Effects of Sulfidation and Synergism in Hydrodechlorination of o‐Dichlorobenzene Over NiMo/Alumina Catalyst

Abstract

AbstractHydrodechlorination of o‐dichlorobenzene was studied in the gas phase at 300°C and 2 MPa over reduced and sulfided Nl, Mo and NiMo catalysts supported on alumina. The work was related to disposal of chlorinated organic wastes containing sulfur impurities. The effect of sulfidation on activity of Ni, Mo and NiMo catalysts was different: the ratio of the activities of the sulfided and unsulfided forms was 0.3, 1.7 and 2.2, respectively. Positive synergism in activity between Ni and Mo was observed with sulfided NiMo catalyst, the NiMo sample being three times more active than the sum of activities of Ni and Mo samples. Reduced catalysts did not exhibit synergism. Chlorobenzene was observed as an intermediate over all catalysts. The selectivity to the intermediate was decreased by presulfidation of the catalyst; for instance the maximum conversion to chlorobenzene at 300°C was 40 and 17% for non–sulfided and sulfided catalyst, respectively. The selectivity to intermediate over sulfided NiMo catalyst increased with decreasing temperature from 300 to 250°C and was not influenced by decrease of pressure from 2 to 1 MPa.