JPS6270342A - Production of methacrylic acid ester - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield, by catalytically reacting isobutylene and/or tert-butanol, nitric acid and an alcohol in the vapor phase in the presence of a catalyst. CONSTITUTION:Isobutylene and/or tert-butanol, nitric acid and an alcohol are reacted in the vapor phase in the presence of a catalyst, e.g. cobalt oxide, to give a methacrylic acid ester. The reaction temperature is within 150-500 deg.C, preferably 200-450 deg.C range. The nitric acid to be used is fuming nitric acid or aqueous solution of nitric acid, i.e. dinitrogen pentoxide. The alcohol to be used is a 1-4C alcohol except tert-butanol and >=1mol, based on 1mol isobutylene or tert-butanol, alcohol is preferably used. The aimed compound is obtained from the inexpensive raw material in one stage and NO2 and water formed as by-products can be reused as the nitric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel method for producing methacrylic esters. More specifically, isobutylene or t,
The present invention relates to a method for producing methacrylic ester by reacting ert-butanol, nitric acid, and alcohol.

(Prior Art) Conventionally, a method for producing methacrylic acid by oxidizing imbutylene with oxygen in the gas phase in the presence of a catalyst is already known. However, the yield is as low as about 25%. (Special Publication No. 42-5403).

Furthermore, a two-stage oxidation method for producing methacrylic acid from inbutylene via mecchlorene is being studied.

Therefore, a one-step method for producing methacrylic acid or methacrylic acid ester from inbutylene has not yet been industrialized.

(Problems to be Solved by the Invention) The object of the present invention is to produce isobutylene or tert-
The object of the present invention is to provide a method for producing methacrylic acid ester from butanol in one step.

(Means for solving the problem) As a result of various studies regarding the above object, the present inventors have developed a method for directly oxidizing isobutylene, in which oxygen is used as the oxidizing agent in place of the conventionally used oxygen. We have discovered that methacrylic acid can be obtained in high yield by using nitric acid, but this time we have discovered that methacrylic acid ester can be obtained in high yield by further adding alcohol to the reaction system. I arrived at a method of invention.

That is, the present invention provides imbutylene or t:ert-
This is a method for producing methacrylic acid ester, which is characterized by subjecting butanol, nitric acid, and alcohol to a gas phase catalytic reaction in the presence of a catalyst.

In the method of the present invention, imbutylene or tert-butanol, nitric acid, and alcohol are used as raw materials and subjected to a gas phase contact reaction in the presence of a catalyst. The reaction is thought to proceed, for example, as shown in the following equation.

CH.

(R represents an alkyl group having 1 to 4 carbon atoms) The nitric acid used in the method of the present invention is fuming nitric acid, 100φ nitric acid, an aqueous nitric acid solution or nitric anhydride, that is, dinitrogen pentoxide. Usually, an aqueous solution is most desirable, and its concentration is not particularly limited, but a nitric acid aqueous solution with a concentration of 0.01 to 60% is preferred. In addition, nitric acid is dinitrogen pentoxide N20. Since it is an aqueous solution of water, the present invention can be carried out by using dinitrogen pentoxide in place of nitric acid in the coexistence of water. Furthermore, water may be added directly to the reaction atmosphere separately from nitric acid.

In order for all isobutylene or tert-butanol to be converted into methacrylic acid ester, the amount of inbutylene or tert-butanol and nitric acid to be used is 6 to 1 mol per mol of isobutylene or tert-butanol, as shown in the above formula. It is desirable to use more than a molar amount of nitric acid. However, it is not particularly limited.

The alcohol used in the present invention is tert = alcohol having 1 to 4 carbon atoms excluding butanol,
For example, methanol, ethanol, n-propanol, 15O-propanol, n-butanol, 5ec-butanol, 1so-butanol. In order to convert all of the inbutylene or tert-butanol into methacrylic acid ester, the amount of alcohol used is 1 mole or more of alcohol per 1 mole of isobutylene or tert-butanol, as shown in the above formula. It is preferable to use However, it is not particularly limited.

