Method and apparatus for preparing epoxypropane by catalyzing propone epoxidation at supercritical condition

Abstract

The invention discloses a method and a device for preparing propylene oxide by catalyzing propylene cycle to be oxidized under supercritical conditions, and belongs to petrochemical material preparation technology. The method comprises the following steps: using supercritical carbon dioxide as a reaction medium, adopting a catalyst with large particle diameter, adding the catalyst into a reactor,then adding gas reactant propylene into a mixer, adding an aqueous solution of liquid reactant hydrogen peroxide and cosolvent methanol into the mixer, and introducing carbon dioxide into the mixer to be mixed with the aqueous solution of the propylene and the hydrogen peroxide and the cosolvent methanol which then react in the reactor to obtain a reaction product of the propylene oxide. The supercritical carbon dioxide has good solubility for propylene gas so as to increase concentration of the reactant in the reaction system, so the supercritical carbon dioxide is favorable for reaction. The supercritical carbon dioxide has excellent diffusivity, so that the product can be shifted out of a molecular sieve in time to reduce generation of secondary reaction, so as to retard inactivation of the catalyst. The TS-1 catalyst with large particle diameter overcomes the defect of difficult separation of the product and the catalyst.

Description

technical field [0001] The invention belongs to the preparation technology of petrochemical raw materials, in particular to the use of supercritical carbon dioxide (SCCO 2 ) as its reaction medium, using tetrapropyl ammonium bromide (TPABr) as template agent to synthesize large particle size titanium-silicon molecular sieve TS-1 as catalyst, the whole reaction is carried out in a supercritical state to catalyze propylene Method and device for preparing propylene oxide by epoxidation. Background technique [0002] Propylene oxide (PO) is an important petrochemical raw material. The traditional preparation method of chlorohydrin method has problems of equipment corrosion and environmental pollution. The co-oxidation method has huge equipment investment and many co-products. Using titanium silicon molecular sieve (TS-1) as catalyst, H 2 O 2 The catalytic reaction as an oxidant has the advantages of mild conditions, rapid reaction, high selectivity and no pollution in the pro...

AI Technical Summary

Problems solved by technology

The diffusion performance of the reactant system is not good, and the products and by-products in the TS-1 pores cannot be removed in time, resulting in the deactivation of the catalyst; also, only TS-1 with small grains can have the corresponding catalytic activity, showing grain Size effect, and the small crystal grains bring the problem of separation and recovery of the catalyst. In addition, in the synthesis process of small grain TS-1, it is necessary to use expensive tetrapropylammonium hydroxide (TPAOH) as a template agent, and the cost is high, while Cheap tetrapropylammonium bromide (TPABr) as a template can only synthesize TS-1 with larger grain size

In short, the application of TS-1 is limited by the factors of diffusion kinetics. It is imperative to improve the diffusion and mass transfer performance of the reaction system by introducing new technologies to solve the problems of easy deactivation and separation and recovery of catalysts.

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