EP0235126A1 - Process for producing a high surface area alumina - Google Patents

Process for producing a high surface area alumina

Info

Publication number
EP0235126A1
EP0235126A1 EP85904387A EP85904387A EP0235126A1 EP 0235126 A1 EP0235126 A1 EP 0235126A1 EP 85904387 A EP85904387 A EP 85904387A EP 85904387 A EP85904387 A EP 85904387A EP 0235126 A1 EP0235126 A1 EP 0235126A1
Authority
EP
European Patent Office
Prior art keywords
alumina
aluminum
surface area
ammonium
cause
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.)
Withdrawn
Application number
EP85904387A
Other languages
German (de)
French (fr)
Other versions
EP0235126A4 (en
Inventor
Paul J. Marcantonio
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chevron USA Inc
Original Assignee
Chevron Research and Technology Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Chevron Research and Technology Co filed Critical Chevron Research and Technology Co
Publication of EP0235126A1 publication Critical patent/EP0235126A1/en
Publication of EP0235126A4 publication Critical patent/EP0235126A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/30—Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/78—Compounds containing aluminium and two or more other elements, with the exception of oxygen and hydrogen
    • C01F7/782—Compounds containing aluminium and two or more other elements, with the exception of oxygen and hydrogen containing carbonate ions, e.g. dawsonite
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area

