Method for preparing propylene glycol monomethyl ether by using propylene

Abstract

The invention discloses a method for preparing propylene glycol monomethyl ether by using propylene, which comprises the following steps that: in the presence of a titanium silicalite molecular sieve composite catalyst, propylene, hydrogen peroxide and lower alcohols are directly subjected to epoxidation and open-loop etherification one-step reaction to obtain the propylene glycol monomethyl ether, and the catalyst consists of a titanium silicalite molecular sieve, an acidic molecular sieve and resin. In the method, the titanium silicalite molecular sieve composite catalyst is adopted to realize the process that the propylene glycol monomethyl ether is directly prepared by the propylene on a fixed bed, the problems that the steps of open-loop etherification two-step reaction of propylene oxide are complicated and the energy consumption is high and the like when the propylene oxide is prepared by the epoxidation of the propylene in the traditional method for preparing the propylene glycol monomethyl ether can be solved, and the reaction efficiency is improved.

Description

technical field [0001] The invention belongs to a preparation method of propylene glycol monoether, which is suitable for the catalytic reaction process in which propylene, hydrogen peroxide and low-carbon alcohol are directly epoxidized and ring-opened etherified to prepare propylene glycol monoether. Background technique [0002] Since the Italian Enichem company first synthesized the lattice oxygen-selective titania-silicon molecular sieve catalyst TS-1 in 1983, it has become a hot spot in the research of oxidation catalysts due to its excellent oxidation selectivity and mild reaction conditions, and this discovery is regarded as environmentally friendly. A major breakthrough in catalyst development. [0003] Titanium-silicon molecular sieve catalysts play a very important role in the epoxidation of olefins. For the epoxidation of low-carbon olefins, the liquid-phase epoxidation process uses titanium-silicon molecular sieves as catalysts and hydrogen peroxide as the oxida...

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Problems solved by technology

However, this method uses propylene oxide as the starting material, and there is a shortcoming of a long reaction route. At the same time, it is produced in a batch tank type, and the production process needs to separate the catalyst, and the process is complicated.

[0007] In the application of olefin epoxidation, titanium-silicon molecular sieve catalysts exhibit excellent shape-selective catalytic performance. Generally, the smaller the particle size, the higher the catalyst activity and the better the selectivity. In practical applications, the particle size of titanium-silicon molecular sieve catalysts is about 0.1-15.0μm, however, such a small particle size will bring great difficulties to the separation of the catalyst and the product, although various research results on filter materials have been applied in practice, but for the separation of titanium silicon molecular sieve catalysts and products Separation, the resistance generated during filtration does not lie in the size of the pores of the filter material, but comes from the extremely fine catalyst particles occupying and blocking the pores of the formed filter cake, especially the catalyst particles with a particle size of less than 2 μm are the most suitable for filtration. Unfavorable, this results in low production efficiency and also affects the process of industrial application of titanium silicon molecular sieves

The catalyst with small particle size will not only block the pores of the filter cake during filtration, but part of it will be lost from the pores of the filter medium. The general loss rate is about 5% to 8% of the input amount of the catalyst, which not only causes unnecessary consumption of the catalyst, but also enters the product. Further side reactions are caused in the material, leading to an increase in separation costs and affecting product quality

[0008] EP 189246 provides a method for the continuous reaction of propylene oxide to synthesize propylene glycol monoether. The process uses an ion exchange resin containing amino groups as a catalyst, the molar ratio of alcohol to alkane is 10, the reaction temperature is 98°C, and the space velocity is 2h -1 Under the conditions, the conversion rate of propylene oxide is 85wt%, and the selectivity is 85wt%. Because the ion exchange resin containing amino groups has poor high temperature resistance, the stability of the catalyst in this process is not very good, and it still does not fundamentally solve the problem of propylene. Preparation of propylene glycol monoether from propylene oxide is complicated (two-step reaction is required)

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