Based On “interface Effect” Design High Stability Acetylene Hydrochlorination Reaction Au-based Catalyst

Polyvinyl chloride(PVC) is the third most used plastic materials, the current industrial production method mainly with mercuric chloride as catalyst, which is prepared with the hydrochlorination of acetylene via vinyl chloride monomer. The main problem is the volatilization of Hg Cl2, not only make the catalyst deactivation, but endanger human health caused by environmental problems. Therefore, developing a new generation of environmentally friendly mercury-free catalyst is urgent issue to solve.After decades of research found that precious metals gold catalysts are most likely to replace mercuric chloride catalyst as a new generation of mercury-free catalyst. Gold catalyst on the conversion of acetylene and selectivity of vinyl chloride exhibit a better catalyst activity than mercuric chloride. However, the main reason of deactivation is the active component of Au3+ was reduced to Au; deposition of carbonaceous residues was the predominant deactivation during the reaction. The current study of noble metal catalyst is concentrated in catalyst active components, carrier selection and modification, the deactivation of the active component, the catalytic mechanism. In this paper, novel metal of gold is the main active component, changing the interface effect of catalyst promoter and Au3+. Discussing the conversion of acetylene, selectivity of vinyl chloride and the mechanism of catalyst in acetylene hydrochlorination reaction are forced. This paper mainly from the following three aspects to study:(1) Ti O2 is added to synthesize Ti O2-Au Cl3/AC(activated carbon) catalyst with active carbon as support, and catalytic performance of the obtained Ti O2-Au Cl3/AC catalyst is applied in acetylene hydrochlorination reaction. 10 Ti O2-Au Cl3/AC is optimized catalyst. Transmission electron microscope(TEM) characterization and X-ray diffraction(XRD) display that the addition of Ti O2 species partly inhibits the reduction of Au3+ to Au0 in acetylene hydrochlorination process. BET and TG experiment have proved that deposition of carbonaceous residues is not reduced; Through the analyzed of the Au3+ interaction with Ti O2 by XPS, it is demonstrated that the addition of Ti O2 species partly inhibits the reduction of Au3+ to Au0, the possible reason is Ti O2 can transfer electron to the Au3+ center increased electron density of Au3+, which enhance the adsorption of HCl, which is proved by TPD. Ti O2 species in Ti O2-Au Cl3/AC catalyst strengthens the adsorption of hydrogen chloride reactant in acetylene hydrochlorination reaction, which is attributed to the strong interaction between Au3+ active site and Ti O2 species;(2) Based on the former part of the research, design and prepared a kind of interface effect Au-CoxOy catalyst is confirmed by TEM. The conversion of the Au-CoxOy/AC catalyst is less high than Au/AC catalyst in acetylene hydrochlorination. The possible reason was that the gold particles become larger after preparation and reaction by XRD characterization; the deactivation rate of Au-CoxOy/AC is larger, which is possible deposition of carbonaceous residues by BET and TG analyzed.(3) This part explores another kind of interface effect, Au(III)/Schiff base catalyst is applied to the acetylene hydrochlorination. The [Au Cl2(phen)]Cl catalyst exhibited excellent stability, and acetylene conversion was maintained at 90% after 40 h of operation. Fresh and used [Au Cl2(phen)]Cl catalyst has no obvious Au3+ reduction into Au by TEM and XRD; Au3+ interation with 1,10-phenanthroline ligand by XPS, it is indicated that the Au3+ center can receive the lone pair of electrons of nitrogen atom, which could improve the electron density of Au3+, and inhibit the reduction of Au3+ active component.