CA1052365A - Stable, catalytically active and coke selective zeolite - Google Patents
Stable, catalytically active and coke selective zeoliteInfo
- Publication number
- CA1052365A CA1052365A CA219,281A CA219281A CA1052365A CA 1052365 A CA1052365 A CA 1052365A CA 219281 A CA219281 A CA 219281A CA 1052365 A CA1052365 A CA 1052365A
- Authority
- CA
- Canada
- Prior art keywords
- zeolite
- rare earth
- oxide content
- percent
- alkali metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G11/00—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
- C10G11/02—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils characterised by the catalyst used
- C10G11/04—Oxides
- C10G11/05—Crystalline alumino-silicates, e.g. molecular sieves
Abstract
Abstract of the Disclosure A stable rare earth exchanged zeolite having high catalytic activity and improved coke selectivity is pre-pared by a series of exchange steps whereby the rare earth is introduced into the zeolite in a multi-step e.g., two step manner. The method comprises exchanging a sodium zeolite to less that 4.0 weight percent Na2O, exchanging with rare earth to give an initial rare earth oxide content of 0.3 to 5 weight percent, calcining, and further rare earth exchanging the zeolite to give a final rare earth content of 1.0 to 10 weight percent.
Description
3~
Background of t~e Invention -This invention relates to crystalline aluminosilicate zeolites, particularly to faujasite type zeolites and more specifically to rare earth exchanged faujasetic crystalline zeolites, preparation thereof and use as a catalyst par-ticularly as a cracking catalyst.
Rare earth exchange crystalline zeolites have been prepared by prior art me~hods whi'ch generally involve ion exchange procedures in which the introduction of the desir-lo ed rare earth metal into the zeolites is accomplished by a conventional single step, such as disclosed in ~. S. Patent 3,595,611. The latter rare earth exchanged zeolites possess catalytic activity and selectivity particularly when util-ized as a cracking catalyst component.
As a result of this invention, it has been found that novel rare earth exchanged crystalline aluminosilicate zeolites having superior catalytic properties compared to other prior art rare earth exchanged zeolites, can be pre-pared by an ion exchange method which incorporates the rare earth into the zeolite in a multi step, particularly a two step manner. We have discovered that if the desired amount of the rare earth metal is introduced into the zeo-lite via a unique two step exchange procedure, the resulting zeolite exhibits an unexpected high degree of catalytic ac-tivity and good selectivity, particularly highly improved coke selectivity.
Brief Statement of the Invention -In summary, the process for preparing the improved rare earth exchanged zeolites involves a series of ion exchange treatments and calcination procedures. Broadly, the process includes the steps of exchanging a faujasite type æeolite, e.g. a aujasite-type Y zeolit~ i~ the sodium form with a hydrogen-containing cation such as an ammonium ion to reduce the original sodium metal content of the zeolite to less than about 4 weight percent, followed by the first step o the series of ion-exchange steps with a rare ear~h salt to impart an initial rare earth con~ent of about 0.3 to 5 percent by weigh~: to the zeolite. After ~ubsequent filtering and washing of the thus exchanged zeol~te, drying and calci~ation of ~he zeolite is conducted a~ a temperature of rom about 700 to 1650F. Thereafter the product is further exchanged with a solution co~taining rare ear~h sal~s, for instance a mixed solution contai~ing rare earth cation sa~ts and an ammonium salt to decrease the sodium oxide content below about 1.0 weight pexcent and to impart a total rare earth content of about 1.0 to 10 percent by weight of the zeolite. After wash-ing and drying the novel zeolite produc~ is recovered.
Thus, in accordance with the present teachings, a process is provided for prepari~g a faujasitic ~rystalline aluminosilicate zeolite which has improved catalytic activity and improved cok~
selectivity. The process comprises the steps of reducing the alkali metal ox~de content of the aujasitic crystalline alumino-silicate zeolite to about 2.0 to 5.0 weight percent by ion exchang-ing with a solution containing a cation which upon thermal decom-position leaves a major portion of the zeolite in the hydrogen form, the zeolite is then ion ex~hanged with a solution containing a rare ear~h salt in a concentration sufficient to impart a rare earth oxide content of about 0.1 to 6.0 percent by weight of the zeolite. The excha~ged zeolite is ~hen dried and calcined at a temperature of about 700 to 1650F for about 0.1 to 3.0 hours and ~he zeoli~e is then ~ubsequently exchanged with a solution containing rare earth salt to decrease the alkali me~al oxide content to below about 1.0 weight percent and to impart a total rare earth oxide content of about 1.0 to 10 percent by weight of ~ L~5'~3~5 of the zeolite and the zeolite is then washed, dried and recovered~
DETAILED DESCRIPTION OF THE INVE
We have ound ~hat fau~asitic zeol.ites, paxticularly those possessing a high silica content, pre]pared according to the process of the instank in~ention when utilized in hyd::ocarbon conversion processes, exhibit an unusually high degree of catalytic activity and selectivi~y compared to zeolites of similar composi-tio~ in which the rare earth metal is introduced in a co~entional one s~ep ~anner. This result is a saving o rare earth which is 10 an expensive conponent of catalysts.
The novel multi-step incorporation of metal cation, specifically ~he rare earth metal into a zeolite structure is applicable to any crys~alline aluminosilicate zeolitic material.
~hus when it is desired ~o use a rare earth ~ 3a ~S,~3~5 exchanged zeolite in hydrocarbon cracking processes, a zeo-li-te suitable as a starting material is one having pores sufficiently large for the en~ry of the molecule to be ca-talyzed such as a Y-type faujasite for large molecule hydro-carbon conversion.
It is well known tha~ faujasite is a naturally occur-ing aluminosilicate having a characteristic X-ray structure.
The synthethic materials designated zeolite X and zeolite Y
by the Linde Division of Union Carbide Corpor'a-tion are com-mon examples of synthetic faujasites. U. S Patent 3,130,007 which describes Y zeolites, and gives the chemical formula as follows:
0.9-~0.2 Na2O:A12O3:wSiO2:xH20 where w has a value of greater than 3 and up to about 6 and x may have a value as high as 9.
