CA1162522A - Catalyst and process for conversion of hydrocarbons - Google Patents
Catalyst and process for conversion of hydrocarbonsInfo
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- CA1162522A CA1162522A CA000379660A CA379660A CA1162522A CA 1162522 A CA1162522 A CA 1162522A CA 000379660 A CA000379660 A CA 000379660A CA 379660 A CA379660 A CA 379660A CA 1162522 A CA1162522 A CA 1162522A
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Abstract
CATALYST AND PROCESS FOR CONVERSION OF HYDROCARBONS ABSTRACT OF THE DISCLOSURE An improved process for converting hydrocarbons using a catalyst which is periodically regenerated to remove carbonaceous deposits, the catalyst being comprised of a mixture containing, as a major component, solid particles capable of promoting hydrocarbon conversion at hydrocarbon conversion conditions, and, as a minor component, discrete entities comprising at least one spinel, preferably alkaline earth metal-containing spinel; thereby reducing the amount of sulfur oxides exiting the catalyst regeneration zone. Improved hydrocarbon conversion catalysts are also disclosed.
Description
i ~f~3,~'~
BACKGROl.lND OF THE INV~NTION
., . _ The invention is concerned with the combusting of solid, sulfur-containing material in a manner to effect ~ reduction in the emission of fiulfur oxides to the atmosphere. ~n one specific embodiment, the invention involves the catalytic cracking of ~ulfur-containing hydrocarbon feedstocks in a manner to effect a reduction in the amount of ~ulfur oxides emitted from the regeneration zone of a hydrocarbon catalytic crac~ing unit.
Typically, catalytic cracking of hydrocarbons takes place in a reaction zone at hydrocarbon cracking conditions to produce at least one hydrocarbon product and to cause carbonaceous material Icoke) to be deposited on the catalyst. Additionally, some sulfur, originally present in the feed hydrocarbon~ may also be deposited, e.g., as a component of the coke, on the catalyst.
It has been reported that approximately 504 of the feed ~ulfur is converted to H2S in the FCC reactor, 40% remains in the liquid products and about 4 to 10% is deposited on the catalyst. Trhese amounts vary with the type of feed, rate of hydrocarbon recycle, steam stripping rate, the type of catalyst, reactor temperature, etc.
Sulfur-containing coke deposits tend to deactivate cracking catalyst. Cracking catalyst is advantaqeously continu~usly regenerated, by combustion with oxygen-containin~ gas in a regeneration zone, to low coke levels, typically below about 0.4% by weight, to perform satisfactorily when it is recycled to the reactor.
In the regeneration zone, at least a portion of sulfur, along with carbon and hydrogen, which is deposited on the catalyct, i~ oxidized and leaves in the form r~) of ~ulfur oxides (SO2 and SO3, hereinafter referred to as ~SOxn~ along with substantial amount~ of CO, C2 and H2O.
Considerable amount of ~tudy and research effort ~as been directed to reducing oxide of sulfur emissions from various gaseous streams, including those from the stacks of the regenerators of FCC units. Rowever, the results leave much to be desired. Many metallic com-pounds have been proposed as materials to Pick uP oxides 10 of ~ulfur in FCC units (and other desulfurization appli-cations) and a variety of supports, including particles of cracking catalysts and ~inerts~, have been suggested as carriers for active metallic reactants. Many of the proposed metallic reactants lose effectiveness when subjected to repeated cycling. Thus when Group II metal oxides are impregnated on FCC catalysts or various supports, the activity of the Group II metals is rapidly reduced under the influence of the cyclic conditions.
Discrete alumina particles, when combined with silica-containing catalyst particles and subjected to steam `at elevated temperatures, e.~., those present in FCC
unit regenerators, are of limited effectiveness in reducing SOx emissions. Incorporation of sufficient chromium on an alumina support to improv2 SOx sorption results in undersirably increased coke and gas productionO
Accordingly, an object of the present inven$ion is the provision of an improved composition and process for reducing emissions o sulfur oxides.
An additional object of the present invention is to provide an improved composiotn and process for reducing the emissions of sulfur oxides from the regeneration zones of hydrocar~on catalytic crackinq units.
Another object of the invention i6 to provide an improved hydrocarbon conversion cataly~t. ~hese and other objects of the invention will become apparent from the followinq description and examples.
In one yeneral aspect, the present invention involves a process for combusting ~olid, sulfur-containing material by contacting the material with gaseous oxygen in a combustion zone at combustion conditions to produce c~mbustion products including sulfur oxide at least a portion of which is sulfur trioxide. The present improvement com-prises carrying out this contacting in the presence of dis-crete entities containing an effective amount, preferably a major amount by weight, of at least one metal-containing spinel, preferably alkaline earth metal-containing spinel, to thereby reduce the amount of sulfur oxide (relative to combustion in the essential absence of the discrete entities) emitted from the combustion zone. In another embodiment, the present inprovement comprises carrying out this contacting in the presence of discrete entities containing an effective amount, preferably a major amount by weight, of at least one alkaline earth metal-containing spinel and a minor amount of at least one rare earth metal component associated with the spinel to thereby reduce the amount of sulfur oxide ~relative to combustion in the essential absence of the discrete entities) emitted from the combustion zore.
In accordance with another aspect, the present invention involves a converstion process which i5 carried out, preferably in the substantial absence of added free hydrogen, in at least one chemical reaction zone in which sulfur-containing hydrocarbon feedstock is contacted with particulate material to form at least one hydro-carbon product and sulfur-containing carbonaceous material deposi~ed on the particulate material and at least ~ ~2i,~.~
one regeneration zone in which at least a portion of the 6ulfur-containing carbonaceous material deposited on the ~olid particles is contacted with gaseous oxygen to combust the sulfur-containing carbonaceous material and to produce combustion products including sulfur oxid~ at least a portion of which is sulfur trioxide.
The pres~nt improvement comprises u6ing a particulate material comprising (A) a major amount of solid particles capable of promoting the desired hydrocarbon chemical conversion at hydrocarbon conver~ion conditions and ~B) a minor amount of discrete entities comprising an effective amount, preferably a major amount of weight, i.e., at least about 50% by weight, of at least one metal-containing spinel, preferably alkaline earth metal containing spinel. In the event such discrete entities comprise alkaline earth metal containing spinel, it is more preferred that such discrete entities further comprise a minor amount of at least one rate earth metal, preferably, ceruim, component associated with the ~pinel. In one pre-ferred e~mbodiment, the discrete entities also include a minor, catalytically effective amount of at least one crystalline aluminosilicate effective to promote hydrocarbon conversion, e.g., cracking at hydrocarbon conversion conditions. The discrete entities are present in an amount sufficient to reduce the amount of sulfur oxides in the regeneration zo~e effluen~ when used in a reaction zone-regeneration zone system as described herein.
In one preferred embodiment, the particulate material, more preferably the discrete entities, further comprise a minor amount of at least one additional metal, e.g., a Group VIII platinum group metal, component capable of promoting the oxidation of sulfur dioxide to sulfur trioxideatthe condition~ in the regeneration zone.
The preferred platinum group ~etals are palladium and platinum, most prèferably platinum.
The prefelred relative amounts of the s~lid particles and discrete entities are a~out 80 to about 99 parts and 1 to about 20 parts by weight, respectively~
This catalyst system is especially effective for the catalytic cracking of a hydrocarbon feedstock to lighter, lower boiling products. The present catalyst system prefer-ably also has improved carbon monoxide oxidation catalytic activity stabilitY-The improvement of this invention can be used to advanta~e with the cat~lyst being disposed in any conven-tional reactor-regenerator system, in ebullating catalyst bed systems, in systems which involve continuously convey-ing or circulating catalyst between reaction zone and re-generation zone and the like. Circulating cataylst 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 conver-sion, e.g., hydrocarbon cracking, operations with the fluidized catalyst bed reactor-regenerator systems being preferred.
The catalyst ~ystem used in accordance with certain embodLments of the invention is comprised of a mixture of two types of solid particles.
Although the presently useful ~olid particles and discrete entities may ~e used as a physical admixture of separate particles, in one embodiment, the discrete entities are combined as part of the solid particles.
That is, the discrete entities, e.g., comprising calcined microspheres containing metal-containing spinel, and prefer-ably, at least one additional metal component, are combined
BACKGROl.lND OF THE INV~NTION
., . _ The invention is concerned with the combusting of solid, sulfur-containing material in a manner to effect ~ reduction in the emission of fiulfur oxides to the atmosphere. ~n one specific embodiment, the invention involves the catalytic cracking of ~ulfur-containing hydrocarbon feedstocks in a manner to effect a reduction in the amount of ~ulfur oxides emitted from the regeneration zone of a hydrocarbon catalytic crac~ing unit.
Typically, catalytic cracking of hydrocarbons takes place in a reaction zone at hydrocarbon cracking conditions to produce at least one hydrocarbon product and to cause carbonaceous material Icoke) to be deposited on the catalyst. Additionally, some sulfur, originally present in the feed hydrocarbon~ may also be deposited, e.g., as a component of the coke, on the catalyst.
It has been reported that approximately 504 of the feed ~ulfur is converted to H2S in the FCC reactor, 40% remains in the liquid products and about 4 to 10% is deposited on the catalyst. Trhese amounts vary with the type of feed, rate of hydrocarbon recycle, steam stripping rate, the type of catalyst, reactor temperature, etc.
Sulfur-containing coke deposits tend to deactivate cracking catalyst. Cracking catalyst is advantaqeously continu~usly regenerated, by combustion with oxygen-containin~ gas in a regeneration zone, to low coke levels, typically below about 0.4% by weight, to perform satisfactorily when it is recycled to the reactor.
In the regeneration zone, at least a portion of sulfur, along with carbon and hydrogen, which is deposited on the catalyct, i~ oxidized and leaves in the form r~) of ~ulfur oxides (SO2 and SO3, hereinafter referred to as ~SOxn~ along with substantial amount~ of CO, C2 and H2O.
Considerable amount of ~tudy and research effort ~as been directed to reducing oxide of sulfur emissions from various gaseous streams, including those from the stacks of the regenerators of FCC units. Rowever, the results leave much to be desired. Many metallic com-pounds have been proposed as materials to Pick uP oxides 10 of ~ulfur in FCC units (and other desulfurization appli-cations) and a variety of supports, including particles of cracking catalysts and ~inerts~, have been suggested as carriers for active metallic reactants. Many of the proposed metallic reactants lose effectiveness when subjected to repeated cycling. Thus when Group II metal oxides are impregnated on FCC catalysts or various supports, the activity of the Group II metals is rapidly reduced under the influence of the cyclic conditions.
Discrete alumina particles, when combined with silica-containing catalyst particles and subjected to steam `at elevated temperatures, e.~., those present in FCC
unit regenerators, are of limited effectiveness in reducing SOx emissions. Incorporation of sufficient chromium on an alumina support to improv2 SOx sorption results in undersirably increased coke and gas productionO
Accordingly, an object of the present inven$ion is the provision of an improved composition and process for reducing emissions o sulfur oxides.
An additional object of the present invention is to provide an improved composiotn and process for reducing the emissions of sulfur oxides from the regeneration zones of hydrocar~on catalytic crackinq units.
Another object of the invention i6 to provide an improved hydrocarbon conversion cataly~t. ~hese and other objects of the invention will become apparent from the followinq description and examples.
In one yeneral aspect, the present invention involves a process for combusting ~olid, sulfur-containing material by contacting the material with gaseous oxygen in a combustion zone at combustion conditions to produce c~mbustion products including sulfur oxide at least a portion of which is sulfur trioxide. The present improvement com-prises carrying out this contacting in the presence of dis-crete entities containing an effective amount, preferably a major amount by weight, of at least one metal-containing spinel, preferably alkaline earth metal-containing spinel, to thereby reduce the amount of sulfur oxide (relative to combustion in the essential absence of the discrete entities) emitted from the combustion zone. In another embodiment, the present inprovement comprises carrying out this contacting in the presence of discrete entities containing an effective amount, preferably a major amount by weight, of at least one alkaline earth metal-containing spinel and a minor amount of at least one rare earth metal component associated with the spinel to thereby reduce the amount of sulfur oxide ~relative to combustion in the essential absence of the discrete entities) emitted from the combustion zore.
In accordance with another aspect, the present invention involves a converstion process which i5 carried out, preferably in the substantial absence of added free hydrogen, in at least one chemical reaction zone in which sulfur-containing hydrocarbon feedstock is contacted with particulate material to form at least one hydro-carbon product and sulfur-containing carbonaceous material deposi~ed on the particulate material and at least ~ ~2i,~.~
one regeneration zone in which at least a portion of the 6ulfur-containing carbonaceous material deposited on the ~olid particles is contacted with gaseous oxygen to combust the sulfur-containing carbonaceous material and to produce combustion products including sulfur oxid~ at least a portion of which is sulfur trioxide.
The pres~nt improvement comprises u6ing a particulate material comprising (A) a major amount of solid particles capable of promoting the desired hydrocarbon chemical conversion at hydrocarbon conver~ion conditions and ~B) a minor amount of discrete entities comprising an effective amount, preferably a major amount of weight, i.e., at least about 50% by weight, of at least one metal-containing spinel, preferably alkaline earth metal containing spinel. In the event such discrete entities comprise alkaline earth metal containing spinel, it is more preferred that such discrete entities further comprise a minor amount of at least one rate earth metal, preferably, ceruim, component associated with the ~pinel. In one pre-ferred e~mbodiment, the discrete entities also include a minor, catalytically effective amount of at least one crystalline aluminosilicate effective to promote hydrocarbon conversion, e.g., cracking at hydrocarbon conversion conditions. The discrete entities are present in an amount sufficient to reduce the amount of sulfur oxides in the regeneration zo~e effluen~ when used in a reaction zone-regeneration zone system as described herein.
In one preferred embodiment, the particulate material, more preferably the discrete entities, further comprise a minor amount of at least one additional metal, e.g., a Group VIII platinum group metal, component capable of promoting the oxidation of sulfur dioxide to sulfur trioxideatthe condition~ in the regeneration zone.
The preferred platinum group ~etals are palladium and platinum, most prèferably platinum.
