NICKEL-CATALYSTS FOR STEAM REFORMING OF HYDROCARBONS - THE REVERSIBILITY OF CARBON DEPOSITION AND GASIFICATION

The influence of temperature on the rates of n-butane steam reforming and the accompanying formation of carbon deposition on nickel catalyst s of var-ious support composition and different nickel dispersion was studied. Catalysts with an appropriate support composition (greater-th an-or-equal-to 40 wt % MgO) and Ni dispersion (< 10 nm) do not undergo coking even with slight steam excess corresponding 10 1120 : C Molar ratios of 1.2-1.5. It was found possible to remove carbon depositions from the catalysts above 600-degrees-C. The rate of carbon removal fro m the catalysts increases with the growth of Ni dispersion and MgO con tent. An explanation of the effects due to MgO introduced into nickel catalysts on the rate of carbon formation and gasification has been pr oposed. At reforming temperatures the occurrence of deactivation proce sses of carbon deposited on catalysts has been ascertained. These proc esses reduce the attainable degree of deposit gasification.