JPH0416242A - Preparation of catalyst for synthesizing methacrylic acid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for preparing a catalyst used in the production of methacrylic acid by gas phase catalytic oxidation of methacrolein.

[Conventional technology]

When producing methacrylic acid by gas-phase catalytic oxidation of methacrolein, it is advantageous to maintain a high yield at a low reaction temperature from the viewpoint of catalyst life, suppression of side reactions, equipment cost, etc. Satisfactory results have not always been obtained using catalysts prepared by this method.

One of the reasons for this is thought to be insufficient control of the specific surface area and pore distribution of the catalyst, which is important for oxidation reactions. In order to improve these points, carboxylic acids and polyhydric alcohols were added during catalyst preparation (Japanese Patent Application Laid-open No.
136615) Addition of alcohol and glycol (see JP-A-55-73347) Addition of pyridines (JP-A-47-38591, JP-A-57-171)
444), addition of quinolines (Japanese Patent Application Laid-open No. 1986-
209258) Addition of aqueous ammonia and ammonium nitrate (see JP-A-57-165040)
etc. have been attempted, but the reaction results are not sufficient,
It has drawbacks such as a large decrease in catalyst activity over time, a too high reaction temperature, and a complicated heat treatment method for catalyst activation due to the use of organic substances, making it unsatisfactory as an industrial catalyst. .

[Problem to be solved by the invention]

The present invention aims to provide a method for preparing a novel catalyst for the advantageous production of methacrylic acid from methacrolein.

[A promising means of solving problems]

In order to improve the conventional catalyst preparation method, the present inventors conducted research focusing on the physical properties of the catalyst. As a result, they found that the catalyst is effective at a lower reaction temperature than when using a catalyst prepared by a conventional method, and that methacrylic We have discovered a new method for preparing a catalyst that provides a high yield of acid.

The present invention uses oxides as raw materials for molybdenum and vanadium components during catalyst preparation, and uses potassium, rubidium,
After heating and reacting a mixture of catalyst raw materials other than cesium and thallium with water at 85°C or higher for 1 to 10 hours, the mixture is cooled to 80°C or lower, and a mixture of catalyst raw materials other than cesium and thallium is heated to react with water. At least one selected
A seed element (group I) is added, and then at least one compound selected from the group consisting of ammonium nitrate, ammonium carbonate, ammonium hydrogen carbonate, ammonium sulfate, and ammonium hydrogen sulfate is added at a temperature of the mixed liquid of 80°C or lower.
After adding group II) and at least one compound (group III) selected from the group consisting of pyridine, piperazine, piperazine, and pyrimidine in any order or simultaneously,
This is a method for producing a catalyst for producing methacrylic acid, which is characterized by removing water and heat-treating the residue.

The catalyst for producing methacrylic acid obtained by the method of the present invention is
General formula % formula %) (In the formula, P, Mo, V, Cu, NH. and 0 are phosphorus, molybdenum, vanadium, copper, ammonium group and oxygen, respectively, X is potassium, rubidium,
At least one element selected from the group consisting of cesium and thallium, Y is silver, magnesium, zinc, arsenic, germanium, silicon, tungsten, boron, bismuth, chromium, lanthanum, barium, antimony, iron, zirconium, tellurium and Indicates at least one element selected from the group consisting of cerium, a, b, c, d, e.

f, g and h represent the atomic ratio of each element, and when b=12, a=0. 5-3, c=0.01-3, d=0
．． 01-2, e = 0.01-2, f = 0-5, h represents the number of oxygen atoms necessary to satisfy the valence of each component, g represents the number of ammonium group molecules, g =0
．． It is preferable to have a composition represented by 01 to 2).

Raw materials for the molybdenum and vanadium components used in the preparation of the catalyst include molybdenum trioxide, molybdic acid and other oxides, and particularly good results are obtained when molybdenum trioxide and vanadium pentoxide are used.

As raw material compounds for other catalyst elements, oxides, carbonates, acetates, hydroxides, etc. can be used in combination.

When carrying out the present invention, first, catalyst raw materials other than potassium, rubidium, cesium and/or thallium raw materials (
At least molybdenum, vanadium, and phosphorus raw materials are dissolved or dispersed in water.

In addition to molybdenum and vanadium oxides and phosphorus compounds, the catalyst raw materials include, for example, copper, silver, magnesium, zinc, arsenic, germanium, silicon, tungsten,
Oxides, carbonates, acetates, hydroxides, etc. of boron, bismuth, chromium, lanthanum, barium, antimony, iron, zirconium, tellurium, cerium, etc. are used.

Next, the aqueous solution or dispersion of the catalyst raw material is heated at 85°C, preferably 90°C or higher, for 1 to 10 hours. Heating temperature is 85
If the heating time is less than 0.degree. C. or the heating time is less than 1 hour, the resulting catalyst will be difficult to form a heteropolyacid structure effective for the reaction.

