CA1092085A - Polycarboxylic acids as extrusion aids for silica- aluminas - Google Patents
Polycarboxylic acids as extrusion aids for silica- aluminasInfo
- Publication number
- CA1092085A CA1092085A CA288,342A CA288342A CA1092085A CA 1092085 A CA1092085 A CA 1092085A CA 288342 A CA288342 A CA 288342A CA 1092085 A CA1092085 A CA 1092085A
- Authority
- CA
- Canada
- Prior art keywords
- silica
- alumina
- polycarboxylic acid
- powder
- extrusion
- 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
Links
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
- B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
- B01J2/20—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by expressing the material, e.g. through sieves and fragmenting the extruded length
-
- 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
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/12—Silica and alumina
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
-
- 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
- C10G49/00—Treatment of hydrocarbon oils, in the presence of hydrogen or hydrogen-generating compounds, not provided for in a single one of groups C10G45/02, C10G45/32, C10G45/44, C10G45/58 or C10G47/00
- C10G49/02—Treatment of hydrocarbon oils, in the presence of hydrogen or hydrogen-generating compounds, not provided for in a single one of groups C10G45/02, C10G45/32, C10G45/44, C10G45/58 or C10G47/00 characterised by the catalyst used
Abstract
APPLICATION OF MONICA E. CHOCA AND GERALD R. FEISTEL
FOR POLYCARBOXYLIC ACIDS AS EXTRUSION
AIDS FOR SILICA-ALUMINAS
ABSTRACT OF THE DISCLOSURE
Silica-alumina powders can be extruded into catalyst supports having improved properties by the addition of up to 15%
by weight of a polycarboxylic acid, containing 2-10 carbon atoms, based on the dry weight of the powder to the silica-alumina powders prior to extrusion. The addition of the polycarboxylic acid also increases the extrusion rate.
FOR POLYCARBOXYLIC ACIDS AS EXTRUSION
AIDS FOR SILICA-ALUMINAS
ABSTRACT OF THE DISCLOSURE
Silica-alumina powders can be extruded into catalyst supports having improved properties by the addition of up to 15%
by weight of a polycarboxylic acid, containing 2-10 carbon atoms, based on the dry weight of the powder to the silica-alumina powders prior to extrusion. The addition of the polycarboxylic acid also increases the extrusion rate.
Description
l~gZ~85 : -:
Silica aluminas are useful materials as catalytic supports for hydrotreating catalysts, hydrocracking catalysts, demetallation catalysts and the like, in petroleum refining ~ ~ -processes. In these particular processes, the support must normally be used as a formed particulate rather than as a powder such as is generally used in fluid cracking processes which also may utilize silica-aluminas.
It is recognized in the art that silica-aluminas are difficult to form, in comparison to hydrated alumina materials, by such inexpensive methods as extrusion. Prior art methods, such as those disclosed in U.S. Patents 3,403,109 and 4,039,474 involve in some way precipitating the silica-alumina ~ ;
so as to make it more extrudable. As long as these precipi-tation methods lead to desirable catalytic properties in addition to satisfactory physical properties these methods are suitable.
However, if one wants to extrude an extant silica-alumina that has otherwise desirable catalytic properties, a more general method of extrusion is desired. ~ :
It is known in the art that alumina hydrates of a certain nature, i.e. alpha alumina monohydrates, so called pseudo-b~ehmites are readily extrudable and give good strength by use of the water as the sole extrusion aid.
The use of extrusion aids other than water for boehmitic aluminas is known in certain special circumstances.
For instance, U.S. 3,679,605 teaches the use of starch and ~ -methyl cellulose along with polyethylene in the extrusion of a hydrated alumina containing large amounts of boehmite to make large size pores and to aid extrusion. U.S. 3,804,781 teaches the use of surfactants including long chain acids in the extrusion of hydrated alumina to increase porosity.
lV~2085 United States 3,917,808 teaches the use of mixtures of poly-protic acids such as citric acid or sulfuric acid in combination with certain monoprotic acids such as hydrochloric acid or nitric acid in order to extrude a particular alpha alumina mono-hydrate made by a special process.
None of the aforementioned prior art patents address themselves to the extrusion of these materials which are known to be difficult to extrude and from which it is difficult to obtain good physical properties on extrusion. This invention concerns itself with materials known to be difficult to extrude.