Definitions

  • This invention relates to a process for produc ⁇ ing a high surface area alumina that is useful in alumina- base catalysts.
  • Catalysts are employed in many chemical indus ⁇ tries to facilitate chemical reactions which would other ⁇ wise require unduly stringent reaction conditions.
  • Many catalysts are based on alumina, used either alone (such as
  • Typical hydrorefining catalysts comprise a Group VIII metal (typically nickel or cobalt) and a Group VIB metal (typically molybdenum or tungsten) sup ⁇ ported on an alumina base. The preparation of such a
  • catalyst may be exemplified by U.S. Patent No. 4,113,661 to Tamm, the disclosure of which is incorporated herein by reference.
  • the alumina present in such catalysts is typically ⁇ -alumina, though some catalysts prepared by higher-temperature calcination contain ⁇ - or ⁇ -alumina.
  • the catalysts are typically particulate, with sizes rang ⁇ ing from 0.8 mm diameter cylinders to 5-10 mm diameter cylinders, and more complex shapes such as ovals, tri- lobes, rings, etc. being common.
  • 35 lyst is dependent in part on the surface area of that catalyst, it would be desirable to have an alumina that has a high surface area so that it could be used in such a catalyst.
  • This invention provides a process for the pro- duction of such a high surface area alumina.
  • this invention provides a process which comprises:
  • alumina-base catalyst means a catalyst the base (i.e., the non-catalytic support, unless the support itself is catalytic) of which comprises alumina.
  • the term refers to a catalyst base comprising at least 50%, usually at least 80%, and preferably at least 90% by weiqht of alumina.
  • the non-alumina components may be, for example, silica or other refractory oxides, aluminosili- cates such as clays or zeolites, etc.
  • aluminum salt particles are treated with an aqueous solu- tion of ammonium hydroxide and ammonium carbonate to cause a reaction converting at least a substantial proportion of the aluminum salt to an ammonium aluminum hydroxycarbo ⁇ nate, which is then heated slowly to between 150° and 400, ⁇ > C for a period of at least 2 hours to cause its decom- position to said alumina.
  • the alumina should have a BET surface area of at least 300 m /g, preferably at least 450 m * Vg, more prefer- ably at least 800 m /g. It is often desirable to have a catalyst of very high surface area with corresponding small pores—less than 50 Angstroms. Such catalysts would be used in processes not limited by diffusion control or size exclusion of the reacting molecule. In these cases, reaction rates would be directly proportional to surface area.
  • aluminum salt particles are treated with an aqueous solution of ammonium hydroxide and ammonium carbonate to cause a reaction converting at least a substantial proportion of the aluminum salt to an ammo ⁇ nium aluminum hydroxycarbonate.
  • the aluminum salt is preferably either aluminum sulfate, aluminum chloride, or aluminum nitrate. More preferably, the aluminum salt is aluminum sulfate, because of its low cost. However when aluminum sulfate is used, the resulting alumina should be washed with water at a temperature of at least 50°C to remove a substantial part of the sulfur, ammonia, and other residuals from the alu ⁇ mina.
  • the reaction pH of the first step is between 9 and 12, preferably between* 10 and 11.
  • a typical solution contains ammonium hydroxide and ammonium carbonate.
  • a typical reaction in this case may be:
  • the ammonium aluminum hydroxycarbonate is heated slowly to between 150° and 400°C for a period of at least two hours to cause its decomposition to said alumina.
  • the heating temperature is about 200°C, for at that temperature, decomposition will occur slowly which is important in obtaining the highest surface area.
  • an alumina having a BET surface area of at least 800 irr/g is produced by treating aluminum sulfate particles with an aqueous solution of ammonium hydroxide and ammonium carbonate at a pH of 10 to 11 to cause a reaction converting at least a substantial proportion of the aluminum sulfate to NH 4 Al(OH) 2 C0 3 * H 2 0, heating said NH 4 A1(0H) 2 C0 3 * H 2 0 to about 200°C for a period of at least 2 hours to cause its decomposition to alumina; and washing the alumina with water at a temperature of at least 50°C to remove a substantial part of the sulfur, ammonia, and other residuals from the alumina.
  • Example 1 An ammonium aluminum hydroxycarbonate was prepared by adding 318 grams of Al 2 (S0 4 ) 3 *16H 2 0 to 1 liter of solution containing 3M NH3 and 1.5 M (NH3) 2 C0 . The mixture was reacted for one hour at 70°C and filtered, then the precipitate was dried in a vacuum oven overnight at 150°C. A similar preparation was made by adding dissolved aluminum sulfate to the same ammonical solution.
  • Example 2 A large preparation was made by adding solid aluminum sulfate as in the previous example. In this case, 704 grams of hydroxycarbonate were decomposed at 250°C for eight hours. As in the previous example, the large mass of material resulted in a relatively slow heating rate. The BET surface area was 700 /g.
  • Example 3 This example shows the adverse effect that rapid : heat-up has on surface area. A hydroxycarbonate prepared as in previous examples was decomposed at various tempera ⁇ tures for three hours. The important variable in this example was the rapid heating rate. Rapid heating resulted from placing only about 8 grams of hydroxycarbon- ' ate into a preheated oven. Table I shows that rapid decomposition even at low temperatures reduced the surface area significantly from the very high values seen previously.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
  • Catalysts (AREA)

Abstract

Une alumine ayant une très grande surface spécifique est produite en traitant des particules de sel d'aluminium avec une solution aqueuse d'hydroxyde d'ammonium et de carbonate d'ammonium à un pH de 9 à 12, afin de convertir le sel d'aluminium en un hydroxycarbonate d'aluminium d'ammonium, et en chauffant ensuite l'hydroxycarbonate d'aluminium d'ammonium à une température située entre 150o et 400oC pendant une période d'au moins deux heures, afin de le décomposer en alumine.An alumina having a very large specific surface is produced by treating particles of aluminum salt with an aqueous solution of ammonium hydroxide and ammonium carbonate at a pH of 9 to 12, in order to convert the salt of aluminum into an aluminum ammonium hydroxycarbonate, and then heating the aluminum ammonium hydroxycarbonate to a temperature between 150o and 400oC for a period of at least two hours, in order to decompose it into alumina.

