Free chlorine removal
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Hydrogen chloride produced using ion exchange membranes may contain free chlorine, which can be removed using a non-gaseous, non-alkaline reducing agent. Formic acid is an appropriate choice among inorganic and organic substances; it meets the requirements without causing problems in the synthesis process. The properties of formic acid are as follows: it can undergo the silver mirror reaction, and can be oxidized by ordinary oxidants to CO2 and H2O. Its melting point is 8.4 degrees, and its boiling point is 100.7 degrees; it is miscible with water. At 160 degrees, it decomposes into CO2 and H2. A small amount of formic acid carried along by hydrogen chloride can be removed using ion exchange membranes or in the conversion graphite cooler; even a very small amount that enters the conversion process has no adverse effects. Part of it also decomposes due to high temperatures
The original poster has made things complicated; wouldn’t it be better to carry out absorption first and then desorption? 【Abstract】: Whether from the perspective of expanding raw material sources or protecting the environment, finding solutions for the reuse of waste hydrogen chloride gas is of practical significance. Given that the amounts of by-product hydrogen chloride and hydrochloric acid generated amount to tens of millions of tons, it is extremely important to develop effective methods for purifying these waste substances. Waste hydrogen chloride can rarely be reused; it is generally concentrated and dehydrated, and thorough dechlorination is necessary. Previously, methods such as absorbing hydrogen chloride with water followed by stripping, and then using the diammonium method to purify hydrochloric acid and remove free chlorine in order to concentrate HCl, were discussed.