Pyrolysis of 1,2-dichloroethane over Ni–Cr catalyst at resistive heating

Abstract

The features of the catalytic pyrolysis of chlorohydrocarbons over resistive Ni–Cr alloy were studied using 1,2-dichloroethane as a model substrate. The heating of the catalyst was provided by a direct supply of current on nichrome spiral wire. Such parameters as the temperature of spiral wire (550–700 °C), hydrogen concentration (0–60 vol%) and preliminary activation conditions (acidic or oxidative-reductive treatment of wire surface) were varied in the study. The formation of dispersive nickel particles (up to 0.5 μm in size) catalyzing carbon fiber growth in accordance with the mechanism of carbide cycle was found to be a result of the carbon corrosion of the resistive Ni–Cr alloy. This process was shown to be conjugated with hydrodechlorination taking place within the studied conditions. The decomposition of chlorohydrocarbon goes preferably through the route of C–Cl bond hydrogenolysis when hydrogen is absent from the reaction mixture. Ethylene was found to be the main gas-phase product. The addition of hydrogen into the reaction mixture leads to the hydrogenation of ethylene with the formation of ethane and increases the amount of deposited carbon, which is subjected to partial hydrogenation with methane formation.