Suitable zeolitic starting materials in the subject process are high silica faujasites such as the afore des-cribed zeolite ~. Preferably a synthetic faujasi-te mater-ial having a silica to alumina ration between 3.2 and 7.0 is utilized.
The various faujasitic zeolites having the desired silica content are either commercially available materials or can be prepared according to conventional methods well known in the art.
The high silica synthetic faujasite is normally in the sodium form. However if desired, any alkali metal form e.g~ potassium may be utilized. As used herein the term !'alkali metal" includes the elements of Group I-A, lithium through cesium.
According to the first step of our process the suitable 3L~5;~5 faujasite is base exchanged to replace most of the alkal.i metal e.g. sodium ions with a cation which upon thermal decomposition leaves an appreciable por-tion of the zeolite in the hydrogen form, such as solutions containing ammonium sal-ts, amine salts or other suitable salts. Examples of suitable ammonium compounds of this type include ammonium chloride, ammonium sulfate, tetraethyl ammonium chloride, tetraethyl ammonium sulfate, etc. Ammonium sulfate, be-cause of its ready availability and low cost, is the pre-ferred reagent in this step of the process.
The replacement of the sodium ions by ammonium ions by base exchange with ammonium salt facili-tates the subse-quent incorporation of the desired rare earth cations in-to the zeolite structure due to the greater ease of exchange-ability of rare earth cations with ammonium and/or hydro-gen ions, as contrasted to alkali metal cations.
The initial ammonium exchange procedure can oe accom-plished in a single step or a series of base exchange steps.
The treated zeolite is filtered after each ammonium exchange step, prior to treatment with a fresh ammonium exchange solu-tion. The ammonium exchange step may be repeated until the original alkali metal content is reduced to about 2.0 to 5.0 , weight percent, preferably to 3.0 to 4.0 percent and more particularly below about 3.5 percent. As used herein the term "alkali metal or rare earth content" refers to the weight percent of the respective cations, expressed as alkali metal oxide or rare earth oxide (REO) respectively.
Temperatures during the base exchange step may vary from room temperature to elevated temperatures below the boiling point of the treating solution. Generally -temperatures from about 25 to about 110C and preEerably Lrom about ~0 to lOO may be employed. The exchange is essentially complete in a period of about 0.1 to 2 hours, and usually from 0.1 to 0.5 hoursO
After completion of the ammonium exchange, -the zeolite is fil-tered and -~he ~eolite is then ion-exchanged with a rare earth salt solution in concentra-tion suffi-cient to provide an initial rare earth content of about 0.1 to 6.0 percent by weight to the zeoli-te, preferably from about 0.3 to 5.0 weight percent.
As used herein the term "rare earth elements" include elements from lan-thanum to luteclum, atomic numbers 57 to 71 inclusive. A large variety of rare earth compounds may be employed as a source of rare ear-th ions, -the only limi-tation being that the rare earth salt be sufficiently soluble in the solvent, usually water, to provide the required amount of rare earth content of the zeolite. Suitable compounds in-clude but are not limited to rare ear-th chlorides, nitrates, sulfates, formates, etc. The rare ear-th salts may be employed as single rare earth metal or a mixture of rare earth cations, such as rare earth chlorides or didymium chloride.
A suitable source or rare earth ions are commercially available rare earth chloride solutions containing chlorides of rare earth mixtures, having the relative composition cesium (as CeO2) - 48%; lanthanum (as La203) - 24%;
praseodymium (as Pr6pll) - 5%; neodymium (as N203) - 17%;
3~i samarium (as Sm2O3) - 3~; gadolinium (as Gd2O3) - 2%
and other rare earth ~ides - 0.8~.
If desired, the rare earth ion exchanye step may be carried out with a solution containing mixtures of rare earth salt and other cation salts such as cations of ammonium, magnesium, aluminum, nickel, iron, chromium etc.
The conditions at which the rare earth exchange is conducted may be the same as those employed in the ammonium exchange step. Satisfactory results are attained if the rare earth exchange is conducted at a temperature from about 50 to 100C for a period of about 0.1 to 3.0 hours It is to be noted that the aEoredescribed ammonium exchange steps and the rare earth exchange step may be combined in a single exchange step. Generally, -the rare earth salt solution is added to the final ammonium exchange solution.
The ammonium and rare earth exchanged zeolite product is then filtered and washed free of excess salts, dried and calcined at a temperature from about 700 to 1650F
preferably from 800 to 1500F, for a period from about 0.1 -to 0.3, preferably from 0.1 to 0.2 hours. During the calcination step the a~monium ions in the zeolite structure are liberated as ammonia gas and the calcination causes an internal rearrangement or transfer which faclli-tates any subsequent ion exchange of the alkali metal ion remaining within the zeolite structure.
Thus in the final exchange step, the calcined zeolite is further exchanged to reduce the alkali metal oxide con-tent of final zeolite product to below about 1.0 ~eight percent, preferably less than 0.5 weight percent; and to s incorpoLate addi~lonal Lare carth ca tiOJIS to give a total rare earth oxide content of about 1.0 to 10 weiyht percent.
It is to be noted that the fi.nal exchange step which accom~lishes -two purposes can, if desired, be carried out by a series of treatments or a combination of cations as long as the leduction of alkali. metal oxide con-tent and the incorporation of the desired rare earth content is at-tained.
Thus the zeolite can be further subjected to ammonium exchange procedures as previously de~cribed in the initial s~eps of our process whereby the original alkali metal conten-t was reduced by ammoniurn exchange steps to the de-sired value. Thereafter the zeolite is fur-ther exchanged with a rare ear-th salt e.g. chloride solution under con-ditions similar to those d~scri~ed in previous rare earth exchange steps. The rare ear-th exchange and reduction of alkali metal oxide content ca~ be carried out with a mixed solution containing the rare earth salts and other cation salts such as magnesium, aluminum, iron, calcium, etc.
Alternatively, the alkali metal oxide content can be reduced to the final required level and -the desired rare earth content can be achieved by employing a mixture oE
ammonium and rare ear-th salts or an admixture of ammonium, rare earth salts and other metal cation salts in a single final exchange step.