The prefelred relative amounts of the s~lid particles and discrete entities are a~out 80 to about 99 parts and 1 to about 20 parts by weight, respectively~
This catalyst system is especially effective for the catalytic cracking of a hydrocarbon feedstock to lighter, lower boiling products. The present catalyst system prefer-ably also has improved carbon monoxide oxidation catalytic activity stabilitY-The improvement of this invention can be used to advanta~e with the cat~lyst being disposed in any conven-tional reactor-regenerator system, in ebullating catalyst bed systems, in systems which involve continuously convey-ing or circulating catalyst between reaction zone and re-generation zone and the like. Circulating cataylst 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 conver-sion, e.g., hydrocarbon cracking, operations with the fluidized catalyst bed reactor-regenerator systems being preferred.
The catalyst ~ystem used in accordance with certain embodLments of the invention is comprised of a mixture of two types of solid particles.
Although the presently useful ~olid particles and discrete entities may ~e used as a physical admixture of separate particles, in one embodiment, the discrete entities are combined as part of the solid particles.
That is, the discrete entities, e.g., comprising calcined microspheres containing metal-containing spinel, and prefer-ably, at least one additional metal component, are combined
2 ~
with the solid particles, e.g., during the manufacture of the solid particles, to form combined particles which function as both the presently useful solid particle~
and discrete entities i8 pre~erably a separate and distinct phase. One preferred method for providing the combined particles is to calcine the discrete entities prior to incorporating the di~crete entitieæ
into the co~bined particles.
The form, i.e., particle size, of the present catalyst particles, e.g., both fiolia 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 ~ystem employed. Such catalyst particles may be formed into any desired shape such a pills, cakes, extrudates, powders, granules, 6pheres and the like, using conventional methods. With regard to fluidized catalyct 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 solid particles are capable of promoting the desired hydrocarbon conversion. The solid particles are further characterized as having a composition (i.e., chemical ma~e-up) wh~ch is different from the discrete entities. In one preferred embodiment, the ~olid particles ~or the ~olid particles portion of the combined particles described above) are substantially free of metal~containing spinel, e.g.; alkaline earth metal-containing spinel.
In one aspect of the present invention, the discrete entitie~ comprise an effect;ve amount of at least one metal-containing spinel, preferably alkaline earth t 1~25~2 metal-containing spinel, and preferably, a minor, catalytically effective amount of at least one crystalline ~luminosilica~e capable of promoting hydrocarbon conver-sion at hydrocarbon conversion conditions. In the event ~uch discrete entities comprise alkaline earth metal-contain-ing spinel, it is more preferred that such discrete entities include a minor amount of at least one rare earth metal com-ponent, preferably a cerium component, associated with the spinel. 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, and/or the solid particles and/or one or more other type of particles (i.e., having compositions different from the present solid particles and discrete entities) further com-prise a minor amount of at least one additional metal, e.g., platinum group metal, component capable of promoting the oxidation of sulfur dioxide to the sulfur trioxide at the conditions in the combustion, e.g., catalyst regen-eration, zone For example, an effective amount of at least one sulfur oxide oxidation catalytic component, e.g., metal or compounds of metals selected from Group VI, IIB, IVB, VIA, ~IB, VIIA and VIII and mixtures thereof, disposed on a support, e.g., one or more inorganic oxides, may be in-cluded with the present solid particles and discrete entities and/or may be included on the solid particles and/or discrete entities. As noted previously, the sulfur oxide oxidation component may be associated with, e.g., deposited on, the spinel com~onent ~f the present discrete entities.
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 l 16~522 compositions ~re conventionally used as catalyst in such hydrocarbon conversion processes, the 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 one of the natural or synthetic materials which are capable of 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 suitabie 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 aluminosilicate 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 aluminosilicate 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. Certain of these procedures are thoroughly described in U.S. Patents 3,140,253 and RE. 27,639.
Compositions of the solid particles which are partisularly 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 porour matrix which comprises, for example, amorphous material which may or may not be itself capable of promoting such hydrocarbon conversion.
Included among such matrix materials are clays and amorphous compositions of silica-alumina, magnesia, zirconia, mixtures of these and the like. The crystalline aluminosilicate is l 162~2 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 formed during and/or as part of the methods of manufacturing the solid particles, discrete entities and/or combined particles are within the scope of the present invention. The solid particles are preferably substantially free of added rare earth metal, e.g., cerium, component disposed on the amorphous matrix material of the catalyst, although such rare earth metal components may be associated with the crystalline aluminosilicate components of the solid particles.
As indicated above, the discrete entities utilized in the present invention comprise an effective amount, preferably a major amount, of at least one metal-containing spinel, preferably alkaline earth metal-containing spinel. In another aspect, the present discrete entities further comprise a minor amount of at least one additional metal, e.g., platinum group metal, component capable of promoting sulfur dioxide oxidation.
The spinel structure is based on a cubic close-packed array of oxide ions. Typically, the crystallographic unit cell of the spinel structure contains 32 oxygen atoms; one-eighth of the tetrahedral holes (of which there are two per anion) are occupied by ~ 1~2522 divalent metal ion, and one-half of the octahedral holes for which there are two per anion) are occupied by trivalent metal ion 5 .
This typical spinel structure or a modification thereof is adaptable to many other mixed metal oxides of the type M M2 4 (e-g-, FeCr204,~nA1204 and Co Co2 04), by some of the type MIVMII204 (e.g., Ti~n204, and SnCo204), and by some of the type M2MVIO4 (e.g., Na2MoO4 and Ag2MoO4).
This structure is often symbolized as X[Y2]04, where square brackets enclose the ions in the octahedral interstices.
An important variant is the inverse spinel structure, Y[XY]04, in which half of the Y ions are in tetrahedral interstices and the X ions are in octahedral ones along with the other half of the Y ions. The inverse spinel structure is intended to be included within the scope of the term "metal-containing spinel" as used herein. The inverse spinel structure occurs often when the X ions have a stronger preference for octahedral coordination than do the Y ions. All MIVM2IIO~ are inverse, e.g., ~n(~nTi)04, and many of the M M2 4 ones are also, e.g., Fe (Co Fe )04, NiA124'Fe (Fe Fe )04 and Fe(NiFe)04. There are also many compounds with distorted spinel structures in which only a fraction of the X ions are in tetrahedral sites. This occurs when the preference of both X and Y ions for octahedral and tetrahedral sites do not differ markedly.
Further, details on the spinel structure are described in the following references: "Modern Aspects of Inorganic Chemistry" by H. I. Emeleus and A. G. Sharpe (1973), pp. 57-58 and 512-513; "Structural Inorganic Chemistry", 3rd edition, (1962) by A. F. Wells, pp. 130, 487 490, 503 and 526; and "Advanced Inorganic Chemistry", 3rd edition, by F. A. Cotton and ~.
1 ~82~22 Wilkinson 11972), PP. 54~55-Metal-containing spinels include the following:
Mn~1204, FeA1204, CoA120~, NiA120~, 2 4 FeMgFeO4, FeTiFeO~ ZnSnZnO4, GaMg~aO~, ~nMg~nO4, BeLi2F4, 2 4 24~ SnMg204~ ~gA1204, CUA1204, (LiAl O ) ZnK2tCN)4, CdK2(CN~4~ ~gK2~N)4~ ZnTi2 4' 2 4 2 4 MnCr o , FeCr204, CoCr~04, NiCr204, ZnCr204, 2 4' 2 4 ZnCr2S4, cdCr2S4, TiMn~04 M~Fe24' FeFe24' CoF 24' 2 4 CuFe2~4, 2nFe20~, CdFe204~ ~gC24~ 2 4 2 4 2 4 2S4, CUC254~ Ge~i2o4~ NiNi2S4, ZnGa2o4, WAg o and ZnSn204.
The preferred metal-containing spinel~ for use in the present invention are alkaline earth metal spinels, in particular magnesium aluminate spinel. Lithium containing spinels,which may be produced using conventional techniques are also preferred for use. With regard to magnesium alumi-nate spinel, there often are eight Mg atoms and sixteen Al atoms to place in a unit cell l8MgA1204). Other alkaline earth metal ions, such as calcium, stronium, barium and mix-tures thereof, may replace all or a part of the magnesiumions. Similarly, other trivalent metal ions, such as iron, chormium, vanadium, manganese, gallium, boron, cobalt and mixtures thereof, may replace all or a part of the aluminum ions.
The metal~containing spinels useful in the present invention may be derived from conventional and well known sources. For example, these spinels may be naturally occurring or may be ~ynthesized using techniques well known in the art. Thus, a detailed description of such techniques is not included herein. However, a brief description of the preparation of the most preferred spinel, i.e., magnesium aluminate spinel,is set forth below. Certain of the tech-niques described, e.g., dryirg l~nd calcining, have applica-bility to other metal-containing ~;pinels.
The magnesi~m aluminate spinel ~uitable for use in the present invention can be prepared, for example, according to the method di~closed in ~.S. Patent No.
2,992,191 The spinel can be formed by reacting, in an aqueous medium, a water-soluble nagnesium inorganic salt and a water-~oluble aluminum salt ~n which the aluminum is present in the anion. Suitable salts are exemplified by the strongly acidic magnesium salts ~uch as the chloride~ nitrate or ~ulfate and the water soluble alkali metal aluminates~ ~he magnesium and aluminate ~alts are dissolved in an aqueous medium and a spinel precursor is precipitated through neutralization of the aluminate by the acidic magnesium salt. Excesses of acid salt or aluminate are preferably not employed, thus avoiding the precipitation of excess magnesia or alumina.
Preferably, the precipi~ate is washed free of extraneous ions before being further processed.
The precipitate can be dried and calcined to yield the magnesium aluminate spinel. Dryinq and cal-cination may take place simultaneously. However, it is preferred that the drying take place at a temperature below which water of hydration is removed from the spinel precursor. Thus, this drying may occur at temperatures ~elow about 500~., preferably from about 220F. to about 450DF. Suitable calcination temperatures are exemplified by temperatures ranging ~rom about 800F. to about 2000F.
or more. Calcination of the spinel precursor may take place in a period of time o~ at least about one half hour and preferably in a period of tLme ranging from about 1 hour to about 10 hours.
Another proceg for ~roducing the presently ~ 162~
Useful magnesium aluminate spinel i5 set forth in U.S.
Patent 3,791,992. This process includes mixing a solution of a soluble acid salt of divalent magnesium with a solution of an alkali metal aluminate; separating and washing the resulting precipitate; exchanging the washed precipitate with a solution of an ammonium compound to decrease the alkali metal content; followed by washing, drying, forming and calcination steps. In general, as indicated previously, the metal-containing spinels useful in the present invention may be prepared by methods which are conventional and well known in the art.
The metal spinel-based composition may be formed into particles of any desired shape such as pills, cake, extrudates, powders, granules, spheres, and the like using conventional methods. ~he 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.
Substantially non-interfering proportions of other well known refractory material, e.g., inorganic oxides such as silica, zirconia, thoria and the like may be included in the present discrete entities. Free magnesia and/or alumina (i.e., apart from the alkaline earth metal containing spinel) also may be included in the discrete entities, e.g., using conventional techniques. For example, the discrete enti-ties may include about 0.1% to about 25% by weight of free magnesia (calculated as MgO). By substantially "non-inter-ferring" is meant amounts of other material which do not have asubstantial deleterious effect on the present catalyst system or hydrocarbon conversion proce~s. ~he inclusion of material~
~uch as silica, zirconia, ~horia and the like into ~he present discrete entities may act ~o improve one or more of the functions of the discrete entitie~.
The presently useful lithi~n containing spinels, e.g., lithium aluminate spinel, preferably are associated with a minor amount of at least one rare earth metal component.
Cerium or other suitable rare earth or rare earth mixture may be associated with the spinel usin~ any suitable technique or combination of techniques; for example, impregnation, coprecipitation, ion-exchange and the like, well known in the art, with impregnation beinq preferred. Impregnation may be carried out by contacting the spinel with a solution, preferably aqueous, of rare earth; for example, a solution containing cerium ions lpreferably Ce~3, Ce+4 or mixtures thereof~ or a mixture of rare earth cations containing a substantial amount ~for example, at least 404) of cerium ions. Water-soluble sources of rare earth include the nitrate and chloride. Solutions having a concentration of rare earth in the range of 3 to 30~ by weight are preferred. Preferably, sufficient rare earth salt is added to incorporate about 0.05 to 254 (weiqht), more preferably about 0.1 to 15% rare earth, and still more preferably about 1.0 to 15% rare earth, by weight, calcula~ed as elemental metal, on the particles.
It may not be necessary to wash the spinel after certain soluble rare earth salts (such as nitrate or acetate) are added. After impxegnation with rare earth salt, ~he spinel can be dried and calcined to decompose the salt,fonn-ing an oxide in the case of nitrate or acetate. Alternatively, the spinel, e.g., in the form of discrete particles, can be charged to a hydrocarbon conversion, e.g., cracking unit, with the rare earth in ~alt form. In this case a rare earth ~alt with a thermally decomposable anion can decompose to 1 ~ 6~1~ $~2 the oxide in the reactor and be available $o associate with S~x in the regenerator.
Especially good results were achieved using ~pinel containing discrete entities 3uch that the concentration of rare earth metal, e.g., cPrium, calculated as the metal, is in the range of about 1 t~-25~, more preferably about 2% to about 15%, by weight of the total di~crete entities.
The present discrete entities preferably further comprise a minor amount ~f at least one crystalline aluminosilicate capable of promoting the desired hydrocarbon conversion. Typical aluminosilicates have been described above. Preferably, such aluminosilicates comprise about 1~ to about 30~, more preferably about 1% to about 10~, by weight of the discrete er.tities. The presence of ~uch aluminosilicates in the present discrete entities acts to increase the overall catalytic activity of the ~olid particles-discrete entities mixture for promoting the desired hydrocarbon conver~ion.
