JPH04321642A - Acrylic acid production method - 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]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing acrylic acid by gas-phase catalytic oxidation of acrolein, and in particular to the catalyst used.

0002

[Prior Art] Regarding the catalyst used in the production of acrylic acid by vapor phase catalytic oxidation of acrolein, JP-A-4
No. 9-47276, No. 50-84521, No. 52-1
No. 53889, No. 53-7614 and No. 58-166
Although many proposals have been made, such as in Japanese Patent No. 939, it is desired to further improve performance as an industrial catalyst.

0003

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for advantageously producing acrylic acid from acrolein using a catalyst that is highly practical in terms of activity, selectivity, and service life.

0004

[Means for Solving the Problems] The present invention provides a method for producing acrylic acid by vapor phase catalytic oxidation of acrolein, using the general formula Moa Vb Sic Nad Ae Xf Yg O
h (wherein Mo, V, Si, Na and O are each,
Molybdenum, vanadium, silicon, sodium and oxygen; A is at least one element selected from the group consisting of iron, chromium, cobalt and strontium; X is selected from the group consisting of germanium, selenium, tin, tellurium and samarium. At least one element Y represents at least one element selected from the group consisting of magnesium, titanium, copper, zinc, niobium, manganese, nickel, silver, tantalum, bismuth, cerium, and tungsten, and a=
12, b=1 to 6, c=0.1 to 15, d=0 to
2, e=0.1-3, f=0.01-3, g=0-3, and h is the number of oxygen atoms necessary to satisfy the valence of each component. ), and when a sodium component is contained in the catalyst, a catalyst in which sodium as a constituent element of the catalyst is derived from water glass consisting of Na2O and SiO2 is used. It's in the manufacturing method.

When preparing the catalyst used in the present invention, a combination of nitrates, carbonates, ammonium salts, sulfates, oxides, etc. of each element is used as a raw material compound for each element. If components are included, it is necessary to use water glass consisting of Na2 O and SiO2 as the starting material for the components. The water glass usually used has the general formula Na2O・nSiO2・nH
Denoted by 2 O. Here, n means molar ratio and n=2
The liquid product in items 4 to 4 is called water glass.

[0006] When raw materials other than water glass are used as raw materials for sodium, such as sodium acetate, sodium bicarbonate, sodium chloride, sodium hydroxide, sodium nitrate, and sodium sulfite, the performance is superior to that when water glass is used. It is not possible to obtain a catalyst having . Therefore, when water glass is used as a starting material in the present invention, most of the silicon raw materials in the above general formula are other raw materials, such as silicon dioxide such as silica sol and silica gel, but sodium The value obtained by adding the amount of silicon dioxide from the water glass used as a raw material is the atomic ratio of silicon.

[0007] The method for producing the catalyst used in the present invention does not need to be limited to a special method, and conventionally well-known evaporation to dryness methods, precipitation methods, Various methods can be used, such as oxide mixing methods.

Although the catalyst used in the method of the present invention is effective without a carrier, it may be supported on an inert carrier such as silica, alumina, silica-alumina, silicon carbide, diatomaceous earth, or diluted with this. is preferred.

When producing acrylic acid by gas-phase catalytic oxidation of acrolein according to the method of the present invention, the concentration of acrolein in the raw material gas can be varied within a wide range, but it ranges from 1 to 20% by volume, particularly from 3 to 10%. is preferred.

The raw material acrolein 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 acrolein, 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.

[0011] The reaction pressure is preferably normal pressure to several atmospheres. The reaction temperature is preferably 200 to 420°C, particularly 220 to 400°C. The reaction can be carried out in a fixed bed or in a fluidized bed.

0012

[Examples] The present invention will be explained below with reference to Examples and Comparative Examples. "Part" in the text means part by weight. Analysis was based on gas chromatography. The reaction rate of acrolein and the selectivity of acrylic acid produced are defined as follows.