Description

PROCESS FOR PRODUCING A HIGH SURFACE AREA ALUMINA
05
FIELD OF THE INVENTION
This invention relates to a process for produc¬ ing a high surface area alumina that is useful in alumina- base catalysts.
10 BACKGROUND OF THE INVENTION
Catalysts are employed in many chemical indus¬ tries to facilitate chemical reactions which would other¬ wise require unduly stringent reaction conditions. Many catalysts are based on alumina, used either alone (such as
,,. in Claus conversion of hydrogen sulfide, alcohol dehydra¬ tion, and olefin isomerization), as a support (such as the Pt/Pd catalysts used in automobile exhaust systems and in gasoline reforming), and as an interactive support (parti¬ cularly in hydrorefining catalysts for petroleum dis-
_n tillates and residual oils).
Typical hydrorefining catalysts comprise a Group VIII metal (typically nickel or cobalt) and a Group VIB metal (typically molybdenum or tungsten) sup¬ ported on an alumina base. The preparation of such a
2_ catalyst may be exemplified by U.S. Patent No. 4,113,661 to Tamm, the disclosure of which is incorporated herein by reference. The alumina present in such catalysts is typically γ-alumina, though some catalysts prepared by higher-temperature calcination contain δ- or θ-alumina.
30 The catalysts are typically particulate, with sizes rang¬ ing from 0.8 mm diameter cylinders to 5-10 mm diameter cylinders, and more complex shapes such as ovals, tri- lobes, rings, etc. being common.
Since the effectiveness of an alumina-base cata¬
35 lyst is dependent in part on the surface area of that catalyst, it would be desirable to have an alumina that has a high surface area so that it could be used in such a catalyst.
40 SUMMARY OF THE INVENTION
This invention provides a process for the pro- duction of such a high surface area alumina.
Specifically, this invention provides a process which comprises:
(a) treating aluminum salt particles with an aqueous solution of ammonium hydroxide and ammonium carbonate at a pH of 9 to 12 to cause a reaction converting at least a substantial proportion of the aluminum salt to an ammonium aluminum hydroxycarbonate; and
(b) heating the ammonium aluminum hydroxycarbonate to between 150° and 400°C for a period of at least 2 hours to cause its decomposition to an alumina that has a very high surface area.
DETAILED DESCRIPTION OF THE INVENTION The process of this invention is applicable to alumina-base catalysts. In this context, the term "alumina-base catalyst" means a catalyst the base (i.e., the non-catalytic support, unless the support itself is catalytic) of which comprises alumina. Generally, the term refers to a catalyst base comprising at least 50%, usually at least 80%, and preferably at least 90% by weiqht of alumina. The non-alumina components may be, for example, silica or other refractory oxides, aluminosili- cates such as clays or zeolites, etc.
To produce an alumina useful in such catalysts, aluminum salt particles are treated with an aqueous solu- tion of ammonium hydroxide and ammonium carbonate to cause a reaction converting at least a substantial proportion of the aluminum salt to an ammonium aluminum hydroxycarbo¬ nate, which is then heated slowly to between 150° and 400,<>C for a period of at least 2 hours to cause its decom- position to said alumina.
The alumina should have a BET surface area of at least 300 m /g, preferably at least 450 m*Vg, more prefer- ably at least 800 m /g. It is often desirable to have a catalyst of very high surface area with corresponding small pores—less than 50 Angstroms. Such catalysts would be used in processes not limited by diffusion control or size exclusion of the reacting molecule. In these cases, reaction rates would be directly proportional to surface area.