As indicated above, in one preferred embodiment the presently useful particulate material, e.g., the discrete entities utilized in the present invention, also contain at least one additional metal, e.g., platinum group metal, component. These additional metal components are defined as being capable of prom~ting the oxidation of sulfur dioxide to sulfur trioxide at combustion conditions~ e.g., the conditions present in the catalyst regenerator. Increased carb~n monoxide oxidation may also be obtained by including at least one of the additisnal metal components. ~uch metal components are selected from the group consi~ting of 30 Group IB, IIB, IVB, YIA~ VIB, VIIA and VIII of the Periodic Table, the rare earth metals, vanadium, iron, tin and antimony and mLxtures thereof and may be incorporated into the presently ~ lS2~2 useful particulate material, e.g., the discrete entities, in any suitable manner. Many techni~ues for including the additional metal in ~he parti~ulate ~aterial are conventional and well known ~n the art. The aaditional metal, e.g., platinum group metal, such 2s platinum, may exi~t within the particula~e material, e.g., discrete entities, at least in part as a compound ~uch a~ an oxide, ~ulfide, halide and the li~e, or in the elemental fitate. Generally, the amount of the platinum group metal component present in the final discrete entities i5 ~mall compared to the ~uantity of the spinel. The platinum group metal component preferably comprises fxom about 0,05 parts-per-million (ppm) to about 1~, more preferably abGut 0.05 ppm. to about 1,000 ppm., and still more preferably about O.S 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 gO ppm., by weight of at least one platinum group metal component. The other add,tional metals may be included in the particùlate material in an amount effective to promote the oxidation of at least a portion, preferably a major portion, of the ~ulfur dioxide present to sulfur trioxide at the conditions of combustion, e.g., conditions present in the catalyst regeneration zone of a hydrocarbon catalytic cracking unit.
Prefera~ly, the present di~crete entities comprise a minor amount by weight of at least one additional ~etal component ~calculated as elemental metal). Of course the amount of additional metal used will depend, for example, on the de~ree of sulfur dioxide oxidation desired and the effective-ness of the additional metal component to promote such oxidation.
~ ~6~
Alternately to inclu~ion in the discrete entities, one or more additional metal components may be pre ent in all or a portion of the above-noted golid particles ~nd/ox may be included in a type of particle other than either the present solid particles or discrete entities. For example, separate particles comprising at least one additional metal component and porous inorganic oxide support, e.g., platinum on alumina, may be included along with the solid particle an~ discrete entities to prom~te sul~ur dioxide 10 oxidation.
The additional metal, e.g., platinum group metal, component may be associated with the spinel based composi-tion in any suitable manner, ~uch as by the impregnation of the spinel at any stage in its preparation and either after or hefore calcination cf the spinel based composition. As indicated previously, vari~us procedures for incorporating the additional metal component or componentsinto the par-ticulate material are conventional an~ well known in the art.
Preferably, the additional metal component is substantially uniformly disposed on the spinel of the present discrete entities ~ne preferxed method for adaing the platinum group metal to the spinel involves the utilization of a water solu~le compound of the platinum group metal to impregnate the spinel. For example, platinum may be added to the spinel by comingling the spinel with an aqueous solution ~f chloroplatinic ~cid. Other water-soluble compounds of platinum may be employed a~ impregnatiOn 801utions, includ-ing, 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 compon~nt into the present di~crete entities. Platinum group metal compounds, ~uch as chlor-~ ~6"522 platinic acid and palladium chloride are preferred.
It may be desirable to be able to separate the discrete entitie~ fr~m the ~olid particle6, for example, when it is desired to use the ~olid particles alone for hydrocarbon conver~ion of where it is desired to recover the discrete entities for other U6e8 or ~or example, for p~atinum group metal rec~very. qhis can be conveniently ~c^D~plished by preparing the ~ec~nd solid particle~
in a manner such that they have a different ~ize thar.
the first ~olid particles. ~he separation of the first 2nd secDnd solid particles can then be easily effected by ~creening or other reans ~f size segre~ation.
As noted above, the presently useful solid particle5 and discrete entities can be employed in a rass of cor~ined particles ~hich function as both the EDlid particles, e.g., promotes hydrocarbon conversion, and the discrete entities. Such combined particles ~,ay ~e produced in any suitable manner, certain of which methods are c~nventional and ~nown in the art.
Although this invention i5 useful in m~ny hydrocarb~n che~,ical conversions, the present catalyst, i.e., mixture comprisinq ~olid part;cles and oiscrete entities, and process ~ md particular applicability in s~stems for the ca~alytic cracking of hydro~arbo~s and the regenerati~n of cataly~t so empl~yed. Such catalytic ~ydrocar~on crac~in~ often ~nvolves c~nverting, i.e., cracking, hea~ier or ~i~her boilinq hydrocarbons to ~asoline and ~ther l~wer boiling c~mpDnents, ~u~h as he~ane, hexene, pentane, pentene, ~utane, butylene, pr~pane, propylene; ethane, ethylene, methane and mixtures thereo~. Often, the ~ubstantially hydrocarbon feedstock c~mpris~s a gas oil fræction, e.g., derived fr~m petroleum, ~hale ~il, tar sand ~il, Cca~ and the like. S~ch feedstock ~ 162522 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 catalyst and method of the present invention.
Such substantially hydrocarbon feedstock often contains 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.
Hydrocarbon cracking conditions are well known and often include temperatures in the range of about 850F. to about 110F., preferably about 900F. to about 1050F. Other reaction conditions usually include pressures of up to about 100 psia.; catalyst ratios of about 1 to 2 to about 25 to 1, preferably about 3 to 1 to about 15 to 1; and weight hourly space velocities (WHSV) of from about 3 to about 60. These hydrocarbon cracking conditions may be varied depending, for example, on the feedstock and solid particles or combined particles being used and the 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 previously used to promote hydrocarbon cracking~
Carbonaceous, in particular sulfur-containing carbonaceous, deposit-containing catalyst particles from the reaction zone are contacted with free oxygen-containing gas in the I lB~
regeneration zone at conditions to restore or maintain the activity of the catalyst by -removing, i.e., combusting, at least a portion o 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 may leave the zone with the regenerator flue gas. The conditions at which such free oxygen-containing gas contacting takes place may vary, for example, over conventional ranges. 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 1100F. to about 1350F. and more preferably about 1100F. to about 1300F. Other conditions within such regeneration zone may include, for example, pressures up to about 100 psia., average catalyst contact times within the range of about 3 minutes to about 120 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 5% by weight of the catalyst. 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 1 ~6~2 catalyst is 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 conventional 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 regeneration zone. Typical among those 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 present invention contain crystalline aluminosilicate, the crystalline aluminosilicate may include minor amounts of conventional metal promoters such as the rare earth metals, in particular, cerium.
As indicated previously, one embodiment of the present invention involves contacting solid, sulfur-containing material in a combustion zone at combustion conditions to produce combustion products including at least one sulfur oxide at least a portion of which is sulfur trioxide. Reduced emissions of sulfur oxide from the combustion zone are achieved by carrying out this contacting in the presence of discrete entities containing at least one alkaline earth metal spinel and at least one rare earth metal component.
Typical solid material combustion zones include, for example, fluid bed coal burning steam boils and fluid sand bed waste combustors. The present discrete entities have sufficient strength to withstand the conditions in such combustion zones. In the coal fired boiler application, the ~ 1625~
discrete entities are added, either separately or with the sulfur-containing coal, to the combustion zone, e.g., boiler, where combustion takes place and at least some sulfur trioxide is formed. The discrete entities leave the combustion zone with the coal ash and can be separated from the ash, e.g., by screening, density separation, or other well known solids separation techniques. The flue gases leaving the combustion zone have reduced amounts of sulfur oxide, e.g., relative to combustion in the absence of the discrete entities. The discrete entities from the combustion zone can then be subjected to a reducing environment, e.g., contacted with H2, at conditions such that at least a portion of the sulfur associated with the discrete entities disassociates with the discrete entities, e.g., in the form of H2S, and is removed for further processing, e.g., sulfur recovery. The discrete entities, after sulfur removal may be recycled to the combustion zone, e.g., boiler.
Conditions with the boiler may be those typically used in fluid-bed coal burning boilers. The amount of discrete entities used is sufficient to reduce sulfur oxide emissions in the boiler flue gas, preferably, by at least about 50% and more preferably by at least about 80%. Conditions within the reducing zone are such that at least a portion, preferably at least about 50% and more preferably at least about 80% of the sulfu~ associated with the discrete entities is removed. For example, reducing conditions may include temperatures in the range of about 900F. to about 1800F.; pressures in the range of about 14 to about 100 psia; and H2 to associated sulfur mole ratio in the range of about 1 to about 10.
In the fluid sand bed waste combustion application, the fluid sand, e.g., which acts as a heat sink, may be combined with the discrete entities and circula-ted from the combustion 1 1~2522 zone to the reduction zone. Reduced emi.ssions of sulfur oxide from the combustion zone are thus achieved.
Conditions in the combustion zone rnay be as typically employed in fluid sand bed waste combustors. The amount of discrete entities employed is sufficient to reduce sulfur oxide emissions in the combustor flue gases, preferably by at least about 50% and more preferably by at least about 80%.
Conditions within the reducing zone are similar to those set forth above for the coal fired boiler application.
The following examples are provided to better illustrate the invention, without limitation, by presenting several specific embodiments of the process of the invention.
EXAMPLE I
This example illustrates the production of discrete entities useful in the present invention.
7.05 lb. sodium aluminate (analyzed as 29.8% by weight Na20 and 44.85% by weight of Al203) was stirred with one gallon deioni.zed water to bring as much as possible into solution.
This was filtered through cloth with a lO" Buchner funnel. The filtered solution was diluted to 8 liters with deionized water.
7.95 lb. Mg(N03)26H20 was dissolved in one gallon deionized water, and 166 ml. of concentrated HN03 was added.
The solution was diluted to 8 liters with deionized water.
The two final solutions were run simultaneously from burettes into 32 liters deionized water in a 30 gallon rubber lined drum. The mix was stirred vigorously during the addition. Addition of the Mg(N03) 2 solution required 36 minutes. 2760 ml. of the sodium aluminate solution was added during this period. The pH was held between 7.0 and 7.5. After addition of all the magnesium nitrate-containing solution, sodium aluminate solution was added to bring the pH to 8.5.
~,' l 16~522 After this, 1080 ml. of sodium aluminate solution remained and was discarded.
The mix was held overnight and then filtered with a plate-frame press. The cake was washed in the press with 110 gallons deiGnized water. A solution of 26 grams Mg(NO326H20 in 200 ml. deionized water was added to the slurry. The slurry was filtered and washed as before. After a repeat of the slurry, filter, and wash, the cake was dried at about 250F. in a forced air drying oven.
The dried product was then hammermilled, first on a 0.050" screen, then the 0-60 mesh portion was hammermilled again, this time on the 0.010" screen. The desirable, fine material was then screened through a 60 mesh screen. The so-obtained product, magnesium aluminate spinel precusor, was then transferred into a 59 mm diameter quartz tube, where it was calcined, in a fluidized state, for 3 hours at 900F. with an air flow rate of about 106 liters per hour to form magnesium aluminate spinel.
The resulting magnesium aluminate spinel particles are screened to produce final particles having diameters less than lO0 microns.
_A_PLE II
Example I is repeated except that final magnesium aluminate spinel particles are impregnated, using conventional techniques, with an aqueous solution of chloroplatinic acid.
The resulting particles are dried and calcined and contain about lO0 ppm. of platinum, by weight of the total platinum-containing particles, calculated as elemental platinum. The platinum is substantially uniform]y distributed on the spinel-containing particles.
. ~ ~
1 ~62~2~
E~AMPLE III
Example I was repeated except that the calcined magnesium aluminate spinel was impregnated with cerium.
For cerium impregnation, 0.39 lb. cerium carbonate was slurried in 1820 mls. of water and mixed with 350 mls. of 70%
nitric acid slowly to dissolve the carbonate. 3.75 lbs. of the calcined magnesium aluminate spinel was placed in a Pyrex tray and impregnated with the cerium solution with hand mixing using rubber gloves. After the impregnation was complete, the mix was allowed to equilibrate overnight.
The impregnated product was dried under IR lamps and finally in a 260F. oven overnight. The dried product was calcined in a fluidized state in a 59 mm. diameter quartz reactor, for 3 hours at 900F. with an air flow rate of about 83 l/hr. The resulting mangesium aluminate spinel particles were screened to produce final particles having diameters less than 100 microns and these final particles contained 5% by weight of cerium, calculated as elemental cerium.
EXAMPLE IV
A quantity of solid particles of a commercially available hydrocarbon cracking 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 final particles from Examp.e I, is combined with the final particles 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 fluid bed catalytic cracking service.
The mixture of solid particles and final particles is loaded to a conventional fluid bed catalytic cracking unit 1 ~2~
(FCCU) and used to crack a petroleum derived gas oil fraction, a combine~ fresh feed and recycle stream. The fresh gas oil fraction boils ln 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 weight ratio of catalyst particles to total (fresh plus recycle) hydrocarbon feed entering the reaction zone is about 6 to 1. Other conditions within the reaction zone include:
Temperature, F. 930 Pressure, psia. 15 Such conditions result in about 70% by volume conversion of the gas oil feedstoc~ to products boiling at 400f. and below.
The catalyst particles from the reaction zone include about 0.8% by weight of carbonaceous deposit material which is at least partially combusted in the regeneration zone. This carbonaceous material also includes a minor amount of sulfur which forms SOz at the combustion conditions formed in the regeneration zone. Air, in an amount so that amount of oxygen in the regeneration 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.1100 Pressure, psia. 15 Average Catalyst Residence Time, min. 30 ~ 1~25~2 After a period of time, the catalyst is shown to remain effective to promote hydrocarbon cracking in the reaction zone, and reduced emissions of sulfur (as sulfur oxides) from the flue gases of the regeneration zone are obtained (relative to processing in the absence of the f:inal magnesium aluminate spinel-containing particles).
EXAMPLE V
Example IV is repeated, except that the platinum-containing particles of Example II are used instead of the magnesium aluminate spinel particles of Example I.
After a period of time, the catalyst is shown to remain effective to promote hydrocarbon cracking in the reaction zone and carbon monoxide and sulfur dioxide oxidation in the regeneration zone. In addition, reduced emissions of sulfur (as sulfur oxides) from the flue gases of the regeneration zone are obtained (relative to processing in the substantial absence of the platinum-containing particles).
EXAMPLE VI
Example IV is repeated except that the cerium-containing particles of Examp].e III are used in place of the particles of Example I.
