Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to the conversion of hydrocarbons
and more particularly to the chemical conversion of hydrocarbons,
preferably sulfur-containing hydrocarbon feedstocks, promoted
by catalyst which is periodically regenerated to remove
carbonaceous deposits.
The terms "hydrocarbon conversion" and "hydrocarbon
chemical conversion" as used herein, in general, refer to those
chemical reactions for improving the octane number of gasoline,`
or converting heavy hydrocarbons to light, low boiling hydro- -
carbons, or converting one or more hydrocarbons to one or more
different hydrocarbon products. Hence, among those reactions
included in such terms are isomerization, cracking, polymerization,
alkylation, dealkylation, disproportionation and the like. -
. .~
Although free molecular hydrogen may be added to the reaction
15 zone, each of these "hydrocarbon conversions" is preferably ~-
carried out in the substantial absence of added free molecular :
hydrogen.
_ Each such "hydrocarbon conversion" is often carried out
commercially by contacting a hydrocarbon feedstock with a solid
catalytic material in at least one reaction zone at conditions
at which the desired hydrocarbon chemical conversion takes
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place. However, such conditions also allow formation of
carbonaceous material, such as coke, which deposits on the !
catalyst. These deposits are periodically removed as they tend
~,
to inactivate the catalyst. The catalyst may be regenerated by
burning or combusting at least a portion of such carbonaceous
deposit material from the catalyst in at least one reaction
zone in the presence of ~ree oxygen. ~uring the catalyst
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regeneration carbon monoxide and carbon dioxide are often
produced as gaseous combustion products, the relative amounts
of each depending upon the efficiency of the oxidation step.
If the hydrocarbon feedstock contains sulfur, the carbonaceous ~
5 deposit material will often also contain sulfur. During ;
catalyst regeneration, at least a portion of the sulfur in
the carbonaceous deposit material may combust or oxidize,
e.g., to SO2 and SO3, and exits with the ~lue gases from the
regeneration zone.
Recent federal and local air pollution control
legislation has made it necessary to eliminate or drastically
reduce the amount of carbon monoxide and/or sulfur (or sulfur
oxides) being discharged into the atmosphere. The amount of
carbon monoxide as a gaseous by-product from hydrocarbon
15 conversion processes using a regenerative catalyst can be ~;
reduced by using a catalyst which contains a promoter, usually
a metal or metal compound, for the conversion of carbon
monoxide to carbon dioxide. U.S. Patent 2,647,860 describes a
hydrocarbon cracking process using a synthetic silica-alumina
20 catalyst which i5 capable of regeneration, and which contains ;~
0.01% to 1% by weight of chromic oxide to promote the oxidation -
of carbon monoxide in the catalyst regenerator. This patent
acknowledges the fact that the chromic acid adversely affects
the cracking reaction. U.S. Patent 3,140,249 describes the
preparation and use of crystalline aluminosilicate compositions
containing small amount of metals such as vanadium and manganese `
in hydrocarbon cracking processes. U.S. Patent 3,140,253
discloses the preparation and use of cyrstalline aluminosilicates
in hydrocarbon conversion processes. This patent states that
metal promoters such as chromium, cobalt and platinum may be
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present in the catalyst in amounts of 5% to 40~ by weight. `~
U.S. Patent 3,173,85~ describes a process for the hydrocracking
of hydrocarbon oils using a crystalline aluminosilicate
containing, as a hydrogenation component, 0.01% to 25% by
weight of a metal selected from Groups VI and VIII of the
Periodic Table. U.S. Patent 3,650,990 discloses the preparation
of a crystalline aluminosilicate useful for the conversion of
hydrocarbons containing a metal promoter selected from Groups
IVB, VB, VIB, VIIB AND VIII of the Periodic Chart. The metal
10 is incorporated into the crystalline aluminosilicate prior to -~
or during its formation and may vary from .001% to 5~ by weight.
U.S. Patent 3,788,977 describes hydrocarbon cracking using a ;
platinum-impregnated inorganic oxide-crystalline aluminosilicate-
containing catalyst. The platinum,which is present in amounts
of at least 100 ppm based on the amount of inorganic oxide,increases
the yield of aromatic product.
U.S. Patent 3,364,136 describes hydrocarbon conversion
using a catalyst comprised of a first component consisting of
solid particles containing a crystalline aluminosilicate which ;
is active for the conversion of the hydrocarbon, and a second
component consisting of solid particles containing a crystalline -
aluminosilicate which is inert with respect to the hydrocarbon
conversion reaction because its pores are too small to admit the
hydrocarbon reactant, but which is effective to promote the
oxidation of carbon monoxide to carbon dioxide. The latter
.: .
component contains from less than 0.01% up to 20% by weight of
a metal, metal oxide or metal sulfide from Groups IB, IIB, VIB,
VIIB or VIII of the Periodic Chart. Belgain Patent 820,181
describes a process of cracking hydrocarbons with a cracking
catalyst material which contains less than the 100 ppm. of a
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metal chosen from Periods 5 and 6 of Group VIII of the Periodic
Chart or rhenium. This patent teaches that the metal may be
applied uniformly over all of the catalyst or it may be applied
at a higher concentration on a portion of the catalyst and
blended with unmodified catalyst provided that the total metal
content of the final catalyst mixture does not exceed 100 ppm.
Such carbon monoxide oxidation catalyst systems have
met with varying degrees of success. One problem which has
become apparent is the tendency of such oxidation catalysts
to rapidly deactivate. The tendency is especially apparent
when the oxidation catalyst comprises a Group VIII, platinum
group metal component. Thus, carbon monoxide oxidation
catalysts which are satisfactory, e.g., reduce carbon monoxide
emissions to meet or approach govermental standards, in the
virgin state, have been found to lose a substantial amount of
carbon monoxide oxidation activity after a relatively short
time in hydrocarbon conversion-catalyst regeneration service.
Accordingly, one object of this invention is to provide
an improved process for hydrocarbon conversion.
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Another object of the invention is to provide an improved
process for hydrocarbon conversion in the substantial absence ~;
of added free molecular hydrogen. ;;
Another object of this invention is to provide an
improved process for hydrocarbon conversion in a two-step
chemical conversion-catalyst regeneration process.
A still further object of this invention is to reduce
the amount of carbon monoxide produced during the regeneration
of a hydrocarbon conversion catalyst.
An additional object of this inventionis to reduce
the emission of carbon monoxide into the atmosphere from a
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hydrocarbon conversion process using a catalyst which is
periodically regenerated to combust carbonaceous deposit
material from the catalyst. ;
Another object of the present invention is to reduce ;
the emission of sulfur into the atmosphere from a hydrocarbon
conversion process using a catalyst which is periodically
regenerated to combust sulfur-containing carbonaceous deposit
material from the catalyst.
Another object of the invention is to provide an
improved hydrocarbon conversion catalyst. A further object
of the invention is to provide an improved carbon monoxide
-. , ,
oxidation catalyst. A still further object of the invention
is to provide an improved sulfur dioxide oxidation catalyst.