The catalyst used in the method of the invention is an oxidation catalyst. Examples of such oxidation catalysts include catalysts used for oxidation reactions of aromatic compounds listed on pages 46-47 of Reaction Catalyst Classification Table 1 (edited by Tarama Laboratory, Kyoto University, published by Kagaku Kogyosha). It will be done. Specifically, vanadium, molybdenum,
oxides of elements selected from the group consisting of bismuth, tungsten, chromium, cobalt, iron, nickel, titanium, lead, silver, platinum, palladium, phosphorus, manganese and copper;
It is a catalyst containing an organic acid salt or at least one metal selected from the group consisting of silver, platinum, and palladium. For example, cobalt oxide, nickel oxide, titanium oxide, lead oxide, iron oxide, steel oxide, chromium oxide, vanadium oxide, molybdenum oxide, zinc oxide, bismuth oxide,
Oxides such as tungsten oxide, cerium molybutate, cobalt naphthenate, cobalt oleate, cobalt phthalate, cobalt tolylate, cobalt stearate, cobalt acetate, manganese rosinate, manganese naphthenate, silver vanadate, copper vanadate , with manganese acetate,
These may be used alone or in combination of two or more. Further, metals such as silver, platinum, and palladium are used alone or in combination. These oxides or metals may be supported on a carrier. As a carrier, silica,
As the catalyst carrier, one or more of commonly used catalyst carriers such as alumina, silica-alumina, zeolite, diatomaceous earth, activated clay, titanium oxide, magnesium oxide, zinc oxide, and boron oxide can be used. Among the above catalysts, catalysts containing vanadium oxide and molybdenum oxide are particularly preferred.

Catalysts containing oxides can be prepared by conventional methods. For example, according to the immersion method, salts containing the metals constituting these oxides are dissolved in water, and a support such as silica or alumina is immersed in the aqueous solution, followed by drying and thermal decomposition. Manufacture. For example, according to the precipitation method, a carrier such as silica or alumina is added to an aqueous solution of a salt containing the metal constituting these oxides, and an alkali substance is added while stirring to form a precipitate. It is prepared by filtering, washing, drying and calcining the precipitate. In addition, there are various catalyst preparation methods, and there are no limitations on the catalyst preparation method.

Further, in the above catalyst, there is no particular restriction on the amount of the catalyst component supported on the carrier, and it is generally sufficient to support an appropriate amount depending on the carrier. Generally, o, oi ~ 100 mil 100
The amount of water is sufficient. Of course, the catalyst components may be used without being supported on a carrier.

In the method of the present invention, the reaction atmosphere is not particularly limited, and may be any of an inert gas atmosphere, an oxidizing active gas atmosphere, or a reducing gas atmosphere.

Inert gases include nitrogen, helium, argon, etc., and oxidizing active gases include oxygen, ozone, and nitrogen oxides. These inert residues and active gas may be used in combination. Further, examples of reducing gases include hydrogen, ammonia, hydrazine, and carbon oxide. These reducing gases may be mixed with inert gas.

In the method of the present invention, the reaction temperature is 150 to 500°C,
Preferably it is in the range of 200 to 450°C. If the temperature is lower than 150°C, the yield of methacrylic ester is low, and if the temperature exceeds 500°C, the yield of methacrylic ester decreases, and a large amount of acetic acid is produced as a by-product, which is not preferable.

The method of the invention can be carried out in the gas phase.

All four can be implemented in fixed bed, fluidized bed or moving bed reactors. In addition, in the presence of the catalyst substance in the reactor or reaction tube, inbutylene or tert, -
It is carried out by heating vapors of butanol and old alcohol nitric acid. At this time, by adding water or steam to the raw material vapor, Nisdel methacrylate can be obtained in a higher yield and more safely.

In the method according to the present invention, Nisder methacrylate can be easily separated and purified from the reaction product by an appropriate method, for example, a conventional method such as distillation.

In the method of the present invention, the by-product nitrogen dioxide and water can be reacted with oxygen or an oxygen-containing gas such as air and used again as nitric acid.

(Functions and Effects) A methacrylic acid ester can be produced in one step by subjecting isobutylene or tert-butanol, nitric acid, and alcohol to a gas phase contact reaction in the presence of a catalyst.

