CA1102777A - Low-metal content olefin hydration catalyst and related process - Google Patents
Low-metal content olefin hydration catalyst and related processInfo
- Publication number
- CA1102777A CA1102777A CA297,355A CA297355A CA1102777A CA 1102777 A CA1102777 A CA 1102777A CA 297355 A CA297355 A CA 297355A CA 1102777 A CA1102777 A CA 1102777A
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- CA
- Canada
- Prior art keywords
- catalyst
- support
- phosphoric acid
- acid
- hydration
- 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.)
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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
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/14—Phosphorus; Compounds thereof
- B01J27/16—Phosphorus; Compounds thereof containing oxygen, i.e. acids, anhydrides and their derivates with N, S, B or halogens without carriers or on carriers based on C, Si, Al or Zr; also salts of Si, Al and Zr
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/03—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by addition of hydroxy groups to unsaturated carbon-to-carbon bonds, e.g. with the aid of H2O2
- C07C29/04—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by addition of hydroxy groups to unsaturated carbon-to-carbon bonds, e.g. with the aid of H2O2 by hydration of carbon-to-carbon double bonds
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT
A process and catalyst for hydrating olefins to form alcohols whereby the olefins are contacted with water vapor in the presence of a hydration catalyst comprising a predominantly siliceous support material impregnated with phosphoric acid. The aluminum and iron content of the supported catalyst is restricted to n collective concentration less than about 2.25%, by weight, of the phosphoric acid-free support.
A process and catalyst for hydrating olefins to form alcohols whereby the olefins are contacted with water vapor in the presence of a hydration catalyst comprising a predominantly siliceous support material impregnated with phosphoric acid. The aluminum and iron content of the supported catalyst is restricted to n collective concentration less than about 2.25%, by weight, of the phosphoric acid-free support.
Description
11,035 1 ~ 2~77 BACKGROUND OF THE INVENTION
This invention relates to an improved process for hydrating olefins to form alcohols, and a catalyst composition useful for such process. More particularly, this invention relates to an olefin hydration process utilizing a phosphoric acid catalyst capable of long-term operation at a relatively high-level of catalytic activ-ity.
Processes for reactmg olefins with water vapor at elevated pressures to form alcohols in the presence of suitable catalysts are ~ell-known in the art. The pre-ferred catalysts for the reaction generally c~mprise phosphoric acid impregnated upon a predominantly silic-eous carrier or support material. Typical of such support materials are the various forms of calcined diatomaceous earth which essentially consist of diatoms of silicon dioxide in intimate admixture with clay or clay-like materials which serve as bonding agents for the silica. U.S. Patent Nos. 2,960,477 and 3,704,329, for example, are descriptive of such olefin hydration processes.
Although phosphoric acid catalysts of the type described above have gained general commercial acceptance, they, nevertheless, have certain disadvantages relating, primarily, to their relatively short opera~ing life.
This is due, in part, to the tendency of phosphoric acid to "drool" during normal operation, namely, the aqueous phosphoric acid tends to seep from the catalyst support 11,03 l~ Z7~7 and flow slowly through the catalyst bed. This adversely affects the physical integrity of the support to the extent that i~ begins to disintegrate and cake together in a relatively short period of time during operation.
This has the effect of plugging up the bed of catalyst support thereby increasing the pressure drop of the gases flowing therethrough, decreasing the ef~ective contact (or surface) area of the catalyst, and, in general, reducing catalyst efficiency.
U.S. Patent No. 2,496,621, discloses a catalyst preparation procedure wherein the catalyst support material is calcined at a temperature in the range of 800-1400C. prior to ~mpregnation with the phosphoric acid catalyst. This results in an independently strong catalyst support capable of maintaining its physical integrity for a relatively long period of time. Un-fortunately, the catalyst is not sufficiently active to provide the level of olefin csnversion required fox a commercial hydration process.
Canadian Patent No. 1076095 describes an olefin hydration process and catalyst wherein the cata-lyst support is prepared from a mixture comprising from about 50-70 (wt.) % diatomaceous earth, a~out 15-25 (wt.) % bentonite and from about 5-35 (wt.) % of a combustible -organic filler material, such mixture being calcined at a temperature of from about 1200 to 1500F prior to im-pregnation with phosphoric acid thereby forming a catalyst ~19035
This invention relates to an improved process for hydrating olefins to form alcohols, and a catalyst composition useful for such process. More particularly, this invention relates to an olefin hydration process utilizing a phosphoric acid catalyst capable of long-term operation at a relatively high-level of catalytic activ-ity.
Processes for reactmg olefins with water vapor at elevated pressures to form alcohols in the presence of suitable catalysts are ~ell-known in the art. The pre-ferred catalysts for the reaction generally c~mprise phosphoric acid impregnated upon a predominantly silic-eous carrier or support material. Typical of such support materials are the various forms of calcined diatomaceous earth which essentially consist of diatoms of silicon dioxide in intimate admixture with clay or clay-like materials which serve as bonding agents for the silica. U.S. Patent Nos. 2,960,477 and 3,704,329, for example, are descriptive of such olefin hydration processes.
Although phosphoric acid catalysts of the type described above have gained general commercial acceptance, they, nevertheless, have certain disadvantages relating, primarily, to their relatively short opera~ing life.
This is due, in part, to the tendency of phosphoric acid to "drool" during normal operation, namely, the aqueous phosphoric acid tends to seep from the catalyst support 11,03 l~ Z7~7 and flow slowly through the catalyst bed. This adversely affects the physical integrity of the support to the extent that i~ begins to disintegrate and cake together in a relatively short period of time during operation.
This has the effect of plugging up the bed of catalyst support thereby increasing the pressure drop of the gases flowing therethrough, decreasing the ef~ective contact (or surface) area of the catalyst, and, in general, reducing catalyst efficiency.