These and other objects of the invention will become apparent
from the following description and examples.
In accordance with the invention, the hydrocarbon
... ., ~
conversion process is carried out using a mixture of solid -
particles comprised of (1) a major amount of solid particles
capable of promoting the desired hydrocarbon chemical -
conversion at hydrocarbon conversion conditions and which
are, preferably, substantially free of Group VIII, platinum
group metal component or components and (2) a minor amount of ~ ! ' '
discrete entities comprising (A) a major a~mount of weight of
alumina and (B) a minor, catalytically effective amount of at
least one Group VIII, platinum group metal component disposed,
preferably substantially uniformly disposed, on the alumina, :
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this metal component being capable of promoting the oxidation
of carbon monoxide to carbon dioxide at carbon monoxide
oxidizing conditions. The Group VIII, platinum group metals
30 include platinum, palladium, osmium, iridium, ruthenium, and ` ;
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rhodium. The preferred platinum group metals are palladium
and platinum, most preferably platinum. The preferred relative ;
amounts of the solid particles and discrete entities are about
80 to about 99 parts and about 1 to about 20 parts by weight,
respectively. This catalyst system is especially effective
for the catalytic cracking of a hydrocarbon feedstock to
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lighter, lower boiling products. The present catalyst system ;
has improved carbon monoxide oxidation catalytic activity
stability. ~ -
In accordance with another aspect of the present
invention, the hydrocarbon conversion process is carried out
in at least one chemical reaction zone and at least one
regeneration zone with a sulfur-containing hydrocarbon feedstock ~-;
using a mixture of solid particles comprising (1) a major amount
15 of solid particles capable of promoting the desired hydrocarbon ~; `
chemical conversion at hydrocarbon conversion conditions and,
which are, preferably, substantially free of Group VIII,
platinum group metal component or components and (2) a minor
amount of discrete entities comprising a major amount of
alumina capable of associating with sulfur trioxide in the
regeneration zone and disassociating with sulfur trioxide in
the chemical reaction zone. In one preferred embodiment, the
discrete entities further comprise a minor amount of at least
one metal, e.g., platinum group metal, component capable of
promoting the oxidation of sulfur dioxide to sulfur trioxide
at the conditions in the reqeneration zone.
The improvement of this invention can be used to
advantage with the catalyst being disposed in any conventional
reactor-regenerator system, e.g., in a fixed catalyst bed
conversion-regeneration system, in ebullating catalyst bed
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systems, in systems which involve continuously conveying or
circulating catalyst between reaction zone and regeneration
zone and the like. Circulating catalyst systems are preferred. ;
Typical of the circulating catalyst bed systems are the
conventional moving bed and fluidized bed reactor-regenerator
systems. Both of these circulating bed systems are conventionally
used in hydrocarbon conversion, e.g., hydrocarbon cracking,
operations with the fluidized catalyst bed reactor-regenerator -
systems being preferred.
The catalyst system used in accordance with certain
embodiments of the invention is comprised of a mixture of two
types of solid particles. -
Although the presently useful solid particles and discrete
entities may be used as a physical admixture of separate particles,
15 in one preferred embodiment, the discrete entities are combined `~
as part of the solid particles. That is, the discrete entities,
e.g., comprising calcined alumina microspheres, are combined with
the solid particles, e.g., during the manufacture of the solid
particles, to form combined particles which function as both the
20 presently useful solid particles and discrete entities. In this ~ ~ `
embodiment, the alumina of the discrete entities is preferably
a separate and distinct phase, and is substantially accessible --
to the carbon monoxide, carbon dioxide and/or sulfur dioxide,
sulfur trioxide present in the regeneration zone and, preferably,
25 to the hydrocarbon feedstock in the reaction zone. By "accessible" `~
is meant that the alumina has physical properties, e.g., porosity, ;
pore volume, surface area and the like, which allow at least a
major portion by weight of the hydrocarbon feedstock and the
carbon and sulfur oxides noted above to come into intimate, e.g.,
30 molecular, contact with the alumina of the discrete entities `
contained in the combined particles. One preferred method for ~-
providing the combined particles with substantially accessible
alumina is to calcine the discrete entities prior to incorporating
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the discrete entities into the combined particles. When the
discrete entities comprise substantially accessible alumina a
major amount of such alumina is preferably extractable by
contacting the discrete entities or the combined particles contain- `~
ing the discrete entities, with 0.2N HCl at about 165-170DF. for
four (4) hours. This indication of substantially accessible
alumina finds particular applicability when the discrete entities
comprise gamma alumina, e.g., alumina derived from hydrous alumina -~
predominating in alumina monohydrate, alumina derived from hydrous
alumina predominating in amorphorous hydrous alumina, and
mixtures thereof.
The form, i.e., particle size, of the present catalyst
particles, e.g., both solid particles and discrete entities as ~-
well as the combined particles, is not critical to the present
invention and may vary depending, for example, on the type of
reaction-regeneration system employed. Such catalyst particles
may be formed into any desired shape such as pills, cakes,
extrudates, powders, granules, spheres and the like using
conventional methods. Where, for example, the final catalyst
is designed for use in hydrocarbon conversion operations employing
a fixed bed of catalyst, the catalyst may preferably be formed into
particles having a minimum dimension of at least about 0.01 inch and
a maximum dimension up to about one-half inch or one inch or more.
Spherical particles having a diameter of about 0.03 inch to about
0.25 inch, preferably about 0.03 inch to about 0.15 inch, are often
useful, especially in fixed catalyst bed or moving catalyst bed
operations. With regard to fluidized catalyst bed systems, it is
preferred that the major amount by weight of the present catalyst
particles have a diameter in the range of about 10 microns to about
250 microns, more preferably about 20 microns to about 150 microns.
The first solid particles are capable of promoting the
desired hydrocarbon conversion and, preferably, are substantially
free of added platinum group metal components.
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In one aspect of the present invention, the second solid
particles, i.e., discrete entities, comprise (A) a major amount,
i.e., at least 50~, by weight of alumina and (B) a minor amount
of at least one platinum group metal component disposed on the ``
alumina and capable of promoting the conversion of carbon monoxide
to carbon dioxide at carbon monoxide oxidizing conditions, e.g.,
conditions existing during contacting the deposit-containing first
solid particles with an oxygen-containing gaseous medium to combust . -
at least a portion of the carbonaceous deposit material from the
first solid particles. In another aspect of the present invention,
the discrete entities, whether present as a separate and distinct
particle and/or combined with the solid particles in a single,
preferably substantially uniform, mass of combined particles `
comprise a major amount of alumina capable of associating and
disassociating with sulfur trioxide in the regeneration zone and
the reaction zone, respectively, and preferably furthe comprise ^
a minor amount of at least one metal,e.g., platinum group metal, `~ ;
component capable of promoting the oxidation of sulfur dioxide
at the conditions in the regeneration zone.
