Reviving an old route to chlorine.

Reviving an old route to chlorine

A chemist at the University of Southern California in Los Angeles has devised a process that promises to cut the cost of converting hydrochloric acid to chlorine. Chlorine is widely used for producing substances such as laundry bleaches, drycleaning fluids and industrial solvents. However, one of the by-products of manufacturing these substances is hydrochloric acid. Because hydrochloric acid has only a limited number of uses industrially, disposing of the excess has been a significant problem.

Chemist Sidney W. Benson and researcher Mohammed Hisham have found an economical way to convert hydrochloric acid into additional chlorine. Their method is a variation on a technique first devised in 1865 by chemical engineer Henry Deacon. Deacon's process involves burning hydrochloric acid in oxygen or air to produce water and chlorine. But the process is slow, and raising the temperature to speed it up encourages the reverse reaction of chlorine with water to give back oxygen and hydrochloric acid. Deacon proposed using a catalyst, but the resulting mixture of products was difficult to separate.

Benson avoids the problem by altering the way in which the reaction is done--by changing the order of steps and the type of equipment used. Because his recipe has potential industrial applications, Benson is not yet ready to reveal its details publicly.