U.S. Patent No. 2,496,621, discloses a catalyst preparation procedure wherein the catalyst support material is calcined at a temperature in the range of 800-1400C. prior to ~mpregnation with the phosphoric acid catalyst. This results in an independently strong catalyst support capable of maintaining its physical integrity for a relatively long period of time. Un-fortunately, the catalyst is not sufficiently active to provide the level of olefin csnversion required fox a commercial hydration process.
Canadian Patent No. 1076095 describes an olefin hydration process and catalyst wherein the cata-lyst support is prepared from a mixture comprising from about 50-70 (wt.) % diatomaceous earth, a~out 15-25 (wt.) % bentonite and from about 5-35 (wt.) % of a combustible -organic filler material, such mixture being calcined at a temperature of from about 1200 to 1500F prior to im-pregnation with phosphoric acid thereby forming a catalyst ~19035
2~7~
support capable of maintaining its physical integrity over a long period of time under normal process operating conditions. The calcined support is thenimpregna~ed with phosphoric acid to form ~he suppor~ed hydration catalyst.
Canadian Patent No. 1076095 is also directed to a process and catalyst wherein the activity and operating life of the hydration catalyst is enhanced by using a catalyst support having a surface area greater than about 12 square meters per gram.
The level of impurities in catalyst supports, spec~fically, the concentration of iron and aluminum, has heretofore gone unrecognized as an important operating variable affec~ing the activity and operating life of an olefin hydration catalyst. U.S. Patent No. 2,960,477 to Smith et al discloces an olefin hydration catalyst comprising a catalyst support impregnated with phosphoric acid, the support consisting of an admixture of diatom-aceous earth and clay. The patentees note the fact that ` the presence of iron in the catalyst may promote olefin cracking. Thus, iron i8 recognized in the art as an un-des~rable element insofar as it promotes a side reaction to the principal olefin hydration process. However, in the absence of any guch side reaction, the presence of iron would appear to have no adverse effect on the activ-ity and oper~ting life of æn olefin hydration catalyst.
, ' 11~035 ~g 27~
U.S. Patent No. 3,704,329 to Rindtorff et al attempts to solve the characteristic problem of conven-tional ealcined diatomaceous earth carriers impregnated with phosphoric acid, namely, the dissolution of aluminum oxide from the carrier. The patent is directed to the use of a bentonite carrier material, normally used for hydrogenation and dehydrogenation reactions, which is pre-treated wlth acid to reduce the aluminum oxide content of the material to about 10 percent or less and thereby render it suitable for catalytic hydration o olefins.
The starting bentonite material preferably contains an ; aluminum oxide content as high as possible, (e.g., above 16 percent), the purpose of acid pre-treatment being prim-arily to increase the surface area and pore volume of the carrier material and, at the same time, improve its resistance to eros~on by min~m~zing the dissolution of al~minum oxide from the carrier during normal process operation.
SUMMARY OF THE INVENTION
The present invention provides an improvement of the olefin hydration process and catalyst described in the aforementioned Canadian Patent No. 1076095.
The olefins are contacted with water vapor in the presence of a supported hydration catalyst which is pre-pared by forming a mixture of from about 50-70 (wt.) %
diatomaceous earth, from about 15-25 (wt.) % bentonite, and from about 5-35 ~wt.) % of a combustible organic filler material, and then calcining the resulting . ' ~ 3 ~3~
~1~27~
mixture at a temperature of from about 1200F to 1500F. Fo~lowing calcination and prior to im-pregnation of the catalyst support with phosphoric acid, the aluminum and iron content of the calcined catalyst support is reduced to a value below about 2,25~/o~ by weight, of the catalyst support. More precisely, the collective concentration of aluminum and iron in the finished catalyst (i.e., following impregnation with phosphoric acid) is maintained below about 2.25%, by weight, based on the acid-free catalyst support. The allowable concentration of aluminum and iron in the supported catalyst is t~erefore independent of the phos-phoric acid "loading" of the finished catalyst, i.e., the weight fraction of H3P04 in the impregnated catalyst.
The present invention is predicated on the discovery that the activity and operating life of the olefin hydration catalysts described in Canadian Patent No. 1076095 are materially enhanced by ~-restricting the aluminum and iron content of the supported hydration catalyst to below the above-described upper limit. Removal of aluminum and iron impur-~ties ~in the form of oxides) from the support material is preferably carried out by contacting the support with a mineral acid, such as phosphoric, hydrochloric or sulphuric, at reaction conditions capable of reducing ; the concentration of the oxide impurities in the supportmaterial to the desired level. Thus, for example, a ~ B
11, 035 typical catalyst support containing about 1.5% iron and
support capable of maintaining its physical integrity over a long period of time under normal process operating conditions. The calcined support is thenimpregna~ed with phosphoric acid to form ~he suppor~ed hydration catalyst.
Canadian Patent No. 1076095 is also directed to a process and catalyst wherein the activity and operating life of the hydration catalyst is enhanced by using a catalyst support having a surface area greater than about 12 square meters per gram.
The level of impurities in catalyst supports, spec~fically, the concentration of iron and aluminum, has heretofore gone unrecognized as an important operating variable affec~ing the activity and operating life of an olefin hydration catalyst. U.S. Patent No. 2,960,477 to Smith et al discloces an olefin hydration catalyst comprising a catalyst support impregnated with phosphoric acid, the support consisting of an admixture of diatom-aceous earth and clay. The patentees note the fact that ` the presence of iron in the catalyst may promote olefin cracking. Thus, iron i8 recognized in the art as an un-des~rable element insofar as it promotes a side reaction to the principal olefin hydration process. However, in the absence of any guch side reaction, the presence of iron would appear to have no adverse effect on the activ-ity and oper~ting life of æn olefin hydration catalyst.
, ' 11~035 ~g 27~
U.S. Patent No. 3,704,329 to Rindtorff et al attempts to solve the characteristic problem of conven-tional ealcined diatomaceous earth carriers impregnated with phosphoric acid, namely, the dissolution of aluminum oxide from the carrier. The patent is directed to the use of a bentonite carrier material, normally used for hydrogenation and dehydrogenation reactions, which is pre-treated wlth acid to reduce the aluminum oxide content of the material to about 10 percent or less and thereby render it suitable for catalytic hydration o olefins.