After a period of time, the catalyst is shown to remain effective to promote hydrocarbon cracking in the reaction zone, and reduced emissions of sulfur (as sulfur oxides~ from the flue gases of the regeneration z~n~ are obtained (relative to processing in the absence of the final magnesium aluminate spinel-containing particles.
EXAMPLE VII
Examples I, II and I~l are repeated, except that the final magnesium aluminate spinel particles, the platinum-containing particles and the cerium-containing particlesr respectively, each include about 7~ by weight of a crystal-line aluminosilicate known to be catalytically active to promote hydrocarbon cracking. The crystalline aluminosili-1~ cate is incorporated into the pàrticles using conventional,well known techniques. The platinum, and particularly the cerium, components are included in the particles so that a substantial amount, e.g., greater than about 50%, of the platinum and cerium is associated with the magnesium alumi-nate spinel of the particles, rather than with the crystal-line aluminosilicate. Cerium associated with the crystalline aluminosilicate is substantially less effective, e.g., in reducing SOx emissions, relative to cerium deposited on the magnesium aluminate spinel portion of the particles.
EXAMP~E VIII
Example IV is repeated three times except that the magnesium aluminate-containing Rpinel particles produced in Example VII are used in place of the particles of Example I.
After a period of time in hydrocarbon cracking service, these catalyst mixtures are shown to be effective to promote hydro-carbon cracXing and reduced sulfur emissions from the regen-eration zone are obtained. In particular, it is found that the crystalline aluminosilicate present in the discretè en-tities improves the hydrocarbon cracking in the reaction zone beyond that occurring in a system with discrete entities containing ~ubstantially no zeolitic component.
l 16~$~2 EXAMPLE IX
A mass of combined particles is prepared as follows:
The magnesium aluminate spinel-based discrete entitie~ are prepared by forming an aq~eous slurry of magnesium aluminate spinel precursor (produced as in Examplc I) 50 that the ~pinel concentration, calculated as MgAl2o4~ is about 9~ by weigh~. S~fficient crystalline alumin~silicate known to be effective to prcmote hydrocarbon cracking i6 added to the slurry ~o that t~e ~inal magnesium alumin~te spinel-based discrete entities contain, on a dry weight basis, about 10~ of ~uch crystalline aluminosilicate. This slurry is ~tirred for about 1 hour to insure uniformity and then ~pray dried at a temperature less than that required to eliminate a substantial portion of the water of hydration to form discrete entities. These diserete entities are calcined in an electric muffle furnace using a programmed timer to increase the temperature 300F. per h~ur to 1050CF. and maintain this te~perature fox 3 hours. The discrete entities are impregnated with platinum and cerium as in Examples II and III. Thefinal discrete entities contain about 7~ by weight of cerium calculated as elemental cerium; and about lQ0 ppm. by weight of platinum.
A major portion of the cerium and platinum is associated with the ~pinel, rather than the crystalline aluminosilicate.
Essenti~ly all the calcined discrete entities have a maximum dimension of less than about 200 microns.
~he discrete entities larger ~han 60 microns are discarded.
The solid particles-binderrmaterial 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-1.23~) H2SO4. After these two solutions are thoroughly mixed, 4000 parts by weight of a solution containing 1200 parts by weight of Al2(SO4)3 18H2O is added.
2 ~
Sufficient crystalline aluminosilicate, known to be effective to promote ~ydrocarbon cracking, i6 added to the mixture so that the final solid particles-binder material contains, on a dry weight basis, about ~ ~f such crystalline alumino-silicate. The resulting mixture is let stand to gel.
~he resulting hydrogel is cut into about 3~4~ cubes and covered with concentrated NH40H diluted with an e~ual vol~me of water.
This material is let stand overnight and has a final pH of ll. 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 weiqht basis) of the remaining calcined discrete entities and lO,000 parts by weight of water are thoroughly 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 disperse the slurry into the drying chamber.
The drying gas, i.e., flue gas from an inline burner, enters the drying chamber at about 750F. and exits the chamber 20 at a temperature which ranges from about 305F. to 315F.
This drying gas in introduced into the top of the drying chamber while the slurry is dispersed upward from near the bottom of the cham~er. In this way, the material to be dried is exposed to both counter-current flow ~during assent from the nozzle system) and co-current flow (during qravity dissent) relative to the downward drying gas flow. The resulting dried particles are calcined in a manner similar to the calcination ~f the spinel based discrete entities described above. The resulting combined particles ~re screened to provide particles proper~y sized for use in a fluidized catalytic bed reaction zone-regenerator hydrocarbon cracking system.
EXAMPLE X
Example IV i~ repeated except that the physical ~ ~2~2 mixture of discrete entities and catalyst particles used in Example IV ~re replaced ~y the combined particle~ produced in Example IX. After a period of time, these combined particles are shown to remain effective to promote b~th hydrocarbon cracking in the react~n z~ne ~nd to reduce the amount of ~ulfur atmospheric emission~ in the regeneration zone flue g~ses.
EXAMPLE XI
Example I is repeated except that Li(NO3)-3H2o is substituted for the Mg(~O3)2 6H2O. The resulting final lithiu~ aluminate spinel particles have diameters less than 100 microns.
- ExAMpLE XII
The final particles of Example XIare impregnated, using conventional techniques with ch~oroplatinic acid. The resulting spinel-containing particles are dried and calcined and contain about 100 ppm. of platinum, by weight of the total platinum-containing particle~, calculated as elemental platinum. The platinum is substantially uniformly distxibuted on the spinel-containing particles.
EXAMPLE XIII
The final particles of Example XI are impregnated, using conventional techniques, with cerium-using as ague~us cerium nitrate solution. The resulting spinel-containing particles are dried and calcined and contain about 10~ by weight of cerium, calculated as elemental cerium.
EXAMPL~S XIV to XVI
Example IV is xepeated three times excep~ that the final particles Pf Example I are replaced by the resulting spinel-containing particles of Examples XI, XII and XIII, reSpectively. In each instance, reduced emissions of sulfur (as sulfur oxides) from the flue gases of the regenerator zone is obtained.
EXAMPLES XVII to XXI
Particles having diameter~ of less than 100 microns of the following ~pinel materials are prepared using conventi~nal techniques:
Example ._ XV~I FeA12O4 XVIII MnA 24 XIX MgCr2O4 10XX Fe2TiO4 XXI MgFe204 EXAMPLES XXII to XXVI
Example ~V is repeated five additional tLmes except that the final particles of Example I are replaced by the 6pinel-containing particl~s of Examples XVII, XVIII, XIX, XX
and XXI, respectively. In each instance, reduced emissions of sulfur (as sulfur oxides) from the flue gases of the re-generator zone is obtained~
EXAMPLES XXVII AND XXVIII
These examples illustrate certain of the surprising benefits of the present invention.
Two blends of particles were prepared for testing.
The blends were as follows:
Blend A - 5~ by weight cerium impregnated magnesium aluminate spinel final particles pro-duced as in Example I, plus 95% by weight of a conventional zeolite-containing hydrocarbon cracking catalyst which had been equilibràted in commercial fluid bed catalytic cracking service.
Blend B - 5% ~y weight cerium impregnated gamma alumina particles containing 5~ by weight of ~ 1~;2~
cerium, calculated a~ elemental cerium, and having a particle size in the range of 25 to 100 microns, plus 95~ by weight of the same conventional zeolite-containing catalyst as to prepare blend A. Cerium-alumina particles are known to possess good initial sulfur oxide removal acti~ity w~en u~ed in fluid catalytic cracking service.
~oth blends were tested to determine their ability to continue to remove sulfur oxides over a period of time.
This test procedure was as follows: Step 1 involved an initial determination of the ability of the blend to remove ~ulfur oxides Erom regenerator flue gases. Step one was carried out in a fluid bed catalytic cracking pilot plant known to provide results which are correlatable to results obtained in commercial ~ized systems. The feedstock and conditions for step 1 were as follows:
Feedstock - mid-continent gas oil containing 2.04 by weight sulfur Reactor temperature - 930F.
Regenerator temperature - 1100`F.
Stripper temperature - 930F.
Pressure - 15 psia.
Approximate catalyst reqeneration time - 30 minutes Approximate stripping time - 10 minutes Approximate reaction time - lminute Steam as inerts in reactcr, 3 mole ~.
Step 2 ~f the test procedure involved continuous and accelerated aging in a fluidized-bed reactor to ~imulate the type of aqinq which occurs in commercial fluid-bed catalytic crackin~ ~ervice. The feedstock and conditions utilized in step 2 were as ~ollows:
2~
Feedstock - Gulf Coast ga~ oil c~ntaining 2 . 0~ by weight ~ulfur r Reactor temperature - 930~F.
Reactor pressuxe - 15 psia.
D Reac~ion residence time v 1 minute Reaction catalyst/oil weight ratio 6 D Stripping temperature - 930~.
Regenerator temperature - 1100F.
~egenerator pressure 15 psia.
~ Catalyst regenerator residence time - 30 D Regenerator combustion air flow ratio -20 lbs.air/
lb.coke Step 3 of the test procedure involved periodically repeating step 1 to determine how much of the blend's acti~ity to remove sulfur oxide had ~een lost during the aging of step 2.
The amount of sulfur oxides emitted wit~ the flue gases from the regeneration using the blend was used as the basis for determining the blend' 6 ability ~or activity) to remove ~u~ ~ulfur oxides.
Results o testing Blends A and ~ following the above procedures were as follows:
Days Aged at Conditions(l) ~ of Initial Activity to Remove of Step 2 Sulfur Oxide Retained Blend A Blend 6 ~1 ~
(l)One day of aging at the condition of step 2 is more severe than the aging which would occur in commercial FCC service. Therefore, there is no direct one-on-one correlation between aging in these two aging modes.
~ 162~22 These results indicate very clearly that the cerium-magnesium alumina-te spinel particles of Blend A maintain sul-fur oxide removal activity much longer than the cerium-alumina particles of Blend s. Relatively rapid loss of sulfur removal activity has been one of the major problems with prior art attempts, e.g., cerium on alumina particles, to reduce sulfur oxide emissions. Therefore, these results show that the pre-sent invention provides substantial and surprising advantages in reducing sulfur oxide emissions from combustion zones, e.g., regeneration zones of fluid bed hydrocarbon catalytic cracking units.
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 practiced within the scope of the follow-ing claims.
SUPPLEMENTAR~ DISCLOSURE
The foregoing description indicates various metal-containing spinels which may be used in the process of this invention.
The presently useful metal-containing spinels include a first metal and a second metal having a valence (oxida-tion state) higher than the valence of the first metal. The first and second metals may be the same metal or different metals. In other words, the same metal may exist in a given spinel in two or more different oxidation states. As indi-cated above, the atomic ratio of the first metal to the second metal in any given spinel need not be consistent with the classical stoichiometric formula for such spinel. In one embodiment, the atomic ratio of the first metal to the second metal in the metal-containing spinel useful in the present in-1 lB2~X2 vention is at least ahout 0.17 and preferably at least about 0.25. If the first metal is a mono-valent metal, the atomic ratio of the first metal to the second metal is pxeferably at least about 0.34, more preferably at least about 0.5.
When the spinel includes a divalent metal (e.g., alu-minum), it is preferred that the atomic ratio of divalent to trivalent metals in the spinel be in the range of about 0.17 to about l, more preferably about 0.25 to about 0.75, still more preferably about 0.35 to about 0.65 and still further more preferably about 0.45 to about 0.55.
The inventive process as claimed herein is furthermore intended to be in a hydrocarbon conversion process for con-verting a sulfur-containing hydrocarbon feedstock which com-prises (l) contacting the feedstock with solid particles cap-able of promoting the conversion of the feedstock at hydro-carbon conversion conditions in at least one reaction zone to produce at least one hydrocarbon product and to cause deacti-vating sulfur-containing carbonaceous material to be formed on the solid particles thereby forming deposit-containing particles; (2) contacting the deposit-containing particles with an oxygen-containing vaporous medium at conditions to combust at least a portion of the carbonaceous deposit material.
in at least one regeneration zone to thereby regenerate at least a portion of the hydrocarbon conversion catalytic acti-vity of the solid particles and to form a regeneration zone flue gas containing sulfur trioxide; and (3) repeating step (l) and (2) periodically, the improvement which comprises:
using, in intimate admixture with the solid particles, a minor amount of discrete entities having a composition different from the solid particles and comprising at least one metal-containing spinel including a first metal and second metal having a valence higher than the valence of the first metal, - 35a -t ~62522 the atomic ratio of the first metal to the second metal in the spinel is at least about 0.17, the discrete entities being present in an amount sufficient to reduce the amount of sulfur oxides in the flue gas.
In an alkaline earth metal-containing spine:L, the atomic ratio of the first metal to the second metal is pre-ferably at least about 0.2.
In a spinel containing magnesium and aluminum, the atomic ratio of magnesium to aluminum is preferably in the range of about 0.25 to about 0.75, more particularly in the range of about 0.35 to about 0.65, and especially in the range of about 0.45 to about 0.55.
The magnesium aluminate spinel prepared in Example I
was found to have an atomic ratio of magnesium to aluminum of about 0.48.
The lithium aluminate spinel prepared in Example XI
was found to have an atomic ratio of lithium ions to aluminum ions of about 0.2.
In Examples XVII to XXI the spinel materials therein prepared are substantially stoichiometric spinel materials prepared using conventional techniques.
- 35b -
with the solid particles, e.g., during the manufacture of the solid particles, to form combined particles which function as both the presently useful solid particle~
and discrete entities i8 pre~erably a separate and distinct phase. One preferred method for providing the combined particles is to calcine the discrete entities prior to incorporating the di~crete entitieæ
into the co~bined particles.
The form, i.e., particle size, of the present catalyst particles, e.g., both fiolia 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 ~ystem employed. Such catalyst particles may be formed into any desired shape such a pills, cakes, extrudates, powders, granules, 6pheres and the like, using conventional methods. With regard to fluidized catalyct 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 solid particles are capable of promoting the desired hydrocarbon conversion. The solid particles are further characterized as having a composition (i.e., chemical ma~e-up) wh~ch is different from the discrete entities. In one preferred embodiment, the ~olid particles ~or the ~olid particles portion of the combined particles described above) are substantially free of metal~containing spinel, e.g.; alkaline earth metal-containing spinel.
