Method for using propylene epoxide in homogeneous system with low propylene using amount

Abstract

The invention belongs to the technical field of petrochemical engineering, relates to a method for preparing epoxide in a homogeneous system with low propylene using amount, and more specifically, relates to a method for synthesizing propylene epoxide by using a first protonic solvent and a second non-protonic solvent as a mixed solvent. An active center is formed by the first protonic solvent, acatalyst and hydrogen peroxide; the second non-protonic solvent can be miscible with the first protonic solvent, and the solubility of propylene inside the mixed solvent is added; the reaction is carried out under the condition of homogeneous phase; propylene can be in contact with hydrogen peroxide sufficiently, the utilization rate of propylene and hydrogen peroxide is improved, and the using amount of propylene and the decomposition rate of hydrogen peroxide are reduced. Simultaneously, the second non-protonic solvent has good solubility for an ether compound formed in the process of an epoxidation reaction, the catalyst deactivation caused by the blockage of a catalyst pore passage can be reduced, and the stable operation time of the catalyst is prolonged effectively. Moreover, the second non-protonic solvent is introduced, the proportion of the first protonic solvent in the system is reduced, the ether byproduct generated in further reaction of propylene epoxide and the first protonic solvent can be reduced, and the yield and selectivity of propylene epoxide are improved. The method has the characteristics of simple process route, low propylene using amount, high propylene epoxide yield and selectivity and the like, and the catalyst is unlikely to inactivate.

Description

technical field [0001] The invention belongs to the field of petrochemical technology, and relates to a method for preparing propylene oxide in a homogeneous system with a low amount of propylene usage, more specifically, to a method for synthesizing propylene oxide using a first protic solvent and a second aprotic solvent as a mixed solvent Propylene oxide method. The first protic solvent forms an active center with the catalyst and hydrogen peroxide, and the second aprotic solvent can be miscible with the first protic solvent and increase the solubility of propylene in the mixed solvent, so that the reaction can be carried out under homogeneous conditions, and propylene can be mixed with the Fully contact with hydrogen peroxide, improve the utilization rate of propylene and hydrogen peroxide, reduce the consumption of propylene and the decomposition rate of hydrogen peroxide. At the same time, the second aprotic solvent has good solubility to the ether adducts formed during...

AI Technical Summary

Problems solved by technology

The large excess of propylene and methanol input in this method will lead to large consumption of propylene and methanol and high energy consumption

[0006] Patent CN201010511514.5 discloses a method for preparing propylene oxide, using methanol as a solvent, through two-stage series reactors, the conversion rate of hydrogen peroxide is 86% to 98%, and the selectivity of propylene oxide is only 84% to 95%. The selectivity of oxypropane is not high, there are more ether by-products, and the two-stage series reaction, the operation is complicated, and the catalyst and energy consumption are high

[0007] Patent CN201610344911.5 discloses a method for preparing propylene oxide. By adding high boiling point non-reactive co-solvents, such as alkanes, halogenated alkanes and aromatic compounds, the propylene oxide generated by the epoxidation reaction is distributed to high-affinity In the non-toxic reaction co-solvent, it avoids the continuous contact between propylene oxide and titanium silicon molecular sieve to generate ether by-products, which improves the selectivity of propylene oxide, but this method still reacts under heterogeneous conditions, and it is difficult to fully contact hydrogen peroxide and propylene. , it is easy to cause hydrogen peroxide to decompose, causing potential safety hazards. At the same time, the amount of propylene used is large and the energy consumption for separation is high.

[0008] Literature (Li Yichuan, Shen Benxian, Zhao Jigang. Study on continuous reaction of direct epoxidation of propylene with acetonitrile as solvent[J]. Journal of China University of Petroleum (Natural Science Edition), 2012,36(6):177-182.) reported the use of acetonitrile Do solvent propylene direct epoxidation method for propylene oxide, adopt acetonitrile aprotic solvent, catalyst activity is low, although can effectively avoid generation of etherification by-product, propylene oxide selectivity is 100%, but hydrogen peroxide conversion rate and ring Propylene oxide yield is 88% and 71%, hydrogen peroxide conversion rate and propylene oxide selectivity are all low

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