Such materials of interest are those containing alumina in cal-cined forms such as gamma alumina, hydrated silica aluminas, or ~
hydrated phosphate aluminas. ~ -We have found that polycarboxylic acids used alone, such as citric acid, provide an extrusion aid effect to allow the rapid extrusion with the obtaining of good physical proper-ties of such difficult to extrude alumina containing bodies.
United States Patent 4,107,087 concerns the extrusion of materials containing calcined alumina. The object of this disclosure is to illustrate the extrusion of silica-aluminas useful in the catalyst area.
For some catalyst applications, it is desirable to increase porosity to ease the diffusion of larger molecules and thus, increase reactivity. However, very little new surface area is obtained by increasing pore volume in the large size pores and since increasing large size pores without concomi-tantly decreasing small size pores increases the overall pore volume, the apparent bulk density falls, and the mass of catalyst that can be loaded into a reactor falls.
On the other hand, in other catalyst applications, it is not desirable to pay the penalty of lower apparent bulk density or one does not wish to admit large molecules because , ' ' , ' ~ , ' ~
.
1~2~?5 they are catalyst poisons.
The process of this application is aimed at making strong extrudates of silica-alumina containing materials; the extrudates having reduced pore volume in larger pores (above 600A diameter). The reduction of the pore volume seems to be ; concomitant with increased shrinkage of the extrudate on cal-cination when the extrusion aids of this patent are used.
It is, therefore, an object of this invention to provide a process for preparing silica-alumina extrudates -having a high crush strength, high shrinkage on calcination, and reduced pore volume in pores above 600 ~ diameter compared to similar extrudates prepared without the use of a water-soluble polycarboxylic acid comprising: A. preparing a ;
purified silica-alumina powder comprising on a dry basis 5-600 SiO2 and 40-95% A12O3. B. Mixing said purified silica-alumina powder with water and from 0.1-15~ by weight of a ; water-soluble polycarboxylic acid containing from 2-10 carbon atoms based on the dry weight of the powder. C. Adjusting the moisture content of said silica-alumina powder to an ~ -; 20 extrudable level so as to allow extrusion; and then, D.
Extruding said silica-alumina powder to prepare a silica-alumina extrudate whereby the extrusion rate is improved over silica-alumina powders not so treated.
It is a further object of this invention to improve the physical properties of the calcined extrudates to obtain higher crush and attrition characteristics.
Other objects will appear hereinaEter, The general method employed in this invention for the preparation of a silica-alumina extrudate includes the steps of:
A. Preparing a purified silica-alumina powder comprising on a dry basis 5-60% SiO2 and ~0-95%
A1 203 .
' : . ' . , . , , ~ , ' :' . . ' :
1~2(~85 B, Mixing said purified silica~alumina powder with water and from 0,1~15% by weight of a water-soluble polycaT~oxylic acid con-taining from 2-lQ carbon atoms based on ~he dry weight of the powder. :;
C. Adjusting the moisture content of said silica.alumina powder to an extrudable l~vel 50 ~5 to allow ext~sion; a~d then, .
`~
.
. ~ .
~1 .
,.
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,;
D. Extruding said silica-alumina powder to prepare silica-alumina extrudate whereby the extrusion rate is improved over silica-alumina powders not so treated, and an extrudate having impr~ved properties is obtained.
Additionally, catalyst supports can be prepared from these extrud-ates by the additional steps of:
A. Drying the silica-alumina extrudate, and then, B. Calcining the dried silica-alumina extrudate whereby a catalyst `
support is formed. ~-Catalysts useful in a variety of refining operations utilizing the silica-alumina catalyst supports can also be prepared by impregnating the ~
calcined alumina extrudates formed above with water-soluble salts of one or ; -more catalytically active metals, drying or otherwise reducing the moisture : .
content from the impregnation step, and then recovering a silica-alumina catalyst.
. ~ .
A purified silica-alumina powder is prepared by any of the stand-ard methods known to the art. A typical prepara-tion of such a silica-alumina powder might be as follows. A dilute solutlon of sodium silicate is titrated with 35% H2S04 to an endpoint of pH 8. The resulting silica gel is mixed with the desired amount of precipitated aluminum hydroxide gel. After ,: , .
good mixing, the silica-alumina gel is spray dried. The spray drièd powder ~
.. ..
is purified by washing and/or ion exchange. The purified powder is dried in ~ , preparation for extrusion. Although this is the possible method, the prep-aration and purification of the silica_alumina powder may follow any of a . .
variety of well-known modifications to reach this point. These preparation techniques are generally known to those familiar with this art, and need not be elaborated on here. The original silica or alumina may be in the form of -any soluble salt solution which gives a gelatinous precipitate on pH titra-; tion.