In one aspect of the present invention, the discrete entitie~ comprise an effect;ve amount of at least one metal-containing spinel, preferably alkaline earth t 1~25~2 metal-containing spinel, and preferably, a minor, catalytically effective amount of at least one crystalline ~luminosilica~e capable of promoting hydrocarbon conver-sion at hydrocarbon conversion conditions. In the event ~uch discrete entities comprise alkaline earth metal-contain-ing spinel, it is more preferred that such discrete entities include a minor amount of at least one rare earth metal com-ponent, preferably a cerium component, associated with the spinel. 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, and/or the solid particles and/or one or more other type of particles (i.e., having compositions different from the present solid particles and discrete entities) further com-prise a minor amount of at least one additional metal, e.g., platinum group metal, component capable of promoting the oxidation of sulfur dioxide to the sulfur trioxide at the conditions in the combustion, e.g., catalyst regen-eration, zone For example, an effective amount of at least one sulfur oxide oxidation catalytic component, e.g., metal or compounds of metals selected from Group VI, IIB, IVB, VIA, ~IB, VIIA and VIII and mixtures thereof, disposed on a support, e.g., one or more inorganic oxides, may be in-cluded with the present solid particles and discrete entities and/or may be included on the solid particles and/or discrete entities. As noted previously, the sulfur oxide oxidation component may be associated with, e.g., deposited on, the spinel com~onent ~f the present discrete entities.
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 l 16~522 compositions ~re conventionally used as catalyst in such hydrocarbon conversion processes, the 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 one of the natural or synthetic materials which are capable of 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 suitabie 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 aluminosilicate 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 aluminosilicate 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. Certain of these procedures are thoroughly described in U.S. Patents 3,140,253 and RE. 27,639.
Compositions of the solid particles which are partisularly 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 porour matrix which comprises, for example, amorphous material which may or may not be itself capable of promoting such hydrocarbon conversion.
Included among such matrix materials are clays and amorphous compositions of silica-alumina, magnesia, zirconia, mixtures of these and the like. The crystalline aluminosilicate is l 162~2 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 formed during and/or as part of the methods of manufacturing the solid particles, discrete entities and/or combined particles are within the scope of the present invention. The solid particles are preferably substantially free of added rare earth metal, e.g., cerium, component disposed on the amorphous matrix material of the catalyst, although such rare earth metal components may be associated with the crystalline aluminosilicate components of the solid particles.
As indicated above, the discrete entities utilized in the present invention comprise an effective amount, preferably a major amount, of at least one metal-containing spinel, preferably alkaline earth metal-containing spinel. In another aspect, the present discrete entities further comprise a minor amount of at least one additional metal, e.g., platinum group metal, component capable of promoting sulfur dioxide oxidation.
The spinel structure is based on a cubic close-packed array of oxide ions. Typically, the crystallographic unit cell of the spinel structure contains 32 oxygen atoms; one-eighth of the tetrahedral holes (of which there are two per anion) are occupied by ~ 1~2522 divalent metal ion, and one-half of the octahedral holes for which there are two per anion) are occupied by trivalent metal ion 5 .
This typical spinel structure or a modification thereof is adaptable to many other mixed metal oxides of the type M M2 4 (e-g-, FeCr204,~nA1204 and Co Co2 04), by some of the type MIVMII204 (e.g., Ti~n204, and SnCo204), and by some of the type M2MVIO4 (e.g., Na2MoO4 and Ag2MoO4).
This structure is often symbolized as X[Y2]04, where square brackets enclose the ions in the octahedral interstices.
An important variant is the inverse spinel structure, Y[XY]04, in which half of the Y ions are in tetrahedral interstices and the X ions are in octahedral ones along with the other half of the Y ions. The inverse spinel structure is intended to be included within the scope of the term "metal-containing spinel" as used herein. The inverse spinel structure occurs often when the X ions have a stronger preference for octahedral coordination than do the Y ions. All MIVM2IIO~ are inverse, e.g., ~n(~nTi)04, and many of the M M2 4 ones are also, e.g., Fe (Co Fe )04, NiA124'Fe (Fe Fe )04 and Fe(NiFe)04. There are also many compounds with distorted spinel structures in which only a fraction of the X ions are in tetrahedral sites. This occurs when the preference of both X and Y ions for octahedral and tetrahedral sites do not differ markedly.
Further, details on the spinel structure are described in the following references: "Modern Aspects of Inorganic Chemistry" by H. I. Emeleus and A. G. Sharpe (1973), pp. 57-58 and 512-513; "Structural Inorganic Chemistry", 3rd edition, (1962) by A. F. Wells, pp. 130, 487 490, 503 and 526; and "Advanced Inorganic Chemistry", 3rd edition, by F. A. Cotton and ~.
1 ~82~22 Wilkinson 11972), PP. 54~55-Metal-containing spinels include the following:
Mn~1204, FeA1204, CoA120~, NiA120~, 2 4 FeMgFeO4, FeTiFeO~ ZnSnZnO4, GaMg~aO~, ~nMg~nO4, BeLi2F4, 2 4 24~ SnMg204~ ~gA1204, CUA1204, (LiAl O ) ZnK2tCN)4, CdK2(CN~4~ ~gK2~N)4~ ZnTi2 4' 2 4 2 4 MnCr o , FeCr204, CoCr~04, NiCr204, ZnCr204, 2 4' 2 4 ZnCr2S4, cdCr2S4, TiMn~04 M~Fe24' FeFe24' CoF 24' 2 4 CuFe2~4, 2nFe20~, CdFe204~ ~gC24~ 2 4 2 4 2 4 2S4, CUC254~ Ge~i2o4~ NiNi2S4, ZnGa2o4, WAg o and ZnSn204.
The preferred metal-containing spinel~ for use in the present invention are alkaline earth metal spinels, in particular magnesium aluminate spinel. Lithium containing spinels,which may be produced using conventional techniques are also preferred for use. With regard to magnesium alumi-nate spinel, there often are eight Mg atoms and sixteen Al atoms to place in a unit cell l8MgA1204). Other alkaline earth metal ions, such as calcium, stronium, barium and mix-tures thereof, may replace all or a part of the magnesiumions. Similarly, other trivalent metal ions, such as iron, chormium, vanadium, manganese, gallium, boron, cobalt and mixtures thereof, may replace all or a part of the aluminum ions.
The metal~containing spinels useful in the present invention may be derived from conventional and well known sources. For example, these spinels may be naturally occurring or may be ~ynthesized using techniques well known in the art. Thus, a detailed description of such techniques is not included herein. However, a brief description of the preparation of the most preferred spinel, i.e., magnesium aluminate spinel,is set forth below. Certain of the tech-niques described, e.g., dryirg l~nd calcining, have applica-bility to other metal-containing ~;pinels.
The magnesi~m aluminate spinel ~uitable for use in the present invention can be prepared, for example, according to the method di~closed in ~.S. Patent No.
2,992,191 The spinel can be formed by reacting, in an aqueous medium, a water-soluble nagnesium inorganic salt and a water-~oluble aluminum salt ~n which the aluminum is present in the anion. Suitable salts are exemplified by the strongly acidic magnesium salts ~uch as the chloride~ nitrate or ~ulfate and the water soluble alkali metal aluminates~ ~he magnesium and aluminate ~alts are dissolved in an aqueous medium and a spinel precursor is precipitated through neutralization of the aluminate by the acidic magnesium salt. Excesses of acid salt or aluminate are preferably not employed, thus avoiding the precipitation of excess magnesia or alumina.
Preferably, the precipi~ate is washed free of extraneous ions before being further processed.
The precipitate can be dried and calcined to yield the magnesium aluminate spinel. Dryinq and cal-cination may take place simultaneously. However, it is preferred that the drying take place at a temperature below which water of hydration is removed from the spinel precursor. Thus, this drying may occur at temperatures ~elow about 500~., preferably from about 220F. to about 450DF. Suitable calcination temperatures are exemplified by temperatures ranging ~rom about 800F. to about 2000F.
or more. Calcination of the spinel precursor may take place in a period of time o~ at least about one half hour and preferably in a period of tLme ranging from about 1 hour to about 10 hours.
Another proceg for ~roducing the presently ~ 162~
Useful magnesium aluminate spinel i5 set forth in U.S.
Patent 3,791,992. This process includes mixing a solution of a soluble acid salt of divalent magnesium with a solution of an alkali metal aluminate; separating and washing the resulting precipitate; exchanging the washed precipitate with a solution of an ammonium compound to decrease the alkali metal content; followed by washing, drying, forming and calcination steps. In general, as indicated previously, the metal-containing spinels useful in the present invention may be prepared by methods which are conventional and well known in the art.
The metal spinel-based composition may be formed into particles of any desired shape such as pills, cake, extrudates, powders, granules, spheres, and the like using conventional methods. ~he 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.
Substantially non-interfering proportions of other well known refractory material, e.g., inorganic oxides such as silica, zirconia, thoria and the like may be included in the present discrete entities. Free magnesia and/or alumina (i.e., apart from the alkaline earth metal containing spinel) also may be included in the discrete entities, e.g., using conventional techniques. For example, the discrete enti-ties may include about 0.1% to about 25% by weight of free magnesia (calculated as MgO). By substantially "non-inter-ferring" is meant amounts of other material which do not have asubstantial deleterious effect on the present catalyst system or hydrocarbon conversion proce~s. ~he inclusion of material~
~uch as silica, zirconia, ~horia and the like into ~he present discrete entities may act ~o improve one or more of the functions of the discrete entitie~.
The presently useful lithi~n containing spinels, e.g., lithium aluminate spinel, preferably are associated with a minor amount of at least one rare earth metal component.
Cerium or other suitable rare earth or rare earth mixture may be associated with the spinel usin~ any suitable technique or combination of techniques; for example, impregnation, coprecipitation, ion-exchange and the like, well known in the art, with impregnation beinq preferred. Impregnation may be carried out by contacting the spinel with a solution, preferably aqueous, of rare earth; for example, a solution containing cerium ions lpreferably Ce~3, Ce+4 or mixtures thereof~ or a mixture of rare earth cations containing a substantial amount ~for example, at least 404) of cerium ions. Water-soluble sources of rare earth include the nitrate and chloride. Solutions having a concentration of rare earth in the range of 3 to 30~ by weight are preferred. Preferably, sufficient rare earth salt is added to incorporate about 0.05 to 254 (weiqht), more preferably about 0.1 to 15% rare earth, and still more preferably about 1.0 to 15% rare earth, by weight, calcula~ed as elemental metal, on the particles.
It may not be necessary to wash the spinel after certain soluble rare earth salts (such as nitrate or acetate) are added. After impxegnation with rare earth salt, ~he spinel can be dried and calcined to decompose the salt,fonn-ing an oxide in the case of nitrate or acetate. Alternatively, the spinel, e.g., in the form of discrete particles, can be charged to a hydrocarbon conversion, e.g., cracking unit, with the rare earth in ~alt form. In this case a rare earth ~alt with a thermally decomposable anion can decompose to 1 ~ 6~1~ $~2 the oxide in the reactor and be available $o associate with S~x in the regenerator.
Especially good results were achieved using ~pinel containing discrete entities 3uch that the concentration of rare earth metal, e.g., cPrium, calculated as the metal, is in the range of about 1 t~-25~, more preferably about 2% to about 15%, by weight of the total di~crete entities.
The present discrete entities preferably further comprise a minor amount ~f at least one crystalline aluminosilicate capable of promoting the desired hydrocarbon conversion. Typical aluminosilicates have been described above. Preferably, such aluminosilicates comprise about 1~ to about 30~, more preferably about 1% to about 10~, by weight of the discrete er.tities. The presence of ~uch aluminosilicates in the present discrete entities acts to increase the overall catalytic activity of the ~olid particles-discrete entities mixture for promoting the desired hydrocarbon conver~ion.
As indicated above, in one preferred embodiment the presently useful particulate material, e.g., the discrete entities utilized in the present invention, also contain at least one additional metal, e.g., platinum group metal, component. These additional metal components are defined as being capable of prom~ting the oxidation of sulfur dioxide to sulfur trioxide at combustion conditions~ e.g., the conditions present in the catalyst regenerator. Increased carb~n monoxide oxidation may also be obtained by including at least one of the additisnal metal components. ~uch metal components are selected from the group consi~ting of 30 Group IB, IIB, IVB, YIA~ VIB, VIIA and VIII of the Periodic Table, the rare earth metals, vanadium, iron, tin and antimony and mLxtures thereof and may be incorporated into the presently ~ lS2~2 useful particulate material, e.g., the discrete entities, in any suitable manner. Many techni~ues for including the additional metal in ~he parti~ulate ~aterial are conventional and well known ~n the art. The aaditional metal, e.g., platinum group metal, such 2s platinum, may exi~t within the particula~e material, e.g., discrete entities, at least in part as a compound ~uch a~ an oxide, ~ulfide, halide and the li~e, or in the elemental fitate. Generally, the amount of the platinum group metal component present in the final discrete entities i5 ~mall compared to the ~uantity of the spinel. The platinum group metal component preferably comprises fxom about 0,05 parts-per-million (ppm) to about 1~, more preferably abGut 0.05 ppm. to about 1,000 ppm., and still more preferably about O.S 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 gO ppm., by weight of at least one platinum group metal component. The other add,tional metals may be included in the particùlate material in an amount effective to promote the oxidation of at least a portion, preferably a major portion, of the ~ulfur dioxide present to sulfur trioxide at the conditions of combustion, e.g., conditions present in the catalyst regeneration zone of a hydrocarbon catalytic cracking unit.
Prefera~ly, the present di~crete entities comprise a minor amount by weight of at least one additional ~etal component ~calculated as elemental metal). Of course the amount of additional metal used will depend, for example, on the de~ree of sulfur dioxide oxidation desired and the effective-ness of the additional metal component to promote such oxidation.
~ ~6~
Alternately to inclu~ion in the discrete entities, one or more additional metal components may be pre ent in all or a portion of the above-noted golid particles ~nd/ox may be included in a type of particle other than either the present solid particles or discrete entities. For example, separate particles comprising at least one additional metal component and porous inorganic oxide support, e.g., platinum on alumina, may be included along with the solid particle an~ discrete entities to prom~te sul~ur dioxide 10 oxidation.
