A kind of catalyst for synthesizing demma and its preparation method, application

Abstract

The invention discloses a supported modified zeolite molecular sieve catalyst, which comprises a modified zeolite molecular sieve carrier and a loaded active component, wherein, the modified zeolite molecular sieve carrier is prepared by modifying the zeolite molecular sieve, including: combining the molecular sieve with an alkali metal The alkaline solution of the elements is mixed, washed, dried, and roasted to obtain a preliminary modified carrier; the preliminary modified carrier is impregnated with a soluble compound solution containing lanthanides and boron, dried, and roasted to obtain oxides containing lanthanides and three The modified zeolite molecular sieve carrier of diboron oxide. The invention also discloses the preparation method of the catalyst and the application in synthesizing DEMMA. The catalyst of the invention has high raw material conversion rate, good product selectivity and few by-products, and meanwhile, the catalyst preparation process is simple and economical, and has good application prospect.

Description

technical field [0001] The invention relates to a method for preparing an environmentally friendly alkyl-substituted aromatic diamine, more specifically to a synthetic liquid aromatic diamine 3,3'-diethyl-4,4'-diaminodiphenylmethane (DEMMA ) catalyst and preparation method thereof, and application in the preparation of DEMMA. Background technique [0002] 3,3'-diethyl-4,4'-diaminodiphenylmethane, also known as 4,4'-methylenebis(2-ethylaniline), referred to as DEMMA, is a light yellow to Brown transparent oily liquid. The structural formula is as follows (formula 1): [0003] [0004] (Formula 1) [0005] 3,3'-diethyl-4,4'-diaminodiphenylmethane mainly has the following uses: [0006] (1) It is used as a raw material for aerospace composite materials and coating materials such as rocket shells, which can greatly improve the anti-expansion strength, tear strength, load-bearing compressive resistance and high-temperature resistance of the product. [0007] (2) Used for ...

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Problems solved by technology

[0017] (1) The above-mentioned few studies at home and abroad are all laboratory synthesis without definite and mature technology, and the products are also mixtures with isomers. The main product is 3,3'-diethyl-4 ,The content of 4'-diaminodiphenylmethane is not high, the product viscosity, free amine content and toxicity are high, and it is impossible to form industrial production

[0018] (2) In the reaction process, the existence of strong acid can bring serious corrosion problems. In addition, the addition of strong acid makes it necessary to neutralize with alkaline solution when the reaction ends, and the disposal of the obtained neutral salt solution is also a serious problem.

[0019] (3) Due to the use of a strong acid as a catalyst, excessive condensation is difficult to avoid. When arylamines without substituents or arylamines with substituents react to produce products, further condensation reactions will occur to generate undesired tricyclic polyamines Resinous substances and tetracyclic polyamine resinous substances affect the purity of the product

[0020] (4) In order to obtain a product with higher purity, it is necessary to separate and purify by vacuum distillation under high temperature and high vacuum, and there are complex problems in process and equipment

The disadvantage of this invention is that the reaction conditions are harsh, especially for the alkylation reaction of ethylene needs higher temperature and pressure (temperature up to 375 ℃, pressure up to 3000psig)

[0023] (1) The reaction conditions are harsh, the reaction temperature is above 300°C, and the reaction pressure is as high as 3000 psig

[0024] (2) The catalyst activity is poor, resulting in a low single-pass conversion rate of the raw material 4,4'-diaminodiphenylmethane

[0025] (3) The selectivity of the catalyst is poor, resulting in low selectivity of the target product 3,3'-diethyl-4,4'-diaminodiphenylmethane, and there are a large amount of 4,4'-diaminodiphenylmethane disproportionation by-products , monoethyl substitution products, N-alkylation by-products and polyethyl substitution by-products, the selectivity of the target product is directly related to the economics of the process

[0026] (4) Among them, the boiling points of the N-alkylated by-product and the target product are very close, and it is difficult to separate it by conventional separation means, thereby increasing the separation difficulty, equipment investment and energy consumption

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