The starting bentonite material preferably contains an ; aluminum oxide content as high as possible, (e.g., above 16 percent), the purpose of acid pre-treatment being prim-arily to increase the surface area and pore volume of the carrier material and, at the same time, improve its resistance to eros~on by min~m~zing the dissolution of al~minum oxide from the carrier during normal process operation.
SUMMARY OF THE INVENTION
The present invention provides an improvement of the olefin hydration process and catalyst described in the aforementioned Canadian Patent No. 1076095.
The olefins are contacted with water vapor in the presence of a supported hydration catalyst which is pre-pared by forming a mixture of from about 50-70 (wt.) %
diatomaceous earth, from about 15-25 (wt.) % bentonite, and from about 5-35 ~wt.) % of a combustible organic filler material, and then calcining the resulting . ' ~ 3 ~3~
~1~27~
mixture at a temperature of from about 1200F to 1500F. Fo~lowing calcination and prior to im-pregnation of the catalyst support with phosphoric acid, the aluminum and iron content of the calcined catalyst support is reduced to a value below about 2,25~/o~ by weight, of the catalyst support. More precisely, the collective concentration of aluminum and iron in the finished catalyst (i.e., following impregnation with phosphoric acid) is maintained below about 2.25%, by weight, based on the acid-free catalyst support. The allowable concentration of aluminum and iron in the supported catalyst is t~erefore independent of the phos-phoric acid "loading" of the finished catalyst, i.e., the weight fraction of H3P04 in the impregnated catalyst.
The present invention is predicated on the discovery that the activity and operating life of the olefin hydration catalysts described in Canadian Patent No. 1076095 are materially enhanced by ~-restricting the aluminum and iron content of the supported hydration catalyst to below the above-described upper limit. Removal of aluminum and iron impur-~ties ~in the form of oxides) from the support material is preferably carried out by contacting the support with a mineral acid, such as phosphoric, hydrochloric or sulphuric, at reaction conditions capable of reducing ; the concentration of the oxide impurities in the supportmaterial to the desired level. Thus, for example, a ~ B
11, 035 typical catalyst support containing about 1.5% iron and
3.8% aluminum may be effectively treated with 85 (wt.) %
H3P0~ at a temperature of from about 150C to 200C in a sealed pressure vessel for a period of time of from about 8 to 15 hours to reduce the concentration of Al plus Fe in the support to about 2%, by weight.
The removal of aluminum and iron from the catalyst support to the low levels desired in accordance with the invention cannot, in general, be accompl~shed with sintered support materials. That is, the oxides of aluminum and iron are not readily leached out of a sintered catalyst support even aiter relatively long periods of acid treabment at elevated temperatures.
Hence, as a practical matter, the present invention is res~ricted to non-sintered catalyst supports. It shoul~
be noted, however, that the surface area of the catalyst support is of no moment for purposes of the present inven-tion and need not necessarily be above 12 meters2/gram, the surface area defined by Canadian Patent No.
1076095. Although sintering of the support is avoided by regulating calcination conditions in the furn-ace so as to produce a surface area above 12 meters2lgramr supports having surface areas below such value are ; not necessarily sintered and may be simply "under-calcinedl', i.e., partially calcined support materials containing unoxidized filler material The removal of aluminum and iron impurities from such support materials is within the scope of the present invention ~ , ~ 77 11,035 DETAILED DESCRIP ION OF THE INVENTION
The composition of the catalyst support employed in preparing the olefin hydration catalysts of the inven-tion is from about 50-70 percent by weight, diatomaceous earth, from about 15-25 percent by weight, bentonite and from about 5-35 percent by weight, of a combustible organic filler material, the above percentages referring to the composition of the support prior to the calcina-tion step. A preferred composition in terms of providing an optimum balance of catalytic activity and mechanical strength is about 62 (wt.) % diatomaceous earth, about 21 (wt.) % bentonite and about 18 (wt.) % filler material.
During calcination, the organic filler material is burned out to provide a structure having sufficient porosity to ensure an even coating of phosphoric acid throughout the support during impregnation and to allow the reacting gases to readily contact the internal active sites of the support during operation. In general, the greater the percentage of filler material in the support-forming mixture, the greater the surface area of the calcined support. It is generally desirable to have as high a surface area as possible provided the mechanical integrity of the supported catalyst and the ultim~te catalyst life are not adversely affected.
11. 9 03~
~L:I~Z777 The combustible organic filler is preferably cornmeal, but powdered combustible materials such as wood, flour, starch, carbon black, and the like may also be used.
To attain the desired porosity, the size of the filler materials admixed with the particles of diatomaceous earth and bentonite should be within the range of about 500 to 2000 microns, and preferably about 1000 microns.
Diatomaceous earth, the main component of the catalyst support, is a naturally occurring fonm of silicon dioxide which serves to provide active sites for the form-ation of the reactive acid film. ~n especially desirable form of tiatomaceous earth is man~factured by Johns-Manville Corporation and is designated as "Celite ~ FC" posRessing R .
surface area of 20-30 meters2/gram. This material has the following average composition:
ComponentWeight Percent SiO2 86.7 Fe2O3 1.2 CaO 0.5 H2O, trace metal 8.3 oxides Bentonite, having a preferred particle size distribution such that about 90% of the particles are below a size of about 74 microns, is admixed with the diatomaceous earth to provide mechanical stren~th to the catalyst ~upport. ~entonite is a hydrated silicate having the following average composition:
~ .
~ ~ 2~7q~ 11,035 ComponentWeight P rcent SiO2 49.0 A123 20.4 Fe2O3 4.1 CaO 1.8 H2O, trace metal 24.7 -oxides To prepare the catalyst support, diatomaceous earth, bentonite and cornmeal, in the proportions recited above, are admixed with water to form a paste which is dried and then calcined to burn out the organic filler and form a hardened support material, typically in the form of a pellet about 1/8 to 1/4 inch in diameter. The purpose of the drying step is to substantially reduce tke moisture content of the pellet prior to calcination.
