Development Of Catalytic Dehydrochlorination Of 1,1,2-Trichloroethane Into Vinylidene Chloride On Liquid Phase

Vinylidene chloride (VDC) is a 1,1-double substituted olefin which has extremely asymmetric structure and polarization degree, lots of compounds could be synthesized, since polymerization, addition, chlorination and decomposition of VDC happened easily. Traditional saponification method produce lots of saline organic wastewater, is not environmentally friendly. Dehydrochlorination of 1,1,2-trichloroethane (TCE) at high temperature has much energy consumption and poor VDC selectivity. Catalytic dehydrochlo-rination of TCE has no pollution and less energy consumption, however the catalyst inactivated easily. The emphasis of this research is to solve problem of catalytic deactivation.Coconut shell activated carbon, γAl2O3, silica gel, ZSM-5 zeolite catalysts are prepared, impregnated CsF, CsCl, BaCl2, NiCl2, BaSO4 Their activities were investigated in gas-liquid-solid three phase reactor, and TCE is at boiling bubble condition. Optimal active component, carrier and its load ratios were studied, and catalyst life was also investigated. Results showed that best formulation is γAl2O3 loaded 2% CsF. TCE conversion is positive correlation of temperature, VDC selectivity was not affected by temperature, TCE conversion is 30%, VDC selectivity is 92% at 190℃. Life of CsF-γAl2O3 was extended to 12h from 0.5h compared with gas phase method.Fresh and deactivated catalyst were characterized by XRD, BET, TEM, TG-DTG and EDS, substance on the surface of deactivated catalyst was characterized by IR and GPC. Results show that inner surface of catalyst was covered by PVDC, weigh ratio was 4.115%, the number-average molecular weight are concentrated at 507 and 16712.Influence of inhibitor to CSF-γAl2O3 activity were investigated in gas-liquid-solid three phase reactor. Results showed that BQ could prolong catalyst life effectively at 113℃,0.1 Mpa, TCE conversion was kept a constant at 5% for 230h, Production rate of VDC is 71080 kg/(m3·year). Inhibition of BQ gradually decreased to zero with rise of temperature. BQ has no effect to selectivity of VDC. Thermal polymerization mechanism of two VDC molecules was proposed, BQ could prevent polymerization of VDC by eliminate free radicals.