Process for preparing sorbic acid

Abstract

The invention provides a process for making a sorbic acid. The process comprises: pyrolysis of acetic acid for producing high purity ketene with coke oven gas as a heat source, polymerization reaction of butenoic aldehyde and ketene gas to give a sorbic acid polyester and acid decomposition of sorbic acid polyester to obtain the sorbic acid, wherein the polymerization reaction of the butenoic aldehyde and the ketene gas, which is performed in a combined polymerization reactor comprising at least of a spray absorption reactor and a packed tower provided with a recycle pump outside continuously, comprises the steps that: fresh butenoic aldehyde and recycle feed from a tower bottom of the packed tower are delivered to the spray absorption reactor to form a sprayed material flow and to react with a low-temperature ketene gas absorbed by formed negative pressure into the reactor; the reaction materials flow into the tower bottom of the packed tower circularly so as to conduct further polymerization reaction of the unreacted ketene and the butenoic aldehyde contained in the material flow; one part of the materials from the tower bottom of the packed tower is used for the inner circulation of a reactor system, while the other part is recovered constantly for use in the next process, thereby realizing continuous production.

Description

technical field [0001] The invention relates to a preparation of sorbic acid, in particular to a production process for preparing sorbic acid by using vinyl ketone and crotonaldehyde as raw materials through polymerization reaction and acid decomposition process. Background technique [0002] Sorbic acid, the scientific name is 2,4-hexadienoic acid, the chemical structure is CH 3 CH=CHCH=CHCOOH, odorless or pungent, slightly soluble in water, easily soluble in organic solvents such as ethanol, melting point 133-135°C, white needle-like or powdery crystal, stable to light and heat , but it is easy to be oxidized and colored if it is placed in the air for a long time. Sorbic acid is an unsaturated fatty acid with conjugated dienes, which is an acidic preservative. When the pH is less than 6, its double bond can combine with the sulfhydryl group of microbial enzymes in food, thereby destroying many important enzyme structures and making it The enzyme loses its activity and pl...

AI Technical Summary

Problems solved by technology

Chinese patent publication 02111368.8 introduces that the polymerization reaction of vinyl ketone and crotonaldehyde is carried out in a packed tower, and adopts tower internal polymerization, tower external circulation cooling, tail gas (containing unreacted vinyl ketone gas) with another packed tower The process of crotonaldehyde absorption in the internal circulation is a batch production process, and its polymerization effect is not much different from that of the batch reactor, and the reaction time is long and the operation is cumbersome.

The advantage of electric heating is that it can control the heating speed and make the material heated evenly, but the disadvantage is that the heating efficiency is low and the heating cost is high

Fuel heating can also achieve stable heating speed, so that the material is heated evenly, and the heating cost is low, but the disadvantage is that it is easy to form carbon deposits on the outer wall of the fuel nozzle and the cracking tube, which affects the heat transfer efficiency and reduces the cracking yield.

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