Furthermore the final rare earth content can be im-p~rted to ~he zeoli~e with a reduction of the sodium oxide content by subjec-ting the zeolites to a multi-step pro-cedure whereby the calcined zeolite is first subjected to a single or series of ammonium exchanges, followed by a rare earth exchange, Eurther ammonium exchanges and a subsequent rare earth exchange.
~ fter the final rare earth exchange the zeolite is filtered, washed and dried and the novel zeolite product is obtained. It has been found that the novel stabilized rare earth exchange zeolites of this invention exhibiting i.mproved catalytic ac`tivity and selectivi~y are obtained if a starting zeolite ma-terial is subjected to a series of exchange steps in which the rare earth content is intro-duced into zealite in at least a two step manner.
Our zeolite has an X-ray diffraction pattern similar to faujasite. The X-ray diffraction pattern w.as determined using a Norelco X-ray diffractometer wi-th a nickel filter copper K radiation. The instrument was operated at 40 kv.
operating potential and 20 ma. The sample -to be run was mixed with lQ~ o~ a suitable inert internal standard r such as sodium chloride and scanned from about 5 two-theta to about 50o two-theta at a goniometer speed of 1/2 per .
minute and a chart speed of 1/2 inch per minute.
S~5 The observed and theoretical (from National Bureau of Standards Circulars) values for the internal standard were used to correct systematic erroxs in the observed value of two-the-ta.
As mentioned above, our rare earth exchanyed zeolite prepared according to our novel process exhibits superior catalytic activity and selectivity as compared to other rare earth zeolites of similar composition. Our rare earth zeolite catalysts exhibit exceptionally good ability to optimize desired yield of g~asoline and other valuable pe-troleum derivatives from cracking of gas oil boiling in the 400 - 1000 F range.
The cracking is carried out at a temperature of 800 to 1050F, a catalyst to oil ratio of 3-6 and a contact time of 0.5 seconds to 10 minutes. The preferred operating conditions are a temperature of 850 - 950F a catalyst to oil ratio of 4.0 to 5Ø
The imp~oved coke selectivity of our zeolite catalysts is manifested by low coke yields. Coke which is a mixture of high molecular weight hydrogen deficient polymers and carbon Eormed in the reactor, plus any unstripped oils present on the catalyst as it enters the regenerator is an undesirable side product obtained in hydrocarbon con-version processes.
Our rare earth exchanged zeolites may be formed into catalysts using a minimum or subs-tantially no binders so as to provide a catalyst which comprises essentlally 100 percent zeolite. Alternatively, 5 to 50 weight percent of the combination of zeolites may be combined with from about 5G to 95 percent by weight inorganic oxide matrix. Typical ~6~3~5 inorganic oxide matrixes include silica, alumina, and sili-ca-alumina hydrogels. It is also contemplated that the matrix may comprise or contain clay such as kaolin and chemically or thermally modified kaolin.
It is understood that the foregoing detailed descrip-tion is given merely by way of illustration and that many variations and modifications may be made therein without departing from the spirit of the invention.
The following examples are meant to illustrate, but not to limit the invention. All parts and percentages are by weight, unless otherwise specified.
Example 1 This example illustrates our novel process for prepar-ing our rare earth exchanged zeolite.
A total of 100 grams (dry basis) of Y zeolite having a silica to alumina ratio of 5.2 and commercially avail-able from Union Carbide was exchanged three times with ammonium sulfate solutions using zeolite to ammonium sul- ;
fate to water weight ratios of 1:1:10, respectively. Each exchange was carried out at about 90 to 100C for about one hour. The zeolite was filtered after each of the first two exchanges and placed in a fresh exchange solution.
Each fresh exchange solution was of the same composition except that ~.25 grams of La(NO3) 6H2O was added to the third exchange solution. The product following the third exchange treatment was filtered, washed free of excess salts and calcined at 1400F for 2 hours. The product at this point contained 3 5% lanthanum oxide and 3 ~ Na2O
(dry basis).
3~ The calcined zeolite was then exchanged two times in 36~
an ammonium sulfate solution using zeolite to ammonium sulfate to water weight ratio 1:2:20 respectively. All exchanges were carried out at a temperature of about 90 -100C for about 1 hour. The zeolite was filtered after each exchange. It was then exchanged in a solution of rare earth chlorides using weight ratios zeolite to rare earth chloride (expressed as REO) to water 1:1:10 respec-tively, The exchange was for 1 hour at about 90 - 100C.
The product after the rare earth exchange was washed free of excess salts and dried and evaluated as the pro-perties of the zeolite product identified as Sample A in Table I are compared with rare earth Y zeolites prepared by other prior art techniques.
The samples were prepared for catalytic cracking evaluation by mixing 10 percent of the zeolite with 90 percent of a commercially available semi-synthetic silica-alumina cracking catalyst containing about 60 percent amor-phous silica-alumina and 40 percent clay. The resulting catalysts were pretreated by steaming at 1350F. for a per-iod of 16 hours in a 100 percent steam atmosphere. The catalytic evaluations were run at 900F at a weight hourly space velocity of 16 using a light West Texas ~il feed. In the Table I, Sample B is identified as the catalyst containing a calcined rare earth zeolite (CREY) having a higher rare earth content while Sample C is one having a similar rare earth content but made by conventional methods.
~05;~3~S
Table I
Sample A Sample B Sample C
Na2O, % 0.29 0.3 0.3 REO, % 9.2 17.7 9.0 Catalytic Activity Conversion Volume, % 71.0 71.0 62.0 Coke, Weight % 2.34 2.76 2.07 Conversion/Coke 30.4 25.7 30.0 These results demonstrate how the rare earth content can be reduced substantially without a loss ln activity and at the same time improved co~e selectivity is obtained.
Example 2 This example shows another modification of our novel procedure.
Two samples of the type Y zeolite utilized in Example 1 were treated in a manner identical to that described in Example 1 through the point when the product had received the fifth exchange with (NH4)2SO4 except that in this ex-periment, each of the samples were calcined at 1000F for 3 hours. At this point the products identified as Sample D
contained 3.5% REO and 3% Na2O, while Sample E contained 3.5% REO and 3% Na2O.