3Q The silica-alumina powders useful for the practice of this inven-~... .
~". ', .
', ., .: . , :, . . ..
.
~l~92~1~S
tion generally comprise on a dry basis 5-60% SiO2 and 40-95% A1203. It is seen that these figures can vary widely based on the type of supports de~
sired and its end utility.
In any case, the purified silica-alumina powder, as is, causes `
some extrusion difficulties as a result of its being somewhat abrasive and difficult to compact. In accordance with our invention, the silica-alumina ls mulled with an aqueous solution containing up to 0.1-15% of a polycarbox-yiic acid and preferably 3-7% polycarboxylic acid by weight (based on the dry weight of the silica-alumina). The moisture is then ad~usted to an ex-trudable level, usually 45-75% by weight, and preferably between 50-70% by weight.
The polycarboxylic acids useful in the practice of this invention contain from 2-10 carbon atoms. Examples of polycarboxylic acids which are useful includes oxalic, citric, malonic, adipic, tartaric, sebacic acids, and all other carboxylic acids falling within the above terms of this inven- ;
tion provided they are water-soluble, aliphatic, and contain from 2-10 car-bon atoms. A particularly useful polycarboxylic acid for the practice of this invention is citric acid.
The powdered material including the polycarboxylic acid of our in-vention can then be extruded at an improved rate yielding an extrudate hav-ing improved properties. The material after extrusion is generally predried at temperatures of from 100 to 300 F. for several hours and is then cal-cined at elevated temperatures generally 1,000 to 1,500 F. for several hours to form catalyst supports which are the subJect of this invetnion. Addi-tionally~, these catalyst supports may then be impregnated with catalytically active metals and dried to form catalysts useful in a variety of refining operations.
It is interesting to note that where the prior art has recognized that shrinkage on calcination is decreased when polycarboxylic acids are used, in the practice of this invention we have actually seen an increase in .. ~ .
6 ~ i ~ \
~gz~ .
the calcination shrinkage rate when catalyst supports or catalysts are prepared by the above methods. In addition, we have seen that the pore vol-ume above 600 ~ of the supports or catalysts prepared by the method of this invention is decreased relative to that where no polycarboxylic acid was used.
As àn additional benefit through the practice of our invention, crush strength of the resultant catalyst supports produced in the practice of our invention generally have a minimum of a 25% increase in crush ~ ; ;
strength over materials extruded without the additives of our invention.
This is important in many petroleum refining operations since the catalyst is not crushed in the bottom of a reactor by its own weight.
Silica-alumina extrudates are utilized in a variety of applica-tions. Among their most important, however, and the one to which this inven- ~ !' tion is directly related, is the use of this type of materials as a catalyst support for materials used in petroleum refining operations. The materials prepared by the method of this invention showed utility when impregnated wi-th catalytically active metals such as cobalt, nickel, molybdenum, and tungsten as hydro-treating catalyst for the removal of sulfur and/or nitrogen com-pounds from both crude and distillate fractions. The catalyst suppor-ts pre-pared by this invention also may find utility as cracking catalyst and cat-alytic supports for other hydrocarbon processing operations. -:. :
To more fully understand the nature of this invention, the follow- ; ~
ing examples are given: ;
In the following examples, crush strength of the extrudate were determined on the side of pills of length to di-ameter ratio of 5:2. The at-` trition was determined by sieving the pills over a 20-mesh screen. 100 g : : .' :' of the sieved pills were tumbled for 30 minutes in a standard attrition '' apparatus. After tumbling, the pills were resifted over a 20-mesh screen.
The amount retained on the screen expressed as a percentage of the original -3o laO g is the attrition resistance.
: ' .
_ :~
: :. .~ , ...... . - , :.
. . : : .
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.
EXAMPLE I
; A purified silica-alumina powder (40% sio2-60% A1203 on dry basis) was dried to 43% loss on ignition. ~ine pounds of the dried powder (5.1 lbs. of silica-alumina solids) were charged to a Simpson muller. A solution of one liter of water containing 0.26 lb. of citric acid (5% by weight of the silica-alumina solids) was added to the muller all at once. The mate-; rial was mulled for 15 mimltes. An additional 200 ml of water were added to adjust the free moisture to 51%. The free moisture was determined on an O~Haus* moisture meter using 10 g of sample heated for 20 minutes at 75 setting. The mulled material was extruded through a one-eighth inch die.
