Method for recovering propylene from direct epoxidation product

Abstract

The invention relates to a method for separating and recovering propylene from reaction product of direct oxidation for preparing epoxypropane, which comprises steps as follows: effluent gas containing propylene, propane, methanol, oxygen and carbon dioxide from an epoxypropane separation system enters a propylene absorption tower to contact an absorbent; the absorbent absorbs and remove the propylene and propane in the effluent gas; the effluent gas without the propylene and propane is discharged from the top of the absorption tower; an mixture of the absorbent, propane and propylene enters a desorption tower to be desorbed at high temperature; the absorbent is discharged from the bottom of the desorption tower, is cooled by heat exchange, and returns into the absorption tower for cyclic use; the propylene and propane at the top pf the desorption tower enter a propylene rectification tower to be separated; and the absorbent is one or mixture of more of alcohols, diol ethers and aldehydes. The propylene recovery rate of the method provided by the invention can reach higher than 95%, and the propylene purity can reach higher than 95%. Compared with the existing method, the absorbent does not need rectification or separation, and obviously lowers the operating cost.

Description

Technical field [0001] The invention relates to a method for physically separating light hydrocarbons in a mixed gas, and more specifically, to a method for recovering propylene from exhaust gas of a process for preparing propylene oxide by reacting hydrogen peroxide with propylene. Background technique [0002] Propylene Oxide is an important raw material for organic synthesis, and is the third largest propylene derivative after polypropylene and acrylonitrile. It is mainly used to produce polyether, propylene glycol, propylene glycol ether, etc., and is also an important raw material for non-ionic surfactants, oil field demulsifiers, and pesticide emulsifiers. Propylene oxide derivatives are also widely used in industries such as food, tobacco, pesticides and cosmetics. Nearly 100 kinds of downstream products have been produced, which are important raw materials for fine chemical products. [0003] Propylene oxide production processes mainly include chlorohydrin method, co-oxid...

AI Technical Summary

Problems solved by technology

However, this method is only applicable to the direct oxidation propylene oxide process with relatively high propane content in circulating propylene. If the propylene purity required by the epoxidation reaction is high, the propane content in the exhaust gas is very low and the propylene content is high. The process disclosed in requires a large amount of propane as an absorbent to absorb the propylene in the exhaust gas, making the operation cost too high

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