Hydrodechlorination of chloromethanes with a highly stable Pt on activated carbon catalyst

A platinum catalyst with activated carbon-support (Pt/C) was prepared and showed a high activity for the deep gas-phase hydrodechlorination (HDC) of dichloromethane (DCM) and chloroform (TCM), with conversions of up to 70% and 100%, respectively (operating conditions: atmospheric pressure, reaction temperatures of 150–250 °C, and space–times of 0.08–1.7 kg h mol−1). The catalyst was highly selective to methane (the only non-chlorinated product) with selectivities of up to 85% for HDC of DCM and 93% for HDC of TCM. The catalyst showed exceptional stability with no loss of activity after 26 days on stream in the HDC of DCM. This can be ascribed to its high resistance to poisoning by organic compounds compared to Pd/C catalysts previously studied. This can be attributed to re-dispersion of Pt during the reaction and to the high proportion of metal in the zero-valent state (Pt0) which disfavors the stabilization of chlorocarbon compounds at the active centers of the catalyst.

Gas-phase hydrodechlorination of dichloromethane and chloroform to methane (CHxCly + yH2 → CHx+y + yHCl), with a prepared Pt/C catalyst, was studied. The catalyst showed a remarkable stability with no loss of activity after 26 days on stream. Re-dispersion of the Pt on the C support occurred upon HDC reaction.Figure optionsDownload high-quality image (61 K)Download as PowerPoint slideHighlights
► High conversion and selectivity to methane were obtained.
► No deactivation of Pt/C catalyst occurred after use (26 days).
► Re-dispersion of the Pt on the C support occurred during time on stream.
► The catalyst shows a high Pt0/Ptn+ ratio which hindered metal poisoning.