2~ The composition of the solid particles useful in the
present invention is not critical, provided that such particles
are capable of promoting the desired hydrocarbon conversion.
Particles having widely varying compositions are conventionally
used as catalysts in such hydrocarbon conversion processes, the
25 particular composition chosen being dependent, for example, on -
the type of hydrocarbon chemical conversion desired. Thus, the
solid particles suitable for use in the present invention include
at least~oneof the natural or synthetic materials which are capable
or promoting the desired hydrocarbon chemical conversion. For
example, when the desired hydrocarbon conversion involves
one or more of hydrocarbon cracking, disproportionation, -~
isomerization, polymerization, alkylation and dealkylation, such
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suitable materials include acid-treated natural clays such as
montmorillonite, kaolin and bentonite clays; natural or synthetic
amorphous materials, such as amorphous silica-alumina, silica-
magnesia and silica-zirconia composites; crystalline alumino-
silicates often referred to as zeolites or molecular sieves and
the like. In certain instances, e.g., hydrocarbon cracking and -
disproportionation, the solid particles preferably include such ~
crystalline aluminosilicates to increase catalytic activity. `
Methods for preparing such solid particles and the combined
solid particles-discrete entities particles are conventional and
well known in the art. For example, crystalline aluminosilicate
compositions can be made from alkali metal silicates and alkali
metal aluminates so that they initially contain significant
concentrations of alkali metal. Sodium tends to reduce the catalyst
activity of the composition for hydrocarbon conversion reactions
such as hydrocarbon cracking and disproportionation. Accordingly,
most or all of the sodium in the crystalline aluminosilicate is
removed or replaced, e.g., with other metal cations such as calcium
or aluminum ions or ions of the rare earths. This can be accom-
plished by contacting the crystalline aluminosilicate with a sourceof hydrogen ions such as acids, or hydrogen precursors such as
ammonium compounds. These procedures are thoroughly described -~
in U.S. Patents 3,140,253 and Re. 27,639.
Compositions of the solid particles which are particularly
useful in the present invention are those in which the crystalline
aluminosilicate is incorporated in an amount effective to promote
the desired hydrocarbon conversion, e.g., a catalytically effective
amount, into a porous matrix which comprises, for example,
amorphous material which may or may not be itself capable of
promoting such hydrocarbon conversion. Included among such
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matrix materials are clays and amorphous compositions of
silica-alumina, magnesia, zirconia, mixtures of these and
the like. ~he crystalline aluminosilicate is preferably
incorporated into the matrix material in amounts within the
range of about 1% to about 75%, more preferably about 2% to
about 50%, by weight of the total solid particles. The
preparation of crystalline aluminosilicate-amorphous matrix
catalytic materials is described in the above-mentioned patents. `
Catalytically active crystalline aluminosilicates which are
10 formed during and/or as part of the method of manufacturing ~ -
the solid particles, discrete entities and/or combined particles
are within the scope of the present invention.
As indicated above, in one aspect the discrete entities
utilized in the present invention comprise a major amount of
alumina and a minor amount of at least one platinum group metal
component disposed on the alumina and present in an amount ;`
sufficient to promote the oxidation of carbon monoxide to carbon
dioxide. In another aspect, the present discrete entities
comprise a major amount of alumina capable of associating and ;
disassociating with sulfur trioxide and, preferably, a minor
amount of at least one metal, e.g., platinum group metal,
component capable of promoting sulfur dioxide oxidation. It is
essential that the discrete entities include at least one ;~
separate alumina phase, e.g. ! on which the platinum group metal ;
is disposed. It is preferred that the discrete entities
comprise a major amount of alumina having a surface area of
from about 25 m.2/gm. to about 600 m.2/gm. or more. The alumina
comprises a major amount, preferably at least about 70%, and
more preferably at least 90%, by weight of the discrete entities.
Suitable aluminas for use in the discrete entities are those
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aluminas derived from hydrous alumina predominating in alumina
trihydrate, alumina monohydrate, amorphous hydrous alumina and -~
mixtures thereof. Alumina in the form of chi-, gamma-, delta-,
eta-, kappa-, and theta-alumina are preferred, while gamma- and
eta-al~lmina are more preferred and gamma-alumina is still more
preferred. Minor, substantially non-interferring proportions
of other well known refractory materials, e.g., inorganic oxides
such as silica, zirconia, magnesia and the like may be included
in the present discrete entities. By "substantially non-
interferring" is meant amounts of other materials which do nothave a substantial deleterious effect on the present catalyst
system or hydrocarbon conversion process. The inclusion of minor
amount of such materials such as silica, zirconia, magnesia and
the like into the present discrete entities may act to improve
the one or more of the functions of the discrete entities. In
one preferred embodiment, the present discrete entities further
comprise a minor amount of at least one aluminosilicate capable
of promoting the desired hydrocarbon conversion. Typical
aluminosilicates have been described above. Preferably, such
aluminosilicates comprise about 1% to about 20%, more preferably
about 1% to about 10%, by weight of the discrete entities. The
presence of such aluminosilicates in the present discrete entities
acts to increase the overall catalytic activity of the solid
particles-discrete entities mixture for promoting the desired
hydrocarbon conversion.
The alumina may be synthetically prepared in any suitable
manner and may be processed prior to use by one or more treatments
including drying, calcination, steaming and the like. Thus, for ;
instance, hydrated alumina in the form of a hydrogel can be
precipitated from an aqueous solution of a soluble aluminum salt
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such as aluminum chloride. Ammonium hydroxide is a useful agent
for effecting the precipitation. Control of the pH to maintain
it within the value of about 7 to about 10 during the
precipita~ion is desirable for obtaining a good rate of ;~
conversion. Extraneous ions, such as halide ions, which are
introduced in preparing the hydrogel, can, if desired, be ;
removed by filtering the alumina hydrogel from its mother liquor
and washing the filter ca~e with water. Also, if desired, the
hydrogel can be aged, say for a period of several days. The
effect of such aging is to build up the concentration of alumina
trihydrate in the hydrogel. Such trihydrate formation can also
be enhanced by seeding an aqueous slurry of the hydrogel with
alumina tri~ydrate crystallites, for example, gibbsite. ~
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The alumina-based composition may be formed into particles ;`~
of any desired shape such as pills, cakes, extrudates, powders,
granules, spheres, and the like using conventional methods. The
size selected for the particles can be dependent upon the intended
environment in which the final discrete entities are to be used --
as, for example, whether in a fixed catalyst bed or circulating
catalyst bed reaction system or whether as a separate particle or
as part of a mass of combined particles.
