Catalytic steam reforming of chlorocarbons: trichloroethane, trichloroethylene and perchloroethylene

The effective destruction of trichloroethane, trichloroethylene and perchloroethylene by steam reforming with a commercial nickel catalyst has been demonstrated. Conversion levels of up to 0.99999 were attained in both laboratory and semi-pilot experiments, with the products consisting of HCI, H(2) and carbon oxides. Care had to be exercised in maintaining these high conversion levels to prevent parallel pyrolysis reactions that resulted in carbonaceous deposits and catalyst deactivation. The importance of these pyrolysis reactions appears to follow established incinerability patterns and is more pronounced for alkanes than alkenes. By using relatively large amounts of catalyst in the large semi-pilot reactor, it was possible to maintain high conversions for up to 50 h without appreciable carbon deposition in the bed. However, the activity of the catalyst for the water gas shift reaction declined progressively with process time. This deactivation effect was reversed by treatment with steam over prolonged periods, leading to the speculation that shift activity is poisoned by exposure to HCI in the product. This process offers an attractive alternative to conventional technologies (thermal incineration and catalytic combustion) for the destruction of chlorocarbons used as industrial solvents or found in waste streams, and applicable process conditions are given. (C) 1998 Elsevier Science B.V. All rights reserved.