JPH0154095B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an oxidative dehydrogenation catalyst for alkyl aromatic compounds. For example, current commercial dehydrogenation processes such as the conversion of ethylbenzene to styrene suffer from low conversion, while higher conversion oxidative dehydrogenation processes suffer from poor selectivity. Selectivity is particularly important in this particular reaction since the starting materials for producing styrene account for more than 80% of its production cost. Thus, the search continues for more effective catalyst materials to minimize side reactions and improve conversion rates. A number of catalysts and catalyst systems have been disclosed that utilize various phosphates and pyrophosphates for the conversion of alkylaromatic compounds to derivatives with side chain unsaturation. For example, US Pat. No. 3,923,916 claims nickel pyrophosphate as an excellent catalyst for the oxidative dehydrogenation of alkyl aromatic compounds. U.S. Patent No. 3933932 and U.S. Patent No.
No. 3,957,897 discloses the use of lanthanum, rare earth and alkaline earth salts of phosphoric acid, respectively, as oxidative dehydrogenation catalysts for alkylaromatics. However, no catalyst composition containing an arsenic, antimony, bismuth, or cadmium salt of phosphoric acid that exhibits a significant effect on the dehydrogenation reaction of the present invention has been disclosed. U.S. Pat. No. 3,873,633 utilizes a cobalt-bismuth-phosphorus-oxygen composition as a catalyst for the oxidative dehydrogenation of paraffinic hydrocarbons to mono-olefins or diolefins, but converts alkyl aromatic compounds to unsaturated side chain derivatives. The use of catalysts of this type for the conversion of is hitherto unknown. The present invention relates to oxidative dehydrogenation catalysts from alkyl-substituted aromatic compounds to corresponding alkenyl-substituted aromatic compounds, provided that the alkyl-substituted aromatic compounds have at least one carbon atom having from 2 to 6 carbon atoms.
1 alkyl group, and the alkyl group is 1
Bonded to only one aromatic ring. ). The aromatic compound may be a monocyclic aromatic compound or a fused-ring bicyclic aromatic compound or a corresponding nitrogen-containing heteroaromatic compound. A gaseous mixture of molecular oxygen, such as air, and an alkyl aromatic compound, in the presence or absence of a diluent, such as water vapor, carbon dioxide, nitrogen, or an inert hydrocarbon, is applied over the catalyst of the invention. It is passed through at a temperature of approximately 300° to 650°C. The catalyst has a composition expressed by the following empirical formula. A _a M _b M _c 〓M _d 〓B _e P _y O _x (wherein A is potassium, M is zinc, cobalt or barium, M is iron, chromium, lanthanum, cerium or deidiumium, M〓 is boron, B is bismuth, P is phosphorus, a=0~5, b=4~20, c=0.1~10, d=0~4, e=0.1~12, y= (8 to 16, x is the number of oxygens required to satisfy the valence requirements of other present elements, and 2b+3(c+e) is greater than 9 and less than 3y). It is a good oxidative dehydrogenation catalyst. For example, in the dehydrogenation of ethylbenzene to styrene, 1 to styrene in the 70% range
Conversion rates per pass and selectivities reaching 90% are obtained. Catalysts useful in the process of the invention may be used alone or supported. Suitable support materials include silica, alundum, titania and mullite and especially phosphate-type supports such as zirconium phosphate, antimony phosphate, aluminum phosphate and especially boron phosphate. Generally, the support may be used in an amount up to 95% by weight of the final catalyst composition, and the catalyst may be mixed into the support by coating, impregnation, and co-precipitation. These catalysts are prepared by coprecipitation or by other methods known to those skilled in the art. Generally they are prepared by mixing an aqueous solution of a metal nitrate salt with an aqueous solution of ammonium dihydrogen phosphate and then drying the precipitate. The catalyst may be calcined to obtain desired physical properties such as attrition resistance, optimal surface area and particle size. It is generally preferred to further heat-treat the calcined catalyst in the presence of oxygen at temperatures above 250 DEG C., but below temperatures harmful to the catalyst. Among the alkyl aromatic compounds that are contemplated to be within the scope of the invention are -substituted aromatic compounds such as, for example, ethylbenzene, isopropylbenzene, sec-butylbenzene; ethyltoluene, diethylbenzene, t-butylethylbenzene, Disubstituted aromatic compounds such as; trisubstituted aromatic compounds such as ethylxylenes; fused ring aromatic compounds such as ethylnaphthalene, methylethylnaphthalene, diethylnaphthalene; and ethylpyridine, methylethylpyridine, ethylquinoline,
These include nitrogen-containing heteroaromatic compounds such as ethylisoquinoline. Particularly preferred reactants in this reaction are ethylbenzene which is readily converted to styrene, diethylbenzene which is converted to a mixture of ethylstyrene and divinylbenzene, ethylpyridine and methylpyridine which are converted to vinylpyridine and methylvinylpyridine, respectively. The reaction is carried out in a fixed bed reactor or a fluidized bed reactor.