Following the fifth ammonium exchange the samples were subjected to a second calcination step. Sample D was cal-cined at 1100F for 2 hours while the Sample E was calcined at 1400F for 2 hours.
Following the second calcination, both samples were exchanged in solutions of rare earth chlorides in a manner identical to that described in Example 1. The products were then washed free of excess salts and dried. The properties ~t~5~ i5 of these samples are compared to zeolites of similar RE contac-t prepared by l~L-ior art IneL~lo~s as shown in ~rable II.
The catalyst samples utilized for catalytic cracking evaluation were prepared in the same manner as described in Example 1 and were subjected to the identical micrO-activity test described in Example 1. The catalyst Sam-ple F and G were promoted W7 th the zeolites prepared according to the process of U. S. Patent 3,595,611.
Table ~I
Sample D Sample E Sample F Sample G
Na2O, ~ .17 .21 .20 .10 REO, % 5.8 3.8 6.0 3.5 Catalytic Activity Conversion, Volume ~69.6 67.2 53.0 46.8 Coke, ~eight ~ 2.0 1.3 1.32 1.14 Conversion/
Coke 34.7 51.6 40.0 41.17 It can be seen from these results that th~s novel pro-cess resul-ts in zeolites of much higher activity than con-ventionally prepared zeolites of similar compositon. The ve:~:y good coke selectivity is also apparent. To appreciate this, it is necessary to be aware that the conversion/coke ratio generally decreases greatly with conversion level for conventional catalysts.
Background of t~e Invention -This invention relates to crystalline aluminosilicate zeolites, particularly to faujasite type zeolites and more specifically to rare earth exchanged faujasetic crystalline zeolites, preparation thereof and use as a catalyst par-ticularly as a cracking catalyst.
Rare earth exchange crystalline zeolites have been prepared by prior art me~hods whi'ch generally involve ion exchange procedures in which the introduction of the desir-lo ed rare earth metal into the zeolites is accomplished by a conventional single step, such as disclosed in ~. S. Patent 3,595,611. The latter rare earth exchanged zeolites possess catalytic activity and selectivity particularly when util-ized as a cracking catalyst component.
As a result of this invention, it has been found that novel rare earth exchanged crystalline aluminosilicate zeolites having superior catalytic properties compared to other prior art rare earth exchanged zeolites, can be pre-pared by an ion exchange method which incorporates the rare earth into the zeolite in a multi step, particularly a two step manner. We have discovered that if the desired amount of the rare earth metal is introduced into the zeo-lite via a unique two step exchange procedure, the resulting zeolite exhibits an unexpected high degree of catalytic ac-tivity and good selectivity, particularly highly improved coke selectivity.
Brief Statement of the Invention -In summary, the process for preparing the improved rare earth exchanged zeolites involves a series of ion exchange treatments and calcination procedures. Broadly, the process includes the steps of exchanging a faujasite type æeolite, e.g. a aujasite-type Y zeolit~ i~ the sodium form with a hydrogen-containing cation such as an ammonium ion to reduce the original sodium metal content of the zeolite to less than about 4 weight percent, followed by the first step o the series of ion-exchange steps with a rare ear~h salt to impart an initial rare earth con~ent of about 0.3 to 5 percent by weigh~: to the zeolite. After ~ubsequent filtering and washing of the thus exchanged zeol~te, drying and calci~ation of ~he zeolite is conducted a~ a temperature of rom about 700 to 1650F. Thereafter the product is further exchanged with a solution co~taining rare ear~h sal~s, for instance a mixed solution contai~ing rare earth cation sa~ts and an ammonium salt to decrease the sodium oxide content below about 1.0 weight pexcent and to impart a total rare earth content of about 1.0 to 10 percent by weight of the zeolite. After wash-ing and drying the novel zeolite produc~ is recovered.
Thus, in accordance with the present teachings, a process is provided for prepari~g a faujasitic ~rystalline aluminosilicate zeolite which has improved catalytic activity and improved cok~
selectivity. The process comprises the steps of reducing the alkali metal ox~de content of the aujasitic crystalline alumino-silicate zeolite to about 2.0 to 5.0 weight percent by ion exchang-ing with a solution containing a cation which upon thermal decom-position leaves a major portion of the zeolite in the hydrogen form, the zeolite is then ion ex~hanged with a solution containing a rare ear~h salt in a concentration sufficient to impart a rare earth oxide content of about 0.1 to 6.0 percent by weight of the zeolite. The excha~ged zeolite is ~hen dried and calcined at a temperature of about 700 to 1650F for about 0.1 to 3.0 hours and ~he zeoli~e is then ~ubsequently exchanged with a solution containing rare earth salt to decrease the alkali me~al oxide content to below about 1.0 weight percent and to impart a total rare earth oxide content of about 1.0 to 10 percent by weight of ~ L~5'~3~5 of the zeolite and the zeolite is then washed, dried and recovered~
DETAILED DESCRIPTION OF THE INVE
We have ound ~hat fau~asitic zeol.ites, paxticularly those possessing a high silica content, pre]pared according to the process of the instank in~ention when utilized in hyd::ocarbon conversion processes, exhibit an unusually high degree of catalytic activity and selectivi~y compared to zeolites of similar composi-tio~ in which the rare earth metal is introduced in a co~entional one s~ep ~anner. This result is a saving o rare earth which is 10 an expensive conponent of catalysts.
The novel multi-step incorporation of metal cation, specifically ~he rare earth metal into a zeolite structure is applicable to any crys~alline aluminosilicate zeolitic material.
~hus when it is desired ~o use a rare earth ~ 3a ~S,~3~5 exchanged zeolite in hydrocarbon cracking processes, a zeo-li-te suitable as a starting material is one having pores sufficiently large for the en~ry of the molecule to be ca-talyzed such as a Y-type faujasite for large molecule hydro-carbon conversion.
It is well known tha~ faujasite is a naturally occur-ing aluminosilicate having a characteristic X-ray structure.
The synthethic materials designated zeolite X and zeolite Y
by the Linde Division of Union Carbide Corpor'a-tion are com-mon examples of synthetic faujasites. U. S Patent 3,130,007 which describes Y zeolites, and gives the chemical formula as follows:
0.9-~0.2 Na2O:A12O3:wSiO2:xH20 where w has a value of greater than 3 and up to about 6 and x may have a value as high as 9.