In the first step, aluminum salt particles are treated with an aqueous solution of ammonium hydroxide and ammonium carbonate to cause a reaction converting at least a substantial proportion of the aluminum salt to an ammo¬ nium aluminum hydroxycarbonate.
The aluminum salt is preferably either aluminum sulfate, aluminum chloride, or aluminum nitrate. More preferably, the aluminum salt is aluminum sulfate, because of its low cost. However when aluminum sulfate is used, the resulting alumina should be washed with water at a temperature of at least 50°C to remove a substantial part of the sulfur, ammonia, and other residuals from the alu¬ mina. The reaction pH of the first step is between 9 and 12, preferably between* 10 and 11.
A typical solution contains ammonium hydroxide and ammonium carbonate. A typical reaction in this case may be:
A12 ( S04 ) 3 ( S ) + 2NH4 + ( aq # ) + 40H" ( aq # ) + 2 C03 2- ( aq > ) ->
2NH4A1 ( 0H ) 2C03 - H20* ( S ) + 3S04 2 " ( aq
* non-gelatinous, easily filterable In the second step, the ammonium aluminum hydroxycarbonate is heated slowly to between 150° and 400°C for a period of at least two hours to cause its decomposition to said alumina.
Preferably, the heating temperature is about 200°C, for at that temperature, decomposition will occur slowly which is important in obtaining the highest surface area.
The heating step should be performed gradually. In order to maximize the resulting surface area, the heating step should occur over a period of at least two hours. In a preferred embodiment, an alumina having a BET surface area of at least 800 irr/g is produced by treating aluminum sulfate particles with an aqueous solution of ammonium hydroxide and ammonium carbonate at a pH of 10 to 11 to cause a reaction converting at least a substantial proportion of the aluminum sulfate to NH4Al(OH)2C03 *H20, heating said NH4A1(0H)2C03 *H20 to about 200°C for a period of at least 2 hours to cause its decomposition to alumina; and washing the alumina with water at a temperature of at least 50°C to remove a substantial part of the sulfur, ammonia, and other residuals from the alumina.
EXAMPLES The invention will be further illustrated, without limitation, by the following Examples.
Example 1 • An ammonium aluminum hydroxycarbonate was prepared by adding 318 grams of Al2(S04)3*16H20 to 1 liter of solution containing 3M NH3 and 1.5 M (NH3)2C0 . The mixture was reacted for one hour at 70°C and filtered, then the precipitate was dried in a vacuum oven overnight at 150°C. A similar preparation was made by adding dissolved aluminum sulfate to the same ammonical solution.
About 160 grams of each of these precipitates were then decomposed in a muffle oven for about sixteen hours at 250°C. Both preparations showed a BET surface area of 840 m2/g.
Example 2 A large preparation was made by adding solid aluminum sulfate as in the previous example. In this case, 704 grams of hydroxycarbonate were decomposed at 250°C for eight hours. As in the previous example, the large mass of material resulted in a relatively slow heating rate. The BET surface area was 700 /g. Example 3 This example shows the adverse effect that rapid : heat-up has on surface area. A hydroxycarbonate prepared as in previous examples was decomposed at various tempera¬ tures for three hours. The important variable in this example was the rapid heating rate. Rapid heating resulted from placing only about 8 grams of hydroxycarbon- ' ate into a preheated oven. Table I shows that rapid decomposition even at low temperatures reduced the surface area significantly from the very high values seen previously.
TABLE I
2 Temperature, °C Specific Surface Area, m /g
200 259
300 312
400 265
500 315 6 60000 333
700 316
800 205
While the present invention has been described with reference to specific embodiments, this application is intended to cover those changes and substitutions which may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

