Catalyst performance of MoS2 and WS2 for the CO2-reforming of CH4 Suppression of carbon deposition Original Research Article

The catalyst performance of MoS2 and WS2 was verified for the CO2-reforming of CH4 through the comparison with that of NiSiO2. No catalyst deactivation was observed on the disulfides, although the rate was much smaller than that on Ni. It was found that the disulfides exhibited a poor ability for the direct decomposition of CH4. The poor ability did not lead to carbon deposition during reforming reaction, which assured a stable activity. It was also observed that the rate equation was completely different between disulfide catalysts and Ni catalyst. The reaction order was positive with respect to the CH4 partial pressure and negative with respect to the CO2 partial pressure on the former catalysts, while negative with respect to CH4 partial pressure and positive with respect to the CO2 partial pressure on the latter. The observed reaction kinetics suggested that the surface of the disulfide catalyst was abundant in adsorbed CO2, while the surface of Ni catalyst was abundant in adsorbed CH4. The abundance in adsorbed CO2 was considered an unfavorable condition for the direct decomposition of CH4 and as a result, carbon deposition was suppressed during CO2-reforming on disulfide catalyst. Sulfur tolerance was found to be an additional performance of the disulfide catalyst.