This is conveniently accomplished by conveying the pellets over a belt-dryer at a temperature in the range of about 150-340~F. for a period of about 30 minutes. Calcination may be effected at a temperature within the range of about 1200F to about 1500F depending somewhat upon the ~mount of filler in the support; the lower the percentage of filler material, the lower the desired temperature within the stated range. For a support containing about 17 (wt.) -i % or~anic iller, the preferred calcination temperature is about 1350F. The time required for calcination in, for exsmple, a rotary kiln wherein uniform heating is provided may vary from about 10-30 minutes depending upon the temperature employed.
11,035 ~l~Z`777 Following calcination and prior to catalyst impregnation, the support material is treated with an acid solution to remove aluminum oxide and iron oxide impurities to the low levels desired in accordance with the invention. The acid treatment is conveniently effected with any strong mineral acid; hydrochloric acid (1:1, about lg.5 wt. %) or phosphoric acid (85%, by weight) being preferred for this purpose. The catalyst support pellets are preferably refluxed with the acid for a period of from about 10-20 hours, or alternatively, contacted with an acid, such as, 85%
phosphoric acid, at a temperature of from about 150-200C
in a sealed pressure vessel for a period of from about 8-15 hours. Following such acid treatment, the support pellets are washed with water at 90~C for a period of about 2 hours until the support material is free of acid.
Impregnation of the calcined support material is carried out in an aqueous solution of phosphoric acid containing from about 40 to 80 percent, by weight, of phosphoric acid. The impregnation can be effected in any ; manner which will result in substantial saturation of the support material with the acid catalyst. Typically, the sup~ort material is soaked in an acid solution maintained at a temperature of about 30C for a period of time of from about 1/2 hour to 8 hours. Generally, a period of about 2 hours will suffice. The saturated support mater-ial is then freed of excess acid and dried at a tempera-ture below 280C to prevent sintering of the support material. Dryint is conveniently carried out at a .
~ .
l~$Z777 11,035 temperature of about 180~. The resulting impregnated catalyst contains from about 30 to 60 percent, by weight, - orthophosphoric acid based on the weight of the composite structure, i.e., support material plus acid catalyst.
Lower olefins, such as, ethylene, propylene and the butenes, may be directly hydrated to the corresponding alcohols by reacting the olefin starting material with water vapor in the presence of a catalyst in accordance with the invention at a temperature within the range of about 175 to 300C., a water vapor to olefin mole ratio of about 0.3 to 1.0, and an operating pressure of about 350 to 12Q0 psig. Preferred operating conditions for the conversion of, for example, ethylene to ethanol are a temperature of about 270C., a water vapor to olefin mole ratio of about 0.6, and a reaction pressure of about 1000 psig. Lower temperatures and higher pressures favor high equilibrium yields. However, if temperatures are - too low, reaction rates decrease, while unduly high pressures result in relatively large amounts of polymeric material in the reaction products. Higher water vapor to olefin mole ratios result in improved conversion, but at the expense of increased energy requirements for vapor-ization.
The caicined catalyst supports prepared in accord-ance with the following examples were found to contain 11,035 1~7 . . , iron and aluminum (prior to acid leaching) in the follow-ing range of concentrations: 1.5 + .25 (wt.) % Fe, and 3.8 ~ .25 (wt.) % Al.
62 parts by weight of "Celite FC" diatomaceous earth, 21 parts by weigh~ of bentonite (90% of the particles being below a size of about 74 microns) and 17 parts by weight of cornmeal (1000 microns), were admixed with water to form pellets, 5/32" in diameter.
The pellets were dried at a temperature of 350F for 30 minutes in a 3-stage belt-dryer to remove moisture and then calcined in air for 40 minutes at 1350F. The surface area of the support as determined by a one-point BET nitrogen adsorption method was 13.5 m2/gm. Following calcination, the support was leached by treating the -pellets with 20~/o hydrochloric acid at 200F for 12 hours to remave metallic impurities, then washed with water at 90C for 2 hours. The leached support pellets were then dried at 350F for 1 hour and impregnated with 65 wt. %
phosphoric acid at 70F for 8 hours. The excess acid was allowed to drain off and the catalyst pellets were dried under lnert conditions at 350F for 32 hours. The metal content of the finished catalyst as determined by atomic absorption (expressed as a percentage of the acld-free catalyst support) was as follows: 0.51 wt. %
iron and 2.16 wt. % aluminum (=2.67% total o iron plus aluminum).
, ~ 13 ~ -11,035 7q7 A gaseous mixture of ethylene and steam in a molar ratio of 1.8:1 was passed through this supported catalyst at the rate of 2000 SCFH per cuft of catalyst.
The reactor pressure was 1000 psig and the temperature of the catalyst bed was maintained at 270C. After 100 hours of operation, ethanol production was 9.1 lbs.
per hour per ft3 of catalyst. At the end of 900 hours, ethanol production declined to a value of 7.6.
Examples 2 and 3 demonstrate the improved activity and catalytic life obtained when the concen-tration of iron and aluminum in t~e supPort is reduced to less than about 2.25 (wt.) %.
Support pellets from the same batch used in Example 1 were subjected to a two-step acid leaching operation. This comprised an initial treatment of the support pellets with 20% HCl for 27 hours at 200F, followed by refluxing with 20% HCl for 6 hours. This was followed by the washing and drying steps described in Example 1. Impregnation was then effected with 70%
phosphoric acid at 75F for 8 hours. The excess acid was then drained and the pellets dried at 900F for 2 hours. The metal content of the catalyst on an acid-free basis, as determined by atomic absorption,was as follows:
0.2~ (wt.) % Fe and 1.29 (wt.) % Al (a total of 1.55 (wt.) %
; of iron plus aluminum).