Suitable zeolitic starting materials in the subject process are high silica faujasites such as the afore des-cribed zeolite ~. Preferably a synthetic faujasi-te mater-ial having a silica to alumina ration between 3.2 and 7.0 is utilized.
The various faujasitic zeolites having the desired silica content are either commercially available materials or can be prepared according to conventional methods well known in the art.
The high silica synthetic faujasite is normally in the sodium form. However if desired, any alkali metal form e.g~ potassium may be utilized. As used herein the term !'alkali metal" includes the elements of Group I-A, lithium through cesium.
According to the first step of our process the suitable 3L~5;~5 faujasite is base exchanged to replace most of the alkal.i metal e.g. sodium ions with a cation which upon thermal decomposition leaves an appreciable por-tion of the zeolite in the hydrogen form, such as solutions containing ammonium sal-ts, amine salts or other suitable salts. Examples of suitable ammonium compounds of this type include ammonium chloride, ammonium sulfate, tetraethyl ammonium chloride, tetraethyl ammonium sulfate, etc. Ammonium sulfate, be-cause of its ready availability and low cost, is the pre-ferred reagent in this step of the process.
The replacement of the sodium ions by ammonium ions by base exchange with ammonium salt facili-tates the subse-quent incorporation of the desired rare earth cations in-to the zeolite structure due to the greater ease of exchange-ability of rare earth cations with ammonium and/or hydro-gen ions, as contrasted to alkali metal cations.
The initial ammonium exchange procedure can oe accom-plished in a single step or a series of base exchange steps.
The treated zeolite is filtered after each ammonium exchange step, prior to treatment with a fresh ammonium exchange solu-tion. The ammonium exchange step may be repeated until the original alkali metal content is reduced to about 2.0 to 5.0 , weight percent, preferably to 3.0 to 4.0 percent and more particularly below about 3.5 percent. As used herein the term "alkali metal or rare earth content" refers to the weight percent of the respective cations, expressed as alkali metal oxide or rare earth oxide (REO) respectively.
Temperatures during the base exchange step may vary from room temperature to elevated temperatures below the boiling point of the treating solution. Generally -temperatures from about 25 to about 110C and preEerably Lrom about ~0 to lOO may be employed. The exchange is essentially complete in a period of about 0.1 to 2 hours, and usually from 0.1 to 0.5 hoursO
After completion of the ammonium exchange, -the zeolite is fil-tered and -~he ~eolite is then ion-exchanged with a rare earth salt solution in concentra-tion suffi-cient to provide an initial rare earth content of about 0.1 to 6.0 percent by weight to the zeoli-te, preferably from about 0.3 to 5.0 weight percent.
As used herein the term "rare earth elements" include elements from lan-thanum to luteclum, atomic numbers 57 to 71 inclusive. A large variety of rare earth compounds may be employed as a source of rare ear-th ions, -the only limi-tation being that the rare earth salt be sufficiently soluble in the solvent, usually water, to provide the required amount of rare earth content of the zeolite. Suitable compounds in-clude but are not limited to rare ear-th chlorides, nitrates, sulfates, formates, etc. The rare ear-th salts may be employed as single rare earth metal or a mixture of rare earth cations, such as rare earth chlorides or didymium chloride.
A suitable source or rare earth ions are commercially available rare earth chloride solutions containing chlorides of rare earth mixtures, having the relative composition cesium (as CeO2) - 48%; lanthanum (as La203) - 24%;
praseodymium (as Pr6pll) - 5%; neodymium (as N203) - 17%;
3~i samarium (as Sm2O3) - 3~; gadolinium (as Gd2O3) - 2%
and other rare earth ~ides - 0.8~.
If desired, the rare earth ion exchanye step may be carried out with a solution containing mixtures of rare earth salt and other cation salts such as cations of ammonium, magnesium, aluminum, nickel, iron, chromium etc.
The conditions at which the rare earth exchange is conducted may be the same as those employed in the ammonium exchange step. Satisfactory results are attained if the rare earth exchange is conducted at a temperature from about 50 to 100C for a period of about 0.1 to 3.0 hours It is to be noted that the aEoredescribed ammonium exchange steps and the rare earth exchange step may be combined in a single exchange step. Generally, -the rare earth salt solution is added to the final ammonium exchange solution.
The ammonium and rare earth exchanged zeolite product is then filtered and washed free of excess salts, dried and calcined at a temperature from about 700 to 1650F
preferably from 800 to 1500F, for a period from about 0.1 -to 0.3, preferably from 0.1 to 0.2 hours. During the calcination step the a~monium ions in the zeolite structure are liberated as ammonia gas and the calcination causes an internal rearrangement or transfer which faclli-tates any subsequent ion exchange of the alkali metal ion remaining within the zeolite structure.
Thus in the final exchange step, the calcined zeolite is further exchanged to reduce the alkali metal oxide con-tent of final zeolite product to below about 1.0 ~eight percent, preferably less than 0.5 weight percent; and to s incorpoLate addi~lonal Lare carth ca tiOJIS to give a total rare earth oxide content of about 1.0 to 10 weiyht percent.
It is to be noted that the fi.nal exchange step which accom~lishes -two purposes can, if desired, be carried out by a series of treatments or a combination of cations as long as the leduction of alkali. metal oxide con-tent and the incorporation of the desired rare earth content is at-tained.
Thus the zeolite can be further subjected to ammonium exchange procedures as previously de~cribed in the initial s~eps of our process whereby the original alkali metal conten-t was reduced by ammoniurn exchange steps to the de-sired value. Thereafter the zeolite is fur-ther exchanged with a rare ear-th salt e.g. chloride solution under con-ditions similar to those d~scri~ed in previous rare earth exchange steps. The rare ear-th exchange and reduction of alkali metal oxide content ca~ be carried out with a mixed solution containing the rare earth salts and other cation salts such as magnesium, aluminum, iron, calcium, etc.