The pills were broken up and predried at 250 F. for three hours and then calcined at 1,000 F. for three hours. The physical properties and pore volume of the calcined extrudates are given in Table I.
EXAMPLE II `
This example serves as a comparison for Example I where another sample of the silica-alumina powder used in Example I was extruded with no citric acid. Ten pounds of the purified silica-alumina powder were charged ;
to a Simpson* muller, mulled 15 minutes with 800 ml of water and then ten minutes more with 700 ml of water to give a material having 53% free mois-ture. The material was extruded through a one-eighth inch die. The pills were broken, dried and calcined as in Example I. The extrusion rate of this sample was markedly slower than that of Example I.
The physical properties and pore volume of the calcined extrudate are given in Table I.
; EXAMPLE III
A purified silica-alumina powder (23% sio2-76% A1203 on a dry c basis) was dried ~ust to an extrudable moisture. The material was extruded first through a half inch grid and then through a .116 inch die after ad-- justing to extrusion moisture. The extruded pills were predried in a pro-grammed drier at 400 F. calcined at 800 to 1,000 F. and finally calcined ~I , *Trademark - 8 -.. . , . . ,: . . ;, . , : . :,.
~9Z08S
at 1,250 F. All drying or calcinations were for no more than two hours.
The physical properties and pore volume of the calcined extrudate : are given in Table I. . :;.
EXAMPLE IV
This example was prepared in a manner similar to Example III ex-cept 4% citric acid was added to the silica-alumina powder prior to extru- . : . :
stion. The extrusion rate of this material was faster than -that of Example .
III.
The physical properties and pore volume of the calcined extrudate are given in Table I.
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TABLE I
PROPERTIES OF CALCINED EXTRUDATES
.. `'.
EXAMPLE
I II III IV
% Ci-tric Acid 5 0 0 4 ABD(l) 46.4 44.6 34 43 Crush(2) 14.7 6.7 4.8 13.1 Attrition % 97.7 94-5 96.5 99-5 Pill Diameter (in.) .112 .115 .108 .098 Composition % by Weight ~ -Si2 4 4 23 23
Silica aluminas are useful materials as catalytic supports for hydrotreating catalysts, hydrocracking catalysts, demetallation catalysts and the like, in petroleum refining ~ ~ -processes. In these particular processes, the support must normally be used as a formed particulate rather than as a powder such as is generally used in fluid cracking processes which also may utilize silica-aluminas.
It is recognized in the art that silica-aluminas are difficult to form, in comparison to hydrated alumina materials, by such inexpensive methods as extrusion. Prior art methods, such as those disclosed in U.S. Patents 3,403,109 and 4,039,474 involve in some way precipitating the silica-alumina ~ ;
so as to make it more extrudable. As long as these precipi-tation methods lead to desirable catalytic properties in addition to satisfactory physical properties these methods are suitable.
However, if one wants to extrude an extant silica-alumina that has otherwise desirable catalytic properties, a more general method of extrusion is desired. ~ :
It is known in the art that alumina hydrates of a certain nature, i.e. alpha alumina monohydrates, so called pseudo-b~ehmites are readily extrudable and give good strength by use of the water as the sole extrusion aid.
The use of extrusion aids other than water for boehmitic aluminas is known in certain special circumstances.
For instance, U.S. 3,679,605 teaches the use of starch and ~ -methyl cellulose along with polyethylene in the extrusion of a hydrated alumina containing large amounts of boehmite to make large size pores and to aid extrusion. U.S. 3,804,781 teaches the use of surfactants including long chain acids in the extrusion of hydrated alumina to increase porosity.
lV~2085 United States 3,917,808 teaches the use of mixtures of poly-protic acids such as citric acid or sulfuric acid in combination with certain monoprotic acids such as hydrochloric acid or nitric acid in order to extrude a particular alpha alumina mono-hydrate made by a special process.
None of the aforementioned prior art patents address themselves to the extrusion of these materials which are known to be difficult to extrude and from which it is difficult to obtain good physical properties on extrusion. This invention concerns itself with materials known to be difficult to extrude.
Such materials of interest are those containing alumina in cal-cined forms such as gamma alumina, hydrated silica aluminas, or ~
hydrated phosphate aluminas. ~ -We have found that polycarboxylic acids used alone, such as citric acid, provide an extrusion aid effect to allow the rapid extrusion with the obtaining of good physical proper-ties of such difficult to extrude alumina containing bodies.