Although it may be carried out at temperatures as low as 300°C, the optimum temperature for dehydrogenation of alkyl side chains is about 400° to 600°C.
℃ range, and there is no obvious advantage to operating at temperatures much above 650℃. The pressure at which the catalyst of the present invention is used is approximately atmospheric, although pressures from slightly below atmospheric to about 3 atmospheres can be used. Apparent contact times in reactions in which the catalysts of the invention are used may range from 0.1 to 50 seconds, with contact times of 1 to 15 seconds being preferred for good selectivity and yield. The molar ratio of oxygen to alkyl aromatic compound fed to the reactor can range from about 0.5 to about 4 moles of oxygen per mole of alkyl aromatic compound, but a preferred range is from about 0.5 to about 4 moles of oxygen per mole of aromatic compound. about
0.5 to about 1.5 moles of oxygen. The oxygen used is
Although pure oxygen may be used, the use of air is preferred for convenience. Diluents such as steam, carbon dioxide, nitrogen, inert hydrocarbons or other inert gases may also be used, and amounts of 0 to 20 volumes per volume of alkyl aromatic compound are suitable. The following examples illustrate the convenience and improvements obtained in the catalytic oxidative dehydrogenation process of the present invention compared to prior art catalysts. Examples 1-14 are representative of the invention, Comparative Examples A-E
represents a prior art method. Catalyst Preparation Comparative Example A Ni ₂ P ₂ O ₇ Nickel nitrate hexahydrate (168.5 g) was dissolved in 500 c.c. of water, and the acidity was then adjusted to PH 6.4 with ammonia. Ammonium dihydrogen phosphate (77.7g)
Dissolve it in 250 c.c. water, then adjust the pH to 6.8 with ammonia.
It was adjusted to The solution was mixed and stirred for 15 minutes at room temperature, the pH was adjusted to 6.0 with ammonia, and then filtered. The light green precipitate was filtered, dried at 110℃, heated to 290℃ for 3 hours, 427℃ for 3 hours, and then dried at 550℃ for 3 hours.
Heat-treatment for 2 hours at <0>C gave a yellow colored solid with a surface area of 14 ^m2 /g. Comparative Example B Mg ₂ P ₂ O ₇ Magnesium nitrate hexahydrate (309.2 g) was added to 60 c.c.
It was heated and dissolved in water. Ammonium dihydrogen phosphate (138.2 g) was heated and dissolved in 100 c.c. of water. The solution was mixed and stirred with heating to form a white thick paste. The paste was dried at 110°C and heat-treated in air for 3 hours at 290°C, 3 hours at 427°C and then 16 hours at 550°C to give a white solid with a surface area of 21.8 m ² /g. Comparative Example C La ₄ (P ₂ O ₇ ) ₃ lanthanum nitrate hexahydrate (Trona Code 548)
(130 g) was dissolved in 31.5 cc of nitric acid and diluted with water to 250 cc. Ammonium dihydrogen phosphate (57.1g)
It was dissolved in 250 c.c. of water and then made acidic with 25 c.c. of nitric acid to a pH of less than 1. When the solution was mixed with stirring, opalescence was produced. After 22 hours of mixing with heating, a milky white precipitate formed. Heating to boiling concentrates the gel. Filter the gel and dry at 110 °C and 290 °C in air.
