JP3024863B2 - Method for producing methacrylic acid and its ester - Google Patents

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 methacrylic acid having one carbon atom and / or an ester thereof by reacting propionic acid with formaldehyde or a formaldehyde derivative in the gas phase in the presence of a catalyst.

[0002]

2. Description of the Related Art Various catalysts for producing methacrylic acid and its esters from propionic acid and formaldehyde or formaldehyde derivatives have been proposed. For example, in U.S. Pat. No. 3,247,248, propionic acid and formaldehyde are reacted with a catalyst in which potassium hydroxide is supported on silica gel or calcium aluminosilicate is used as a catalyst. In addition, Japanese Unexamined Patent Publication No.
SiO ₂ The 7-123138 discloses -Al ₂ O ₃ to K, V, catalyst supporting Sb, JP 61-22984
No. 0 discloses a catalyst in which V and P are supported on ZrO ₂ —Al ₂ O ₃ , and JP-A-62-36340 discloses an active Al
A catalyst in which an alkali metal is supported on ₂ O ₃ has been proposed.

[0003]

However, these catalysts often have insufficient yields of the desired product. In addition, in the reaction between propionic acid and formaldehyde or a formaldehyde derivative, if the reaction is carried out for a long time, high-boiling substances and carbonaceous materials mainly derived from formaldehyde are deposited, and it is difficult to stably maintain the activity of the catalyst for a long time. there were. An object of the present invention is to obtain the desired product in a high yield and a high selectivity by improving the catalyst, and to add oxygen to the raw material gas to eliminate the above-mentioned disadvantages and maintain the reaction stably for a long time. Is to do.

[0004]

That is, the present invention relates to a method for producing methacrylic acid and its ester by reacting propionic acid with formaldehyde or a formaldehyde derivative in the gas phase to produce methacrylic acid and its ester. Represents silicon, cesium, tungsten, and oxygen, respectively, and X represents at least one element selected from the group consisting of silver, niobium, magnesium, aluminum, nickel, zinc, molybdenum, chromium, antimony, titanium, and platinum. Where a,
b, c, d and e represent the atomic ratio of each element, and a = 1
When 0, b = 0.1-1, c = 0.1-1, d = 0-1
And e is the number of oxygen atoms necessary to satisfy the valence of each component. A method for producing methacrylic acid characterized by using a catalyst represented by the formula (1), and a method for keeping the reaction stable for a long period of time by including 0.1 to 10% by volume of molecular oxygen in a raw material gas. And a method for simultaneously producing methacrylic acid and methacrylic acid ester by containing a lower alcohol in the raw material gas.

The formaldehyde or formaldehyde derivative used as a starting material for the reaction of the present invention includes a formaldehyde methanol solution, methylal, trioxane,
Paraformaldehyde and the like, and these may be used as a mixture with formaldehyde or an aqueous formaldehyde solution. When a methanol solution or the like is used as formaldehyde, methacrylic acid esters can be produced together with methacrylic acid according to the amount of methanol supplied.

As the raw material compound used for preparing the catalyst, nitrate, carbonate, ammonium salt, halide, oxide and the like of each element can be used in combination. The catalyst used in the method of the present invention is effective without a carrier, but may be supported on a carrier such as magnesium oxide or titanium oxide. The supporting method is not particularly limited, but various methods such as an impregnation method, a kneading method, and a coprecipitation method can be used. The catalyst of the present invention is generally used in a fixed bed, but can also be used in a fluidized bed.

The ratio of the supplied amount of propionic acid to the total supplied amount of formaldehyde and its derivatives is suitably from 1:10 to 10: 1 in terms of the molar ratio of the formaldehyde derivative to formaldehyde, especially 1: 5. ~
5: 1 is preferred. These raw materials are supplied as a mixed gas and are brought into contact with the catalyst in gaseous form. In this case, the source gas may be diluted by adding an inert gas such as nitrogen or carbon dioxide, or may contain water vapor.

The space velocity (SV) on the catalyst is 50 to 500.
0 ml / hr / ml-cat. Can be selected in the range of 100 to 3000 ml / hr / ml-ca.
t. Is preferred. The reaction temperature can be selected in the range of 200 to 500 ° C, and particularly preferably 250 to 450 ° C.