Further, even if the heating time is longer than this, no particular improvement in the effect is observed.

After heating, the catalyst mixture is heated to 80°C or lower, preferably 35 to 70°C.
Cool to 0.degree. C. and add potassium, rubidium, cesium and/or thallium raw materials (group I).

Next, ammonium nitrate, ammonium carbonate, ammonium hydrogen carbonate, ammonium sulfate and/or ammonium hydrogen sulfate (group II) and pyridine, piperidine, piperazine and/or pyrimidine (group III) are added at a temperature of the mixed liquid of 80°C or lower, preferably 40 to 70°C. Add.

If the liquid temperature at the time of addition of the compounds of Groups 1, 2, and 2 exceeds 80°C, it is difficult to prepare a catalyst with a high yield of methacrylic acid.

The amounts of ammonium nitrate, ammonium carbonate, ammonium hydrogen carbonate, ammonium sulfate and/or ammonium hydrogen sulfate (group II) and pyridine, piperidine, piperazine and/or pyrimidine (group III) are each from 0.5 to 0.5 of the total weight of the catalyst raw materials. 30% by weight especially 1-20
Weight percent is preferred. The amount of compound used in group ■ and group ■ is
If the amount is less than this, the performance of the catalyst will be insufficient, and if it is more than this, no particular improvement in effectiveness will be observed.

Next, the mixture containing the catalyst raw materials and the compounds of group 1 and group 2 is heat-treated to obtain the desired catalyst.

The heat treatment is preferably carried out at a temperature of 300 to 430°C, for example, under air flow and/or gas flow with an oxygen concentration of 5% by volume or more. When the mixture is an aqueous solution or an aqueous dispersion, it is usually preferable to perform heat treatment after removing water.

Although the catalyst obtained by the method of the present invention is effective without a carrier, it is preferably supported on an inert carrier such as silica, alumina, silica-alumina, diatomaceous earth, or diluted with such carrier.

When producing methacrylic acid using the catalyst obtained by the method of the present invention, the concentration of methacrolein in the raw material gas can be varied within a wide range, but is preferably 1 to 20% by volume, particularly 3 to 10%. .

The raw material methacrolein may contain small amounts of impurities such as water and lower saturated aldehydes, but these impurities do not substantially affect the reaction.

Although it is economical to use air as the oxygen source, air enriched with pure oxygen can also be used if necessary. The oxygen concentration in the raw material gas is defined by the molar ratio to methacrolein, and this value is preferably 0.3 to 4, particularly 0.4 to 2.5. The raw material gas may be diluted by adding an inert gas such as nitrogen, water vapor, or carbon dioxide gas. The reaction pressure is preferably normal pressure or diffused pressure. The reaction temperature is 200-420℃, especially 23
0 to 400°C is preferred. The reaction can be carried out in a fixed bed or in a fluidized bed.

〔Example〕

The reaction rate of methacrolein and the selectivity of the produced methacrylic acid in the following Examples and Comparative Examples are defined as follows.

Reaction rate of methacrolein (%) = Selectivity of methacrylic acid (%) = In the following Examples and Comparative Examples, parts mean parts by weight, and the analysis was performed by gas chromatography.

Example: 100 parts of molybdic acid trioxide, 2.6 parts of vanadium pentoxide
and 6.7 parts of 85% phosphoric acid to 800 parts of pure water,
The mixture was heated under reflux at 00°C for 6 hours. To this was added 1.2 parts of copper acetate, and the mixture was further heated under reflux at 100°C for 3 hours. After refluxing, the temperature of the mixture was cooled to 40°C, 11.2 parts of cesium bicarbonate dissolved in 100 parts of pure water was added, and 6.9 parts of ammonium nitrate dissolved in 100 parts of pure water at a temperature of 40°C was added. In addition, 6.9 parts of pyridine dissolved in 100 parts of pure water was added, and the mixture was evaporated to dryness while heating. After drying the obtained solid material at 120°C for 16 hours, it was pressure-molded,
After being heat-treated at 400°C for 3 hours under nitrogen flow, it was further heat-treated at 380°C for 5 hours under air flow. The composition of the components other than oxygen in the obtained catalyst (the same applies hereinafter) is P+M.

+zVo-5cuo, +CJ (NH'a) o,
It was s.

This catalyst was packed in a reactor, and a mixed gas of 5% methacrolein, 10% oxygen, 30% water vapor, and 55% nitrogen (volume %) was passed through the reactor at a reaction temperature of 285° C. and a contact time of 3.6 seconds.

When the product was collected and analyzed by gas chromatography, the reaction rate for methacrolein was 86.8% and the selectivity for methacrylic acid was 83.9%.