Alternatively, the alkali metal oxide content can be reduced to the final required level and -the desired rare earth content can be achieved by employing a mixture oE
ammonium and rare ear-th salts or an admixture of ammonium, rare earth salts and other metal cation salts in a single final exchange step.
Furthermore the final rare earth content can be im-p~rted to ~he zeoli~e with a reduction of the sodium oxide content by subjec-ting the zeolites to a multi-step pro-cedure whereby the calcined zeolite is first subjected to a single or series of ammonium exchanges, followed by a rare earth exchange, Eurther ammonium exchanges and a subsequent rare earth exchange.
~ fter the final rare earth exchange the zeolite is filtered, washed and dried and the novel zeolite product is obtained. It has been found that the novel stabilized rare earth exchange zeolites of this invention exhibiting i.mproved catalytic ac`tivity and selectivi~y are obtained if a starting zeolite ma-terial is subjected to a series of exchange steps in which the rare earth content is intro-duced into zealite in at least a two step manner.
Our zeolite has an X-ray diffraction pattern similar to faujasite. The X-ray diffraction pattern w.as determined using a Norelco X-ray diffractometer wi-th a nickel filter copper K radiation. The instrument was operated at 40 kv.
operating potential and 20 ma. The sample -to be run was mixed with lQ~ o~ a suitable inert internal standard r such as sodium chloride and scanned from about 5 two-theta to about 50o two-theta at a goniometer speed of 1/2 per .
minute and a chart speed of 1/2 inch per minute.
S~5 The observed and theoretical (from National Bureau of Standards Circulars) values for the internal standard were used to correct systematic erroxs in the observed value of two-the-ta.
As mentioned above, our rare earth exchanyed zeolite prepared according to our novel process exhibits superior catalytic activity and selectivity as compared to other rare earth zeolites of similar composition. Our rare earth zeolite catalysts exhibit exceptionally good ability to optimize desired yield of g~asoline and other valuable pe-troleum derivatives from cracking of gas oil boiling in the 400 - 1000 F range.
The cracking is carried out at a temperature of 800 to 1050F, a catalyst to oil ratio of 3-6 and a contact time of 0.5 seconds to 10 minutes. The preferred operating conditions are a temperature of 850 - 950F a catalyst to oil ratio of 4.0 to 5Ø
The imp~oved coke selectivity of our zeolite catalysts is manifested by low coke yields. Coke which is a mixture of high molecular weight hydrogen deficient polymers and carbon Eormed in the reactor, plus any unstripped oils present on the catalyst as it enters the regenerator is an undesirable side product obtained in hydrocarbon con-version processes.
Our rare earth exchanged zeolites may be formed into catalysts using a minimum or subs-tantially no binders so as to provide a catalyst which comprises essentlally 100 percent zeolite. Alternatively, 5 to 50 weight percent of the combination of zeolites may be combined with from about 5G to 95 percent by weight inorganic oxide matrix. Typical ~6~3~5 inorganic oxide matrixes include silica, alumina, and sili-ca-alumina hydrogels. It is also contemplated that the matrix may comprise or contain clay such as kaolin and chemically or thermally modified kaolin.
It is understood that the foregoing detailed descrip-tion is given merely by way of illustration and that many variations and modifications may be made therein without departing from the spirit of the invention.
The following examples are meant to illustrate, but not to limit the invention. All parts and percentages are by weight, unless otherwise specified.
Example 1 This example illustrates our novel process for prepar-ing our rare earth exchanged zeolite.
A total of 100 grams (dry basis) of Y zeolite having a silica to alumina ratio of 5.2 and commercially avail-able from Union Carbide was exchanged three times with ammonium sulfate solutions using zeolite to ammonium sul- ;
fate to water weight ratios of 1:1:10, respectively. Each exchange was carried out at about 90 to 100C for about one hour. The zeolite was filtered after each of the first two exchanges and placed in a fresh exchange solution.
Each fresh exchange solution was of the same composition except that ~.25 grams of La(NO3) 6H2O was added to the third exchange solution. The product following the third exchange treatment was filtered, washed free of excess salts and calcined at 1400F for 2 hours. The product at this point contained 3 5% lanthanum oxide and 3 ~ Na2O
(dry basis).
3~ The calcined zeolite was then exchanged two times in 36~
an ammonium sulfate solution using zeolite to ammonium sulfate to water weight ratio 1:2:20 respectively. All exchanges were carried out at a temperature of about 90 -100C for about 1 hour. The zeolite was filtered after each exchange. It was then exchanged in a solution of rare earth chlorides using weight ratios zeolite to rare earth chloride (expressed as REO) to water 1:1:10 respec-tively, The exchange was for 1 hour at about 90 - 100C.
The product after the rare earth exchange was washed free of excess salts and dried and evaluated as the pro-perties of the zeolite product identified as Sample A in Table I are compared with rare earth Y zeolites prepared by other prior art techniques.
The samples were prepared for catalytic cracking evaluation by mixing 10 percent of the zeolite with 90 percent of a commercially available semi-synthetic silica-alumina cracking catalyst containing about 60 percent amor-phous silica-alumina and 40 percent clay. The resulting catalysts were pretreated by steaming at 1350F. for a per-iod of 16 hours in a 100 percent steam atmosphere. The catalytic evaluations were run at 900F at a weight hourly space velocity of 16 using a light West Texas ~il feed. In the Table I, Sample B is identified as the catalyst containing a calcined rare earth zeolite (CREY) having a higher rare earth content while Sample C is one having a similar rare earth content but made by conventional methods.
~05;~3~S
Table I
Sample A Sample B Sample C
Na2O, % 0.29 0.3 0.3 REO, % 9.2 17.7 9.0 Catalytic Activity Conversion Volume, % 71.0 71.0 62.0 Coke, Weight % 2.34 2.76 2.07 Conversion/Coke 30.4 25.7 30.0 These results demonstrate how the rare earth content can be reduced substantially without a loss ln activity and at the same time improved co~e selectivity is obtained.
Example 2 This example shows another modification of our novel procedure.