Claims

HAT IS CLAIMED IS:
1. A process for producing an alumina that has a BET surface area of at least 300 m2/g, said process comprising:
(a) treating aluminum salt particles with an aqueous solution of ammonium hydroxide and ammonium carbonate at a pH of 9 to 12 to cause a reaction converting at least a substantial proportion of the aluminum salt to an ammonium aluminum hydroxycarbonate; and
(b) heatinq said ammonium aluminum hydroxycarbonate to between 150° and 400°C for a period of at least 2 hours to cause its decomposition to said alumina.
2. The process of Claim 1 wherein the surface area is at least 450 m-~/q .
3. The process of Claim 2 wherein the surface area is at least 800 m2/g.
4. The process of Claim 1 wherein the aluminum salt is selected from the group consisting of aluminum sulfate, aluminum chloride, and aluminum nitrate.
5. The process of Claim 4 wherein the aluminum salt is aluminum sulfate.
6. The process of Claim 5 wherein the alumina is washed with water at a temperature of at least 50°C to remove a substantial part of the sulfur, ammonia, and other residuals from the alumina.
7. The process of Claim 1 wherein the pH of the solution is between 10 and 11.
8. The process of Claim 1 wherein the ammonium aluminum hydroxycarbonate is NH4A1(0H) 2CO3Η2O.
9. The process of Claim 1 wherein the heating tern- ' perature is about 200°C.
10. A process for producing an alumina that has a BET surface area of at least 800 m2/g, said process comprising:
(a) treating aluminum sulfate particles with an aqueous solution of ammonium hydroxide and ammonium carbo¬ nate at a pH of 10 to 11 to cause a reaction converting at least a substantial proportion of the aluminum sulfate to NH4A1(0H)2C03 *H20;
(b) heating said NH4A1(0H) 2C03 *H20 to between 150° and 300°C for a period of at least 2 hours to cause its decomposition to said alumina; and
(c) washing said alumina with water at a temperature of at least 50°C to remove a substantial part of the sul¬ fur, ammonia, and other residuals from the alumina.
11. - The process of Claim 10 wherein the heating temperature is about 200°C.
EP19850904387 1985-08-27 1985-08-27 Process for producing a high surface area alumina. Withdrawn EP0235126A4 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1985/001649 WO1987001365A1 (en) 1985-08-27 1985-08-27 Process for producing a high surface area alumina

Publications (2)

Publication Number Publication Date
EP0235126A1 true EP0235126A1 (en) 1987-09-09
EP0235126A4 EP0235126A4 (en) 1988-05-10

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19850904387 Withdrawn EP0235126A4 (en) 1985-08-27 1985-08-27 Process for producing a high surface area alumina.

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EP (1) EP0235126A4 (en)
JP (1) JPS63500794A (en)
DE (1) DE3590012T1 (en)
NL (1) NL8520271A (en)
WO (1) WO1987001365A1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1048471C (en) * 1994-12-29 2000-01-19 重庆大学 Process for preparing aluminium hydroxide from coal gangue
US8007760B2 (en) * 2008-12-11 2011-08-30 Uop Llc Process for producing enhanced alumina
US7947250B2 (en) * 2008-12-11 2011-05-24 Uop Llc Process for conversion of aluminum oxide hydroxide
CN103332717A (en) * 2013-07-18 2013-10-02 北京世纪地和控股有限公司 Production method of high-activity aluminium oxide
RU2632437C1 (en) * 2016-10-21 2017-10-04 Федеральное государственное бюджетное учреждение науки Институт химии и технологии редких элементов и минерального сырья им. И.В. Тананаева Кольского научного центра Российской академии наук (ИХТРЭМС КНЦ РАН) Method of producng aluminium oxide
CN108970628B (en) * 2018-08-08 2023-08-29 北京众智创新科技开发有限公司 Preparation method of ebullated bed hydrotreating catalyst

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3557025A (en) * 1968-05-13 1971-01-19 Kaiser Aluminium Chem Corp Method of producing alkalized alumina and products produced thereby
JPS51140900A (en) * 1975-05-29 1976-12-04 Agency Of Ind Science & Technol Process for production of aluminum carbonate hydroxide:ammonium
GB2072636B (en) * 1980-03-28 1983-07-27 Nicholas Pty Ltd Preparation of dihydroxyaluminium sodium carbonate
US4356157A (en) * 1980-08-14 1982-10-26 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Synthesis of dawsonites
US4495087A (en) * 1982-12-27 1985-01-22 Ng Tai Wing Preparation of aluminum hydroxycarbonate gels by a continuous process

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
No relevant documents have been disclosed. *
See also references of WO8701365A1 *

Also Published As

Publication number Publication date
NL8520271A (en) 1987-06-01
WO1987001365A1 (en) 1987-03-12
EP0235126A4 (en) 1988-05-10
JPS63500794A (en) 1988-03-24
DE3590012T1 (en) 1987-07-16

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