriding the metallic reforming catalyst.
U.S~ Patent No. 3,702,312 (Wilson) discloses a dual-
function catalyst comprising a fluoxided zeolite and a
hydrogenative metal component prepared by a sequence of
steps to incorporate f luorine into the crystalline structure
of the zeolite. Attempts to fluoride crystalline alumino-
silicate by conventional halide impregnation with an
aqueous solution of hydrogen fluoride destroyed the
crystalline stxucture of the zeolite.
U.S. Patent Nos. 4,097,368 (Hayes) and 4,098,679 (Hayes)
describe dual-function composite catalysts comprising
a combination of three or four metals on a porous carrier
which may comprise a zeolite. Halogen may be added to
the carrier material in any suitable manner, for example,
by treatment of the carrier material with an aqueous
solution of hydrogen f luoride.
:
The present invention relates to a fluorided cracking
catalyst comprising a physical mixture of a fluorided
reforming catalyst and a zeolite-containing cracking
catalyst. The improved cracking catalyst of the present
invention is prepared by treating a metallic reforming
catalyst with an aqueous solution containing a fluorine
~,
.
.
~1~7'~
compound, and then physically mixing the fluorided reformlng catalyst with a
zeolite-containing cracking catalyst. Use of the catalyst of this invention
in cracking reactions yields higher octane products than can be obtained with
conventional cracking catalyst.
Summary and Detailed Description of the Invention
According to the present invention there is provided an improved
cracking catalyst comprising a composite of zeolite, a carrier material and about
5 to about 10 percent by weight of a metallic reforming catalyst comprising
0.01 to about 2 percent by weight of platinum on an alumina support, said re-
forming catalyst also comprising between about 0.5 to about 5 percent by weight
of fluorine, said improved cracking catalyst having been prepared by treating
the platinum containing metallic reforming catalyst with an aqueous solution
containing a fluorine compound dissolved therein, followed by drying and cal-
cining the resulting fluorided reforming catalyst and physically mixing the
fluorided reforming catalyst with a zeolite-containing cracking catalyst.
In one embodiment of the invention, the zeolite-containing cracking
catalyst is itself fluorided. In another embodiment of the invention, the
zeolite-containing catalyst is unf]uorided.
The metallic reforming catalyst of the present invention comprises
about 0.01 to about 2 percent by weight of platinum on an alumina support,
preferably gamma alumina. Optionally, the reforming catalyst also contains
about 0.01 to about 5 percent by weight of a metal selected from the group
consisting of germanium, tin, and rhenium. A reforming catalyst containing
0.375 percent by weight of Pt and 0.25 percent by weight of Ge on a gamma alum-
ina support commercially sold under the trade name of UOP R-22 by UOP, Inc.,
Des Plaines, Illinois, is suitable.
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Although the pracise form in which fluorine combines
with ~he reforming catalyst i5 not entirely known, it is
customary in the art to refer to the fluorine as being
present in the form of fluoride. The present invention,
however, is not limited to fluorides but embraces all
forms of fluorine incorporated into the metallic reform-
ing catalyst when prepared as described above.
Hydrogen fluoride is the preferred fluoriding agent for
this invention although other fluorine compounds, such as
ammonium fluoride, ammonium bifluoride, boron trifluoride,
ammonium fluoborate, and ammonium fluosilicate, are also
suitable. Fluoriding of the metallic reforming catalyst
may be accomplished by an incipient wetness impregnation
technique carried out a~ 32F. Other fluoriding methods,
especially impregnation methods, may also be suitable.
Following the fluoriding step, the metallic reforming
catalyst should contain about 0.5 to about 5 percent by
weight of fluoride, most preferably, about 1 percent by
weight. The fluorided metallic reforming catalyst is
then dried a~ a temperature of about 200F to about 600F,
preferably about 300F, for about 2 to about 24 hours.
The fluorided metallic reforming catalyst is then calcined
for about 0.5 to about 10 hours at a temperature of about
700F to about 1100F, preferably at about 1000F.
Finally, the fluorided reforming catalyst is physically
mixed with a zeolite-containing cracking catalyst.
.
~ 30 The zeolite which may be used in the practice of this
i invention may be a naturally occurring or synthetically
prepaxed Y zeolite. Preferably, the zeolite is associated
with an alumina-silica matrix that may contain free alumina
or free silica. The zeolite-containing cracking catalyst which
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is used in the practices of this invention may be
fluorided. Fluoriding may be accomplished by any known
technique, such as by a technique similar to the one in
accordance with this invention.
Cracking is achieved by placing a hydrocarbon charge
stock in contact with the improved cracking catalyst
described herein. The contacting may be accomplished by
any conventional technique, for example, by using the
catalyst in a fixed bed system, a moving bed system,
a fluidized bed system, or in a batch type operation.
The conditions under which the improved cracking
catalyst may be used are those customarily used in the
art for cracking reactions. Thus, temperatures from
about 850F to about 1025~F and pressures of about 10
to about 25 psig are ordinarily usedL
`:
The following examples are presented to illustrate more
fully the nature and manner of practicing the invention.