11,035 77~7 Steam and ethylene were passed through a bed of the above-described catalyst under process conditions described in Example 1. The initial ethanol production of 9.1 lbs. per hour per cuft. of catalyst was unchanged after 900 hours of operation.
Catalyst support pellets having the same com-position disclosed in Example 1, were dried in a tunnel dryer for 48 hours at a temperature of from about 350-400F. Calcination at 1350F for 30 minutes pro-vided a sample with a surface area of 14.9 m2/gm. The support pellets were thereafter leached by refluxing with 20% HCl for 10 hours to remove metallic impurities.
The leached support was then washed and dried as in Example 2. The pellets were thereafter impregnated with 70% phosphoric acid at 75F and then dried at 320F for 16 hours. The metal content of the catalyst on an acid-free basis, as determined by atomic absorption,was as follows:
0.27 (wt.) % Fe and 1.75 (wt.) % Al (a total of 2.02 (wt.) % iron plus aluminum).
Steam and ethylene were passed through a bed of this catalyst under process conditions described in E~ample 1. The initial productivity (at the end of 100 hours) was 9.4 lbs. of ethanol per hour per ft.3 of catalyst. At the end of 900 hours of operation the ethanol production was essentially unchanged at 9.2.
-11,035 ~1();~7~77 This example demonstrates an alternate acidleaching procedure for effectively removing metals from the support.
Catalyst support pellets having the same com-position described in Example 1, were dried at 350F
for 40 minutes with a belt-dryer and calcined in air at 1250F for 40 minutes. The surface area of the support was 13.2 m2/gm. Following calcination, the support was leached with 85% phosphoric acid for 10 hours at 160C in a sealed pressure vessel, then washed with water at 90C for 2 hours. The leached support was then dried at 140C for 18 hours and impregnated with 62%
phosphoric acid at room temperature for 8 hours. The excess acid was allowed to drain off and the catalyst pellets were dried under inert conditions at 110C for 18 hours. The metal content of this catalyst on an acid-free basis was found to be the following: 0.09 (wt.)%
iron and 0.57 (wt.) % aluminum (- 0.66 (wt.) % total iron plus aluminum).
Ethylene hydration was carried out in accord-ance with the procedure described in Example 1. The catalyst activity was constant over gO0 hours of operation resulting in a constant ethanol production of 9.0 lbs. per hour per ft.3 of catalyst.
11,035 This example demonstrates the adverse effect of sintering the catalyst support with regard to the removal of metals from said support by acid treatment, and the effect of the resulting high metal content on catalyst life.
Catalyst support pellets of similar size and composition to those described in Exampie 1 were dried in accordance with the procedure disclosed in that Example, but were calcined at a temperature of about 1400F for 40 minutes. The measured BET surface area of the support was a relatively low 8.2 m2/gm. Acid leaching, impregna-tion and final drying were then carried out as described in Example 4. Although the leaching process was identical to that described in Example 4, the resulting catalyst had a high residual metal content. The metal content of the catalyst (on an acid-free basis) as measured by atomic absorption was as follows: 0.42 (wt.) % iron and 2.1 (wt.) % aluminum (- 2.52 (wt.) % total iron plus alumi.num).
Steam and ethylene were passed through a bed of the above-described catalyst as described in Example 1.
After 900 hours of operation, ethanol production declined from an initial value of 9.1 lbs. per hour per ft.3 of catalyst to about 7Ø
This example demonstrates that metal removal may be accomplished in accordance with the invention from low surface area support materials provided they are not overcalcined ox sintered.
11,035 11~*777 Catalyst support pellets of similar size and composition to those described in Example 1, were dried in accordance with the procedure of that Example. The pellets were calcined at 1350F for 32 minutes3 20% less time than that employed in Example 1. This resulted in black specks of unburned cornmeal remaining in the pellets due to incomplete combustion. The surface area of the support was a relatively low 9.3 m2/gm. Leaching, drying, impregnation and final drying were carriecl out as in Example 4. The metal content of the catalyst on an acid-free basis, as measured by atomic absorption,was as follows: 0.27 (wt.) % Fe and 1.22 (wt.) /0 Al (a total of 1.49 (wt.) /O iron plus aluminum).
Ethylene hydration was carried out under the process conditions described in Example 1. The ethanol production rate remained invariant over 900 hours of operation at 8.7 lbs. per hour per ft.3 of catalyst.
H3P0~ at a temperature of from about 150C to 200C in a sealed pressure vessel for a period of time of from about 8 to 15 hours to reduce the concentration of Al plus Fe in the support to about 2%, by weight.
The removal of aluminum and iron from the catalyst support to the low levels desired in accordance with the invention cannot, in general, be accompl~shed with sintered support materials. That is, the oxides of aluminum and iron are not readily leached out of a sintered catalyst support even aiter relatively long periods of acid treabment at elevated temperatures.
Hence, as a practical matter, the present invention is res~ricted to non-sintered catalyst supports. It shoul~
be noted, however, that the surface area of the catalyst support is of no moment for purposes of the present inven-tion and need not necessarily be above 12 meters2/gram, the surface area defined by Canadian Patent No.
1076095. Although sintering of the support is avoided by regulating calcination conditions in the furn-ace so as to produce a surface area above 12 meters2lgramr supports having surface areas below such value are ; not necessarily sintered and may be simply "under-calcinedl', i.e., partially calcined support materials containing unoxidized filler material The removal of aluminum and iron impurities from such support materials is within the scope of the present invention ~ , ~ 77 11,035 DETAILED DESCRIP ION OF THE INVENTION
The composition of the catalyst support employed in preparing the olefin hydration catalysts of the inven-tion is from about 50-70 percent by weight, diatomaceous earth, from about 15-25 percent by weight, bentonite and from about 5-35 percent by weight, of a combustible organic filler material, the above percentages referring to the composition of the support prior to the calcina-tion step. A preferred composition in terms of providing an optimum balance of catalytic activity and mechanical strength is about 62 (wt.) % diatomaceous earth, about 21 (wt.) % bentonite and about 18 (wt.) % filler material.