United States Patent 4,107,087 concerns the extrusion of materials containing calcined alumina. The object of this disclosure is to illustrate the extrusion of silica-aluminas useful in the catalyst area.
For some catalyst applications, it is desirable to increase porosity to ease the diffusion of larger molecules and thus, increase reactivity. However, very little new surface area is obtained by increasing pore volume in the large size pores and since increasing large size pores without concomi-tantly decreasing small size pores increases the overall pore volume, the apparent bulk density falls, and the mass of catalyst that can be loaded into a reactor falls.
On the other hand, in other catalyst applications, it is not desirable to pay the penalty of lower apparent bulk density or one does not wish to admit large molecules because , ' ' , ' ~ , ' ~
.
1~2~?5 they are catalyst poisons.
The process of this application is aimed at making strong extrudates of silica-alumina containing materials; the extrudates having reduced pore volume in larger pores (above 600A diameter). The reduction of the pore volume seems to be ; concomitant with increased shrinkage of the extrudate on cal-cination when the extrusion aids of this patent are used.
It is, therefore, an object of this invention to provide a process for preparing silica-alumina extrudates -having a high crush strength, high shrinkage on calcination, and reduced pore volume in pores above 600 ~ diameter compared to similar extrudates prepared without the use of a water-soluble polycarboxylic acid comprising: A. preparing a ;
purified silica-alumina powder comprising on a dry basis 5-600 SiO2 and 40-95% A12O3. B. Mixing said purified silica-alumina powder with water and from 0.1-15~ by weight of a ; water-soluble polycarboxylic acid containing from 2-10 carbon atoms based on the dry weight of the powder. C. Adjusting the moisture content of said silica-alumina powder to an ~ -; 20 extrudable level so as to allow extrusion; and then, D.
Extruding said silica-alumina powder to prepare a silica-alumina extrudate whereby the extrusion rate is improved over silica-alumina powders not so treated.
It is a further object of this invention to improve the physical properties of the calcined extrudates to obtain higher crush and attrition characteristics.
Other objects will appear hereinaEter, The general method employed in this invention for the preparation of a silica-alumina extrudate includes the steps of:
A. Preparing a purified silica-alumina powder comprising on a dry basis 5-60% SiO2 and ~0-95%
A1 203 .
' : . ' . , . , , ~ , ' :' . . ' :
1~2(~85 B, Mixing said purified silica~alumina powder with water and from 0,1~15% by weight of a water-soluble polycaT~oxylic acid con-taining from 2-lQ carbon atoms based on ~he dry weight of the powder. :;
C. Adjusting the moisture content of said silica.alumina powder to an extrudable l~vel 50 ~5 to allow ext~sion; a~d then, .
`~
.
. ~ .
~1 .
,.
` :
` B ~ 4a - ' , ~. ., , : ~
, Z~85 ::
,;
D. Extruding said silica-alumina powder to prepare silica-alumina extrudate whereby the extrusion rate is improved over silica-alumina powders not so treated, and an extrudate having impr~ved properties is obtained.
Additionally, catalyst supports can be prepared from these extrud-ates by the additional steps of:
A. Drying the silica-alumina extrudate, and then, B. Calcining the dried silica-alumina extrudate whereby a catalyst `
support is formed. ~-Catalysts useful in a variety of refining operations utilizing the silica-alumina catalyst supports can also be prepared by impregnating the ~
calcined alumina extrudates formed above with water-soluble salts of one or ; -more catalytically active metals, drying or otherwise reducing the moisture : .
content from the impregnation step, and then recovering a silica-alumina catalyst.
. ~ .
A purified silica-alumina powder is prepared by any of the stand-ard methods known to the art. A typical prepara-tion of such a silica-alumina powder might be as follows. A dilute solutlon of sodium silicate is titrated with 35% H2S04 to an endpoint of pH 8. The resulting silica gel is mixed with the desired amount of precipitated aluminum hydroxide gel. After ,: , .
good mixing, the silica-alumina gel is spray dried. The spray drièd powder ~
.. ..
is purified by washing and/or ion exchange. The purified powder is dried in ~ , preparation for extrusion. Although this is the possible method, the prep-aration and purification of the silica_alumina powder may follow any of a . .
variety of well-known modifications to reach this point. These preparation techniques are generally known to those familiar with this art, and need not be elaborated on here. The original silica or alumina may be in the form of -any soluble salt solution which gives a gelatinous precipitate on pH titra-; tion.
