Effect of Temperature on Structure and Performance of In-House Cobalt-Tungsten Carbide Catalyst for Dry Reforming of Methane

The bimetallic carbide catalyst Co6W6C has been shown to be useful for the reforming of methane to synthesis gas (methane dry reforming). With use of material manufactured by Nanodyne, work in this laboratory has indicated that the catalyst is converted to a more stable form, containing Co, WC, and C, and this form is active and stable for the production of synthesis gas. Further, in-house preparation can yield Co6W6C with similar catalytic properties. In this work, the in-house catalyst was used for dry reforming at temperatures ranging from 500 (degree)C to 850 (degree)C, and then back down to 500 (degree)C. The fresh and spent catalysts were characterized by BET, XRD, SEM, and EDS. The catalyst was found to be ineffective below 850 (degree)C. However, once the catalyst is exposed to reactants at that temperature, the activity is much greater at lower temperatures than the activity before exposure at 850 (degree)C. XRD, SEM, and EDS indicate that the low-temperature catalyst is different from that exposed to 850 (degree)C. However, after returning the catalyst to the lower temperatures, the structure is similar to that at 850 (degree)C. After reaction at 850 (degree)C, the amount of oxygen (oxides) is decreased and the presence of carbon is increased. Reactant methane at 850 (degree)C (or higher) reacts with oxides left during the preparation procedure and converts the surface to a more catalytically active state containing carbon.