Heterogeneous non-mercury catalysts for acetylene hydrochlorination: progress, challenges, and opportunities

The replacement of mercuric chloride with non-mercury catalysts in acetylene hydrochlorination for the production of a vinyl chloride monomer (VCM), the precursor to polyvinyl chloride (PVC), would meet the requirements of green chemistry. The aim of this tutorial review is to discuss the design criteria for non-mercury catalysts, with the focus on the relationship between the catalytic activity/stability and the electronic properties, adsorption, and reducibility of the catalysts. The developments of Au-based catalysts, Ru-based catalysts and other monometallic catalysts are briefly covered in the first part, with emphasis on the active species, reaction mechanism, and alternative preparation methods of Au-based catalysts. An overview of the development of bimetallic/trimetallic catalysts is highlighted in the second part. Then the modification strategies (e.g. heteroatom modification of support, ionic liquid modification) and explorations of the support/preparation method are addressed. Finally, particular attention is paid to the applications of metal-free catalysts and other catalysts (e.g. heteroatom-doped carbon material, nitride and zeolite).