As indicated above the discrete entities utilized in the
present invention preferably also contain at least one metal, e.g., ;
platinum group metal, component disposed onthe alumina. The metal
components are capable of promoting the oxidation of carbon
monoxide and/or the oxidation of sulfur dioxide to sulfur trioxide
at the condiiions present in the regenerator. Such metal components
are selected from the group consisting of Group IB, IIB, VIB, VIIB,
VIII of the Periodic Table, vanadium and mixtures thereof and may
be incorporated onto the alumina of the discrete entities in any
-13-
suitable manner. The metal, e.g., platinum group metal, such
as platinum, may exist within the final discrete entities at
least in part as a compound such as an oxide, sulfide, halide
and the like, or in the elemental state. Generally, the amount
of the platinum group metal component present inth~ final
discrete entities is small compared to the quantity of the
alumina. The platinum group metal component preferably comprises
from about 0.05 parts-per-million (ppm.) to about 1~, more
preferably about 0.05 ppm. to about 1,000 ppm., and still more
preferably about 0.5 ppm. to about 500 ppm., by weight of the
discrete entities, calculated on an elemental basis. Excellent
results are obtained when the discrete entities contain about
50 ppm. to about 200 ppm., and in particular about 50 ppm. to ;~-~
about 90 ppm., by weight of at least one platinum group metal
component.
The metal, e. g., platinum group metal, component may be
incorporated in the alumina based composition in any suitable
manner, such as by coprecipitation or cogellation with the
alumina, ion-exchange with ~e alumina and/or alumina hydrogel,
20 or by the impregnation of the alumina and/or alumina hydrogel -
at any stage in its preparation and either after or before
calcination of the alumina hydrogel. Preferably, the platinum ~
group metal component is substantially uniformly disposed on ~-
the alumina of the present discrete entities. One preferred
method for adding the platinum group metal to the alumina
involves the utilization of a water soluble compound of the
platinum group metal to impregnate the alumina prior to ;;
calcination. For example, platinum may be added to the alumina ~
by comingling the uncalcined alumina with an aqueous solution ~ -
of chloroplatlnic acid. Other w~ter-soluble ccmpcund~ o
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platinum may be employed as impregnation solutions, including,
for example, ammonium chloroplatinate and platinum chloride.
Both inorganic and organic compounds of the platinum
group metals are useful for incorporating the platinum group
metal component into the presentdiscrete entities. Typically,
such inorganic compounds include ruthenium nitrate, ruthenium
chloride, rhodium trichloride, ammonium palladium hexachloride,
palladium chloride, diamminedichloropalladium, diamminedinitro-
palladium, tetraamminepalladium chloride, tetraaminepalladium
hydroxide, palladium nitrate, palladium acetate, osmium tetroxide,
ammonium platinum hexachloride, diamminodichloroplatinum,
diamminedinitroplatinum, tetraammineplatinous hydroxide and the
like. Platinum group metal compounds, such as chloroplatinic
acid and palladium chloride are preferred. -
15Representative organic metal-containing compounds which
can be used to incorporate the platinum group metal component into
the discrete entities include ruthenocene, tricarbonyltris
(triphenylphosphino) ruthenium, palladium acetylacetonate,
tetrakis (triphenylphosphino) palladium, dichloro(ethylene)
palladium (II) dimer, ~-cyclopentadinyldicarbonylosmium (I)
dimer, platinum acetylacetonate, dichlorodicarbonylplatinum (II),
trimethylplatinum chloride, dichlorotetracarbonyldirhodium (I?,
chlorocarbonylbis (tri-phenylphosphino)rhodium (I), triiiodo~ri-
carbonyliridium (III), trichlorobis (trichlorophosphino) iridium
(III) and the like.
It may be desirable to be able to separate the discrete
entities from the solid particles, for example, when it is
desired to use the solid particles alone for hydrocarbon conver-
sion or where it is desired to recover the discrete entities for `
other uses or for platinum group metal recovery. This can be
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conveniently accomplished by preparing the second solid particles
in a manner such that they have a different size than the first
solid particles. The separation of the first and second solid ;~
particles can then be easily effected by screening or other
means of size segregation.
As noted above, the presently useful solid particles and
discrete entities can be employed in a mass of ~ombined particles
which function as both the solid particles, e.g., promotes hydro-
carbon conversion, and the alumina-based discrete entities, e.g~,
promotes oxidation of carbon monoxide and/or associates-disassociates ;
with sulfur-containing combustion products. Such combined
particles may be produced in any suitable manner, certain of
which methods are conventional and known in the art.
One particularly preferred method for manufacturing the
presently useful combined particles has special application for
providing combined particles useful in a conventional fluidized
bed reaction zone-regenerator system. A major portion by weight
of such combined particles preferably have diameters in the range
of about 10 microns to about 250 microns. This improved method
comprises:
l. forming a mixture of a minor amount, preferably about
1% to about ~0%, more preferably about 1% to about 20%
and still more preferably about 1% to about 10%, by -
weight of calcined alumina-based discrete entities and
a major amount, preferably about 60~ to about 99%,more `
preferably about 80~ to about 99% and still more preferably
about 90~ to about 99%, by weight of a binder, as herein-
after defined, in a hydrous state, the weight proportions
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being based on the proportions present in the combined
particles hereinafter described, the binder, after cal- ~-
cination, haviny substantially the same properties and
composition as the presently useful solid particles,described
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previously, at least a portion of the hydrous binder
preferably being able to wet the external surface of
discrete entities; and
2. drying and forming the mixture and thereby
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producing from the mixture combined particles which
when calcined are of a size suitable for use a~ a ; !~
catalyst in a fluidized bed reactor-regenerator system.
The average size, i.e., in diameter, of the calcined
alumina-based discrete entities may be in the range of about
1 micron to about 135 microns, preferably about 1 micron to about -~
70 microns. ~`
The calcined alumina-based discrete entities may be
produced in any suitable manner. One particularly preferred
method of manufacturing these entities comprises forming an
aqueous slurry of hydrous alumina, drying and calcining at least
a portion of the hydrous alumina thereby forming properly sized
discrete entities. The aqueous slurry preferably contains about
5 to about 16, more preferably about 8 to about 14, weight
percent of alumina tcalculated as A1203). The metal, e.g.,
- 20 platinum group metal, component or components may be added to the ~;
alumina-based discrete entities at one or more of various stages
in the manufacture of such entities. -
Step (2) of the present improvement may involve spray -
drying. Equipment which is conventionally used to produce
catalyst particles suitable for use in fluidized bed reactors
may be utilized in the practice of the present invention. For
example, this equipment may involve at least one restriction or
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high pressure nozzle having a diameter in the range from about
0.01 in. to about 0.2 in., preferably from about 0.013 in. to
about 0.15 in. The pressure upstream of this high pressure
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nozzle may range from about 400 psig. to about 10,000 psig.,
preferably from about 400 psig. to about 7000 psig. The
material to be dried i5 sent through the nozzle system into a
space or chamber. The pressure in the space or chamber down-
stream from the nozzle system is lower than that immediatelyupstream of the nozzle and is typically in the range from about
0 psig. to about 100 psig., preferably from about 0 psig. to
about 20 psig. Once through the nozzle, the material to be dried
is contacted for a relatively short time, e.g., from about 0.1
10 seconds to about 20 seconds with a gas stream which is at a temp- ;~
erature of ~rom about 200F. to about 1500F., preferably from
about 200F. to about 750F. The gas stream which may be, for
example, air or the flue gases from an inline burner (used to
provide a gas stream having the proper temperature) or a sub-
stantially oxygen-free gas, may flow co-current, counter-current
or a combination of the two relative to the direction of flow of ~ -
the material to be dried. The spray drying conditions, such as
temperatures, pressures and the like, may be adjusted because,
for example, of varying the composition of the material to be ;;
dried to obtain optimum results. However, this optimization may
be achieved through routine experimentation.
