EFFECTS OF SULFIDATION AND SYNERGISM IN HYDRODECHLORINATION OF O-DICHLOROBENZENE OVER NIMO ALUMINA CATALYST

Hydrodechlorination of o-dichlorobenzene was studied in the gas phase at 300-degrees-C and 2 MPa over reduced and sulfided Ni, Mo and NiMo c atalysts supported on alumina. The work was related to disposal of chl orinated organic wastes containing sulfur impurities. The effect of su lfidation 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 a nd Mo was observed with sulfided NiMo catalyst, the NiMo sample being three times more active than the sum of activities of Ni and Mo sample s. Reduced catalysts did not exhibit synergism. Chlorobenzene was obse rved as an intermediate over all catalysts. The selectivity to the int ermediate was decreased by presulfidation of the catalyst; for instanc e the maximum conversion to chlorobenzene at 300-degrees-C was 40 and 17% for non-sulfided and sulfided catalyst , respectively. The selecti vity to intermediate over sulfided NiMo catalyst increased with decrea sing temperature from 300 to 250-degrees-C and was not influenced by d ecrease of pressure from 2 to 1 MPa.