Reductive catalytic dehalogenation of light chlorocarbons

Several palladium and platinum supported catalysts have been employed in the gas-phase dehalogenation of chloromethanes (CCl4, CHCl3 and CH2Cl2) and chlorobenzene by using molecular hydrogen under mild conditions. A new porous glass material (Vycor) has been found to be a promising carrier for platinum in the selective hydrogenation of CCl4 to CHCl3 ensuring high selectivity and durability. Palladium on alumina showed the best performance in the deep dehalogenation of CHCl3 and CH2Cl2 to CH4 and HCl. Chlorobenzene dehalogenation is a fast reaction with many catalytic systems. However, palladium catalysts produce mostly C6H6, whereas platinum ones induce overhydrogenation to cyclohexane. A comparison of reductive and oxidative processes for chloromethane disposal is presented. (C) 1999 Elsevier Science B.V. All rights reserved.