Acetylene Hydrochlorination Over Non-mercury Catalysts For Vinyl Chloride Monomer Production

PVC resin is a kind of synthetic materials that is produced with vinyl chloridemonomer?VCM? and used widely in our daily life. VCM can be produced fromethane oxychlorination, ethylene oxychlorination and acetylene hydrochlorination.Acetylene hydeochlorination is the main process for the production of VCM in chinabecause of the structure of energy resources. However, the mercuric chloride catalystfor acetylene hydrochlorination is quite deficient and the toxicity and volatility ofmercury is a serious pollution problem. The exploitation of new non-mercury catalystfor acetylene hydrochlorination is the only way to resolve the problem.Supported SnCl2/C catalyst was prepared under N2atmosphere with activatedcarbon as support and SnCl2as active component. The relationship of activity andselectivity of the catalyst with the SnCl2load was obtained. The deactivationmechanism was determined as the loss of SnCl2under the reaction condition.Since the activity and stability of Sn-based catalyst can't meet the requirements ofindustrial applications, we changed the research direction to Cu-based catalyst. It wasfound that the optimal preparation conditions of CuCl2/C catalyst were: the carbonwas washed with1mol/L H3PO4; calcinated at500?under N2atmosphere; with1mol/L HCl as solvent. The CuCl2/C catalyst prepared under this condition has goodactivity and selectivity. Under the reaction condition of15%mass loading, T=180?,GHSV=180h-1, VHCl/V??=1.1, the acetylene conversion and selectivity can reach68%and99.5%, respectively. The deactivation of the catalyst was caused mainly bythe aggregation of active components under this condition. The experimental resultsshow that the addition of H3PO4could improve the dispersion of active sites on thesupport and enhance the electropositivity of copper ion which improve the activity ofClPCu/C catalyst significantly. However, excessive H3PO4may be adsorbed by theactive sites and occupy the room for coordination, leading to the loss of catalyticactivity. Experimental results show that when Cl:P:Cu=4:2:5, ClPCu/C (15%) catalysthas the highest catalytic activity. The decrease of catalysts activity under thiscondition was mainly due to partly reduction of Cu2+and the loss of activecomponent.