JPH0532582A - Production of acrylic acid - Google Patents

Abstract

PURPOSE:To produce acrylic acid by catalytically oxidizing acrolein in the vapor phase in the presence of a catalyst. CONSTITUTION:A catalyst is expressed by the general formula MoaVbSicNadAeXfYgOh (Mo, V, Si, Na and O denote respective elements; A denotes at least one selected from Fe, Cr, Co and Sr; X denotes at least one selected from Ca, Mn, Ni, As, Ba, Pb and Ce; Y denotes at least one selected from Mg, Ti, Cu, Zn, Nb, Ag, Ta, Bi and W; when (a) is 12, (b) is 1-6; (c) is 0.1-15; (d) is 0.1-2; (e) is 0.1-3; (f) is 0.01-3; (g) is 0-3 and (h) is the number of oxygen atoms required to satisfy the valences of the respective components) and the starting raw material of Na is derived from water glass composed of Na2O and SiO2. The resultant catalyst is used.

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a process for the production of acrylic acid by the vapor phase catalytic oxidation of acrolein, in particular to the catalyst used.

[0002]

2. Description of the Related Art Conventionally, a method for producing acrylic acid by vapor-phase catalytic oxidation of acrolein has been disclosed in JP-A-49-472.
No. 76, No. 50-84521, No. 52-153889.
No. 53-7614, No. 58-166939 and the like have been proposed in great numbers, but it is desired to further improve the performance as an industrial catalyst.

[0003]

The present invention is particularly active,
An object of the present invention is to provide a method for advantageously producing acrylic acid from acrolein by using a catalyst having high selectivity and long life.

[0004]

According to the present invention, when acrolein is subjected to vapor-phase catalytic oxidation to produce acrylic acid, the general formula Mo _a V _b Si _c Na _d A _e X _f Y _g O _h (in the formula, Mo , V, Si, Na and O are molybdenum, vanadium, silicon, sodium and oxygen, A, respectively.
Is at least one element selected from the group consisting of iron, chromium, cobalt and strontium, X is calcium,
At least one element selected from the group consisting of manganese, nickel, arsenic, barium, lead and cerium, Y is selected from the group consisting of magnesium, titanium, copper, zinc, niobium, silver, tantalum, bismuth and tungsten. At least one element is shown, and when a = 12, b = 1 to
6, c = 0.1-15, d = 0.1-2, e = 0.1
3, f = 0.01 to 3, g = 0 to 3, and h is the number of oxygen atoms required to satisfy the valence of each component)
And a starting material of sodium is a catalyst derived from water glass consisting of Na ₂ O and SiO ₂ .

The present invention makes it possible to obtain acrylic acid from acrolein in high yield using a catalyst which maintains high activity for a long period of time. The catalyst used in the present invention is
It is necessary to use water glass composed of Na ₂ O and SiO ₂ as a starting material for sodium. Commonly used as water glass is the general formula Na ₂ O ・ nSiO ₂・ nH
Designated by ₂ O. Here, n means a molar ratio, and n = 2
Liquid products of ~ 4 are said to be water glass.

When a raw material other than water glass is used as the raw material of sodium, for example, sodium acetate, sodium bicarbonate, sodium chloride, sodium hydroxide, sodium nitrate, sodium nitrite, etc., it is superior to the case of using water glass. A catalyst with performance cannot be obtained. Therefore, in the general formula of the catalyst used in the present invention, most of the silicon raw materials are other raw materials, for example, silicon dioxide such as silica sol and silica gel, but from the water glass used as the sodium raw material. The value obtained by adding the amount of silicon dioxide is the atomic ratio of silicon.

As the raw material compounds of elements other than sodium, nitrates, carbonates, ammonium salts, sulfates, oxides and the like of each element can be used in combination.

The method of preparing the catalyst used in the present invention does not have to be limited to a special method, and as long as there is no significant uneven distribution of components, the well-known evaporation-drying method, precipitation method and oxidation method are used. Various methods such as a material mixing method can be used.

The catalyst used in the present invention is effective even without a carrier, but it is supported on an inert carrier such as silica, alumina, silica-alumina, silicon carbide, magnesia, titania, or diluted with them. It is preferable to use.

In the production of acrylic acid by vapor-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 over a wide range, but the volume is 1 to 20%, particularly The range of 3 to 10% is preferable.

The raw material acrolein may contain a small amount of impurities such as water and lower saturated aldehydes, and these impurities do not substantially affect the reaction. It is economical to use air as the oxygen source, but 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 with respect to acrolein, and this value is 0.3 to 4, especially 0.1.
4-2.5 is preferable. The raw material gas may be diluted by adding an inert gas such as nitrogen, steam or carbon dioxide gas. The reaction pressure is preferably normal pressure to several atmospheres. Reaction temperature is 200-4
20 degreeC and especially 220-400 degreeC are preferable. The reaction can be carried out in a fixed bed or a fluidized bed.