[0013]

[Math 1]

[0014]

[Math 2]

Example 1 100 parts of ammonium paramolybdate and 16.6 parts of ammonium metavanadate were dissolved in 1000 parts of pure water. To this was added a solution prepared by dissolving 19.1 parts of ferric nitrate in 200 parts of pure water, and further added 1.0 part of germanium oxide. Next, 56.7 parts of 20% silica sol was added, and the mixture was evaporated to dryness while stirring under heating.

The obtained solid material was dried at 130° C. for 16 hours, then pressure molded, and heat treated at 380° C. for 5 hours under air circulation. The composition of elements other than oxygen (the same applies hereinafter) of the obtained catalyst was Mo12V3 Si4 Fe1 Ge0.2.

[0017] This catalyst was packed in a reactor, and the mixture was mixed with 5% acrolein, 10% oxygen, 30% water vapor, and 55% nitrogen (by volume).
) was passed through the mixture at a reaction temperature of 270° C. and a contact time of 3.6 seconds. When the product was collected and analyzed, it was found that the acrolein reaction rate was 99.0% and the acrylic acid selectivity was 95.0%.

Example 2 100 parts of ammonium paramolybdate, 6.2 parts of ammonium paratungstate and 16.6 parts of ammonium metavanadate were dissolved in 1000 parts of pure water. To this was added a solution prepared by dissolving 19.1 parts of ferric nitrate in 200 parts of pure water, and further added 1.9 parts of stannous oxide. Next, a solution prepared by dissolving 3.9 parts of water glass represented by the general formula Na2O. The mixture was evaporated to dryness while stirring while heating. The obtained solid material was dried at 130° C. for 16 hours, then pressure molded, and heat-treated at 380° C. for 5 hours under air circulation.

The composition of the obtained catalyst was Mo12V3S
i4.3 Fe1 Sn0.3 W0.5 Na0.7
Met. Here, the atomic ratio of Si means the sum of 0.8 from water glass and 3.5 from 20% silica sol. When this catalyst was used to react under the same conditions as in Example 1, the acrolein reaction rate was 99.2% and the acrylic acid selectivity was 95.2%.

Examples 3 to 7 Catalysts having the compositions shown in Table 1 were prepared according to Example 1, and reacted under the same conditions as in Example 1 to obtain the results shown in Table 1.

[0021]

[Table 1]

Examples 8 to 12 Catalysts having the compositions shown in Table 2 were prepared according to Example 2, and reacted under the same conditions as in Example 1 to obtain the results shown in Table 2.

[0023]

[Table 2]

Comparative Example 1 In Example 2, ammonium paratungstate 6
．． The same method as in Example 2 was used except that 2 parts and 1.9 parts of stannous oxide were added, and the composition was Mo12V3 Si4.3 F.
When a comparative catalyst of e1 Na0.7 was prepared and reacted under the same conditions as in Example 1, the acrolein reaction rate was 98.
4%, and the acrylic acid selectivity was 93.8%.

[0025]

Effects of the Invention The catalyst used in the present invention maintains high activity for a long period of time, and therefore can stably produce acrylic acid from acrolein in high yield, and has great industrial significance.

[Math 1]

[Math 1]

Claims (1)

[Claims] Claim 1: In producing acrylic acid by vapor phase catalytic oxidation of acrolein, the general formula Moa Vb Sic Nad Ae Xf Yg O
h (wherein Mo, V, Si, Na and O are each,
Molybdenum, vanadium, silicon, sodium and oxygen; A is at least one element selected from the group consisting of iron, chromium, cobalt and strontium; X is selected from the group consisting of germanium, selenium, tin, tellurium and samarium. At least one element Y represents at least one element selected from the group consisting of magnesium, titanium, copper, zinc, niobium, manganese, nickel, silver, tantalum, bismuth, cerium, and tungsten, and a=
12, b=1 to 6, c=0.1 to 15, d=0 to
2, e=0.1-3, f=0.01-3, g=0-3, and h is the number of oxygen atoms necessary to satisfy the valence of each component. ), and when the catalyst contains a sodium component, the production of acrylic acid is characterized in that sodium as a constituent element of the catalyst is derived from water glass consisting of Na2O and SiO2. Law.