During calcination, the organic filler material is burned out to provide a structure having sufficient porosity to ensure an even coating of phosphoric acid throughout the support during impregnation and to allow the reacting gases to readily contact the internal active sites of the support during operation. In general, the greater the percentage of filler material in the support-forming mixture, the greater the surface area of the calcined support. It is generally desirable to have as high a surface area as possible provided the mechanical integrity of the supported catalyst and the ultim~te catalyst life are not adversely affected.
11. 9 03~
~L:I~Z777 The combustible organic filler is preferably cornmeal, but powdered combustible materials such as wood, flour, starch, carbon black, and the like may also be used.
To attain the desired porosity, the size of the filler materials admixed with the particles of diatomaceous earth and bentonite should be within the range of about 500 to 2000 microns, and preferably about 1000 microns.
Diatomaceous earth, the main component of the catalyst support, is a naturally occurring fonm of silicon dioxide which serves to provide active sites for the form-ation of the reactive acid film. ~n especially desirable form of tiatomaceous earth is man~factured by Johns-Manville Corporation and is designated as "Celite ~ FC" posRessing R .
surface area of 20-30 meters2/gram. This material has the following average composition:
ComponentWeight Percent SiO2 86.7 Fe2O3 1.2 CaO 0.5 H2O, trace metal 8.3 oxides Bentonite, having a preferred particle size distribution such that about 90% of the particles are below a size of about 74 microns, is admixed with the diatomaceous earth to provide mechanical stren~th to the catalyst ~upport. ~entonite is a hydrated silicate having the following average composition:
~ .
~ ~ 2~7q~ 11,035 ComponentWeight P rcent SiO2 49.0 A123 20.4 Fe2O3 4.1 CaO 1.8 H2O, trace metal 24.7 -oxides To prepare the catalyst support, diatomaceous earth, bentonite and cornmeal, in the proportions recited above, are admixed with water to form a paste which is dried and then calcined to burn out the organic filler and form a hardened support material, typically in the form of a pellet about 1/8 to 1/4 inch in diameter. The purpose of the drying step is to substantially reduce tke moisture content of the pellet prior to calcination.
This is conveniently accomplished by conveying the pellets over a belt-dryer at a temperature in the range of about 150-340~F. for a period of about 30 minutes. Calcination may be effected at a temperature within the range of about 1200F to about 1500F depending somewhat upon the ~mount of filler in the support; the lower the percentage of filler material, the lower the desired temperature within the stated range. For a support containing about 17 (wt.) -i % or~anic iller, the preferred calcination temperature is about 1350F. The time required for calcination in, for exsmple, a rotary kiln wherein uniform heating is provided may vary from about 10-30 minutes depending upon the temperature employed.
11,035 ~l~Z`777 Following calcination and prior to catalyst impregnation, the support material is treated with an acid solution to remove aluminum oxide and iron oxide impurities to the low levels desired in accordance with the invention. The acid treatment is conveniently effected with any strong mineral acid; hydrochloric acid (1:1, about lg.5 wt. %) or phosphoric acid (85%, by weight) being preferred for this purpose. The catalyst support pellets are preferably refluxed with the acid for a period of from about 10-20 hours, or alternatively, contacted with an acid, such as, 85%
phosphoric acid, at a temperature of from about 150-200C
in a sealed pressure vessel for a period of from about 8-15 hours. Following such acid treatment, the support pellets are washed with water at 90~C for a period of about 2 hours until the support material is free of acid.
Impregnation of the calcined support material is carried out in an aqueous solution of phosphoric acid containing from about 40 to 80 percent, by weight, of phosphoric acid. The impregnation can be effected in any ; manner which will result in substantial saturation of the support material with the acid catalyst. Typically, the sup~ort material is soaked in an acid solution maintained at a temperature of about 30C for a period of time of from about 1/2 hour to 8 hours. Generally, a period of about 2 hours will suffice. The saturated support mater-ial is then freed of excess acid and dried at a tempera-ture below 280C to prevent sintering of the support material. Dryint is conveniently carried out at a .
~ .
l~$Z777 11,035 temperature of about 180~. The resulting impregnated catalyst contains from about 30 to 60 percent, by weight, - orthophosphoric acid based on the weight of the composite structure, i.e., support material plus acid catalyst.
Lower olefins, such as, ethylene, propylene and the butenes, may be directly hydrated to the corresponding alcohols by reacting the olefin starting material with water vapor in the presence of a catalyst in accordance with the invention at a temperature within the range of about 175 to 300C., a water vapor to olefin mole ratio of about 0.3 to 1.0, and an operating pressure of about 350 to 12Q0 psig. Preferred operating conditions for the conversion of, for example, ethylene to ethanol are a temperature of about 270C., a water vapor to olefin mole ratio of about 0.6, and a reaction pressure of about 1000 psig. Lower temperatures and higher pressures favor high equilibrium yields. However, if temperatures are - too low, reaction rates decrease, while unduly high pressures result in relatively large amounts of polymeric material in the reaction products. Higher water vapor to olefin mole ratios result in improved conversion, but at the expense of increased energy requirements for vapor-ization.
The caicined catalyst supports prepared in accord-ance with the following examples were found to contain 11,035 1~7 . . , iron and aluminum (prior to acid leaching) in the follow-ing range of concentrations: 1.5 + .25 (wt.) % Fe, and 3.8 ~ .25 (wt.) % Al.
62 parts by weight of "Celite FC" diatomaceous earth, 21 parts by weigh~ of bentonite (90% of the particles being below a size of about 74 microns) and 17 parts by weight of cornmeal (1000 microns), were admixed with water to form pellets, 5/32" in diameter.
