Simulation and experimental study on mechanism and kinetics of 1,1,2-trichloroethane dehydrochlorination reaction

Abstract

Dehydrochlorination of 1,1,2-trichloroethane (112TCE) is a widely used method for preparing vinylidene chloride (VDC), which is an important polymeric monomer and intermediate of refrigerant. However, there are few reports on kinetics of this reaction system. In this work, density functional theory (DFT) calculation analyses and experiments were conducted to investigate the reaction mechanism and kinetics of 112TCE dehydrochlorination with sodium hydroxide (NaOH). DFT simulation results unveiled there were three parallel reactions which produce VDC, cis-1,2-dichloroethylene (C12DE) and trans-1,2-dichloroethylene (T12DE) respectively in the reaction process of 112TCE and NaOH. The activation energy of the reaction to produce VDC was lower than those of the other two reactions. Moreover, the kinetic parameters of the three parallel reactions, such as reaction orders, rate constants, pre-exponential factors and activation energies, were experimentally obtained by decoupling the overall reaction kinetics. All the parallel reactions are bimolecular elimination reactions and the rate expression of the intrinsic kinetics for generating VDC isdCtdt=1.668×1011e-75662RTCACB. The reaction rate is three orders of magnitude higher than those of producing C12DE and T12DE, which is consistent with the DFT simulation results. These kinetics results are useful for the process optimization and reactor design in VDC production process.