` Examples
,
An improved cracking catalyst was prepared in accordance
with the present invention. Catalyst A comprised a
metallic reforming catalyst having 0.375 percent by
weight platinum and 0.25 percent by weight germanium on
a gamma alumina support. Catalyst A was ground to 50 to
200 mesh particle size and was then fluorided with
aqueous hydrogen fluoride by an incipient wetness impreg-
nation technique. The aqueous solution containing 0.014gm of HF per cc was prepared by diluting 4 gm of concen-
trated HF acid with 136 ml of distilled water. 70 ml of
the HF solution was added to 100 gm of Catalyst A at
32F with mixing in order to distribute the solution on
the catalyst. The nominal loadiny of the fluoride was
~ 6-
1 percent by weight. After contacting Catal~st A with
the HF solution ~or periods o~ either 3 or 1~ hours,
moisture was removed by drying the catalyst at 30QP~
The fluor;ded reforming catalyst was tfien ca`lci`ned at
1000F for three hours.
:;
In examples 2 through 6, Catalyst A was physically ~ixed
with a commercial zeolite-contaïning cracki~ catalyst,
Catalyst B. Catalyst B compris~d a Y zeolite in an
alumina-silica matrix. Catalyst B had previously been
used in a commercial cracking operation and had the
following characteristics: surface area = 98 m2/gm, pore
volume = 0.36 cc/gm, density (loose) = 48.0 lbs/cu. ft.,
alumina = 38.1 wt.%, average par~icle size = 55 microns.
~ In examples 5 and 6, Catalyst B was fluorided by the
; method described above prior to mixing with Catalyst A.
Nominal loading of Catalyst B with fluoride was 1
-~ percent by weight. Table 1 sets out the catalysts used
~ 20 in the examples, the period of contact with the fluoriding
;~; solution, and the calcining conditions.
TABLE 1
:
HF Contact Calcination Calcination
25 ~ Catalyst Tlme, hrs. ~ Time, hrs.
1 B 0 - -
2 10%A~ 0 - -
90%B 0 - -
3 10%A(1%HF)~ 16 1000 3
~ '
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TABLE 1 (cont'd.)
HF Contact Calcination Calcination
Example Catalyst Time, hrs. Temp., F Time, hrs.
4 10%A(1%HF)+ 3 1000 3
- %B ~ _
10%Atl%HF)~16 1000 3
90%B(l~HF) 3 1100 16
6 10%A(1%HF)+ 3 1000 3
90%B(l~HF) 16 1000 3
Tests were conducted in a pulsed feed, fixed bed micro-
xeactor unit designed to evaluate cracking catalysts.
. The tests were conducted at 900F with a hydrocarbon
- charge stock having the following properties:
TABLE 2
~ravity, API 36.7
Viscosity at 100F, cs. 4.3
Vis~osity at 210 DF, CS . 1 . 5
25 Pour Point, F Z0
Sulfux wt.% 0.08
Conradson Carbon Residue, wt.~ None
Bromine No. 3
ASTM Distillation (D-2887) F
Initial Boiling Point 318
: - 5% 435
10%. 465
20% 498
30% 522
40% 543
~' 50% 566
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TABLE 2 (cont'd.~
60% S86
70% 610
80% 645
90% 692
95% 735
End Point 856
In each of the test runs of the examples~ 4 grams of
catalyst were contacted with 1~3 grams of the test feed
during a 75 second pulse at 1 atmosphere pressure. The
catalyst to oil weight ratio was 3 and the Weight Hourly
- Space Velocity (WHSV) was 16.
The liquid products from the tests were collected in a
receiver cooled in an ice-water bath and analyzed on
a chromatograph. Conversion, naphtha and gas oil were
determined by ASTM Method D-2887-73. The naphtha was
the liquid product fraction with a boiling point below
421F. The gas oil was the fraction with a boiling
point above 421F. Conversion was calculated as the
percentage of the original charge with a boiling point
- below 421F $ollowing cracking.
Research Octane Numbers (RON) were calculated by analyzing
the naphtha fraction into specific groups and assigning
an octane factor to each group. The octane numbers of
the products are based upon the amount of each specific
group in the product and the octane factor assigned to
each group. See P. C. Anderson~ J. M. Sharkey, and R. P.
Walsh, J. Inst. Pet., 58, 83 (1972)
.
_g_
~i~ferences between similar preparations are attributed
to the different fluoriding conditions shown in Table 1.
For instance, the contact period was 16 hours for example
3 and 3 hours for example 4. Results of the test runs
are summarized in Table 3 below.
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oo
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o 1~ c~
~i ~ t` ~ o
~ a: ~ +
o'P d~
o o
a~ Lno ~ I` o ~3 co co
:` ~ o +
.. ~ ~,
.~ +
:. _
:~ m
~) r-l O ~ G _I O O
+
O
~~ ~ t~cn o In ~g ~r co o
o o
a~ .
O C~ Q l` ~D
N ~r O W ~ i~
.o ~ ~P
~1 0 ~ Z ~ S o o
X ~ z ~ ~0 ~ P P
1~1 00 11~ 0 ~ /~
c~ Z ~ a t~ 3 z 3 ~ 3
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The test runs demonstrate that a fluorided metallic
reforming catalyst mixed with a zeolite-containing
cracking catalyst yields a higher octane product than
is produced by unfluorided catalysts. A simple mixture
of unfluorided A and unfluorided B produces a higher
octane product than unfluorided B alone. However, the
: best results are produced by a composite of fluorided A
and either fluorided or unfluorided B. In most cases,
the fluorided composites of A and B increase the octane
number more than ~wice as much as the unfluorided com-
posite of A and B. The improvement in octane number
demonstrated in these test runs may be attributed to the
enhanced aromatization and dehydrogenation activity of
fluorided reforming catalyst.
While the invention has been described by reference to
specific examples, these examples were for purposes of
illustration only. They should not be construed to
limit the spirit or scope of the invention.