3Q The silica-alumina powders useful for the practice of this inven-~... .
~". ', .
', ., .: . , :, . . ..
.
~l~92~1~S
tion generally comprise on a dry basis 5-60% SiO2 and 40-95% A1203. It is seen that these figures can vary widely based on the type of supports de~
sired and its end utility.
In any case, the purified silica-alumina powder, as is, causes `
some extrusion difficulties as a result of its being somewhat abrasive and difficult to compact. In accordance with our invention, the silica-alumina ls mulled with an aqueous solution containing up to 0.1-15% of a polycarbox-yiic acid and preferably 3-7% polycarboxylic acid by weight (based on the dry weight of the silica-alumina). The moisture is then ad~usted to an ex-trudable level, usually 45-75% by weight, and preferably between 50-70% by weight.
The polycarboxylic acids useful in the practice of this invention contain from 2-10 carbon atoms. Examples of polycarboxylic acids which are useful includes oxalic, citric, malonic, adipic, tartaric, sebacic acids, and all other carboxylic acids falling within the above terms of this inven- ;
tion provided they are water-soluble, aliphatic, and contain from 2-10 car-bon atoms. A particularly useful polycarboxylic acid for the practice of this invention is citric acid.
The powdered material including the polycarboxylic acid of our in-vention can then be extruded at an improved rate yielding an extrudate hav-ing improved properties. The material after extrusion is generally predried at temperatures of from 100 to 300 F. for several hours and is then cal-cined at elevated temperatures generally 1,000 to 1,500 F. for several hours to form catalyst supports which are the subJect of this invetnion. Addi-tionally~, these catalyst supports may then be impregnated with catalytically active metals and dried to form catalysts useful in a variety of refining operations.
It is interesting to note that where the prior art has recognized that shrinkage on calcination is decreased when polycarboxylic acids are used, in the practice of this invention we have actually seen an increase in .. ~ .
6 ~ i ~ \
~gz~ .
the calcination shrinkage rate when catalyst supports or catalysts are prepared by the above methods. In addition, we have seen that the pore vol-ume above 600 ~ of the supports or catalysts prepared by the method of this invention is decreased relative to that where no polycarboxylic acid was used.
As àn additional benefit through the practice of our invention, crush strength of the resultant catalyst supports produced in the practice of our invention generally have a minimum of a 25% increase in crush ~ ; ;
strength over materials extruded without the additives of our invention.
This is important in many petroleum refining operations since the catalyst is not crushed in the bottom of a reactor by its own weight.
Silica-alumina extrudates are utilized in a variety of applica-tions. Among their most important, however, and the one to which this inven- ~ !' tion is directly related, is the use of this type of materials as a catalyst support for materials used in petroleum refining operations. The materials prepared by the method of this invention showed utility when impregnated wi-th catalytically active metals such as cobalt, nickel, molybdenum, and tungsten as hydro-treating catalyst for the removal of sulfur and/or nitrogen com-pounds from both crude and distillate fractions. The catalyst suppor-ts pre-pared by this invention also may find utility as cracking catalyst and cat-alytic supports for other hydrocarbon processing operations. -:. :
To more fully understand the nature of this invention, the follow- ; ~
ing examples are given: ;
In the following examples, crush strength of the extrudate were determined on the side of pills of length to di-ameter ratio of 5:2. The at-` trition was determined by sieving the pills over a 20-mesh screen. 100 g : : .' :' of the sieved pills were tumbled for 30 minutes in a standard attrition '' apparatus. After tumbling, the pills were resifted over a 20-mesh screen.
The amount retained on the screen expressed as a percentage of the original -3o laO g is the attrition resistance.
: ' .
_ :~
: :. .~ , ...... . - , :.
. . : : .
~ 9ZC~S
.
EXAMPLE I
; A purified silica-alumina powder (40% sio2-60% A1203 on dry basis) was dried to 43% loss on ignition. ~ine pounds of the dried powder (5.1 lbs. of silica-alumina solids) were charged to a Simpson muller. A solution of one liter of water containing 0.26 lb. of citric acid (5% by weight of the silica-alumina solids) was added to the muller all at once. The mate-; rial was mulled for 15 mimltes. An additional 200 ml of water were added to adjust the free moisture to 51%. The free moisture was determined on an O~Haus* moisture meter using 10 g of sample heated for 20 minutes at 75 setting. The mulled material was extruded through a one-eighth inch die.