Two samples of the type Y zeolite utilized in Example 1 were treated in a manner identical to that described in Example 1 through the point when the product had received the fifth exchange with (NH4)2SO4 except that in this ex-periment, each of the samples were calcined at 1000F for 3 hours. At this point the products identified as Sample D
contained 3.5% REO and 3% Na2O, while Sample E contained 3.5% REO and 3% Na2O.
Following the fifth ammonium exchange the samples were subjected to a second calcination step. Sample D was cal-cined at 1100F for 2 hours while the Sample E was calcined at 1400F for 2 hours.
Following the second calcination, both samples were exchanged in solutions of rare earth chlorides in a manner identical to that described in Example 1. The products were then washed free of excess salts and dried. The properties ~t~5~ i5 of these samples are compared to zeolites of similar RE contac-t prepared by l~L-ior art IneL~lo~s as shown in ~rable II.
The catalyst samples utilized for catalytic cracking evaluation were prepared in the same manner as described in Example 1 and were subjected to the identical micrO-activity test described in Example 1. The catalyst Sam-ple F and G were promoted W7 th the zeolites prepared according to the process of U. S. Patent 3,595,611.
Table ~I
Sample D Sample E Sample F Sample G
Na2O, ~ .17 .21 .20 .10 REO, % 5.8 3.8 6.0 3.5 Catalytic Activity Conversion, Volume ~69.6 67.2 53.0 46.8 Coke, ~eight ~ 2.0 1.3 1.32 1.14 Conversion/
Coke 34.7 51.6 40.0 41.17 It can be seen from these results that th~s novel pro-cess resul-ts in zeolites of much higher activity than con-ventionally prepared zeolites of similar compositon. The ve:~:y good coke selectivity is also apparent. To appreciate this, it is necessary to be aware that the conversion/coke ratio generally decreases greatly with conversion level for conventional catalysts.
Claims (8)
1. A process for preparing a faujasitic crystalline aluminosilicate zeolite having improved catalytic activity and improved coke selectivity which comprises the steps of:
(a) reducing the alkali metal oxide content of a faujasitic crystalline aluminosilicate zeolite to about 2.0 to 5.0 weight percent by ion exchanging with a sol-ution containing a cation which upon thermal decompo-sition leaves a major portion of the zeolite in the hydrogen form, (b) ion exchanging said zeolite with a solution containing a rare earth salt in a concentration suf-ficient to impart a rare earth oxide content of about 0.1 to 6.0 percent by weight of the zeolite, (c) drying, calcining said exchanged zeolite at a temperature of from about 700° to 1650°F for about 0.1 to 3.0 hours, (d) further exchanging said zeolite with a solu-tion containing rare earth salt to decrease the alkali metal oxide content to below about 1.0 weight percent and to impart a total rare earth oxide content of about 1.0 to 10 percent by weight of the zeolite; and (e) washing, drying and recovering the zeolite product.
(a) reducing the alkali metal oxide content of a faujasitic crystalline aluminosilicate zeolite to about 2.0 to 5.0 weight percent by ion exchanging with a sol-ution containing a cation which upon thermal decompo-sition leaves a major portion of the zeolite in the hydrogen form, (b) ion exchanging said zeolite with a solution containing a rare earth salt in a concentration suf-ficient to impart a rare earth oxide content of about 0.1 to 6.0 percent by weight of the zeolite, (c) drying, calcining said exchanged zeolite at a temperature of from about 700° to 1650°F for about 0.1 to 3.0 hours, (d) further exchanging said zeolite with a solu-tion containing rare earth salt to decrease the alkali metal oxide content to below about 1.0 weight percent and to impart a total rare earth oxide content of about 1.0 to 10 percent by weight of the zeolite; and (e) washing, drying and recovering the zeolite product.
2. The process of Claim 1 wherein the ion exchange in step (a) is carried out with an ammonium salt solution.
3. The process of Claim 1 wherein the alkali metal oxide is sodium oxide.
4. The process of Claim 3 wherein the ion-exchange in step (a) is carried out until the sodium oxide content of the zeolite is reduced to less than 3 weight percent.
5. A process for the catalytic cracking of a hydro-carbon charge which comprises contacting said charge under catalytic cracking conditions with a catalyst comprising a faujasitic crystalline aluminosilicate zeolite in the stabil-ized rare earth form, said zeolite being prepared by a process which comprises the steps of:
(a) reducing the alkali metal oxide content of a faujasitic crystalline aluminosilicate zeolite to about 2.0 to 5.0 weight percent by ion exchanging with a sol-ution containing a cation which upon thermal decompo-sition leaves a major portion of the zeolite in the hydrogen form, (b) ion exchanging said zeolite with a solution containing a rare earth salt in a concentration suf-ficient to impart a rare earth oxide content of about 0.1 to 6.0 percent by weight of the zeolite, (c) drying, calcining said exchanged zeolite at a temperature of from about 700° to 1650°F for about 0.1 to 3.0 hours, (d) further exchanging said zeolite with a solu-tion containing rare earth salt to decrease the alkali metal oxide content to below about 1.0 weight percent and to impart a total rare earth oxide content of about 1.0 to 10 percent by weight of the zeolite; and (e) washing, drying and recovering the zeolite product and recovering the cracked hydrocarbon product.
(a) reducing the alkali metal oxide content of a faujasitic crystalline aluminosilicate zeolite to about 2.0 to 5.0 weight percent by ion exchanging with a sol-ution containing a cation which upon thermal decompo-sition leaves a major portion of the zeolite in the hydrogen form, (b) ion exchanging said zeolite with a solution containing a rare earth salt in a concentration suf-ficient to impart a rare earth oxide content of about 0.1 to 6.0 percent by weight of the zeolite, (c) drying, calcining said exchanged zeolite at a temperature of from about 700° to 1650°F for about 0.1 to 3.0 hours, (d) further exchanging said zeolite with a solu-tion containing rare earth salt to decrease the alkali metal oxide content to below about 1.0 weight percent and to impart a total rare earth oxide content of about 1.0 to 10 percent by weight of the zeolite; and (e) washing, drying and recovering the zeolite product and recovering the cracked hydrocarbon product.