An alternative to the high pressure nozzle described
above is the "two-fluid" nozzle in which the material to be dried
is dispersed by a stream of gas, typically air. The two fluid
nozzle has the advantage of low operating pressure, e.g., from
about 0 psig. to about 60 psig. for the material to be dried and
from about 10 psig. to about 100 psig. for the dispersing gas.
The dispersing gas may also function as at least a portion of the ~ ~
drying gas stream. The various operating parameters noted above -
30 may be varied in order to achieve the correct or desired ~ -
combined particle size.
..~'~:
.
,~
-18-
~L~9Z~82
In order to minimize contact between the chamber walls ~-
and wet material, the chamber downstream from the nozzle system
is large in size, e.g., from about 4 to about 30 feet in diameter
and from about 7 to about 30 feet long, often with an additional
conical shaped portion for convenient withdrawal of the dried
material. The spray drying apparatus may also inslude separation
means, e.g., cyclone separators, in the outlet gas line to recover
at least a portion of the dried material entrained in this stream.
If the dried material collected in the outlet gas separation -
means is not of the proper size to be of value as a fluid bed
catalyst, this material may be recycled back to step (1) thus ;
providing for optimum utilization of the catalyst materials.
The solid particles, alumina-based discrete entities
and bound particles are often used in the reaction zone-regenerator
system in the calcined state. Calcination may occur as part of
the method of manufacturing and/or may occur in situ, i.e., during
use in the reaction zone-regenerator system.
Calcination often involves treating the catalyst -
particles at high temperatures, e.g., from about ~00F. to about
20 1700F. or more, for a period of time, e.g., about 4 hours, to -
release at least a portion of the water of hydration from the
particles and catalytically activate the particles. Calcination
may occur in an inert, oxidizing or reducing environment.
Preferred calcination conditions include a temperature in the
., . : .
range of about 700F. to about 1600~F., more preferably about
800F. to about 1500F., for a period of time in the range of
about 0.1 hours to 48 hours, more preferably about 0.5 hours ~ -
: . .
to about 20 hours.
~ ~.. ' , . .
- 1 9- ,, , '
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Although this invention is useful in many hydrocarbon
chemical conversions, the present catalyst, i.e., mixture
comprising solid particles and discrete entities, and process
find particular applicability in systems for the catalytic
cracking of hydrocarbons and the regeneration of catalyst so
employed. Such catalytic hydrocarbon cracking often involves
converting, i.e., cracking, heavier or higher boiling hydro-
carbons to gasoline and other lower boiling components, such as
hexane, hexene, pentane, pentene, butane, butylene, propane,
propylene, ethane, ethylene, methane and mixtures thereof. Often,
the substantially hydrocarbon feedstock comprises a gas oil
fraction, e.g., derived from petroleum, shale oil, tar sand oil,
coal and the like. Such feedstock may comprise a mixture of
straight run, e.g., virgin, gas oil. Such gas oil fractions
often boil primarily in the range of about 400F. to about 1000F.
Other substantially hydrocarbon feedstocks, e.g., other high
boiling or heavy fractions of petroleum, shale oil, tar sand oil,
coal and the like may be cracked using the apparatus and method ~
of the present invention. Such substantially hydrocarbon feedstock `
20 often contain minor amounts of contaminants, e.g., sulfur, nitrogen -
and the like. In one aspect, the present invention involves
converting a hydrocarbon feedstock containing sulfur and/or
sulfur chemically combined with the molecules of hydrocarbon
feedstock. The present invention is particularly useful when
the amount of sulfur in such hydrocarbon feedstock is in the range
of about 0.01% to about 5%, preferably about 0.1% to about 3%,
by weight of the total feedstock. ~ -
~.'' ": ' :~ '
~
,. . .
: ,.. . .
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Hydrocarbon cracking conditions are well known and ~-
often include temperatures in the range of about 850F. to about
1100F., preferably about 900F. to about 1050F. Other reaction
conditions usually include pressures of up to about 100 psig.; ~;
catalyst to oil ratios of about 1 to 5 to about 25 to 1; and
weight hourly space velocities (WHSV) of from about 3 to about 60.
These hydrocarbon cracking conditions are not critlcal to the
presentinvention and may be varied depending, for example, on the
feedstock and solid particles or combined particles being used
andthe product or products wanted.
In addition, the catalytic hydrocarbon cracking system
includes a regeneration zone for restoring the catalytic activity
of the solid particles or combined particles of catalyst pre- ;;;
viously used to prom~te hydrocarbon cracking. Carbonaceous,ln ;
particular sulfur-containing carbonaceous, deposit-containing
catalyst particles from the reaction zone are contacted with free
oxygen-containing gas in the regeneration zone at conditions to
restore or maintain the activity of the catalyst by removing, i.e.,
combusting, at least a portion of the carbonaceous material from
., ,' :
the catalyst particles. When the carbonaceous deposit material
contains sulfur, at least one sulfur-containing combustion product
is produced in the regeneration zone and ma~ leave the zone with `
the regenerator flue gas. The conditions at which such free
oxygen-containing gas contacting takes place are not critical
to the presen~invention. The temperature in the catalyst
regeneration zone of a hydrocarbon cracking system is often
in the range of about 900F. to about 1500F., preferably about
900 F. to about 1300F. and more preferably about 1100F. to about
1300 F. Other conditions within such regeneration zone include,
30 for example, pressures up to about 100 psig., average catalyst -~
contact times within the range o~ about 3 minutes to about 120
: .
-21-
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,, , ~,. . .
Z~2
: .,
minutes, preferably from about 3 minutes to about 75 minutes.
Sufficient oxygen is preferably present in the regeneration
zone to completely combust the carbon and hydrogen of the ~`
carbonaceous deposit material, for example, to carbon dioxide
and water. The amount of carbonaceous material deposited on
the catalyst in the reaction zone is preferably in the range
of about 0.005% to about 15%, more preferably about 0.1~ to ;~
about 10%, by weight of the catalyst. The amount of sulfur,
if any, contained in the carbonaceous deposit material depends,
for example, on the amount of sulfur in the hydrocarbon feedstock.