The pills were broken up and predried at 250 F. for three hours and then calcined at 1,000 F. for three hours. The physical properties and pore volume of the calcined extrudates are given in Table I.
EXAMPLE II `
This example serves as a comparison for Example I where another sample of the silica-alumina powder used in Example I was extruded with no citric acid. Ten pounds of the purified silica-alumina powder were charged ;
to a Simpson* muller, mulled 15 minutes with 800 ml of water and then ten minutes more with 700 ml of water to give a material having 53% free mois-ture. The material was extruded through a one-eighth inch die. The pills were broken, dried and calcined as in Example I. The extrusion rate of this sample was markedly slower than that of Example I.
The physical properties and pore volume of the calcined extrudate are given in Table I.
; EXAMPLE III
A purified silica-alumina powder (23% sio2-76% A1203 on a dry c basis) was dried ~ust to an extrudable moisture. The material was extruded first through a half inch grid and then through a .116 inch die after ad-- justing to extrusion moisture. The extruded pills were predried in a pro-grammed drier at 400 F. calcined at 800 to 1,000 F. and finally calcined ~I , *Trademark - 8 -.. . , . . ,: . . ;, . , : . :,.
~9Z08S
at 1,250 F. All drying or calcinations were for no more than two hours.
The physical properties and pore volume of the calcined extrudate : are given in Table I. . :;.
EXAMPLE IV
This example was prepared in a manner similar to Example III ex-cept 4% citric acid was added to the silica-alumina powder prior to extru- . : . :
stion. The extrusion rate of this material was faster than -that of Example .
III.
The physical properties and pore volume of the calcined extrudate are given in Table I.
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TABLE I
PROPERTIES OF CALCINED EXTRUDATES
.. `'.
EXAMPLE
I II III IV
% Ci-tric Acid 5 0 0 4 ABD(l) 46.4 44.6 34 43 Crush(2) 14.7 6.7 4.8 13.1 Attrition % 97.7 94-5 96.5 99-5 Pill Diameter (in.) .112 .115 .108 .098 Composition % by Weight ~ -Si2 4 4 23 23
2 3 59 59 76 76 Na20 .02 .02 .04 .04 SOl~ .44 .4~ .25 25 % Pore Volume in Pores -> 600~ Diameter 26 34 45 29 Surface Area (m /g) BET(3)494.3 479-5 457-5 ~36.4 ( )A~erage bulk density in grams/ml (2)Crush strength ~lbs.)
(3)Brunnauer-Emmett-Teller method '~
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EXAMPLE V
,.' This example shows the use of the silica-alumina base, extruded with citric acid, as a catalytic support for hydrotreating purposes.
The 1/8" extrudates from Example IV were pore volume impregnated with a nickel-molybdenum-phosphorus solution. The solution was prepared `
according to the methods of United States 3,232,887. The catalyst was cal-cined to give a material containing 11.3% MoO3, 3.84% ~iO, and 4.4% P205 by ;~
weight. The density of the catalyst was 0.55 gm/ml.
.
The desulfurization and denitrogenation activity were tested as `
follows. Sixty milliliters of catalyst were tested ~or hydrotreating activ-ity on heavy vacuum gas oil (gravity, API 20.0, boiling range 742-1,065 F.) containing 2.7% sulfur by weight, and 1,562 ppm nitrogen. The run conditions ., : .
were 675 F., 1,000 psig, 1.5 L~SV [volume oil/hour/volume catal-yst and .~ 4,100 SCF/bbl oil of H2 (100%)]. The product sulfur was o.65% and the prod-.
uct nitrogen was 1,063 ppm.
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EXAMPLE V
,.' This example shows the use of the silica-alumina base, extruded with citric acid, as a catalytic support for hydrotreating purposes.
The 1/8" extrudates from Example IV were pore volume impregnated with a nickel-molybdenum-phosphorus solution. The solution was prepared `
according to the methods of United States 3,232,887. The catalyst was cal-cined to give a material containing 11.3% MoO3, 3.84% ~iO, and 4.4% P205 by ;~
weight. The density of the catalyst was 0.55 gm/ml.
.
The desulfurization and denitrogenation activity were tested as `
follows. Sixty milliliters of catalyst were tested ~or hydrotreating activ-ity on heavy vacuum gas oil (gravity, API 20.0, boiling range 742-1,065 F.) containing 2.7% sulfur by weight, and 1,562 ppm nitrogen. The run conditions ., : .
were 675 F., 1,000 psig, 1.5 L~SV [volume oil/hour/volume catal-yst and .~ 4,100 SCF/bbl oil of H2 (100%)]. The product sulfur was o.65% and the prod-.
uct nitrogen was 1,063 ppm.