In the case where molecular oxygen is added to the raw material gas, the amount of oxygen is set to 0.1.
The content is adjusted so as to be 1 to 10% by volume, particularly preferably 1 to 6% by volume. By adding molecular oxygen, the activity of the catalyst can be kept high for a long time.

In the reaction between propionic acid and formaldehyde or a formaldehyde derivative, if the reaction is carried out for a long time, carbonaceous substances are deposited on the catalyst, and it is difficult to maintain the activity stably for a long time. However, it is possible to regenerate the catalyst inside or outside the reactor at a temperature of about 500 ° C. to 600 ° C. in an oxygen-containing gas atmosphere or in the presence of an oxygen-containing gas and steam. Therefore, the reaction can be performed for a long time by applying the above method.

In the present invention, when methacrylic acid and a methacrylic acid ester are to be obtained at the same time, a lower alcohol such as methanol or ethanol is contained in the raw material gas. The lower alcohol can be supplied into the raw material gas mixture by a metering pump, or may be supplied by mixing with formaldehyde.

[00012]

The method of the present invention will be described in more detail with reference to the following Examples and Comparative Examples. In the examples, "parts" means parts by weight, and the conversion of propionic acid and the selectivity of methacrylic acid and its ester formed are defined as follows.

[0013]

(Equation 1)

[0014]

(Equation 2)

[0015]

(Equation 3)

Example 1 2.6 parts of cesium nitrate and 3.5 parts of ammonium paratungstate were heated and mixed with 200 parts of pure water. After 100 parts of 20% silica sol was added thereto with stirring, the mixture was heated and evaporated to dryness. The obtained solid product was dried at 120 ° C. for 17 hours, molded under pressure, and heat-treated at 500 ° C. for 5 hours in an air stream to use as a catalyst. The composition of the elements other than oxygen in the obtained catalyst (the same applies hereinafter) is Si ₁₀ Cs _0.4 W _0.4 , and the catalyst is filled in a reactor, and contains 10.0% by weight of propionic acid and a small amount of methanol. Formaldehyde 7.4%, nitrogen 82.
6% raw material gas at reaction temperature 330 ° C, space velocity 800m
l / hr / ml-cat. Supplied with

After one hour, the product was collected and analyzed by gas chromatography. As a result, the conversion of propionic acid was 37.9%, the selectivity of methacrylic acid was 95.0%, and the selectivity of methyl methacrylate was 2 0.5%.

Example 2 In Example 1, 4.6% of oxygen was added to the raw material gas, so that the molar fraction of nitrogen was 78.0%.
When the reaction was carried out in the same manner as in Example 1 using the raw material gas prepared as above, the conversion of propionic acid at the point of time one hour after the start of the reaction was 39.8%, and the selectivity of methacrylic acid was 86.
The selectivity for methyl methacrylate was 2.4%, but the conversion of propionic acid was 39.8 even after 10 days.
%, The selectivity of methacrylic acid was 86.8%, and the selectivity of methyl methacrylate was 2.4%, and the same catalyst performance as in the initial stage of the reaction was maintained.

Example 3 2.6 parts of cesium nitrate, 0.3 part of silver nitrate and 3.5 parts of ammonium paratungstate
Was heated and mixed with 200 parts of pure water. After 100 parts of 20% silica sol was added thereto with stirring, the mixture was heated and evaporated to dryness. The obtained solid product was dried at 120 ° C. for 17 hours, molded under pressure, and heat-treated at 500 ° C. for 5 hours in an air stream to use as a catalyst. The composition of the resulting catalyst was Si ₁₀
Cs _0.4 W _0.4 Ag _0.05 . When reacted under the same conditions as in Example 1, the conversion of propionic acid was 40.5%,
The selectivity of methacrylic acid was 96.1%, and the selectivity of methyl methacrylate was 2.6%.

Example 4 The reaction was carried out under the same conditions as in Example 3 except that oxygen was added at 4.6% and nitrogen was set at 78.0%. The conversion of propionic acid at one hour from the start of the reaction was confirmed. 41.3%, selectivity of methacrylic acid
7% and a selectivity of methyl methacrylate of 2.5%.
Further conversion of propionic acid after 10 days has passed 4
The selectivity for methacrylic acid was 1.3%, the selectivity for methyl methacrylate was 2.5%, and the same catalytic performance as in the initial stage of the reaction was maintained.