The pellets were dried at a temperature of 350F for 30 minutes in a 3-stage belt-dryer to remove moisture and then calcined in air for 40 minutes at 1350F. The surface area of the support as determined by a one-point BET nitrogen adsorption method was 13.5 m2/gm. Following calcination, the support was leached by treating the -pellets with 20~/o hydrochloric acid at 200F for 12 hours to remave metallic impurities, then washed with water at 90C for 2 hours. The leached support pellets were then dried at 350F for 1 hour and impregnated with 65 wt. %
phosphoric acid at 70F for 8 hours. The excess acid was allowed to drain off and the catalyst pellets were dried under lnert conditions at 350F for 32 hours. The metal content of the finished catalyst as determined by atomic absorption (expressed as a percentage of the acld-free catalyst support) was as follows: 0.51 wt. %
iron and 2.16 wt. % aluminum (=2.67% total o iron plus aluminum).
, ~ 13 ~ -11,035 7q7 A gaseous mixture of ethylene and steam in a molar ratio of 1.8:1 was passed through this supported catalyst at the rate of 2000 SCFH per cuft of catalyst.
The reactor pressure was 1000 psig and the temperature of the catalyst bed was maintained at 270C. After 100 hours of operation, ethanol production was 9.1 lbs.
per hour per ft3 of catalyst. At the end of 900 hours, ethanol production declined to a value of 7.6.
Examples 2 and 3 demonstrate the improved activity and catalytic life obtained when the concen-tration of iron and aluminum in t~e supPort is reduced to less than about 2.25 (wt.) %.
Support pellets from the same batch used in Example 1 were subjected to a two-step acid leaching operation. This comprised an initial treatment of the support pellets with 20% HCl for 27 hours at 200F, followed by refluxing with 20% HCl for 6 hours. This was followed by the washing and drying steps described in Example 1. Impregnation was then effected with 70%
phosphoric acid at 75F for 8 hours. The excess acid was then drained and the pellets dried at 900F for 2 hours. The metal content of the catalyst on an acid-free basis, as determined by atomic absorption,was as follows:
0.2~ (wt.) % Fe and 1.29 (wt.) % Al (a total of 1.55 (wt.) %
; of iron plus aluminum).
11,035 77~7 Steam and ethylene were passed through a bed of the above-described catalyst under process conditions described in Example 1. The initial ethanol production of 9.1 lbs. per hour per cuft. of catalyst was unchanged after 900 hours of operation.
Catalyst support pellets having the same com-position disclosed in Example 1, were dried in a tunnel dryer for 48 hours at a temperature of from about 350-400F. Calcination at 1350F for 30 minutes pro-vided a sample with a surface area of 14.9 m2/gm. The support pellets were thereafter leached by refluxing with 20% HCl for 10 hours to remove metallic impurities.
The leached support was then washed and dried as in Example 2. The pellets were thereafter impregnated with 70% phosphoric acid at 75F and then dried at 320F for 16 hours. The metal content of the catalyst on an acid-free basis, as determined by atomic absorption,was as follows:
0.27 (wt.) % Fe and 1.75 (wt.) % Al (a total of 2.02 (wt.) % iron plus aluminum).
Steam and ethylene were passed through a bed of this catalyst under process conditions described in E~ample 1. The initial productivity (at the end of 100 hours) was 9.4 lbs. of ethanol per hour per ft.3 of catalyst. At the end of 900 hours of operation the ethanol production was essentially unchanged at 9.2.
-11,035 ~1();~7~77 This example demonstrates an alternate acidleaching procedure for effectively removing metals from the support.
Catalyst support pellets having the same com-position described in Example 1, were dried at 350F
for 40 minutes with a belt-dryer and calcined in air at 1250F for 40 minutes. The surface area of the support was 13.2 m2/gm. Following calcination, the support was leached with 85% phosphoric acid for 10 hours at 160C in a sealed pressure vessel, then washed with water at 90C for 2 hours. The leached support was then dried at 140C for 18 hours and impregnated with 62%
phosphoric acid at room temperature for 8 hours. The excess acid was allowed to drain off and the catalyst pellets were dried under inert conditions at 110C for 18 hours. The metal content of this catalyst on an acid-free basis was found to be the following: 0.09 (wt.)%
iron and 0.57 (wt.) % aluminum (- 0.66 (wt.) % total iron plus aluminum).
Ethylene hydration was carried out in accord-ance with the procedure described in Example 1. The catalyst activity was constant over gO0 hours of operation resulting in a constant ethanol production of 9.0 lbs. per hour per ft.3 of catalyst.
11,035 This example demonstrates the adverse effect of sintering the catalyst support with regard to the removal of metals from said support by acid treatment, and the effect of the resulting high metal content on catalyst life.
Catalyst support pellets of similar size and composition to those described in Exampie 1 were dried in accordance with the procedure disclosed in that Example, but were calcined at a temperature of about 1400F for 40 minutes. The measured BET surface area of the support was a relatively low 8.2 m2/gm. Acid leaching, impregna-tion and final drying were then carried out as described in Example 4. Although the leaching process was identical to that described in Example 4, the resulting catalyst had a high residual metal content. The metal content of the catalyst (on an acid-free basis) as measured by atomic absorption was as follows: 0.42 (wt.) % iron and 2.1 (wt.) % aluminum (- 2.52 (wt.) % total iron plus alumi.num).
Steam and ethylene were passed through a bed of the above-described catalyst as described in Example 1.
After 900 hours of operation, ethanol production declined from an initial value of 9.1 lbs. per hour per ft.3 of catalyst to about 7Ø
This example demonstrates that metal removal may be accomplished in accordance with the invention from low surface area support materials provided they are not overcalcined ox sintered.
11,035 11~*777 Catalyst support pellets of similar size and composition to those described in Example 1, were dried in accordance with the procedure of that Example. The pellets were calcined at 1350F for 32 minutes3 20% less time than that employed in Example 1. This resulted in black specks of unburned cornmeal remaining in the pellets due to incomplete combustion. The surface area of the support was a relatively low 9.3 m2/gm. Leaching, drying, impregnation and final drying were carriecl out as in Example 4. The metal content of the catalyst on an acid-free basis, as measured by atomic absorption,was as follows: 0.27 (wt.) % Fe and 1.22 (wt.) /0 Al (a total of 1.49 (wt.) /O iron plus aluminum).
