阅读说明：本技术 一种酸碱复合催化剂以及使用其制备甲基丙烯醛的方法 (Acid-base composite catalyst and method for preparing methacrolein by using same ) 是由 郭振兴 崔课贤 周立亮 杨彬 于 2019-11-22 设计创作，主要内容包括：本发明涉及一种酸碱复合催化剂以及使用其制备甲基丙烯醛的方法,具体地,本发明的酸碱复合催化剂包括复合酸和复合碱。本发明的酸碱复合催化剂在用于制备甲基丙烯醛时,可表现出高活性和高稳定性,而且产品纯度高,适合于连续生产。(The invention relates to an acid-base composite catalyst and a method for preparing methacrolein by using the same, in particular to the acid-base composite catalyst which comprises a composite acid and a composite base. When the acid-base composite catalyst is used for preparing methacrolein, the acid-base composite catalyst has high activity and high stability, and the product purity is high, so that the acid-base composite catalyst is suitable for continuous production.)

1. An acid-base composite catalyst for preparing methacrolein comprises a composite acid and a composite base.

2. The acid-base composite catalyst according to claim 1, wherein the molar ratio of the composite acid to the composite base is 1: 0.5-3, preferably 1: 0.5-1.5.

3. The acid-base composite catalyst according to claim 1, wherein the composite acid comprises two or more saturated monobasic fatty acids having 1 to 4 carbon atoms and the composite base comprises two or more, preferably three or more, secondary amines.

4. The acid-base composite catalyst according to claim 3, wherein the saturated monobasic fatty acid is any one selected from formic acid, acetic acid, propionic acid and butyric acid, and the secondary amine is any one selected from dimethylamine, diethylamine, diethanolamine and dipropylamine.

5. The acid-base composite catalyst according to claim 1, wherein the composite acid comprises, preferably consists of, acetic acid and propionic acid, and the composite base comprises, preferably consists of, dimethylamine, diethylamine and diethanolamine.

6. The acid-base composite catalyst according to claim 5,

the composite acid is composed of acetic acid and propionic acid, the molar ratio of the acetic acid to the propionic acid is 1: 0.1-2, the composite base is composed of dimethylamine, diethylamine and diethanolamine, and the molar ratio of the dimethylamine, diethylamine and diethanolamine is 1: 0.1-5.

7. A method of preparing methacrolein, the method comprising: reacting formaldehyde and propionaldehyde in the presence of an acid-base composite catalyst as claimed in any one of claims 1 to 6 to produce methacrolein.

8. The method of claim 7, wherein the molar ratio of formaldehyde to propionaldehyde is 1:0.1 to 10.

9. The process of claim 8, wherein the catalyst is used in an amount of 0.01 to 4 times the weight of the reactants, based on the weight of the reactants.

10. The process according to claim 7, wherein the reaction is carried out under the following conditions:

the reaction temperature is between 30 and 200 ℃, preferably between 50 and 150 ℃, and most preferably 120 ℃; and/or the reaction time is 0.1 second to 180 minutes, preferably 3 seconds to 60 minutes; and/or the reaction pressure is 0-5 MPa.

Technical Field

The invention relates to an acid-base composite catalyst and a method for preparing methacrolein by using the same.

Background

Methacrolein is an important chemical intermediate, widely applied to polymers, and is a basic raw material in the industries of textile size, surface coating, medicine and the like. The existing synthesis method of methacrolein mainly comprises the steps of isobutene oxidation, isobutane oxidation and aldol condensation. The oxidation of isobutene and isobutane depends on petrochemical industry, a P-Mo-V catalyst is usually used, the cost is high, the efficiency is low, the catalyst dosage is large, a huge reactor is required, the service life of the catalyst is short, the selectivity is poor due to high-temperature oxidation, a large number of byproducts are generated, the subsequent separation is difficult, the separation energy consumption is high, and a large number of product impurities are generated. The condensation synthesis of methyl acrolein by formaldehyde and propionaldehyde has the advantages of mild reaction conditions, high efficiency and high yield, thereby having good application prospect.