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Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing silica-alumina extrudates having a high crush strength, high shrinkage on calcination, and reduced pore volume in pores above 600 .ANG. diameter compared to similar extrudates prepared without the use of a water-soluble polycarboxylic acid comprising:
A. Preparing a purified silica-alum m a powder comprising on a dry basis 5-60% SiO2 and 40-95% A12O3.
B. Mixing said purified silica-alumina powder with water and from 0.1-15% by weight of a water-soluble polycarboxylic acid containing from 2-10 carbon atoms based on the dry weight of the powder.
C. Adjusting the moisture content of said silica-alumina powder to an extrudable level so as to allow extrusion;
and then, D. Extruding said silica-alumina powder to prepare a silica-alumina extrudate whereby the extrusion rate is improved over silica-alumina powders not so treated.
A. Preparing a purified silica-alum m a powder comprising on a dry basis 5-60% SiO2 and 40-95% A12O3.
B. Mixing said purified silica-alumina powder with water and from 0.1-15% by weight of a water-soluble polycarboxylic acid containing from 2-10 carbon atoms based on the dry weight of the powder.
C. Adjusting the moisture content of said silica-alumina powder to an extrudable level so as to allow extrusion;
and then, D. Extruding said silica-alumina powder to prepare a silica-alumina extrudate whereby the extrusion rate is improved over silica-alumina powders not so treated.
2. The process of claim 1 where the polycarboxylic acid is citric acid.
3. The process of claim 1 wherein the silica-alumina extrudate is dried and calcined to prepare a catalyst support.
4. The process of claim 1 where the crush strength is increased by at least 25% over non-polycarboxylic acid treated material.
5. The process of claim 1 where pore volume above 600 .ANG. of the product is decreased relative to that where no polycarboxylic acid is used.
6. The process of claim 1 where the shrinkage on calcination is increased over that where no polycarboxylic acid is used.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US82954177A | 1977-08-31 | 1977-08-31 | |
| US829,541 | 1977-08-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1092085A true CA1092085A (en) | 1980-12-23 |
Family
ID=25254813
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA288,342A Expired CA1092085A (en) | 1977-08-31 | 1977-10-07 | Polycarboxylic acids as extrusion aids for silica- aluminas |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5438289A (en) |
| BE (1) | BE860947A (en) |
| CA (1) | CA1092085A (en) |
| DE (1) | DE2751269C3 (en) |
| GB (1) | GB1549548A (en) |
| NL (1) | NL7712703A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2935914A1 (en) * | 1979-09-06 | 1981-04-02 | Kali-Chemie Ag, 3000 Hannover | METHOD FOR PRODUCING SPHERICAL SHAPED BODIES BASED ON AL (ARROW DOWN) 2 (ARROW DOWN) O (ARROW DOWN) 3 (ARROW DOWN) AND / OR SIO (ARROW DOWN) 2 (ARROW DOWN) |
| JP5690634B2 (en) * | 2011-03-31 | 2015-03-25 | 独立行政法人石油天然ガス・金属鉱物資源機構 | Hydrorefining catalyst and method for producing hydrocarbon oil |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3917808A (en) * | 1972-10-16 | 1975-11-04 | Continental Oil Co | Method for extruding alumina |
-
1977
- 1977-10-07 CA CA288,342A patent/CA1092085A/en not_active Expired
- 1977-10-31 GB GB4526777A patent/GB1549548A/en not_active Expired
- 1977-11-14 DE DE19772751269 patent/DE2751269C3/en not_active Expired
- 1977-11-17 NL NL7712703A patent/NL7712703A/en not_active Application Discontinuation
- 1977-11-18 BE BE1008524A patent/BE860947A/en not_active IP Right Cessation
- 1977-11-22 JP JP13953777A patent/JPS5438289A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE2751269C3 (en) | 1981-09-03 |
| JPS5723539B2 (en) | 1982-05-19 |
| NL7712703A (en) | 1979-03-02 |
| BE860947A (en) | 1978-05-18 |
| GB1549548A (en) | 1979-08-08 |
| DE2751269B2 (en) | 1980-07-10 |
| JPS5438289A (en) | 1979-03-22 |
| DE2751269A1 (en) | 1979-03-08 |
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