This deposit material may contain about 0.01% to about 10% or -
." ..... .
more by weight of sulfur. At least a portion of the regenerated
catalystis often returned to the hydrocarbon cracking reaction zone.
The solid particles useful in the catalytic hydrocarbon
cracking embodiment of the present invention may be any conven-
tional catalyst capable of promoting hydrocarbon cracking at the
conditions present in the reaction zone, i.e., hydrocarbon
cracking conditions. Similarly, the catalytic activity of such
solid particles is restored at the conditions present in the ~-
20 regeneration zone. Typical among these conventional catalysts ;
are those which comprise amorphous silica alumina and at least
one crystalline aluminosilicate having pore diameters of about 8A ~-
to about 15A and mixtures thereof. When the solid particles
and/or discrete entities to be used in the hydrocarbon cracking
embodiment of the presentinvention contain crystalline alumino-
silicate, the compositions may also include minor amounts of
conventional metal promotors such as the rare earth metals, in
particular, cerium. ;
The catalyst, i.e., mixture comprising solid particles
and discrete entities and/or combined particles, and process of
. : ,.
. '., .
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-22-
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8Z
the invention can be ~eneficially used for the disproportion-
ation of paraffinic or aromatic hydrocarbons. For example,
the present invention is well adaptable to the disproportion-
ation of paraffinic hydrocarbons containing about 3 to about
20 carbon atoms per molecule and aromatic hydrocarbons containing
one or two rings and from 7 to about 18 carbon atoms per
molecule. The process of the inventionis particularly useful
for the disproportionation of methyl benzenes containing 7 to
about 10 carbon atoms per molecule and is especially useful for
10 the disproportionation of toluene to mixed xylenes and benzene. ~-
When disproportionating specific hydrocarbons it is often
desirable to add a higher molecular weight hydrocarbon to the ~ ~
feedstock for the purpose of increasing the yield of a desired ~ -
product. For example, when disproportionating toluene to benzene
and mixed xylenes the yield to xylenes can be increased by intro-
ducing higher methyl-benzenes with the toluene feed. These
higher methyl-benzenes usually have 9 to 10 carbon atoms and
1 to 4 methyl groups, and thus other alkyl groups such as ethyl ~;
or propyl groups may be present. Thus, the aromatic streams
available as a source of methyl groups for alkylation of toluene
frequently do not consist only of methylaromatics. For example,
the Cg+ product obtained from a xylene isomerization process
normally contains substantial ethyl (and possibly higher alkyl)
ring substituents. Ethyl or higher alkylaromatic substituents
tend to crack more readily than methyl groups to form olefins
and the parent aromatic ring. Higher temperatures also promote
the cracking reaction. As a result, the preferred conditions
for a particular operation can be dependent on the composition
of the Cg+ stream, the extent to ~hich the Cg+ stream is recycled,
and the ratio of benzene to xylenes desired in the productO In a
~., .
-23- ~
1~9Z~8~
~ ::
process involving recycle, the ethyl substituents may also be
controlled by fractionating and removing a portion of the stream
rich in n-propylbenzenes and ethyltoluenes, or rich in ethyl-
xylenes. The Cg+ hydrocarbons can be obtained from various
sources such as naphtha reformate and coal tar, and in addition,
the concentration of aromatics in the hydrocarbon streams can
be increased by fractionation or solvent extraction procedures.
Thus, trimethylbenzenes, for example, those formed as by-products
of the disproportionation reaction, can be incorporated in the `~
toluene feed, thus effecting additional xylene production through
transalkylation. The amount of the higher methylaromatics added
to the feed, either from an external supply or by recycling, can
be a small amount effective to increase the xylene/benzene ratio ~ ~ -
in the product, as about 5 to 60, preferably about 15 to 50,
weight percent based on the toluene fed to the reaction zone.
In accordance with a preferred embodiment a hydrocarbon
feedstock, such as toluene, which is in the vapor phase is dis- ~-
proportionated in a moving catalyst bed reactor in which the
catalyst comprises a mixture of about 80 to 99~ by weight of solid
particles which contain about 5% to 50% of a crystalline alumino-
silicate having a pore size of at least 5A disposed in a porous
matrix of silica-alumina and about 1% to about 20% of discrete
entities comprising about 1% to about 20% by weight of a
crystalline aluminosilicate of substantially the same pore size ;~
as the crystalline aluminosilicate included in the solid particles,
at least about 80~ by weight of alumina and about 0.05 ppm. to
about 1000 ppm. by weight of at least one platinum group metal
co~ponent disposed substantially uniformly in the alumina. The
disproportionation reaction zone is preferably operated at a
temperature of about 70F. to about 1200F. and more preferably
' ' ~'' '
~..;,,
-24-
~ . .
about 800F. to about 1000F. and preferably at approximately
atmospheric pressures such as about 0 psig. to about 30 psig.
The catalyst holding time, i.e., the average length of time
that the catalyst remains in the reaction zone is preferably
kept in the range of about 6 to about 240 and more preferably
about 12 to about 120 minutes.
After the catalyst particles leave the disproportion- `
ation reaction zone they enter the catalyst regeneration zone
where at least a portion of the carbonaceous substances which -
were deposited on the catalyst particle surfaces during the
disproportionation reaction are removed. This is accomplished
by contacting the catalyst with an oxygen-containing gas stream,
such as air, at temperatures preferably in the range of about
800F. to about 1500F. and more preferably about 900F. to about ~ ;
1200F. The temperature and flow rate of the oxygen-containing
gas stream is preferably such that the temperature in the
regeneration zone is maintained in the preferred temperature
range specified above.
The following examples clearly illustrate the present
invention. However, these examples are not to be interpreted
as specific limitations on the invention.
EXAMPLE I
This example illustrates certain of the advantages of
the present invention.
A quantity of alumina based particles of substantially
pure gamma alumina, which is derived from a mixture of alumina ~ -
monohydrate and amorphous hydrous alumina, in the shape of
spheres having a diameter of abollt 1/16 - 1/4 inch is charged
into a vessel equipped with means for evacuating the vessel.
These spheres can be obtained, for example, by the conventional
oil-drop method. The vessel is evacuated and maintained under
.
-25
~ 9~ 1532
a vacuum of about 28 inches Hg for 20 minutes. An aqueous
solution of chloroplatinic acid is introduced into the vessel
and the vessel is agitated sufficiently to effect a substan- ;;
tially uniform distribution of the platinum on the alumina
particles. The concentration of chloroplatinic acid in the
solution is sufficient to impregnate the alumina with about
100 ppm., based on weight, of platinum, calculated as elemental ;
platinum. The resulting discrete entities are dried in a hot
air stream for three hours and then calcined in an air stream -
at 1200~F. for one hour.