The additional metal, e.g., platinum group metal, component may be associated with the spinel based composi-tion in any suitable manner, ~uch as by the impregnation of the spinel at any stage in its preparation and either after or hefore calcination cf the spinel based composition. As indicated previously, vari~us procedures for incorporating the additional metal component or componentsinto the par-ticulate material are conventional an~ well known in the art.
Preferably, the additional metal component is substantially uniformly disposed on the spinel of the present discrete entities ~ne preferxed method for adaing the platinum group metal to the spinel involves the utilization of a water solu~le compound of the platinum group metal to impregnate the spinel. For example, platinum may be added to the spinel by comingling the spinel with an aqueous solution ~f chloroplatinic ~cid. Other water-soluble compounds of platinum may be employed a~ impregnatiOn 801utions, includ-ing, 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 compon~nt into the present di~crete entities. Platinum group metal compounds, ~uch as chlor-~ ~6"522 platinic acid and palladium chloride are preferred.
It may be desirable to be able to separate the discrete entitie~ fr~m the ~olid particle6, for example, when it is desired to use the ~olid particles alone for hydrocarbon conver~ion of where it is desired to recover the discrete entities for other U6e8 or ~or example, for p~atinum group metal rec~very. qhis can be conveniently ~c^D~plished by preparing the ~ec~nd solid particle~
in a manner such that they have a different ~ize thar.
the first ~olid particles. ~he separation of the first 2nd secDnd solid particles can then be easily effected by ~creening or other reans ~f size segre~ation.
As noted above, the presently useful solid particle5 and discrete entities can be employed in a rass of cor~ined particles ~hich function as both the EDlid particles, e.g., promotes hydrocarbon conversion, and the discrete entities. Such combined particles ~,ay ~e produced in any suitable manner, certain of which methods are c~nventional and ~nown in the art.
Although this invention i5 useful in m~ny hydrocarb~n che~,ical conversions, the present catalyst, i.e., mixture comprisinq ~olid part;cles and oiscrete entities, and process ~ md particular applicability in s~stems for the ca~alytic cracking of hydro~arbo~s and the regenerati~n of cataly~t so empl~yed. Such catalytic ~ydrocar~on crac~in~ often ~nvolves c~nverting, i.e., cracking, hea~ier or ~i~her boilinq hydrocarbons to ~asoline and ~ther l~wer boiling c~mpDnents, ~u~h as he~ane, hexene, pentane, pentene, ~utane, butylene, pr~pane, propylene; ethane, ethylene, methane and mixtures thereo~. Often, the ~ubstantially hydrocarbon feedstock c~mpris~s a gas oil fræction, e.g., derived fr~m petroleum, ~hale ~il, tar sand ~il, Cca~ and the like. S~ch feedstock ~ 162522 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 catalyst and method of the present invention.
Such substantially hydrocarbon feedstock often contains 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.
Hydrocarbon cracking conditions are well known and often include temperatures in the range of about 850F. to about 110F., preferably about 900F. to about 1050F. Other reaction conditions usually include pressures of up to about 100 psia.; catalyst ratios of about 1 to 2 to about 25 to 1, preferably about 3 to 1 to about 15 to 1; and weight hourly space velocities (WHSV) of from about 3 to about 60. These hydrocarbon cracking conditions may be varied depending, for example, on the feedstock and solid particles or combined particles being used and the 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 previously used to promote hydrocarbon cracking~
Carbonaceous, in particular sulfur-containing carbonaceous, deposit-containing catalyst particles from the reaction zone are contacted with free oxygen-containing gas in the I lB~
regeneration zone at conditions to restore or maintain the activity of the catalyst by -removing, i.e., combusting, at least a portion o 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 may leave the zone with the regenerator flue gas. The conditions at which such free oxygen-containing gas contacting takes place may vary, for example, over conventional ranges. 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 1100F. to about 1350F. and more preferably about 1100F. to about 1300F. Other conditions within such regeneration zone may include, for example, pressures up to about 100 psia., average catalyst contact times within the range of about 3 minutes to about 120 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 5% by weight of the catalyst. 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 1 ~6~2 catalyst is 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 conventional 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 regeneration zone. Typical among those 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 present invention contain crystalline aluminosilicate, the crystalline aluminosilicate may include minor amounts of conventional metal promoters such as the rare earth metals, in particular, cerium.
As indicated previously, one embodiment of the present invention involves contacting solid, sulfur-containing material in a combustion zone at combustion conditions to produce combustion products including at least one sulfur oxide at least a portion of which is sulfur trioxide. Reduced emissions of sulfur oxide from the combustion zone are achieved by carrying out this contacting in the presence of discrete entities containing at least one alkaline earth metal spinel and at least one rare earth metal component.
Typical solid material combustion zones include, for example, fluid bed coal burning steam boils and fluid sand bed waste combustors. The present discrete entities have sufficient strength to withstand the conditions in such combustion zones. In the coal fired boiler application, the ~ 1625~
discrete entities are added, either separately or with the sulfur-containing coal, to the combustion zone, e.g., boiler, where combustion takes place and at least some sulfur trioxide is formed. The discrete entities leave the combustion zone with the coal ash and can be separated from the ash, e.g., by screening, density separation, or other well known solids separation techniques. The flue gases leaving the combustion zone have reduced amounts of sulfur oxide, e.g., relative to combustion in the absence of the discrete entities. The discrete entities from the combustion zone can then be subjected to a reducing environment, e.g., contacted with H2, at conditions such that at least a portion of the sulfur associated with the discrete entities disassociates with the discrete entities, e.g., in the form of H2S, and is removed for further processing, e.g., sulfur recovery. The discrete entities, after sulfur removal may be recycled to the combustion zone, e.g., boiler.
Conditions with the boiler may be those typically used in fluid-bed coal burning boilers. The amount of discrete entities used is sufficient to reduce sulfur oxide emissions in the boiler flue gas, preferably, by at least about 50% and more preferably by at least about 80%. Conditions within the reducing zone are such that at least a portion, preferably at least about 50% and more preferably at least about 80% of the sulfu~ associated with the discrete entities is removed. For example, reducing conditions may include temperatures in the range of about 900F. to about 1800F.; pressures in the range of about 14 to about 100 psia; and H2 to associated sulfur mole ratio in the range of about 1 to about 10.
In the fluid sand bed waste combustion application, the fluid sand, e.g., which acts as a heat sink, may be combined with the discrete entities and circula-ted from the combustion 1 1~2522 zone to the reduction zone. Reduced emi.ssions of sulfur oxide from the combustion zone are thus achieved.
Conditions in the combustion zone rnay be as typically employed in fluid sand bed waste combustors. The amount of discrete entities employed is sufficient to reduce sulfur oxide emissions in the combustor flue gases, preferably by at least about 50% and more preferably by at least about 80%.
Conditions within the reducing zone are similar to those set forth above for the coal fired boiler application.
The following examples are provided to better illustrate the invention, without limitation, by presenting several specific embodiments of the process of the invention.
EXAMPLE I
This example illustrates the production of discrete entities useful in the present invention.
7.05 lb. sodium aluminate (analyzed as 29.8% by weight Na20 and 44.85% by weight of Al203) was stirred with one gallon deioni.zed water to bring as much as possible into solution.
This was filtered through cloth with a lO" Buchner funnel. The filtered solution was diluted to 8 liters with deionized water.
7.95 lb. Mg(N03)26H20 was dissolved in one gallon deionized water, and 166 ml. of concentrated HN03 was added.
The solution was diluted to 8 liters with deionized water.
The two final solutions were run simultaneously from burettes into 32 liters deionized water in a 30 gallon rubber lined drum. The mix was stirred vigorously during the addition. Addition of the Mg(N03) 2 solution required 36 minutes. 2760 ml. of the sodium aluminate solution was added during this period. The pH was held between 7.0 and 7.5. After addition of all the magnesium nitrate-containing solution, sodium aluminate solution was added to bring the pH to 8.5.
~,' l 16~522 After this, 1080 ml. of sodium aluminate solution remained and was discarded.
The mix was held overnight and then filtered with a plate-frame press. The cake was washed in the press with 110 gallons deiGnized water. A solution of 26 grams Mg(NO326H20 in 200 ml. deionized water was added to the slurry. The slurry was filtered and washed as before. After a repeat of the slurry, filter, and wash, the cake was dried at about 250F. in a forced air drying oven.
The dried product was then hammermilled, first on a 0.050" screen, then the 0-60 mesh portion was hammermilled again, this time on the 0.010" screen. The desirable, fine material was then screened through a 60 mesh screen. The so-obtained product, magnesium aluminate spinel precusor, was then transferred into a 59 mm diameter quartz tube, where it was calcined, in a fluidized state, for 3 hours at 900F. with an air flow rate of about 106 liters per hour to form magnesium aluminate spinel.
The resulting magnesium aluminate spinel particles are screened to produce final particles having diameters less than lO0 microns.
_A_PLE II
Example I is repeated except that final magnesium aluminate spinel particles are impregnated, using conventional techniques, with an aqueous solution of chloroplatinic acid.
The resulting particles are dried and calcined and contain about lO0 ppm. of platinum, by weight of the total platinum-containing particles, calculated as elemental platinum. The platinum is substantially uniform]y distributed on the spinel-containing particles.
. ~ ~
1 ~62~2~
E~AMPLE III
Example I was repeated except that the calcined magnesium aluminate spinel was impregnated with cerium.
For cerium impregnation, 0.39 lb. cerium carbonate was slurried in 1820 mls. of water and mixed with 350 mls. of 70%
nitric acid slowly to dissolve the carbonate. 3.75 lbs. of the calcined magnesium aluminate spinel was placed in a Pyrex tray and impregnated with the cerium solution with hand mixing using rubber gloves. After the impregnation was complete, the mix was allowed to equilibrate overnight.
The impregnated product was dried under IR lamps and finally in a 260F. oven overnight. The dried product was calcined in a fluidized state in a 59 mm. diameter quartz reactor, for 3 hours at 900F. with an air flow rate of about 83 l/hr. The resulting mangesium aluminate spinel particles were screened to produce final particles having diameters less than 100 microns and these final particles contained 5% by weight of cerium, calculated as elemental cerium.
EXAMPLE IV
A quantity of solid particles of a commercially available hydrocarbon cracking 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 final particles from Examp.e I, is combined with the final particles 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 fluid bed catalytic cracking service.
The mixture of solid particles and final particles is loaded to a conventional fluid bed catalytic cracking unit 1 ~2~
(FCCU) and used to crack a petroleum derived gas oil fraction, a combine~ fresh feed and recycle stream. The fresh gas oil fraction boils ln 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 weight ratio of catalyst particles to total (fresh plus recycle) hydrocarbon feed entering the reaction zone is about 6 to 1. Other conditions within the reaction zone include:
Temperature, F. 930 Pressure, psia. 15 Such conditions result in about 70% by volume conversion of the gas oil feedstoc~ to products boiling at 400f. and below.
The catalyst particles from the reaction zone include about 0.8% by weight of carbonaceous deposit material which is at least partially combusted in the regeneration zone. This carbonaceous material also includes a minor amount of sulfur which forms SOz at the combustion conditions formed in the regeneration zone. Air, in an amount so that amount of oxygen in the regeneration 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.1100 Pressure, psia. 15 Average Catalyst Residence Time, min. 30 ~ 1~25~2 After a period of time, the catalyst is shown to remain effective to promote hydrocarbon cracking in the reaction zone, and reduced emissions of sulfur (as sulfur oxides) from the flue gases of the regeneration zone are obtained (relative to processing in the absence of the f:inal magnesium aluminate spinel-containing particles).
EXAMPLE V
Example IV is repeated, except that the platinum-containing particles of Example II are used instead of the magnesium aluminate spinel particles of Example I.
After a period of time, the catalyst is shown to remain effective to promote hydrocarbon cracking in the reaction zone and carbon monoxide and sulfur dioxide oxidation in the regeneration zone. In addition, reduced emissions of sulfur (as sulfur oxides) from the flue gases of the regeneration zone are obtained (relative to processing in the substantial absence of the platinum-containing particles).
EXAMPLE VI
Example IV is repeated except that the cerium-containing particles of Examp].e III are used in place of the particles of Example I.
After a period of time, the catalyst is shown to remain effective to promote hydrocarbon cracking in the reaction zone, and reduced emissions of sulfur (as sulfur oxides~ from the flue gases of the regeneration z~n~ are obtained (relative to processing in the absence of the final magnesium aluminate spinel-containing particles.
EXAMPLE VII
Examples I, II and I~l are repeated, except that the final magnesium aluminate spinel particles, the platinum-containing particles and the cerium-containing particlesr respectively, each include about 7~ by weight of a crystal-line aluminosilicate known to be catalytically active to promote hydrocarbon cracking. The crystalline aluminosili-1~ cate is incorporated into the pàrticles using conventional,well known techniques. The platinum, and particularly the cerium, components are included in the particles so that a substantial amount, e.g., greater than about 50%, of the platinum and cerium is associated with the magnesium alumi-nate spinel of the particles, rather than with the crystal-line aluminosilicate. Cerium associated with the crystalline aluminosilicate is substantially less effective, e.g., in reducing SOx emissions, relative to cerium deposited on the magnesium aluminate spinel portion of the particles.
EXAMP~E VIII
Example IV is repeated three times except that the magnesium aluminate-containing Rpinel particles produced in Example VII are used in place of the particles of Example I.
After a period of time in hydrocarbon cracking service, these catalyst mixtures are shown to be effective to promote hydro-carbon cracXing and reduced sulfur emissions from the regen-eration zone are obtained. In particular, it is found that the crystalline aluminosilicate present in the discretè en-tities improves the hydrocarbon cracking in the reaction zone beyond that occurring in a system with discrete entities containing ~ubstantially no zeolitic component.
l 16~$~2 EXAMPLE IX
A mass of combined particles is prepared as follows:
The magnesium aluminate spinel-based discrete entitie~ are prepared by forming an aq~eous slurry of magnesium aluminate spinel precursor (produced as in Examplc I) 50 that the ~pinel concentration, calculated as MgAl2o4~ is about 9~ by weigh~. S~fficient crystalline alumin~silicate known to be effective to prcmote hydrocarbon cracking i6 added to the slurry ~o that t~e ~inal magnesium alumin~te spinel-based discrete entities contain, on a dry weight basis, about 10~ of ~uch crystalline aluminosilicate. This slurry is ~tirred for about 1 hour to insure uniformity and then ~pray dried at a temperature less than that required to eliminate a substantial portion of the water of hydration to form discrete entities. These diserete entities are calcined in an electric muffle furnace using a programmed timer to increase the temperature 300F. per h~ur to 1050CF. and maintain this te~perature fox 3 hours. The discrete entities are impregnated with platinum and cerium as in Examples II and III. Thefinal discrete entities contain about 7~ by weight of cerium calculated as elemental cerium; and about lQ0 ppm. by weight of platinum.
