Synergetic effect of a mixture of activated carbon + Ni/Al 2O 3 used as catalysts for the CO 2 reforming of CH 4

Abstract

In this work the catalytic activity of heterogeneous mixtures of an activated carbon, FY5, and an in-lab prepared Ni/Al 2O 3 in the CO 2 reforming of CH 4 reaction was investigated. Initially, the reaction was carried out over FY5 and Ni/Al 2O 3 separately. Under the operating conditions employed, the CO 2 and CH 4 conversions obtained over FY5 were negligible, whereas they were high and steady over Ni/Al 2O 3. In the latter case, it was found that the spinel NiAl 2O 4 was formed due to the interaction between the reduced Ni and the support during heating under a N 2 atmosphere. The reaction was also carried out over different mixtures of FY5 + Ni/Al 2O 3. The experimental conversions thus attained were higher than the conversions calculated by adding the weighted individual conversions (mixtures law). Therefore, a synergetic effect exists between the carbonaceous fraction and the metal-based fraction. This effect was found to increase with temperature. Differences between the experimental and theoretical CO 2 conversion were also observed to increase when the proportion of FY5 in the mixture was increased, whereas in the case of CH 4 conversion, the increase depended on the proportion of Ni/Al 2O 3 added. It was also observed that, when a heterogeneous mixture FY5 + Ni/Al 2O 3 was used as catalyst for the CO 2 reforming of methane, the decomposition of CH 4 occurred preferentially over the Ni-based fraction and that CO 2 tended to gasify both the initial carbonaceous fraction and the carbon deposits from methane.