EXAMPLE II
Example I is repeated except that substantially all `
of the alumina based particles have diameters in the range of
about 50 microns to about 100 microns. Such particles can be
obtained by conventional spray drying techniques. As in
Example I, the final discrete entities contain about 100 ppm.
of platinum, by weight of the total discrete entities, calculated ~ `~
as elemental platinum. Also, as in Example I, the platinum is ~
substantially uniformly distributed in the discrete entities. ~ -
EXAMPLE III
A quantity of solid particles of a commercially available
hydrocarbon conversion catalyst containing about 6% by weight of
crystalline aluminosilicate, about 54% by weight amorphous silica-
alumina and 40% by weight alpha alumina, and having the same
approximate size as the discrete entities from Example I, is
combined with the discrete entities of Example I so that a mixture
of 5 parts by weight of discrete entities and 95 parts by weight
of the solid particles results. The catalytic activity of the ;~-
solid particles is equilibrated by using same (prior to combining
with the discrete entities) in commercial moving-bed hydrocarbon
conversion service. ~
'~'
-26-
: ~
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The mixture of solid particles and discrete entities
is loaded to a conventional TCC moving catalyst bed reaction-
catalyst regeneration system. Briefly, this system causes
catalyst particles to flow by gravity from supply hopper through
a reaction zone, where the catalyst is contacted with hydro-
carbon feedstock at hydrocarbon conversion conditions and the
desired hydrocarbon chemical conversion takes place. The catalyst
then flows to a catalyst regeneration zone where the catalyst is
contacted with an oxygen-containing gaseous medium to combust at
least a portion of the catalyst carbonaceous deposits which are
formed in the reaction zone. The regenerated catalyst leaves
the regeneration zone and is air lifted back to the supply hopper
and the cycle is repeated.
Toluene is disproportionated in this moving catalyst
bed reactor system loaded with the catalyst mixture. The catalyst
is advanced through at a rate such that each particle has an
average residence time in the reaction zone of about 50 minutes.
With ~quilibrium conditions achieved the reaction zone temperature ;~
is maintained at about 955F. and a reaction zone pressure of
between about 5 psig. and about 20 psig. is maintained. Toluene
is fed into the reactor at a weight hourly space velocity (WHSV)
of abou~ 1.3. Air is fed to the catalyst regeneration zone which
is maintained at conditions to combust at least a portion of the
carbonaceous catalyst deposit material, e.g., temperature of
about 1000F. to 1100F. and average catalyst residence time of
about 50 minutes.
After a period of time in operation, it is determined
that the catalyst mixture according to thepresent invention is
effective both to promote toluene disproportionation in the
reaction zone and to promote the oxidation of carbon monoxide
: . .
-27- ~
,
to carbon dioxide in the regeneration zone. The catalyst
mixture of this invention is found to provide improved results,
e.g., improved carbon monoxide oxidation catalytic activity
stability while having substantially no deleterious effect on
the hydrocarbon conversion in the reaction zone~
EXAMPLE IV
Example I is repeated, except that the alumina-based -
spheres include about 7~ by weight of a crystalline alumino-
silicate known to be catalytically active to promote hydrocarbon
conversion.
EXAMPLE V
Example III is repeated except that the discrete
entities produced in Example I are replaced by the discrete
entities of Example IVo After a period of time in toluene
disproportionation-catalyst regeneration service, this catalyst
mixture is shown to be effective to promote both toluene
disproportionation in the reaction zone and carbon monoxide
oxidation in the regeneration zone.
EXAMPLES VI AND VII
Examples III and V are repeated except that the catalyst
mixtures are used to crack a petroleum derived gas oil fraction,
a combined fresh feed and recycle stream, in the moving catalyst ~`
bed reaction-regeneration system. The fresh gas oil fraction ~ ~
boils in the range of about 400F. to about 1000F. and is ~ -
substantially hydrocarbon in nature, containing minor amounts
of sulfur and nitrogen as contaminants. Conventional hydrocarbon
cracking and catalyst regeneration conditions are employed in -
the reaction zone and regeneration zone, respectively.
The catalyst mixtures are found to be effective to
promote hydrocarbon cracking and to promote carbon monoxide
':'
-28-
~ 3~Z~
oxidation. Such hydrocarbon cracking operation provides
improved results, e.g., prolonged carbon monoxide oxidation
catalytic activity while providing for effective hydrocarbon
cracking catalytic activity.
EXAMPLE VIII ~
The discrete entities produced in Example II are -
intimately comingled with solid particles of commercially
available hydrocarbon cracking catalyst similar to that used -
in Example III except that the substantially all, by weight, of
the particles have diameters in the range of about 20 microns to
about 150 microns. The hydrocarbon cracking catalytic activity
of such particles is equilibrated by service in a conventional
commercial fluid-bed catalyst cracking (FCC) unit. The resulting
catalyst mixture includes 5 parts by weight of discrete entities
and 95 parts by weight of the solid particles.
This catalyst mixture is used to crack a petroleum
derived gas oil stream, similar to that described in Examples
VI and VII, to lower boiling hydrocarbons in a conventional `
FCC unit.
Briefly, such unit involves two vessels in at least
limited fluid communication with each other. One vessel serves
as a reaction zone. Hydrocarbon feedstock and catalyst particles
;~ , , .
are fed to the reaction zone at hydrocarbon cracking conditions.
At least a portion of the hydrocarbon cracking occurs in this
reaction zone, where the catalyst and hydrocarbon form a fluid
phase or bed.
Catalyst and hydrocarbon are continuously drawn from
the reaction zone. The hydrocarbon is sent for further processing, ;~
distillation and the like. Catalyst,stripped of hydrocarbon, -
flows to the other vessel, catalyst regeneration zone, where it
.. . ..
~':'.,:'' "
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-29-
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is combined with air at proper conditions to combust at least
a portion of the carbonaceous deposits from the catalyst formed -
during the hydrocarbon cracking reaction. The catalyst and ;
vapors in the regeneration zone form a fluid phase or ~ed.
Catalyst is continuously removed from the regeneration zone
and is combined with the hydrocarbon feedstock prior to being ~ -
fed to the reaction zone.
The weight ratio of catalyst particles to total
(~resh plus recycle) hydrocarbon feed entering the reaction
zone is about 8 to 1. Other conditions within the reaction
zone include:
Temperature, ~F. 930
Pressure, psig. 8
WHSV 15
Such conditions result in about 70% by volume conversion of the
gas oil feedstock to products boiling at 400F. and below.
The catalyst particles from the reaction zone include
about 1.5% byweight of carbonaceous deposit material which is
at least partially combusted in the regeneration zone. Air, in
an amount so that amount of oxygen in the regenexation zone is
about 1.15 times the amount theoretically required to completely
.
combust this deposit material, is heated to the desired temperature
before being admitted to the regeneration zone. Conditions within ~
the regeneration zone include: ; -
.: .
Temperature, F. 1150
Pressure, psig. 8
Average Catalyst
Residence Time, min. 12
After a period of t~, the catalyst is shown to remain
effective to promote both hydrocarbon cracking in the reaction
zone and carbon monoxide oxidation in the regeneration zone.