°C (3 hours), 427 °C (3 hours), then 550 °C (16
A white solid with a surface area of 17 m ² /g was obtained. Comparative Example D Co ₇ Fe ₃ P ₁₂ O _41.5 Ferric nitrate nonahydrate (121.2 g) and cobalt nitrate hexahydrate (203.8 g) were heated and dissolved in 10 ml of water. Ammonium dihydrogen phosphate (138.0g)
was heated and dissolved in 100ml of water. The solution was mixed and stirred with heating to form a thick paste. The paste was dried at 110°C, then 290°C (3 hours), 427°C (3 hours) and 550°C in air.
Heat-treatment (3 hours) gave a blue solid with a surface area of 0.8 m ² /g. Comparative Example E Co ₂ P ₂ O ₇ Cobalt nitrate hexahydrate (349.1 g) was heated and dissolved in 20 c.c. of water. Ammonium dihydrogen phosphate (138.0 g) was heated and dissolved in 100 c.c. of water. The solution was mixed and stirred with heating to form a thick purple paste. The paste was dried at 110°C, then 290°C (3 hours) and 427°C (3 hours).
Then heat treated at 550℃ (16 hours) to reduce the surface area to 12.2
A blue solid with m ² /g was obtained. Example 1 A Co ₇ Fe ₃ Bi _0.7 P ₁₂ O ₄₃ nitrate solution was mixed with cobalt nitrate hexahydrate (203.8
g) from ferric nitrate nonahydrate (121.2 g), bismuth nitrate pentahydrate (35.1 g) and 10 c.c. added to the solution. Next, the obtained paste was heated in air at 290°C (5 hours) and at 427°C (3 hours).
After heat-treatment at 550° C. (3 hours), the resulting blue solid had a surface area of 7.7 m ² /g. Example 2 50% Co ₇ Fe ₃ Bi ₁ P ₁₂ O ₄₃ −50% BPO ₄ nitrate solution was mixed with cobalt nitrate hexahydrate (85 g),
It was made from ferric nitrate nonahydrate (50.5 g) and bismuth nitrate pentahydrate (20.2 g) with 5 c.c. of water. This was mixed with ammonium dihydrogen phosphate (57.5
g) Added to the solution, to which was then added 53 g of boron phosphate. After stirring and heating the slurry to 110℃
It was dried and baked. The resulting blue solid had a surface area of 11.9 m ² /g. Example 3 Co _9.5 Fe _0.5 BiP ₁₂ O ₄₂ nitrate solution was converted into cobalt nitrate hexahydrate (276.5
g), prepared from ferric nitrate nonahydrate (20.2g) and bismuth nitrate pentahydrate (48.5g). It was added to a solution of ammonium dihydrogen phosphate (138 g) in 100 c.c. of water, dried at 110 DEG C. and heat-treated as in Example 1. The resulting blue solid had a surface area of 12.6 m ² /g. Example 4 A Co ₉ CrBiP ₁₂ O ₄₂ nitrate solution was mixed with cobalt nitrate hexahydrate (131
g), chromium nitrate nonahydrate (20 g), bismuth nitrate pentahydrate (24.3 g) and water 5 c.c. It was added to a solution of ammonium dihydrogen phosphate (69 g) in 50 c.c. of water, dried and heat-treated as in Example 1. The resulting blue solid had a surface area of 14.3 m ² /g. Example 5 A Co ₇ La _1.5 Bi ₂ P ₁₂ O ₄₂ nitrate solution was mixed with cobalt nitrate hexahydrate (101.9
g), lanthanum nitrate hexahydrate (32.8 g), bismuth nitrate pentahydrate (48.5 g) and concentrated nitric acid 7 c.c. It was added to a solution of ammonium dihydrogen phosphate (69 g) in 50 c.c. of water, dried at 110°C, except that the 550°C heat-treatment was extended to 16 hours, and heat-treated as in Example 1. . The resulting blue solid had a surface area of 19.4 m ² /g. Example 6 Co ₈ La _0.5 Bi ₂ P ₁₂ O ₄₂ nitrate solution was mixed with cobalt nitrate hexahydrate (116.4
g), lanthanum nitrate hexahydrate (10.9 g), bismuth nitrate pentahydrate (48.5 g), and water from concentrated nitric acid 3 c.c.