A major portion of the cerium and platinum is associated with the ~pinel, rather than the crystalline aluminosilicate.
Essenti~ly all the calcined discrete entities have a maximum dimension of less than about 200 microns.
~he discrete entities larger ~han 60 microns are discarded.
The solid particles-binderrmaterial 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-1.23~) H2SO4. After these two solutions are thoroughly mixed, 4000 parts by weight of a solution containing 1200 parts by weight of Al2(SO4)3 18H2O is added.
2 ~
Sufficient crystalline aluminosilicate, known to be effective to promote ~ydrocarbon cracking, i6 added to the mixture so that the final solid particles-binder material contains, on a dry weight basis, about ~ ~f such crystalline alumino-silicate. The resulting mixture is let stand to gel.
~he resulting hydrogel is cut into about 3~4~ cubes and covered with concentrated NH40H diluted with an e~ual vol~me of water.
This material is let stand overnight and has a final pH of ll. 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 weiqht basis) of the remaining calcined discrete entities and lO,000 parts by weight of water are thoroughly 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 disperse the slurry into the drying chamber.
The drying gas, i.e., flue gas from an inline burner, enters the drying chamber at about 750F. and exits the chamber 20 at a temperature which ranges from about 305F. to 315F.
This drying gas in introduced into the top of the drying chamber while the slurry is dispersed upward from near the bottom of the cham~er. In this way, the material to be dried is exposed to both counter-current flow ~during assent from the nozzle system) and co-current flow (during qravity dissent) relative to the downward drying gas flow. The resulting dried particles are calcined in a manner similar to the calcination ~f the spinel based discrete entities described above. The resulting combined particles ~re screened to provide particles proper~y sized for use in a fluidized catalytic bed reaction zone-regenerator hydrocarbon cracking system.
EXAMPLE X
Example IV i~ repeated except that the physical ~ ~2~2 mixture of discrete entities and catalyst particles used in Example IV ~re replaced ~y the combined particle~ produced in Example IX. After a period of time, these combined particles are shown to remain effective to promote b~th hydrocarbon cracking in the react~n z~ne ~nd to reduce the amount of ~ulfur atmospheric emission~ in the regeneration zone flue g~ses.
EXAMPLE XI
Example I is repeated except that Li(NO3)-3H2o is substituted for the Mg(~O3)2 6H2O. The resulting final lithiu~ aluminate spinel particles have diameters less than 100 microns.
- ExAMpLE XII
The final particles of Example XIare impregnated, using conventional techniques with ch~oroplatinic acid. The resulting spinel-containing particles are dried and calcined and contain about 100 ppm. of platinum, by weight of the total platinum-containing particle~, calculated as elemental platinum. The platinum is substantially uniformly distxibuted on the spinel-containing particles.
EXAMPLE XIII
The final particles of Example XI are impregnated, using conventional techniques, with cerium-using as ague~us cerium nitrate solution. The resulting spinel-containing particles are dried and calcined and contain about 10~ by weight of cerium, calculated as elemental cerium.
EXAMPL~S XIV to XVI
Example IV is xepeated three times excep~ that the final particles Pf Example I are replaced by the resulting spinel-containing particles of Examples XI, XII and XIII, reSpectively. In each instance, reduced emissions of sulfur (as sulfur oxides) from the flue gases of the regenerator zone is obtained.
EXAMPLES XVII to XXI
Particles having diameter~ of less than 100 microns of the following ~pinel materials are prepared using conventi~nal techniques:
Example ._ XV~I FeA12O4 XVIII MnA 24 XIX MgCr2O4 10XX Fe2TiO4 XXI MgFe204 EXAMPLES XXII to XXVI
Example ~V is repeated five additional tLmes except that the final particles of Example I are replaced by the 6pinel-containing particl~s of Examples XVII, XVIII, XIX, XX
and XXI, respectively. In each instance, reduced emissions of sulfur (as sulfur oxides) from the flue gases of the re-generator zone is obtained~
EXAMPLES XXVII AND XXVIII
These examples illustrate certain of the surprising benefits of the present invention.
Two blends of particles were prepared for testing.
The blends were as follows:
Blend A - 5~ by weight cerium impregnated magnesium aluminate spinel final particles pro-duced as in Example I, plus 95% by weight of a conventional zeolite-containing hydrocarbon cracking catalyst which had been equilibràted in commercial fluid bed catalytic cracking service.
Blend B - 5% ~y weight cerium impregnated gamma alumina particles containing 5~ by weight of ~ 1~;2~
cerium, calculated a~ elemental cerium, and having a particle size in the range of 25 to 100 microns, plus 95~ by weight of the same conventional zeolite-containing catalyst as to prepare blend A. Cerium-alumina particles are known to possess good initial sulfur oxide removal acti~ity w~en u~ed in fluid catalytic cracking service.
~oth blends were tested to determine their ability to continue to remove sulfur oxides over a period of time.
This test procedure was as follows: Step 1 involved an initial determination of the ability of the blend to remove ~ulfur oxides Erom regenerator flue gases. Step one was carried out in a fluid bed catalytic cracking pilot plant known to provide results which are correlatable to results obtained in commercial ~ized systems. The feedstock and conditions for step 1 were as follows:
Feedstock - mid-continent gas oil containing 2.04 by weight sulfur Reactor temperature - 930F.
Regenerator temperature - 1100`F.
Stripper temperature - 930F.
Pressure - 15 psia.
Approximate catalyst reqeneration time - 30 minutes Approximate stripping time - 10 minutes Approximate reaction time - lminute Steam as inerts in reactcr, 3 mole ~.
Step 2 ~f the test procedure involved continuous and accelerated aging in a fluidized-bed reactor to ~imulate the type of aqinq which occurs in commercial fluid-bed catalytic crackin~ ~ervice. The feedstock and conditions utilized in step 2 were as ~ollows:
2~
Feedstock - Gulf Coast ga~ oil c~ntaining 2 . 0~ by weight ~ulfur r Reactor temperature - 930~F.
Reactor pressuxe - 15 psia.
D Reac~ion residence time v 1 minute Reaction catalyst/oil weight ratio 6 D Stripping temperature - 930~.
Regenerator temperature - 1100F.
~egenerator pressure 15 psia.
~ Catalyst regenerator residence time - 30 D Regenerator combustion air flow ratio -20 lbs.air/
lb.coke Step 3 of the test procedure involved periodically repeating step 1 to determine how much of the blend's acti~ity to remove sulfur oxide had ~een lost during the aging of step 2.
The amount of sulfur oxides emitted wit~ the flue gases from the regeneration using the blend was used as the basis for determining the blend' 6 ability ~or activity) to remove ~u~ ~ulfur oxides.
Results o testing Blends A and ~ following the above procedures were as follows:
Days Aged at Conditions(l) ~ of Initial Activity to Remove of Step 2 Sulfur Oxide Retained Blend A Blend 6 ~1 ~
(l)One day of aging at the condition of step 2 is more severe than the aging which would occur in commercial FCC service. Therefore, there is no direct one-on-one correlation between aging in these two aging modes.
~ 162~22 These results indicate very clearly that the cerium-magnesium alumina-te spinel particles of Blend A maintain sul-fur oxide removal activity much longer than the cerium-alumina particles of Blend s. Relatively rapid loss of sulfur removal activity has been one of the major problems with prior art attempts, e.g., cerium on alumina particles, to reduce sulfur oxide emissions. Therefore, these results show that the pre-sent invention provides substantial and surprising advantages in reducing sulfur oxide emissions from combustion zones, e.g., regeneration zones of fluid bed hydrocarbon catalytic cracking units.
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 practiced within the scope of the follow-ing claims.
SUPPLEMENTAR~ DISCLOSURE
The foregoing description indicates various metal-containing spinels which may be used in the process of this invention.
The presently useful metal-containing spinels include a first metal and a second metal having a valence (oxida-tion state) higher than the valence of the first metal. The first and second metals may be the same metal or different metals. In other words, the same metal may exist in a given spinel in two or more different oxidation states. As indi-cated above, the atomic ratio of the first metal to the second metal in any given spinel need not be consistent with the classical stoichiometric formula for such spinel. In one embodiment, the atomic ratio of the first metal to the second metal in the metal-containing spinel useful in the present in-1 lB2~X2 vention is at least ahout 0.17 and preferably at least about 0.25. If the first metal is a mono-valent metal, the atomic ratio of the first metal to the second metal is pxeferably at least about 0.34, more preferably at least about 0.5.
When the spinel includes a divalent metal (e.g., alu-minum), it is preferred that the atomic ratio of divalent to trivalent metals in the spinel be in the range of about 0.17 to about l, more preferably about 0.25 to about 0.75, still more preferably about 0.35 to about 0.65 and still further more preferably about 0.45 to about 0.55.
The inventive process as claimed herein is furthermore intended to be in a hydrocarbon conversion process for con-verting a sulfur-containing hydrocarbon feedstock which com-prises (l) contacting the feedstock with solid particles cap-able of promoting the conversion of the feedstock at hydro-carbon conversion conditions in at least one reaction zone to produce at least one hydrocarbon product and to cause deacti-vating sulfur-containing carbonaceous material to be formed on the solid particles thereby forming deposit-containing particles; (2) contacting the deposit-containing particles with an oxygen-containing vaporous medium at conditions to combust at least a portion of the carbonaceous deposit material.
in at least one regeneration zone to thereby regenerate at least a portion of the hydrocarbon conversion catalytic acti-vity of the solid particles and to form a regeneration zone flue gas containing sulfur trioxide; and (3) repeating step (l) and (2) periodically, the improvement which comprises:
using, in intimate admixture with the solid particles, a minor amount of discrete entities having a composition different from the solid particles and comprising at least one metal-containing spinel including a first metal and second metal having a valence higher than the valence of the first metal, - 35a -t ~62522 the atomic ratio of the first metal to the second metal in the spinel is at least about 0.17, the discrete entities being present in an amount sufficient to reduce the amount of sulfur oxides in the flue gas.
In an alkaline earth metal-containing spine:L, the atomic ratio of the first metal to the second metal is pre-ferably at least about 0.2.
In a spinel containing magnesium and aluminum, the atomic ratio of magnesium to aluminum is preferably in the range of about 0.25 to about 0.75, more particularly in the range of about 0.35 to about 0.65, and especially in the range of about 0.45 to about 0.55.
The magnesium aluminate spinel prepared in Example I
was found to have an atomic ratio of magnesium to aluminum of about 0.48.
The lithium aluminate spinel prepared in Example XI
was found to have an atomic ratio of lithium ions to aluminum ions of about 0.2.
In Examples XVII to XXI the spinel materials therein prepared are substantially stoichiometric spinel materials prepared using conventional techniques.
- 35b -
Claims (78)
1. In a hydrocarbon conversion process for convert-ing a sulfur-containing hydrocarbon feedstock which comprises (1) contacting said feedstock with solid particles capable of promoting the conversion of said feedstock at hydrocarbon conversion conditions in at least one reaction zone to pro-duce at least one hydrocarbon product and to cause deactiva-ting sulfur-containing carbonaceous material to be formed on said solid particles thereby forming deposit-containing par-ticles; (2) contacting said deposit-containing particles with an oxygen-containing vaporous medium at conditions to combust at least a portion of said carbonaceous deposit material in at least one regeneration zone to thereby regen-erate at least a portion of the hydrocarbon conversion cata-lytic activity of said solid particles and to form a regene-ration zone flue gas containing sulfur trioxide; and (3) re-peating step (1) and (2) periodically, the improvement which comprises: using, in intimate admixture with said solid particles, a minor amount of discrete entities having a com-position different from said solid particles and comprising at least one metal-containing spinel including a first metal and a second metal having a valence higher than the valence of said first metal, said spinel having a surface area of about 25 m2/gm. to about 600 m2/gm., said discrete entities being present in an amount sufficient to reduce the amount of sulfur oxides in said flue gas.
2. The process of claim 1 wherein said discrete entities comprise at least one alkaline earth metal-contain-ing spinel and at least one rare earth metal component associated with said spinel.
3. The process of claim 1 wherein said conversion comprises hydrocarbon cracking in the substantial absence of added molecular hydrogen, said solid particles and dis-crete entities being fluidizable and circulating between said reaction zone and said regeneration zone.
4. The process of claim 2 wherein said conversion comprises hydrocarbon cracking in the substantial absence of added molecular hydrogen, said solid particles and dis-crete entities being fluidizable and circulating between said reaction zone and said regeneration zone.
5. The process of claim 3 wherein said discrete entities contains at least about 70% by weight of said spinel and said spinel has a surface area of about 25 m.2/gm. to about 600 m.2/gm.
6. The process of claim 3 wherein at least one of said solid particles and discrete entities further comprise a minor, catalytically effective amount of at least one additional metal component capable of promoting the conver-sion of sulfur dioxide to sulfur trioxide at the conditions of step (2).
7. The process of claim 6 wherein said additional metal component is at least one platinum group metal com-ponent.
8. The process of claim 4 wherein at least one of said solid particles and discrete entities further comprise a minor, catalytically effective amount of at least one additional metal component capable of promoting the conver-sion of sulfur dioxide to sulfur trioxide at the conditions of step (2).
9. The process of claim 8 wherein said additional metal component is at least one platinum group metal compo-nent.
10. The process of claim 3 wherein said discrete en-tities comprise a major amount of said spinel and said spinel comprises alkaline earth metal-containing spinel.
