Progress on cleaner production of vinyl chloride monomers over non-mercury catalysts

Polyvinyl chloride (PVC) has become the third most used plastic after polyethylene and polypropylene and the worldwide demand continues to increase. Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer (VCM), which is manufactured industrially via the dehydrochlorination of dichloroethane or the hydrochlorination of acetylene. Currently PVC production through the acetylene hydrochlorination method accounts for about 70% of the total PVC production capacity in China. However, the industrial production of VCM utilizes a mercuric chloride catalyst to promote the reaction of acetylene and hydrogen chloride. During the hydrochlorination, the highly toxic mercuric chloride tends to sublime, resulting in the deactivation of the catalyst and also in severe environmental pollution problems. Hence, for China, it is necessary to explore environmental friendly non-mercury catalysts for acetylene hydrochlorination as well as high efficiency novel reactors, with the aim of sustainable PVC production via the acetylene-based method. This paper presents a review of non-mercury heterogeneous and homogeneous catalysts as well as reactor designs, and recommends future work for developing cleaner processes to produce VCM over nonmercury catalysts with high activity and long stability.