Made with 10c.c. It was added to ammonium dihydrogen phosphate (69 g) dissolved in 50 c.c. of water, then dried and heat-treated as in Example 5. The resulting blue solid had a surface area of 7.7 m ² /g. Example 7 A Co ₉ La _1.0 Bi ₁ P ₁₂ O ₄₂ nitrate solution was mixed with cobalt nitrate hexahydrate (131
g), lanthanum nitrate hexahydrate (217 g), and bismuth nitrate pentahydrate (24.3 g) in 10 c.c. of water. It was added to ammonium dihydrogen phosphate (69 g) dissolved in 50 c.c. of water. The slurry was dried at 110°C and heat-treated as in Example 1. The resulting blue solid had a surface area of 10.5 m ² /g. Example 8 A K _0.01 Co ₉ La ₁ BiP ₁₂ O ₄₂ nitrate solution was prepared as in Example 7. 10c.c.
of potassium acetate solution (0.5 g/100 c.c.) was added to the mixed nitrate and the nitrate solution was then added to ammonium dihydrogen phosphate as in Example 7. The slurry was dried and heat-treated as in Example 5. The resulting blue solid had a surface area of 19.0 m ² /g. Example 9 A Co ₇ Zn ₂ La ₁ BiP ₁₂ O ₄₂ nitrate solution was mixed with cobalt nitrate hexahydrate (101.9 g), zinc nitrate hexahydrate (29.8 g), and lanthanum nitrate hexahydrate in 5 c.c. of water. (21.7 g) and bismuth nitrate pentahydrate (24.3 g).It was mixed with 50 c.c. of water.
Added to medium ammonium dihydrogen phosphate (69 g).
After stirring and heating, the slurry was dried and heat-treated as in Example 5. The blue solid produced is 8.6m ² /
It had a surface area of g. Example 10 Co ₉ CeBiP ₁₃ O ₄₅ Ceric ammonium nitrate (27.4 g)
Dissolved in cc concentrated nitric acid and 100 cc water. Bismuth nitrate pentahydrate (24.3 g) and cobalt nitrate hexahydrate (131 g) were added to and dissolved in the cerium solution. The resulting solution was dissolved in ammonium dihydrogen phosphate (74.8
g) added to the solution. The resulting slurry was dried at 110°C and heat-treated as in Example 1. The solid produced had a surface area of 10.3 m ² /g. Example 11 Co ₉ “Di ₁ ” BiP ₁₂ O ₄₂ “Didymium” Oxide, Mixed Rare Earths (16.5 g) (Trona Corp. Code 422)
was dissolved in 25 c.c. of concentrated nitric acid. Bismuth nitrate pentahydrate (24.3 g) was added to the "Deidymium" solution, which was then added to a solution of ammonium dihydrogen phosphate (69 g) in 50 c.c. of water. A solution of cobalt nitrate hexahydrate (131 g) in 10 c.c. of water was then added. The slurry was dried at 110°C and heat-treated as in Example 1. The resulting blue solid had a surface area of 15.4 m ² /g. Example 12 Co ₈ BaFeBiP ₁₂ O ₄₂ nitrate solution was converted into cobalt nitrate hexahydrate (116.4
g), bismuth nitrate pentahydrate (24.3 g), ferric nitrate nonahydrate (20.2 g) and water 50 c.c.