11. The process of claim 10 wherein said spinel con-tains magnesium and aluminum.
12. The process of claim 4 wherein said spinel con-tains magnesium and aluminum.
13. The process of claim 3 wherein said discrete en-tities contain at least about 90% by weight of said spinel.
14. The process of claim 12 wherein said discrete en-tities contain at least about 90% by weight of said spinel.
15. The process of claim 2 wherein said rare earth metal component comprises cerium.
16. The process of claim 12 wherein said rare earth metal component is cerium component and is present in an amount of about 1% to about 25% by weight of said discrete entities.
17. In a process for combusting solid, sulfur-con-taining material by contacting said material with gaseous oxygen in a combustion zone at combustion conditions to produce combustion products including at least one sulfur oxide, the improvement comprising carrying out said contact-ing in the presence of discrete particles containing a major amount of metal-containing spinel including a first metal and a second metal having a valence higher than the valence of said first metal, thereby reducing the amount of sulfur oxide emitted from said combustion zone.
15. In a process for combusting solid, sulfur-contain-ing material by contacting said material with gaseous oxygen in a combustion zone at combustion conditions to produce com-bustion products including at least one sulfur oxide, the im-provement comprising carrying out said contacting in the pres-ence of discrete particles containing a major amount of alka-line earth metal-containing spinel including an alkaline earth metal and a second metal having a valence higher than the val-ence of said alkaline earth metal and a minor amount of at least one rare earth metal component, thereby reducing the amount of sulfur oxide emitted from said combustion zone.
19. A composition of matter comprising, in intimate admixture, a major amount of solid particles capable of pro-moting hydrocarbon conversion at hydrocarbon conversion con-ditions, said solid particles including at least one crystal-line aluminosilicate capable of promoting said hydrocarbon conversion, and a minor amount of discrete entities having a composition different from said solid particles and comprising at least one metal-containing spinel which includes a first metal and a second metal having a valence higher than the valence of said first metal, said spinel having a surface area of about 25 m2/gm. to about 600 m2/gm.
20. The composition of claim 19 wherein said discrete entities comprise at least one alkaline earth metal spinel and at least one rare earth metal component.
21. The composition of claim 19 wherein said hydro-carbon conversion comprises hydrocarbon cracking in the sub-stantial absence of added molecular hydrogen and a major a-mount, by weight of said solid particles having diameters in the range of about 10 microns to about 250 microns.
22. The composition of claim 20 wherein said hydro-carbon conversion comprises hydrocarbon cracking in the substantial absence of added molecular hydrogen and a major amount, by weight of said solid particles having diameters in the range of about 10 microns to about 250 microns.
23. The composition of claim 21 wherein said discrete entities contains at least about 70% by weight of said spinel.
24. The composition of claim 22 wherein said discrete entities contains at least about 70% by weight of said spinel.
25. The composition of claim 21 wherein at least one of said solid particles and discrete entities further comprise a minor, catalytically effective amount of at least one additional metal component capable of promoting the con-version of sulfur dioxide to sulfur trioxide.
26. The composition of claim 22 wherein at least one of said solid particles and discrete entities further comprise a minor, catalytically effective amount of at least one additional metal component capable of promoting the con-version of sulfur dioxide to sulfur trioxide.
27. The composition of claim 25 wherein said addi-tional metal component is at least one platinum group metal component.
28. The composition of claim 26 wherein said addi-tional metal component is at least one platinum group metal component.
29. The composition of claim 19 wherein said spinel comprises alkaline earth metal-containing spinel.
30. The composition of claim 19 wherein said spinel contains magnesium and aluminum.
31. The composition of claim 24 wherein said spinel contains magnesium and aluminum, and said rare earth metal component is a cerium component and is present in an amount in the range of about 1% to about 25% by weight of the total discrete entities.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
32. In a hydrocarbon conversion process for convert-ing a sulfur-containing hydrocarbon feedstock which comprises (1) contacting said feedstock with solid particles capable of promoting the conversion of said feedstock at hydrocarbon conversion conditions in at least one reaction zone to pro-duce at least one hydrocarbon product and to cause deactiva-ting sulfur-containing carbonaceous material to be formed on said solid particles thereby forming deposit-containing par-ticles; (2) contacting said deposit-containing particles with an oxygen-containing vaporous medium at conditions to combust at least a portion of said carbonaceous deposit material in at least one regeneration zone to thereby regenerate at least a portion of the hydrocarbon conversion catalytic acti-vity of said solid particles and to form a regeneration zone flue gas containing sulfur trioxide; and (3) repeating step (1) and (2) periodically, the improvement which comprises:
using, in intimate admixture with said solid particles, a minor amount of discrete entities having a composition dif-ferent from said solid particles and comprising at least one metal-containing spinel including a first metal and a second metal having a valence higher than the valence of said first metal, the atomic ratio of said first metal to said second metal in said spinel is at least about 0.2, said spinel hav-ing a surface area of about 25 m.2 /gm. to about 600 m.2 /gm., said discrete entities being present in an amount sufficient to reduce the amount of sulfur oxides in said flue gas.
using, in intimate admixture with said solid particles, a minor amount of discrete entities having a composition dif-ferent from said solid particles and comprising at least one metal-containing spinel including a first metal and a second metal having a valence higher than the valence of said first metal, the atomic ratio of said first metal to said second metal in said spinel is at least about 0.2, said spinel hav-ing a surface area of about 25 m.2 /gm. to about 600 m.2 /gm., said discrete entities being present in an amount sufficient to reduce the amount of sulfur oxides in said flue gas.
33. The process of claim 32 wherein said discrete entities comprise at least one alkaline earth metal-contain-ing spinel and at least one rare earth metal component associated with said spinel.
34. The process of claim 32 wherein said conversion comprises hydrocarbon cracking in the substantial absence of added molecular hydrogen, said solid particles and discrete entities being fluidizable and circulating between said re-action zone and said regeneration zone.
35. The process of claim 33 wherein said conversion comprises hydrocarbon cracking in the substantial absence of added molecular hydrogen, said solid particles and discrete entities being fluidizable and circulating between said re-action zone and said regeneration zone.
36. The process of claim 34 wherein said discrete entities contains at least about 70% by weight of said spinel.
37. The process of claim 34 wherein at least one of said solid particles and discrete entities further comprise a minor, catalytically effective amount of at least one addi-tional metal component capable of promoting the conversion of sulfur dioxide to sulfur trioxide at the conditions of step (2).
38. The process of claim 37 wherein said additional metal component is at least one platinum group metal compo-nent.
39. The process of claim 35 wherein at least one of said solid particles and discrete entities further comprise a minor, catalytically effective amount of at least one addi-tional metal component capable of promoting the conversion of sulfur dioxide to sulfur trioxide at the conditions of step (2).
40. The process of claim 39 wherein said additional metal component is at least one platinum group metal compo-nent.
41. The process of claim 34 wherein said discrete entities comprise a major amount of said spinel and said spinel comprises alkaline earth metal-containing spinel.
42. The process of claim 41 wherein said spinel con-tains magnesium and aluminum and the atomic ratio of magne-sium to aluminum in said spinel is in the range of about 0.25 to about 0.75.
43. The process of claim 35 wherein said spinel con-tains magnesium and aluminum and the atomic ratio of magne-sium to aluminum in said spinel is in the range of about 0.35 to about 0.65.
44. The process of claim 34 wherein said discrete entities contain at least about 90% by weight of said spinel.
45. The process of claim 43 wherein said discrete entities contain at least about 90% by weight of said spinel.
46. The process of claim 33 wherein said rare earth metal component comprises cerium.
47. The process of claim 43 wherein said rare earth metal component is cerium component and is present in an amount of about 1% to about 25% by weight of said discrete entities.
48. In a process for combusting solid, sulfur-contain-? material by contacting said material with gaseous oxygen in a combustion zone at combustion conditions to produce com-bustion products including at least one sulfur oxide, the im-provement comprising carrying out said contacting in the pres-ence of discrete particles containing a major amount of metal-containing spinel, thereby reducing the amount of sulfur oxide emitted from said combustion zone, said metal-containing spinel including a first metal and a second metal having a valence higher than the valence of said first metal, the atomic ratio of said first metal to said second metal in said spinel at least about 0.2.
49. In a process for combusting solid, sulfur contain-ing material by contacting said material with gaseous oxygen in a combustion zone at combustion conditions to produce com-bustion products including at least one sulfur oxide, the im-provement comprising carrying out said contacting in the pres-ence of discrete particles containing a major amount of alka-line earth metal-containing spinel and a minor amount of at least one rare earth metal component, thereby reducing the amount of sulfur oxide emitted from said combustion zone, said alkaline earth metal-containing spinel including an alka-line earth metal and a second metal having a valence higher than the valence of said alkaline earth metal, the atomic ratio of said alkaline earth metal to said second metal in said spinel is at least about 0.25.
50. A composition of matter comprising, in intimate admixture, a major amount of solid particles capable of pro-moting hydrocarbon conversion at hydrocarbon conversion con-ditions, said solid particles including at least one crystal-line aluminosilicate capable of promoting said hydrocarbon conversion, and a minor amount of discrete entities having a composition different from said solid particles and comprising at least one metal-containing spinel which includes a first metal and and a second metal having a valence higher than the valence of said first metal, -the atomic ratio of said first metal to said second metal in said spinel being at least about 0.2 and said spinel has a surface area of about 25 m.2 /gm. to about 600 m.2/gm.
51. The composition of claim 50 wherein said discrete entities comprise at least one alkaline earth metal spinel and at least one rare earth metal component.
52. The composition of claim 50 wherein said hydro-carbon conversion comprises hydrocarbon cracking in the sub-stantial absence of added molecular hydrogen and a major amount, by weight of said solid particles having diameters in the range of about 10 microns to about 250 microns.
53. The composition of claim 51 wherein said hydro-carbon conversion comprises hydrocarbon cracking in the sub-stantial absence of added molecular hydrogen and a major amount, by weight of said solid particles having diameters in the range of about 10 microns to about 250 microns.
54. The composition of claim 52 wherein said dis-crete entities contains at least about 70% by weight of said spinel.
55. The composition of claim 53 wherein said dis-crete entities contains at least about 70% by weight of said spinel.
56. The composition of claim 52 wherein at least one of said solid particles and discrete entities further com-prise a minor, catalytically effective amount of at least one additional metal component capable of promoting the con-version of sulfur dioxide to sulfur trioxide.
57. The composition of claim 53 wherein at least one of said solid particles and discrete entities further com-prise a minor, catalytically effective amount of at least one additional metal component capable of promoting the con-version of sulfur dioxide to sulfur trioxide.
58. The composition of claim 56 wherein said addi-tional metal component is at least one platinum group metal component.
59. The composition of claim 57 wherein said addi-tional metal component is at least one platinum group metal component.
60. The composition of claim 50 wherein said spinel comprises alkaline earth metal-containing spinel.
61. The composition of claim 50 wherein said spinel contains magnesium and aluminum and the atomic ratio of magnesium to aluminum in said spinel is in the range of about 0.35 to about 0.65.
62. The composition of claim 55 wherein said spinel contains magnesium and aluminum and the atomic ratio of magnesium to aluminum in said spinel is in the range of about 0.45 to about 0.55, and said rare earth metal compo-nent is a cerium component and is present in an amount in the range of about 1% to about 25% by weight of the total discrete entities.
63. A composition of matter comprising a major amount of at least one metal-containing spinel including a first metal and a second metal having a valence higher than the valence of said first metal, the atomic ratio of said first metal to said second metal in said spinel being at least about 0.17, said spinel having a surface area in the range of about 25 m.2/gm. to about 600 m.2/gm., and a minor amount of at least one rare earth metal component associated with said spinel.
64. The composition of claim 63 wherein said composition of matter comprises discrete entities having diame?ers in the range of about 10 microns to about 250 microns.
65. The composition of claim 64 wherein said discrete entities contain at least about 70% by weight of said spinel.
66. The composition of claim 63 which further comprises about 0.1% to about 25% by weight of free magnesia, calculated as MgO.
67. The composition of claim 63 wherein said first metal is an alkaline earth metal
68. The composition of claim 63 wherein said spinel includes magnesium and aluminum, and the atomic ratio of magnesium to aluminum in said spinel is in the range of about 0.25 to about 0.75.
69. The composition of claim 63 wherein said spinel includes magnesium and aluminum, and the atomic ratio of magnesium to aluminum in said spinel is in the range of about 0.35 to about 0.65.
70. The composition of claim 63 wherein said spinel includes magnesium and aluminum, and the atomic ratio of magnesium to aluminum in said spinel is in the range of about 0.45 to about 0.55.
71. The composition of claim 64 wherein said discrete entities further comprise about 0.1% to about 25% by weight of free magnesia, calculated as MgO.
72. The composition of claim 67 wherein said discrete entities further comprise about 0.1% to about 25% by weight of free magnesia, calculated as MgO.
73. The composition of claim 69 wherein said discrete entities further comprise about 0.1% to about 25% by weight of free magnesia, calculated as MgO.
74. The composition of claim 70 wherein said discrete entities further comprise about 0.1% to about 25% by weight of free magnesia, calculated as MgO.
75. The composition of claim 63 wherein said rare earth metal component is present in an amount in the range of about 1%
to about 25% by weight of said composition.
to about 25% by weight of said composition.
76. The composition of claim 64 wherein said rare earth metal component is present in an amount in the range of about 1%
to about 25% by weight of said composition.
to about 25% by weight of said composition.
77. The composition of claim 75 wherein said rare earth metal component is at least one cerium component.
78. The composition of claim 76 wherein said rare earth metal component is at least one cerium component.
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17332080A | 1980-07-29 | 1980-07-29 | |
| US17331580A | 1980-07-29 | 1980-07-29 | |
| US173,320 | 1980-07-29 | ||
| US173,315 | 1980-07-29 | ||
| US30167881A | 1981-09-14 | 1981-09-14 | |
| US30167681A | 1981-09-14 | 1981-09-14 | |
| US301,678 | 1981-09-14 | ||
| US301,676 | 1981-09-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162522A true CA1162522A (en) | 1984-02-21 |
Family
ID=27497051
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379660A Expired CA1162522A (en) | 1980-07-29 | 1981-06-12 | Catalyst and process for conversion of hydrocarbons |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1162522A (en) |
-
1981
- 1981-06-12 CA CA000379660A patent/CA1162522A/en not_active Expired
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| MKEX | Expiry | ||
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