The Sudy On Au Catalysispoisoning Mechanismand Metal-free Catalyst Foracetylene Hydrochlorination

Polyvinylchloride(PVC) polymerization from vinyl chloride monomer(VCM) is one of the most widely used engineering plastics in various aspects of national economy. Based on the coal-rich, oil-poor, less gas of China special energy distribution characteristic, theindustrial production of VCM is mainly through acetylene hydrochlorination catlaysted by mercuric chloride(HgCl2) with active carbon(AC) catalyst. However, as the global mercury pollution prevented and control policy initiatived. Thus, it has important practical significance to develop environment-friendlyand high-efficiency non-mercury catalyst.Attention has been focused on the nobal metal catalyst since Hutchings found that Au-based catalysts were the optimal metal chloride catalysts for acetylene hydrochlorinatio. However, there is no report on Au catalysis poisioning mechanism.Therefore, poisoning effect of H2 S on the catalytic performance of Au-based catalyst in acetylene hydrochlorination was studied.Then, the effect of sulfur and nitrogen was exployed for metal-free catalyst poly p-phenylenediamine(PpPD). Finally,Nitrogen-doped active carbon(PANI-AC) was prepared to explore the relationship between the activity and the different nitrogen species.(1)A study aboutpoisoning effect of H2 Son the catalytic performance of 1% AuCl3/AC during acetylene hydrochlorination deactivation is described and discussed. Activity tests demonstrated that H2 S poisoning resulted in the rapid and irreversible deactivation of AuCl3/AC catalyst. The reason of deactivation was attribute to accelerate active Au3+ reduction to metallic Au0 in presence of H2 S. On the other hand, the formation of metal sulfide may also lead to catalyst deactivation. Namely, with the increase of H2 Sadded to the feed gases, the content of Au3+ was greatly reduced to metallic Au0. Moreover, the active sites are covered with Au-S compound, which could reduce the effective active component, leading to the deactivation of the AuCl3/AC catalyst.(2) Sulfur-nitrogen coexist PpPD catalyst was prepared through C6H8N2 and APS polymerisation. The plate like structure was formed through the amount of different of APS. The results demonstrated that the most suitable mole ration between theC6H7 Nand was 2:1, the PpPD-2.0 catalyst revealed the best catalytic activity and stability. N-doped oxide graphere was synthesized in order to explore the the synergy effect through sulfur-nitrogen coexist PpPD catalyst in acetylene hydrochlorination, in addition, the results were confirmed by the means of BET, XPS and other characterizations.(3) To explore the relationship between the activity and the different nitrogen species. Nitrogen-doped active carbon(PANI-AC) catalyst was prepared by post-treatment of ACwith polyaniline followed by pyrolyzation at high temperature. By adjusting the mass ratio between AC and C6H7 N, which demonstrated that catalytic activity was positively correlation with nitrogen content with a certain range. And then the optimal catalyst was choosed to control the nitrogen species under different calcinations temperature. The results revealed that the most suitable mass ratio between the AC and C6H7 N was 1:5 and the calcinations temperature was 900℃,which showed the excellent acetylene conversion(76.27%). XPS results demonstrated that the order of nitrogen species’ role for acetylene hydrochlorination is as follows: pyrrolic N > graphitic N > pyridinic N.