Barium hydroxide octahydrate (15.8g) in concentrated nitric acid/water
Acidified to pH 1.5 with a 10% solution and then added to the nitrate. The resulting slurry was added to a solution of ammonium dihydrogen phosphate (69 g) in 50 c.c. of water. the slurry
dried at 110°C and heat-treated as in Example 1;
A solid with a surface area of 10.6 m ² /g was obtained. Example 13 Co ₉ CeBiP ₁₂ O ₄₅ The same catalyst as in Example 9 was regenerated by passing air over the catalyst at the reaction temperature. Example 14 K _0.1 CO ₉ Cr ₁ Bi ₁ P ₁₂ O _42This catalyst was added to a nitrate solution with potassium acetate (0.49
The catalyst was prepared in the same manner as in Example 4 except that g) was added. The surface area was 15.2 m ² /g. The number of oxygen atoms in the catalysts of Examples 1-14 is estimated. However, the oxygen number actually varies from about 30 to 60, depending on the reaction conditions. The above catalyst is 1/2 with a catalyst volume capacity of 15 c.c.
It was used for the oxidative dehydrogenation of ethylbenzene to styrene, diethylbenzene to divinylbenzene, and methylethylpyridine to methylvinylpyridine in a fixed bed reactor consisting of -inch (outside diameter) stainless steel tubing. A reaction mixture of air, aromatics and nitrogen,
They were each premixed in a molar ratio of 5/1/2 and fed to the reactor. The reactor was maintained at a temperature of 530-532°C and atmospheric pressure. The liquid hourly space velocity of the aromatic feed onto the catalyst is 0.23/hour and the contact time is 3.3
It was hot in seconds. The particle size of the catalyst used was 20-35 mesh. The percent conversion per pass to the desired alkenyl aromatic compound as well as the selectivity of the reaction reported in Tables 1-3 were calculated as follows. Conversion rate (%) = Number of moles of alkyl aromatic compound converted/Number of moles of alkyl aromatic compound fed x 100 One pass yield (%) = Number of moles of alkenyl aromatic compound obtained/Number of moles of alkenyl aromatic compound fed Number of moles of alkenyl aromatic compound obtained × 100 Selectivity = Number of moles of alkenyl aromatic compound obtained /
Number of moles of converted alkyl aromatic compound x 100

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Claims (1)

[Scope of Claims] 1 Contains at least one alkyl group of 2 to 6 carbon atoms bonded to a single aromatic ring, and the aromatic group is a monocyclic aromatic or a fused bicyclic aromatic and a corresponding nitrogen-containing heteroaromatic compound for the dehydrogenation of an alkyl aromatic compound to a corresponding alkenyl aromatic compound, the catalyst having the following formula: A _a M _b M _c 〓M _d 〓B _e P _y O _x (where A is potassium, M is zinc, cobalt or barium, M is iron, chromium, lanthanum, cerium or deidiumium, M is boron) Yes, B is bismuth, P is phosphorus, a=0-5, b=4-20, c=0.1-10, d=0-4, e=0.1-12, y=8-16, x is the number of oxygens necessary to satisfy the valence requirements of other elements present, and 2b+3(c+e) is greater than 9 and less than 3y). 2 a=0-1, b=4-12, c=0.1-4, d=0-2, e=0.1-4, 2b+3(c+e) is greater than 9 and smaller than 3y, Claim 1 Catalysts as described in section. 3. The catalyst according to claim 1, wherein M is cobalt and M is lanthanum. 4. The catalyst according to claim 1, wherein M is cobalt and M is iron. 5. The catalyst according to claim 1, wherein d is 0. 6. The catalyst according to claim 1, wherein d is greater than 0.