Preparation Of New Catalyst For Vinyl Chloride By Acetylene Process

At present, the high mercury content catalyst with the activated carbon as the carrier has been widely applied to industrial hydrochloride of acetylene for vinyl chloride synthesis. However, the deactivation of the catalyst with mercuric chloride as active sites cause by the sublimation of mercury.In the paper, by taking coconut shell activated carbon as the carrier, the impregnation method has been applied to produce new type of catalyst with low mercury content or mercury-free catalysfor acetylene hydrochloride. The fixed bed reactor is used to investigate the catalytic performance of the prepared catalysts; Thermogravimetry and nitrogen adsorption methods are applied to characterize the prepared catalysts. The impregnation conditions, amount of carrier, ratio of additives to mercuric chloride, drying conditions and the effect of activation conditions on the performance of catalyst are explored. Besides, the optimum reaction conditions for catalytic synthesis of vinyl chloride are explored; The conclusions are as follows:(1)For the low mercury contents catalyst synthesis, the mercuric chloride and additives compound(cerium chloride and potassium chloride mixture) in a 1: 1 molar ratio at the p H = 1 of the impregnation solution,after 6 h impregnation at 60 ℃,vacuum drying under 120 ℃ for 14 h. Acetylene hydrochlorination conditions are preferably in the activation of the catalyst at 130 in 2 h℃,hydrogen chloride and acetylene ingredient ratio of 1.1: 1 mixture of gases,acetylene airspeed control 30h-1, reaction temperature was 170 ℃。The new low mercury content catalyst acetylene conversion was 97.61% under these conditions, the selectivity was 99.7 % vinyl chloride. The reason may be because the compound additive and mercury chloride catalyst occurred coordination role in making activity and enhance the thermal stability of the catalyst, helping to react. Determination of the catalyst after the reaction of mercuric chloride is added proof additives inhibit the sublimation reaction of the active ingredient。For mercury free catalyst synthesis, with Ba Cl2 and Zn Cl2 active ingredient for the composite, each metal chloride adding 3 g,adding 1g Bi Cl3 as assistant,Dipping at 60 6 h, 1℃ 4 h and dried in vacuo at 120 vested ℃catalyst. The catalyst was activated at 130 ℃2h,Hydrogen chloride and acetylene ingredient ratio of 1.1: 1 mixture of gases,Acetylene airspeed control 25h-1, reaction temperature was 150 ℃. Acetylene conversion was 98.63% under these conditions, a vinyl chloride selectivity of 99.9 %.It is indicated that the performance of mercury free catalyst can reach that of the low mercury contents catalyst.