Method for tail gas purification and material recovery in pivaloyl chloride production process

Abstract

The invention discloses a method for tail gas purification and material recovery in a pivaloyl chloride production process. The method comprises the following steps: recovering a part of materials entrained in tail gas in a condensation mode, feeding the tail gas into a specially-made absorption tower, and further absorbing organic matters in the tail gas by using low-volatility benzal dichlorideas an absorbent; introducing hydrogen chloride gas obtained through condensation and adsorption treatment into a falling film absorption tower to prepare hydrochloric acid; standing the prepared hydrochloric acid in a standing tank for layering, and recoverying an upper organic phase; wherein the condensed and recovered material and a benzal dichloride absorption liquid are directly reused in a pivaloyl chloride synthesis kettle, and the organic phase separated from hydrochloric acid is dried and dewatered by using a molecular sieve and then reused in the pivaloyl chloride synthesis kettle. The method has the advantages of high tail gas purification efficiency, thorough material recovery, deep purification of the hydrogen chloride gas, improvement of the quality of the byproduct hydrochloric acid, and reduction of the material consumption.

Description

technical field [0001] The invention belongs to the field of tail gas purification and relates to a method for tail gas purification and material recovery in the production process of pivaloyl chloride. Background technique [0002] A large amount of hydrogen chloride gas (see chemical reaction equation 1) is produced in the process of producing pivaloyl chloride with pivalic acid and benzylidene dichloride as raw materials. According to calculation, every 1t of pivaloyl chloride produced will produce 186.7m 3 of hydrogen chloride gas. During the production process of pivaloyl chloride, the reaction temperature is maintained above 120°C. Under the dual effects of high-temperature heating of the synthesis kettle and micro-negative pressure removal of tail gas in the vacuum circulation system, hydrogen chloride gas entrains a large amount of organic materials and forms pivaloyl chloride production together with a small amount of air. process exhaust. According to the test, t...

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Problems solved by technology

[0008] Condensation is used only to recover organic materials entrained by hydrogen chloride gas. The recovery of organic matter is not complete, and there are still a large amount of non-condensable organic matter that enters the falling film absorption tower with hydrogen chloride gas.

Absorbent spraying to absorb organic matter in exhaust gas is also a common exhaust gas purification method, but the absorption effect of this method cannot reach the level of deep purification

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