Study On The Synthesis Of VDC Via Gas-phase Catalytic Dehydrochlorination Of 1,1,2-TCE Over The Activated Carbon

Vinylidene chloride is used to produce polyvinylidene chloride,chlorofluorocarbons substitutes,medicine and dyestuff.Using 1,1,2-trichloroethane and alkali to produce vinylidene chloride will generate a large number of high salt waste water.Gas phase dehydrochlorination method does not consume alkali and generate high salt waste water.Therefore,the research of developing the efficient,green and solid catalyst to produce vinylidene chloride is significant.Firstly,the catalytic performance of AC,SiO2 and Al2O3 was investigated to analyze the mechanism of catalyst deactivation.The stability of AC was far higher than the results of SiO2 and Al2O3.The activity of deactivated catalysts treated with high temperature in air was restored,but not in N2.The excellent stability of AC attributed to its low carbon deposit rate with the results of BET,NH3-TPD,TG-MS and XRD.It suggested that the deactivation of catalyst was mainly caused by carbon deposit.Secondly,a series of g-C₃N₄/AC catalysts had been synthesized to catalyze 1,1,2-trichloroethane to generate vinylidene chloride in this paper.Studies showed that the conversion of 1,1,2-trichloroethane was 32%,and the selectivity of vinylidene chloride was 9.5%.It proved that g-C₃N₄/AC catalysts exhibited catalytic performance.Finally,we studied the catalytic performance of the g-C₃N₄/AC supported CsCl catalysts.Results showed that g-C₃N₄ promoted the dispersion of CsCl by anchoring it.The conversion of 1,1,2-trichloroethane was 39% without decreasing in 30 h,and the selectivity of vinylidene chloride was 37%.The physicochemical properties of the synthesized catalysts were characterized by BET,EDS,FT-IR,TPD and XRD.Results showed that we successfully prepared the g-C₃N₄/AC and g-C₃N₄-CsCl/AC catalysts.We also put forward the optimal preparation conditions of g-C₃N₄-CsCl/AC catalysts.