This method has the following advantages. First, the raw material is inbutylene or tert-butanol, which is inexpensive. Second, methacrylic acid ester is produced from raw materials in one step. Fifth, the yield of methacrylic acid ester is high. Fourthly, nitrogen dioxide and water produced as by-products can be reacted with an oxygen-containing gas to form nitric acid, which can be used again.

That is, the present invention provides a novel reaction as a method for producing methacrylic acid ester, and a method that can be carried out industrially advantageously.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 V2 by dipping method of granular ammonium metavanadate
05/S 102 catalyst (V2O5 content 5ch) 5om
1 was filled into a Pyrex glass flow-through reactor having an inner diameter of 25 mm. The front part of this reactor is connected to a raw material insertion pipe and a gas introduction pipe to constitute a raw material vaporization part, and the rear part is connected to a receiver via an air cooling part. The reaction section maintains the internal temperature of this reactor at 250°C, and the liquid hourly space velocity is OAl/l-catalyst/kl.
r, isobutylene 0.56 j! (0,01moJ(1
) (!: 21.0 g (0.1 mol) of 50% nitric acid aqueous solution (!: 5.29 (0.1 mol) of methanol was separately inserted through the raw material insertion tube, and at the same time, 10 g of 50% nitric acid aqueous solution was added to the raw material imbutylene. Double the molar amount of nitrogen was passed under normal pressure.

When the reaction product passed through the reactor and was condensed was analyzed by gas chromatography, 0.4711 methyl methacrylate was produced, the conversion rate of inbutylene was 935 cm, and the selectivity was 50.
``Methyl methacrylate (abbreviation), AMA) was obtained with a yield of 47.0% and a yield of 47.0%, and a small amount of methacrylic acid and acetone acetate were obtained as by-products. Examples 2 to 16 In Example 1, the catalyst The results of an experiment conducted in the same manner as in Example 1 in the same reaction apparatus as in Example 1, using the catalyst shown in Table 1 instead of V2O, /Sin, and setting the reaction temperature to 250 ° C. are shown in Table 1.

11-Example 17 In Example 1, the catalyst was replaced with V2O,-Mob3/5in2 catalyst ("205 content 3
Mob, content 3%), and 0.74 g of tert-butanol (0,0
As a result, 0.47 g of MMA was produced, and the reaction temperature was 275°C using the same reaction apparatus as in Example 1. As a result, 0.47 g of MMA was produced, and the conversion of tert-butanol was rate 100%, selectivity 472% and yield 47
．． MMA was obtained at 2%, and small amounts of methacrylic acid, acetic acid, and acetone were obtained as by-products.

Examples 18-62 In Example 17, the catalyst was V2O, -Mob3/5i
Using the catalyst shown in Table 2 instead of n2, the reaction temperature was set to 2.
Table 2 shows the results of an experiment conducted in the same manner as in Example 17 using the same reaction apparatus as in Example 17 at 75°C.

Example 3 In Example 17, 4.6 g (0.1 mol) of ethanol was used instead of mechnol, and in the same reaction apparatus as in Example 17, Example 17 (!: in the same manner) was used. As a result of the reaction, 058g of ethyl methacrylate was produced,
tort-“Buknol conversion rate 100%, selectivity 3
Ethyl methacrylate was obtained in 37% and yield of 637%.

Example 64 In Example 17, methanol was added to n-p[
A reaction was carried out in the same manner as in Example 17 using 1 panol 6, OF (0.1 mol) in the same reaction apparatus as in Example 17, and as a result, 0.26 g of propyl methacrylate was produced, Propyl methacrylate was obtained with a conversion of tert-bucnol of 100%, a selectivity of 20.5%, and a yield of 20.5%.

Example 35 In Example 17, methanol was replaced with r1-bucnol 7.4,! Using i' (0.1 mol), a reaction was carried out in the same reactor as in Example 17 and in the same manner as in Example 17. As a result, butyl methacrylate of 018y was produced, and the tert-buknol conversion rate was Butyl methacrylate was obtained with a selectivity of 128% and a yield of 128%.

Claims (1)

[Scope of Claims] 1) A method for producing methacrylic acid ester, which comprises subjecting isobutylene and/or tert-butanol, nitric acid, and alcohol to a gas phase contact reaction in the presence of a catalyst. 2) The production method according to claim 1, wherein the gas phase catalytic reaction is carried out in the presence of water.