-30-
~?Z~82
One additional feature of the present invention
illustrated by the above Example involves the processing of
sulfur contaminated hydrocarbon feedstock. For example, fresh
hydrocarbon feedstocks, e.g., petroleum derived gas oils,
often contain about 0.01% to about 5~ or more, preferably from
about 0.1% to about 3%, by weight of sulfur. Such feedstocks
form carbonaceous deposits on the catalyst which also contain
sulfur. During regeneration of such catalyst by contacting with
an oxygen-containing gaseous stream, at least a portion of this
deposit sulfur is oxidized to sulfur dioxide and, ordinarily,
leaves the system with combustion flue gases. It is now found
that the presence of at least one platinum group metal component
in the catalyst regeneration zone acts to promote the further
oxidation of sulfur and sulfur-containing compounds to SO3. The
SO3 thus formed,associates with the alumina of the discrete
entities,until such entities are placed in a hydrocarbon
chemical conversion reaction zone environment. Under such ;
reaction zone conditions, at least a portion of this sulfur -
trioxide is converted to H2S which is removed from the reaction ~
20 zone with the hydrocarbon conversion products. Thus, in this ~ -
embodiment, i.e., when processing a sulfur contaminated hydro-
carbon feedstock, the present catalyst and process provide
for reduced sulfur dioxide emissions from the regenerator zone `
combustion flue gases.
EXAMPLE IX
Example VIII is repeated except that the discrete
entities employed include about 7~ by weight of a crystalline
aluminosilicate known to be catalytically active to promote
hydrocarbon cracking.
-~
,~ ,~',.'
-31- ;~
~ .. . . . . . , : , - .
- -- :
l~ Pl~
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The present catalyst and process provide improved
properties and results. For example, the present alumina-based
discrete entities have outstanding carbon monoxide oxidation
catalytic activity stability. That is, the time rate decline
; 5 of carbon monoxide oxidation catalytic activity of the present
catalyst is reduced. Clearly, the present catalyst and process
provide for improved hydrocarbon chemical conversion.
EXAMPLE X ;
A mass of combined particles is prepared as follows:
The alumina-based discrete entities are prepared by
forming an aqueous slurry of alumina hydrate so that the
alumina concentration, calculated as A12O3, is about 9% by weight.
~ The composition of the alumina hydrate is established by X-ray
i diffraction to be about 56% by weight boehmite, and 44% by weight
amorphous alumina hydrate. The average boehmite crystallite
size is about 56 ~ units. This slurry is stirred for about 1 hour
to insure uniformity and then spray dried at a temperature less ~ ~
than that required to eliminate a substantial portion of the ;
water of hydration to form discrete entities. These discrete
entities are calcined in an electric muffle furnace using a
programmed timer to increase the temperature 300F. per hour to
1050F. and maintain this temperature for 3 hours. ~-
Essentially all the calcined discrete entities have a
maximum dimension of less than about 200 microns. Micromesh
., .
analysis of these calcined discrete entities is as follows:
Wt.% of Total
Calcined Disc_ete Entities
On 75 Micron Screen 23.5
On 60 Micron Screen 14.4
On 45 Micron Screen 15.7
30 On 30 Micron Screen 21.6 ;
On 20 Micron Screen 17.0
Through 20 Micron Screen 7.8
,. ..
Total 100.0
-32-
~,
The discrete entities larger than 60 microns are
discarded.
The solid particles-binder material is prepared by
adding 6000 parts by weight of a solution containing Philadelphia
Quartz Company "E" brand sodium silicate solution diluted with an
equal weight of water to 3000 parts by weight of dilute (density -
1.234) H2SO~. After these two solutions are thoroughly mixed,
4000 parts by weight of a solution containing 1200 parts by weight
of A12(SO4)3 18 H2O is added. Sufficient crystalline alumino-
silicate, known to be effective to promote hydrocarbon cracking,is added to the mixture so that the final solid particles-binder
material contains, on a dry weight basis, about 10~ of such
cyrstalline aluminosilicate. The resulting mixture is let stand
to gel. The resulting hydrogel is cut into about 3/4" cubes and
15 covered with concentrated N~40H diluted with an equal volume of - ;
waterO This material is let stand overnight and has a final pH
of 11. The material is then washed by percolation until free of ~
Na~ and S04=ion. `
500 parts (on a dry weight basis) of the washed hydrogel
.. ~ .
and 80 parts (on a dry weight basis) of the remaining calcined
discrete entities and 10,000 parts by weight of water are
:.: .: : . .
throughly mulled, ground and mixed with agitation. The resulting ~ `
slurry is dried in a spray drier. This drier is equipped with a
two-fluid nozzle system which uses air at about 20 psig. to dis- `~
perse the slurry into the drying chamber. The drying gas, i.e.,
flue gas from an inline burner, enters the drying chamber at -~
about 705F. and exits the chamber at a temperature which
ranges from about 305F. to 315F. This drying gas is intro-
duced into the top of the drying chamber while the slurry
is dispersed upward from near the bottom of the chamber.
In this way, the material to be dried is exposed to
, .
~.
-33-
p~z
both counter current flow (during assent fxom the nozzle system) ~-
and co-current flow (during gravity dissent) relative to the
downward drying gas flow. The resulting dried particles are
calcined in a manner similar to the calcination of the alumina
based discrete entities described above. The resulting combined
particles are screened to provide particles properly sized for
use in a fluidized catalytic bed reaction zone-regenerator
hydrocarbon cracking system.
.
EXAMPLE XI -~
,. .
Example X is repeated except that thealumina-based ~
discrete entities are impregnated with platinum as in Examples ;
I and II prior to being incorporated into the combined particles.
The discrete entities contain about 100 ppm by weight of platinum,
calculated as elemental platinum, substantially uniformily
15 distributed in the discrete entities. -;
EXAMPLE XII
Example VIII is repeated except that the physical
mixture of discrete entities and catalyst particles used in ; ;
Example VIII are replaced by the combined particles produced
in Example X and the hydrocarbon feed contains about 0.5% by
weight of sulfur. After a period of time, these combined
particles are shown to remain effective to promote both hydro- -~
carbon cracking in the reaction zone and to reduce the amount of
sulfur atmospheric emissions in the regeneration zone flue gases.
EXAMPLE XIII
Example XII is repeated using the combined particles
produced in Example XI as catalysts. Over a period of time,
. . .~ . .
these co~bined particlPs remain effective to promote hydrocarbon
cracking in the reaction zone, reduce the amount of sulfur
atmospheric emissions in the regeneration zone flue gases and,
,, ''~ .
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also, promote the oxidation of carbon monoxide in the regeneration `-
zone.
While this invention has been described with respect
to various specific examples and embodiments, it is to be
understood that the invention is not limited thereto and that
it can be variously practi.ced within the scope of the `.
iollDwing claimq . ~ ~
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