In the preparation of methacrolein, aldol condensation is a very economical and widely used process. Usually, mannich base is prepared by reacting formalin with propionaldehyde by using an alkali catalyst or an acid-base composite catalyst, and then methacrolein is produced by thermal decomposition, and patent reports on the mannich base include JP4173762, JP3069420, US4408079, JP4173757, US4496770, JP4173757 and the like, which are carried out under the condition of single acid and/or single base, and have the defects that the temperature is higher for improving the efficiency, more polymerization byproducts (oligomers such as dimer and the like) are generated, and impurities and organic base enter the product and are difficult to separate, so that the subsequent use is influenced.

Therefore, there is still a need to develop a catalyst that can efficiently produce methacrolein.

Disclosure of Invention

The present invention aims to provide a catalyst capable of efficiently producing methacrolein and a method for producing methacrolein using the same.

In one aspect, the present invention provides an acid-base composite catalyst for preparing methacrolein, which includes a composite acid and a composite base.

In a specific embodiment, the molar ratio of the complex acid to the complex base is 1: 0.5-3, preferably 1: 0.5-1.5.

In a specific embodiment, the complex acid comprises two or more saturated monobasic fatty acids having 1 to 4 carbon atoms and the complex base comprises two or more secondary amines, preferably, three or more secondary amines.

In a specific embodiment, the saturated monobasic fatty acid may be selected from any of formic acid, acetic acid, propionic acid and butyric acid, and the secondary amine may be selected from any of dimethylamine, diethylamine, diethanolamine, dipropylamine.

In a preferred embodiment, the complex acid comprises, preferably consists of, acetic acid and propionic acid, and the complex base comprises, preferably consists of, dimethylamine, diethylamine and diethanolamine.

In a preferred embodiment, the complex acid is composed of acetic acid and propionic acid, and the molar ratio of acetic acid to propionic acid may be 1: 0.1-2, the complex base is composed of dimethylamine, diethylamine and diethanolamine, and the molar ratio of dimethylamine, diethylamine and diethanolamine may be 1: 0.1-5.

In another aspect, the present invention provides a method for preparing methacrolein, the method including: methacrolein is produced by reacting formaldehyde and propionaldehyde in the presence of the above-mentioned catalyst.

In particular embodiments, the formaldehyde may be provided in the form of foliomalin.

In a specific embodiment, the molar ratio of formaldehyde to propionaldehyde can be 1: 0.1-10.

In a specific embodiment, in the above method, the catalyst may be used in an amount of 0.01 to 4 times the weight of the reactants.

In a particular embodiment, in the above process, the reaction temperature is between 30 and 200 ℃, preferably between 50 and 150 ℃, most preferably 120 ℃.

In a specific embodiment, in the above method, the reaction time may be 0.1 second to 180 minutes, preferably 3 seconds to 60 minutes.

In a specific embodiment, in the above process, the reaction pressure may be 0 to 5 MPa.

In a specific embodiment, in the above process, a combination of a tank reactor and a tubular reactor may be used.

In a specific embodiment, in the above method, the reaction temperature in the tank reactor is 50 to 70 ℃, and the reaction temperature in the tubular reactor is 110 to 150 ℃.

Advantageous effects

When the acid-base composite catalyst is used for preparing the methacrolein, the conversion rate of raw materials and the selectivity of a product can reach more than 93 percent, the content of organic base in the product is as low as less than 1ppm, and the catalyst also has high stability and is suitable for continuous production.

Therefore, the acid-base composite catalyst for preparing methacrolein of the present invention has advantages of ensuring catalytic activity, reducing component loss and byproduct generation, and preventing impurities and organic base from entering into final products.

Detailed Description

Hereinafter, the present invention will be described by way of specific examples so that those skilled in the art can well understand the technical aspects of the present invention. The scope of the present invention is not limited by these embodiments but includes various modifications similar or equivalent to the embodiments described below, which can be understood and made by those skilled in the art.

Term(s) for

In this context, the term "complex" refers to a collection of more than one substance, which in the present application may refer to an acid, but also to a base.

In the following examples, the reaction effect analysis method is as follows: sampling the system before and after the reaction, and performing GC analysis, wherein the conversion rate is (mole of propionaldehyde added-remaining mole of propionaldehyde)/mole of propionaldehyde added 100%; selectivity to methacrolein moles/(moles of propionaldehyde added-remaining moles of propionaldehyde) 100%. The organic base content was determined by gas chromatography-mass spectrometry.