Si,P And Ca Modified Low Gold Content Of Mercury Free Catalyst Research For Acetylene Hydrochlorination

At present,highly toxic mercury catalysts used for acetylene hydrochlorination to produce vinyl chloride pollute the environment seriously and is hazardous to human health.Therefore,the development of environmentally friendly and less harmful to people mercury-free catalysts becomes the most important issue in front of the entire vinyl chloride industry.This paper selects the ultrasonic assisted impregnation method for the Au/Si-AC,Au/P-AC,and Au-Ca/AC catalyst,which are used for acetylene and hydrogen chloride preparation of catalytic reaction of vinyl chloride.We are preliminary studied that four ethyl silicate,phosphate,calcium chloride three substances added effect on the properties of low gold content mercury-free catalyst.In addition,We are respectively study the Si,P and Ca modification effects on the properties of low gold catalyst,at the same time by XRD,BET,SEM,TEM and XPS characterization,H2-TPR and TG.Get the following results:?1?Au/Si-AC catalyst by Si oxide modified in the XRD and TEM characterization experiments show that can reduce Au⁰ and gold nanoparticles reunited.BET characterization results show that after the activity of 8 h reactivity test the silicon modified Au/Si-AC catalyst is less than the surface area reduction.TG analysis of experimental data show that the silicon modified Au/Si-AC catalyst of coke deposition quantity is less.H2-TPR experiment found that the silicon modified Au/Si-AC catalyst of reduction temperature is 3 80.4 ? in Au3+ ?Au⁰ proccess,and the undecorated Au/AC catalyst of reduction temperature is 363.3? than moving 17.1? in the direction of high temperature.XPS found that after the reaction of silicon modified Au/Si-AC catalyst Au3+ species relative percentage content of 16%,higher than the undecorated Au/AC catalyst after the reaction of Au3+ species content?11%?,so the Si oxide modified can make Au/Si-AC catalyst Au3+ harder to be reduced.?2?The phosphorus modified Au/P-AC catalyst after 1 h the reaction of acetylene conversion rate reached 71.4%,the selectivity is as high as 99%,and the undecorated single gold catalyst Au/AC after 1h the reaction of acetylene conversion rate reached 47.4%,the selectivity of 97.4%.the selectivity increased by 1.6%,and conversion rate increased by 26%.After 8 h activity and reactivity test,phosphorus modified Au/P-AC catalyst Au3+ species relative percentage content is 13%,slightly higher than that of without modification after the reaction single gold Au/AC catalyst?11%?,and illustrate that catalyst by phosphorus oxide modified can improve the initial activity of Au/AC catalyst.TG characterization of experimental data analysis found that adding phosphorus oxide can also reduce the formation of coke deposition.?3?The preparation of Au-CaCl12/AC catalyst by adding CaCl₂ after 8h activity reactivity test than single gold Au/AC catalyst,increased by 11%of catalytic activity.Characterized by XRD and TEM results show that Au-CaCl₂/AC catalyst can reduce Au⁰ and gold nanoparticles reunited.TG experiment data analysis found that catalyst adding calcium chloride can reduce the formation of coke deposition.BET characterization,the experimental results show that the after reaction Au-CaCl₂/AC catalyst is less than reduction of the surface area,this may be due to catalyst of adding calcium chloride which can reduce gold nanoparticles reunited.XPS experimental data analysis found that,after the reaction of Au-CaCl₂/AC catalyst Au3+ species relative percentage content is 14%,higher than the relative content of Au/AC catalyst after the reaction?11%?.It showed that catalyst by adding CaCl₂ of Au3+ content increased and can effectively improve the acetylene hydrochlorination the reaction of acetylene conversion rate.