[0013]

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples. In the text, “part” means part by weight. The reaction rate of acrolein and the selectivity of acrylic acid produced are defined as follows. The analysis was by gas chromatography.

[0014]

[Equation 1]

[0015]

[Equation 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, a solution prepared by dissolving 19.1 parts of ferric nitrate in 200 parts of pure water was added, and further 3.7 parts of barium nitrate was added to 2 parts of pure water.
A solution dissolved in 00 parts was added. Next, the general formula Na ₂ O
2.2SiO 3.9 parts of water glass represented by ₂ · 2.2H ₂ O, and the solution was added dissolved in pure water 30 parts, further 2
49.6 parts of 0% silica sol was added, and the mixture was evaporated to dryness with heating and stirring.

The solid obtained was dried at 130 ° C. for 16 hours, pressure-molded, and then heat-treated at 380 ° C. for 5 hours under air flow, which was used as a catalyst. The composition of the elements other than oxygen of the obtained catalyst (hereinafter the same) is Mo ₁₂ V ₃ Si _4.3 Na
_{It was 0.7} Fe ₁ Ba _0.3 . Here, the atomic ratio of Si is 0.8 from water glass and 3. from 20% silica sol.
It means a value obtained by adding 5.

This catalyst was charged into a reactor, and a mixed gas of 5% acrolein, 10% oxygen, 30% steam and 55% nitrogen (volume%) was passed through at a reaction temperature of 270 ° C. and a contact time of 3.6 seconds. When the product was collected and analyzed by gas chromatography, the acrolein conversion was 99.1% and the acrylic acid selectivity was 95.3%.

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, a solution prepared by dissolving 9.5 parts of ferric nitrate in 200 parts of pure water was added, and further 6.9 parts of cobalt nitrate was dissolved in 200 parts of pure water. 4.1 parts of manganese nitrate was added to 200 parts of pure water. What was melt | dissolved in was added one by one. Next, the general formula Na ₂ O · 2.2Si
A solution prepared by dissolving 3.9 parts of water glass represented by O ₂ .2.2H ₂ O in 30 parts of pure water was added, 49.6 parts of 20% silica sol was further added, and the mixture was evaporated to dryness while heating and stirring. did.

The solid obtained was dried at 130 ° C. for 16 hours, pressure-molded, and then heat-treated at 380 ° C. for 5 hours under air flow to be used as a catalyst. The composition of the obtained catalyst is M
_{o 12 V 3 Si 4.3 Na 0.7} Fe 0.5 Co 0.5 Mn 0. 3 W
It was _0.5 . Here, the atomic ratio of Si means a value obtained by adding 0.8 from water glass and 3.5 from 20% silica sol. When this catalyst was used for the reaction under the same conditions as in Example 1, the acrolein conversion was 99.2% and the acrylic acid selectivity was 95.4%.

Examples 3 to 10 Each catalyst having the composition shown in Table 1 was prepared according to Example 1,
The reaction was carried out under the same conditions as in the example. The results are shown in Table 1.

[0022]

[Table 1]

Comparative Example 1 The same method as in Example 1 was repeated except that 3.7 parts of barium nitrate was omitted, and the composition was Mo ₁₂ V ₃ Si _4.3 N.
When a comparative catalyst of a _0.7 Fe ₁ was prepared and reacted under the same conditions as in Example 1, the acrolein conversion was 98.4% and the acrylic acid selectivity was 93.8%.

[0024]

INDUSTRIAL APPLICABILITY The catalyst used in the present invention maintains high activity for a long period of time, and therefore acrylic acid can be stably produced from acrolein in a high yield, and its industrial value is extremely large.

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[Procedure amendment]

[Submission date] December 12, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

As a method of, prepare catalyst used in the present invention need not be limited to a special method, unless accompanied by significant uneven distribution of components, evaporation to dryness method is well known in the art, precipitation, Various methods such as an oxide mixing method can be used.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

[0015]

[Equation 2]

Claims (1)

The Patent Claims 1 acrolein in producing the gas phase catalytic oxidation of acrylic acid, the general formula _{Mo a V b Si c Na d} A e X f Y g O h ( wherein, Mo, V , Si, Na and O are 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 calcium,
At least one element selected from the group consisting of manganese, nickel, arsenic, barium, lead and cerium, Y is selected from the group consisting of magnesium, titanium, copper, zinc, niobium, silver, tantalum, bismuth and tungsten. At least one element is shown, and when a = 12, b = 1 to
6, c = 0.1-15, d = 0.1-2, e = 0.1
3, f = 0.01 to 3, g = 0 to 3, and h is the number of oxygen atoms required to satisfy the valence of each component. ) And the sodium starting material is Na
_A method for producing acrylic acid, which comprises using a catalyst derived from water glass composed of ₂ O and SiO ₂ .