6. The process of Claim 5 wherein the catalyst includes a silica-alumina support.
7. The process of Claim 5 wherein said hydrocarbon charge is contacted at a temperature of from about 800 to 1050°F.
8. The process of Claim 5 wherein the alkali metal oxide is sodium oxide.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/463,611 US3957623A (en) | 1974-04-24 | 1974-04-24 | Stable, catalytically active and coke selective zeolite |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1052365A true CA1052365A (en) | 1979-04-10 |
Family
ID=23840704
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA219,281A Expired CA1052365A (en) | 1974-04-24 | 1975-02-03 | Stable, catalytically active and coke selective zeolite |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US3957623A (en) |
| CA (1) | CA1052365A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8969599B2 (en) | 2013-03-08 | 2015-03-03 | University Of Notre Dame Du Lac | Cerium-containing zeolites and coke reduction methods |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4218307A (en) * | 1975-04-24 | 1980-08-19 | W. R. Grace & Co. | Hydrocarbon cracking catalyst |
| US4153535A (en) * | 1975-12-19 | 1979-05-08 | Standard Oil Company (Indiana) | Catalytic cracking with reduced emission of noxious gases |
| US4153534A (en) * | 1975-12-19 | 1979-05-08 | Standard Oil Company (Indiana) | Catalytic cracking with reduced emission of noxious gases |
| US4219406A (en) * | 1976-10-15 | 1980-08-26 | Mobil Oil Corporation | Catalytic cracking with zeolite-containing silica-alumina hydrogel catalyst |
| US4208269A (en) * | 1977-11-09 | 1980-06-17 | Exxon Research & Engineering Co. | Hydrocarbon cracking using combined perovskite and zeolite catalyst |
| US4179409A (en) * | 1977-11-09 | 1979-12-18 | Exxon Research & Engineering Co. | Hydrocarbon cracking catalyst |
| US4268376A (en) * | 1979-03-23 | 1981-05-19 | Chevron Research Company | Cracking catalyst rejuvenation |
| US4376039A (en) * | 1980-10-10 | 1983-03-08 | Exxon Research And Engineering Co. | Hydrocarbon conversion catalysts and processes utilizing the same |
| US4339354A (en) * | 1980-10-10 | 1982-07-13 | Exxon Research & Engineering Co. | Hydrocarbon conversion catalysts |
| US4457833A (en) * | 1981-08-27 | 1984-07-03 | Ashland Oil, Inc. | Process and catalyst for the conversion of carbo-metallic containing oils |
| US4584287A (en) * | 1981-12-04 | 1986-04-22 | Union Oil Company Of California | Rare earth-containing Y zeolite compositions |
| US4604187A (en) * | 1981-12-04 | 1986-08-05 | Union Oil Company Of California | Hydrocracking with rare earth-containing Y zeolite compositions |
| US4565621A (en) * | 1981-12-04 | 1986-01-21 | Union Oil Company Of California | Hydrocracking with rare earth-containing Y zeolite compositions |
| US5008225A (en) * | 1984-05-24 | 1991-04-16 | The B. F. Goodrich Company | Catalytic dehydrohalogenation catalyst |
| US4842714A (en) * | 1984-11-27 | 1989-06-27 | Uop | Catalytic cracking process using silicoaluminophosphate molecular sieves |
| US4900428A (en) * | 1985-07-26 | 1990-02-13 | Union Oil Company Of California | Process for the catalytic cracking of vanadium-containing feedstocks |
| US4898846A (en) * | 1986-03-21 | 1990-02-06 | W. R. Grace & Co.-Conn. | Cracking catalysts with octane enhancement |
| US4800185A (en) * | 1986-08-11 | 1989-01-24 | Chemcat Corporation | Regeneraation of metal contaminated hydrocarbon conversion catalytsts |
| US5173174A (en) * | 1988-07-07 | 1992-12-22 | Uop | Metal-tolerant FCC catalyst and process |
| US5382420A (en) * | 1992-09-25 | 1995-01-17 | Exxon Research & Engineering Company | ECR-33: a stabilized rare-earth exchanged Q type zeolite |
| US5308475A (en) * | 1992-11-23 | 1994-05-03 | Mobil Oil Corporation | Use of ZSM-12 in catalytic cracking for gasoline octane improvement and co-production of light olefins |
| US11111152B2 (en) | 2015-08-05 | 2021-09-07 | Petrochina Company Limited | Preparation method for modified molecular sieve and modified molecular sieve-containing catalytic cracking catalyst |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3816342A (en) * | 1963-05-14 | 1974-06-11 | Mobil Oil Corp | Process for preparing a crystalline aluminosilicate zeolite |
| US3393147A (en) * | 1966-03-02 | 1968-07-16 | Mobil Oil Corp | Catalysts having improved thermal stability and method of preparing the same |
| US3533939A (en) * | 1966-10-12 | 1970-10-13 | Mobil Oil Corp | Reforming with a crystalline aluminosilicate free of hydrogenation activity |
| US3402996A (en) * | 1966-12-19 | 1968-09-24 | Grace W R & Co | Ion exchange of crystalline zeolites |
| US3462377A (en) * | 1967-05-08 | 1969-08-19 | Mobil Oil Corp | Catalyst prepared by steaming partially base-exchanged zeolite x in a matrix |
| JPS546519B1 (en) * | 1969-02-03 | 1979-03-29 | ||
| US3676368A (en) * | 1970-08-26 | 1972-07-11 | Grace W R & Co | Rare earth-hydrogen exchanged zeolites |
| US3835032A (en) * | 1971-07-26 | 1974-09-10 | Grace W R & Co | Catalytic cracking with silver-rare earth or copper-rare earth exchanged y-type zeolite |
| US3823092A (en) * | 1972-01-24 | 1974-07-09 | Exxon Research Engineering Co | Process for preparing cracking catalysts having improved regeneration properties |
-
1974
- 1974-04-24 US US05/463,611 patent/US3957623A/en not_active Expired - Lifetime
-
1975
- 1975-02-03 CA CA219,281A patent/CA1052365A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8969599B2 (en) | 2013-03-08 | 2015-03-03 | University Of Notre Dame Du Lac | Cerium-containing zeolites and coke reduction methods |
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| Publication number | Publication date |
|---|---|
| US3957623A (en) | 1976-05-18 |
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