Example 2 A catalyst having the same composition as in Example 1 was refluxed and the mixture temperature was 100°C.
Cesium bicarbonate was added while the mixture was kept at 40°C, and a mixed solution of ammonium nitrate and pyridine was added at a temperature of 40°C. When this catalyst was used to react under the same conditions as in Example 1, the reaction rate of methacrolein was 86.5%.
, the selectivity of methacrylic acid was 84.0%.

Example 3 Cesium bicarbonate was added to a catalyst having the same composition as in Example 1 while the mixture temperature was maintained at 40°C after reflux, and the mixture temperature was further increased to 40°C.
It was prepared by adding a mixed solution of ammonium nitrate and pyridine at 0°C. When this catalyst was used to react under the same conditions as in Example 1, the reaction rate for methacrolein was 86.7% and the selectivity for methacrylic acid was 83.9%.

Comparative Example 1 A catalyst having the same composition as in Example 1 was used at a mixed liquid temperature of 100°C after reflux.
Add cesium bicarbonate while keeping the temperature at
It was prepared by adding pyridine at 00°C. Using this catalyst,
When the reaction was carried out under the same conditions as in Example 1, the reaction rate of methacrolein was 84.6% and the selectivity of methacrylic acid was 83.9.
%Met.

Comparative Example 2 A catalyst with the same composition as in Example 1 was used, and the temperature of the mixed liquid after reflux was 40°C.
After cooling to 4, add ammonium nitrate and further cool the mixture to 4
It was prepared by adding cesium bicarbonate at 0°C and then adding pyridine at a mixture temperature of 40°C. Using this catalyst, Example 1
When the reaction was carried out under the same conditions as above, the reaction rate of methacrolein was 85.1% and the selectivity of methacrylic acid was 84.0%.

Comparative Example 3 A catalyst having the same composition as in Example 1 was prepared under the same preparation conditions as in Example 1 without adding pyridine. When this catalyst was used to react under the same conditions as in Example 1, the reaction rate for methacrolein was 85.7% and the selectivity for methacrylic acid was 84.0%.

Comparative Example 4 A catalyst having the same composition as in Example 1 was prepared under the same preparation conditions as in Example 1 without adding ammonium nitrate. When this catalyst was used for reaction under the same conditions as in Example 1, the reaction rate of methacrolein was 85.6% and the selectivity of methacrylic acid was 8.
It was 4.2%.

Comparative Example 5 A catalyst having the same composition as in Example 1 was prepared under the same preparation conditions as in Example 1 without adding ammonium nitrate and pyridine. When this catalyst was used and the reaction temperature was changed to 290°C and the other conditions were the same as in Example 1, the reaction rate of methacrolein was 80.5% and the selectivity of methacrylic acid was 81.
It was 7%.

Example 4 The composition was P+Mo+□v0.5Cuo according to Example 1 except that 4.2 parts of ammonium carbonate was added instead of ammonium nitrate and 7.4 parts of piperidine was added instead of pyridine to 100 parts of molybdenum trioxide. , +LSto
, s^So, -(NH-) 0.2 catalyst was prepared.

When this catalyst was used and the reaction temperature was changed to 270°C and the other conditions were the same as in Example 1, the reaction rate of methacrolein was 86.8%, and the selectivity of methacrylic acid was 86.9.
%Met.

Comparative Example 6 A catalyst having the same composition as in Example 4 was prepared under the same preparation conditions as in Example 4 except that the reflux temperature was changed to 70°C. When this catalyst was used and the reaction temperature was changed to 270°C and the other conditions were the same as in Example 1, the reaction rate of methacrolein was 84.6% and the selectivity of methacrylic acid was 86.6%. .

Comparative Example 7 Prepared under the same conditions. Using this catalyst, the reaction temperature was set to 2
When the reaction temperature was changed to 80° C. and the other conditions were the same as in Example 1, the reaction rate of methacrolein was 79.3% and the selectivity of methacrylic acid was 84.2%.

Example 5 To 100 parts of molybdenum trioxide, 2.8 parts of ammonium carbonate and 2.3 parts of ammonium hydrogen carbonate were added in place of ammonium nitrate, and 7.5 parts of piperazine was added in place of pyridine.
The composition was P 1.5 in the same manner as in Example 1.
M012VO,8CIJ0.2R1]+ceo, IP
A catalyst with eo, 2sbo, a (N)+4) 0.4 was prepared. At this time, antimony trioxide was used as an antimony raw material source. Using this catalyst, the reaction temperature was 270
When the reaction was carried out under the same conditions as in Example 1 except that the temperature was changed to .degree. C., the reaction rate of methacrolein was 91.8% and the selectivity of methacrylic acid was 89.0%.

