Study On Multiple Component Low-mercury Catalysts For Preparation Of Vinyl Chloride By Calcium Carbibe Process

With the social development and improvement of environment protection,low-mercury catalyst investigation is a necessary for development of PVC industry to replace the high-mercruy catalysts.The low mercury catalyst with multi-components is necessary to remain its high performance with half of the mercury loadings comparable to high mercury catalysts.Thus the compostion of multiply-composites low-mercury was fully studied.The analysis method of HgCl₂ loading on low-mercury catalyst was also studied in detail since the loading of HgCl₂ is a crutial index for low-mercury catalyst.The following conclusions were obtained:1.This paper studies the accuracy and repeatability of titration method via the copper reagent method and KI method.It is found that the copper reagent method is more accurate and repeatable.The concentration of mercury chloride solution analysed by KI method is about 5%less than real concentration.2.More than ten metal chlorides were studied to choose the proper promoters for low-mercury catalyst and special attension was paid for A.It is fould that A can improve the HgCl₂ loading ratio and the optimal A:HgCl₂ molar ratio is 0.79.BaCl₂,ZnCl₂,CuCl₂ can improve the initial activity of low-mercury catalysts and NiCl₂,ZnCl₂,BaCl₂,CuCl₂ can improve the stability of the catalysts.In the case of HgCl₂ loading is less than 4%,binary low-mercury catalyst still cannot be commertialized due to its low performance.3.The effects of multiple promoters for activity and stability of low-mercury catalyst were studied by the orthogonal experimental design.The optimal multiple-components catalyst was obtained.The loss ratio of HgCl₂ after thermal treated at 250 ^oC for 3h is less than 3%,which is better than any commertialized low-mercury catalyst.The acetylene conversion was higher than 84%at 140 ^oC,28 h^-1,reaction time 5000 h.Predicted life is more than 10,000 hours.The effect of different supports on the ultra-low-mercury catalysts has been studied.We found N-modified activated carbon support and mesoporous carbon support is good to improve the reactivity of acetylene hydrochlorination.