Hydrodechlorination of dichloromethane with a Pd/AC catalyst: Reaction pathway and kinetics

The kinetics of gas-phase hydrodechlorination (HDC) of dichloromethane (DCM) with a Pd on activated carbon commercial catalyst has been studied in a fixed bed reactor within the 200–350 °C temperature range. Different kinetic equations have been checked for describing the evolution of DCM. Statistical and physical reliable parameters were found for a Langmuir–Hinshelwood type expression with DCM adsorption as the controlling step. The reaction pathway and the kinetic model have been elucidated from the evolution of dichloromethane and the identified reaction products (methane, monochloromethane, ethane and ethylene). Adsorbed CH2Cl* radical, CH2** and C2H4** carbene species are proposed as the three intermediates evolving to the final reaction products. An apparent activation energy of 23.9 ± 2.3 kJ mol−1 has been obtained for dichloromethane disappearance.