Ethylene hydration was carried out under the process conditions described in Example 1. The ethanol production rate remained invariant over 900 hours of operation at 8.7 lbs. per hour per ft.3 of catalyst.
Claims (6)
- WHAT IS CLAIMED IS:
l. In a process for hydrating an olefin to form an alcohol wherein said olefin is contacted with water vapor in the presence of a supported hydration catalyst comprising a predominantly siliceous support material impregnated with phosphoric acid, said hydration catalyst being prepared by forming a mixture comprising of from about 50-70 (wt.) % diatomaceous earth, from about 15-25 (wt.) % bentonite, and from about 5-35 (wt.) %
of a combustible organic filler material; calcining said mixture prior to the addition of phosphoric acid at a temperature of from about 1200 to about 1500°F so as to form a mechanically strong catalyst support; and there-after impregnating said support with phosphoric acid to form the supported hydration catalyst, the improvement for enhancing the activity and operating life of said hydration catalyst which comprises restricting the content of aluminum and iron in the supported hydration catalyst to a collective concentration less than about 2.25%, by weight, of the phosphoric acid-free catalyst support, by treating the catalyst support with a strong mineral acid prior to impregnation with phosphoric acid. - 2. The process of claim 1 wherein the calcination temperature is about 1350°F.
- 3. The process of claim 1 wherein the composi-tion of said mixture comprises about 62 (wt.) % diatoma-ceous earth, about 21 (wt.) % bentonite and about 17 (wt.) % of a combustible organic filler material.
- 4. In a supported catalyst composition com-prising a predominantly siliceous support material impregnated with phosphoric acid, said catalyst having been prepared by calcining the siliceous support material at a temperature of from about 1200°F to about 1500°F
prior to the addition of phosphoric acid so as to form an independently strong catalyst support, and thereafter impregnating said support with phosphoric acid, the com-position of said siliceous support material prior to calcination comprising of from about 50-70 (wt.) %
diatomaceous earth, from about 15-25 (wt.) % bentonite, and from about 5-35 (wt.) % of a combustible organic filler material, the improvement wherein the concentration of aluminum plus iron in the supported catalyst is less than about 2.25%, by weight, of the phosphoric acid-free catalyst support. - 5. The composition of claim 4 wherein the composition of said siliceous support material prior to calcination is comprised of about 62 (wt.) % diatomaceous earth, about 21 (wt.) % bentonite and about 17 (wt.) %
of a combustible organic filler material. - 6. The composition of claim 4 wherein the calcination temperature is about 1350°F.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77466877A | 1977-03-04 | 1977-03-04 | |
| US774,668 | 1977-03-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1102777A true CA1102777A (en) | 1981-06-09 |
Family
ID=25101901
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA297,355A Expired CA1102777A (en) | 1977-03-04 | 1978-02-21 | Low-metal content olefin hydration catalyst and related process |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS53108889A (en) |
| BE (1) | BE864540R (en) |
| CA (1) | CA1102777A (en) |
| DE (1) | DE2809309B2 (en) |
| ES (1) | ES467522A1 (en) |
| FR (1) | FR2382423A2 (en) |
| GB (1) | GB1598150A (en) |
| IT (1) | IT1094172B (en) |
| NL (1) | NL7802397A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2578448B1 (en) * | 1985-01-31 | 1990-11-16 | Manville Corp | PROCESS FOR PRODUCING CATALYST SUPPORTS AND PRODUCTS OBTAINED |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2694048A (en) * | 1950-03-18 | 1954-11-09 | Universal Oil Prod Co | Manufacture of improved solid catalysts |
| GB981237A (en) * | 1961-02-21 | 1965-01-20 | Hibernia Chemie G M B H | Process for the production of a catalyst for the catalytic hydration of olefins intoalcohols |
| DE1156772B (en) * | 1961-02-21 | 1963-11-07 | Bergwerksgesellschaft Hibernia | Process for the production of a catalyst for the production of alcohols by the catalytic hydration of olefins |
| GB1075895A (en) * | 1964-06-21 | 1967-07-12 | Nii Sint Spirtov I Orch Produk | Improvements relating to catalysis |
| FR1531086A (en) * | 1966-07-12 | 1968-06-28 | Scholven Chemie Ag | Process for the manufacture of alcohols by catalytic hydration of olefins, as well as products conforming to those obtained |
| CA1076095A (en) * | 1976-09-28 | 1980-04-22 | Charles E. Moyer (Jr.) | Olefin hydration process and catalyst |
| JPS5721250A (en) * | 1980-07-07 | 1982-02-03 | Shiyuukou Seimitsu Kk | Method of presetting tool position in metal machining device and setting jig used therefor |
-
1978
- 1978-02-21 CA CA297,355A patent/CA1102777A/en not_active Expired
- 1978-03-03 ES ES467522A patent/ES467522A1/en not_active Expired
- 1978-03-03 JP JP2371578A patent/JPS53108889A/en active Pending
- 1978-03-03 FR FR7806151A patent/FR2382423A2/en active Pending
- 1978-03-03 NL NL7802397A patent/NL7802397A/en not_active Application Discontinuation
- 1978-03-03 DE DE2809309A patent/DE2809309B2/en not_active Withdrawn
- 1978-03-03 IT IT20876/78A patent/IT1094172B/en active
- 1978-03-03 BE BE185651A patent/BE864540R/en active
- 1978-03-03 GB GB8455/78A patent/GB1598150A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| BE864540R (en) | 1978-09-04 |
| IT7820876A0 (en) | 1978-03-03 |
| NL7802397A (en) | 1978-09-06 |
| ES467522A1 (en) | 1979-08-01 |
| DE2809309B2 (en) | 1981-05-21 |
| JPS53108889A (en) | 1978-09-22 |
| GB1598150A (en) | 1981-09-16 |
| FR2382423A2 (en) | 1978-09-29 |
| DE2809309A1 (en) | 1978-09-07 |
| IT1094172B (en) | 1985-07-26 |
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