Hydrotalcite-derived Co/Mg(Al)O as a stable and coke-resistant catalyst for low-temperature carbon dioxide reforming of methane

Abstract

The Co catalyst using hydrotalcite-derived Mg(Al)O as support shows promising catalytic activity for low-temperature CH4-CO2 reforming. Under a wide range of reaction conditions, that is T = 773–1023 K, CH4/CO2/N2 = 25/25/50–50/25/25, WHSV = 60,000–120,000 mL h−1 g−1, and TOS = 25–200 h, the Co catalyst exhibits stable activity and high coke resistance. The performance is superior to the Ni counterpart which readily deactivates at 773 K due to severe coke deposition. The initial coking rate on the Co catalyst was estimated to be about 1/20 times that on the Ni catalyst. The kinetic study suggests that the dissociative adsorption of CH4 is favored on the Ni catalyst, whereas the Co catalyst has high affinity for CO2 adsorption. The results of CH4-TPSR and direct CH4 decomposition experiments further reveal that the Co catalyst is much less active for carbon formation through CH4 decomposition. It is deduced that a combination of lower activity for CH4 dissociation/decomposition and higher affinity for CO2 adsorption as well as a stronger metal-support interaction is responsible for the higher coke resistance of the Co catalyst.