EXAMPLE 5 The catalyst of Example 3 was charged into a reactor, and a raw material gas containing 10.0% by weight of propionic acid, 7.4% of formaldehyde and 82.6% of nitrogen was reacted at a reaction temperature of 330 ° C. , Space velocity 800 ml / hr / ml-cat.
Supplied with After 1 hour, the product was collected and analyzed by gas chromatography. As a result, the conversion of propionic acid was 40.5% and the selectivity of methacrylic acid was 98.8%.

Example 6 The catalyst of Example 3 was charged into a reactor, and propionic acid 10.0%, formaldehyde 7.4%, methanol 10.0%, and nitrogen 72.6 were used in terms of mole fractions.
% Raw material gas at a reaction temperature of 330 ° C and a space velocity of 800 ml
/ Hr / ml-cat. Supplied with After 1 hour, the product was collected and analyzed by gas chromatography. The conversion of propionic acid was 41.3%, the selectivity of methacrylic acid was 32.3%, and the selectivity of methyl methacrylate was 64.
6%.

[Examples 7 to 14] Table 1 in accordance with Example 1
Were prepared and reacted under the same conditions as in Example 1 (a raw material gas containing 10.0% by weight of propionic acid, 7.4% of formaldehyde containing a small amount of methanol, and 82.6% of nitrogen). did. Table 1 shows the results.

[0024]

[Table 1]

[Comparative Example 1] In Example 1, cesium nitrate and ammonium paratungstate were not added.
Therefore, a comparative catalyst consisting only of Si was prepared. When the reaction was carried out using this catalyst under the same conditions as in Example 1, the conversion of propionic acid was 64.0% and the selectivity of methacrylic acid was 9.5.
%, Almost no methyl methacrylate was formed.

Comparative Example 2 A comparative catalyst was prepared in the same manner as in Example 1 except that cesium nitrate was not added, that is, Si ₁₀ W _0.4 was used. When the reaction was carried out under the same conditions as in Example 1 using this catalyst, the conversion of propionic acid was 38.5%, the selectivity of methacrylic acid was 26.0%, and the selectivity of methyl methacrylate was 1.
4%.

Comparative Example 3 In Example 1, no ammonium paratungstate was added, that is, Si ₁₀ Cs
_A comparative catalyst of _0.4 was prepared. Example 1 using this catalyst
When the reaction was carried out under the same conditions as in
The selectivity was 3.5%, the selectivity for methacrylic acid was 37.1%, and the selectivity for methyl methacrylate was 1.1%.

Example 15 Using the catalyst of Example 1, the reaction was continued for 10 days without adding oxygen to the raw material gas. As a result, the conversion of propionic acid was 37.5%, and the selectivity of methacrylic acid was 93.2.
% And a selectivity of methyl methacrylate of 2.4%, the catalyst performance was slightly reduced.

[0029]

According to the present invention, the use of a novel catalyst makes it possible to improve the yield of methacrylic acid and stably maintain the reaction for a long period of time. Can be co-produced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C07C 51/347 C07C 67/08 67/08 69/54 Z 69/54 C07B 61/00 300 // C07B 61/00 300 B01J 23 / 64 103X (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 57/05 C07C 51/347 C07C 67/08 C07C 69/54 CAPPLUS (STN) REGISTRY (STN) WPIDS (STN)

Claims (3)

(57) [Claims] In producing methacrylic acid by reacting propionic acid with formaldehyde or a formaldehyde derivative in the gas phase, a general formula SiaCsbWcXdOe (wherein Si, Cs, W and O represent silicon, cesium, tungsten and oxygen, respectively) X represents at least one element selected from the group consisting of silver, niobium, magnesium, aluminum, nickel, zinc, molybdenum, chromium, antimony, titanium, and platinum, where a,
b, c, d and e represent the atomic ratio of each element, and a = 1
When 0, b = 0.1-1, c = 0.1-1, d = 0-1
And e is the number of oxygen atoms necessary to satisfy the valence of each component. A method for producing methacrylic acid, comprising using a catalyst represented by the following formula: 2. The method for producing methacrylic acid according to claim 1, wherein the raw material gas contains 0.1 to 10% by volume of molecular oxygen. 3. The method for producing methacrylic acid and its ester according to claim 1, wherein the raw material gas contains a lower alcohol.