Comparative Example 8 A catalyst having the same composition as in Example 5 was used at a mixed liquid temperature of 100°C after reflux.
Cesium bicarbonate was added while the mixture was maintained at 100°C, ammonium carbonate and ammonium hydrogen carbonate were added at a temperature of 100°C, and then piperazine was added at a temperature of 100°C.

Using this catalyst, a reaction was carried out under the same conditions as in Example 1 except that the reaction temperature was changed to 270°C. The reaction rate of methacrolein was 90.3%, and the selectivity of methacrylic acid was 88.8%.
Met.

Comparative Example 9 A catalyst with the same composition as in Example 5 was prepared under the same preparation conditions as in Example 5 without adding ammonium carbonate, ammonium bicarbonate, and piperazine. Using this catalyst, the reaction temperature was changed to 270°C and the other conditions were the same as in Example 1. As a result, the reaction rate of methacrolein was 77.8%.
The selectivity of methacrylic acid was 87.1%.

Example 6 To 100 parts of molybdenum trioxide, 6.3 parts of ammonium sulfate was added instead of ammonium nitrate, 4.8 parts of pyridine and 2.0 parts of pyrimidine were added instead of pyridine, and the other composition was the same as in Example 1. P+, 1M012VO
,acuo, 2KO,vcso, Jto, 2Sb
o, 7(NH,). , 4 catalyst was prepared. On this occasion,
Antimony pentoxide was used as the antimony raw material source.

When this catalyst was used and the reaction temperature was changed to 270°C and the other conditions were the same as in Example 1, the reaction rate of methacrolein was 92.6% and the selectivity of methacrylic acid was 88.8%.
Met.

Comparative Example 10 A catalyst having the same composition as in Example 6 was refluxed and the mixed liquid temperature was 100°C.
Cesium bicarbonate was added while the mixture was maintained at 100°C, ammonium sulfate was added at a temperature of 100°C, and then pyridine and pyridine were added at a temperature of 100°C. Using this catalyst, the reaction temperature was changed to 270°C and the other conditions were the same as in Example 1. As a result, the reaction rate of methacrolein was 90.9%, the selectivity of methacrylic acid was 88,
It was 8%.

Examples 7-12 Each catalyst shown in Table 1 was prepared according to Example 5.

The parts by weight of ammonium carbonate, ammonium hydrogen carbonate, ammonium sulfate, and ammonium hydrogen sulfate and the parts by weight of pyridine in the table mean parts by weight based on 100 parts of molybdenum trioxide. Moreover, the addition liquid temperature means the liquid temperature at the time of addition of the compounds of Group 1, Group 2, and Group 2.

A reaction was carried out in the same manner as in Example 1 except that these catalysts were used and the reaction temperature was changed. The results are also shown in Table 1.

Voluntary writing of procedural amendments) September 26, 1990 Correction (Patent Application No. 119697/1999) Detailed Cattle The following corrections will be made.

Claims (1)

[Claims] 1. During catalyst preparation, oxides are used as raw materials for molybdenum and vanadium components, and a mixture of catalyst raw materials other than potassium, rubidium, cesium, and thallium and water is heated at 85°C.
After heating for 1 to 10 hours, the mixture was cooled to 80°C or less, and at least one element selected from the group consisting of potassium, rubidium, cesium, and thallium (
At least one compound selected from the group consisting of ammonium nitrate, ammonium carbonate, ammonium hydrogen carbonate, ammonium sulfate, and ammonium hydrogen sulfate (group II), pyridine, and piperidine. , at least one compound (group III) selected from the group consisting of piperazine and pyrimidine is added in any order or simultaneously, water is removed and the residue is heat treated. A method for preparing a multicomponent catalyst for the production of methacrylic acid. 2. The catalyst for producing methacrylic acid has the general formula P_aMo_bV_cCu_dX_eY_f(NH_4
)_9O_h (wherein P, Mo, V, Cu, NH_4 and O are respectively phosphorus, molybdenum, vanadium, copper,
ammonium group and oxygen, X is potassium, rubidium,
At least one element selected from the group consisting of cesium and thallium, Y is silver, magnesium, zinc, arsenic, germanium, silicon, tungsten, boron, bismuth, chromium, lanthanum, barium, antimony, iron, zirconium, tellurium and Indicates at least one element selected from the group consisting of cerium, a, b, C, d, e, f, g
and h represent the atomic ratio of each element, and when b=12, a
=0.5~3, c=0.01~3, d=0.01~2,
e = 0.01 to 2, f = 0 to 5, h represents the number of oxygen atoms necessary to satisfy the valence of each component, g represents the number of ammonium group molecules, g = 0.01 ~2)
The method according to claim 1, characterized in that the catalyst is represented by: