Ni-Co catalyst-assisted carbon cycling for CH4-CO2 reforming

Abstract

Carbon cycling, instead of conventional oxygen cycling in chemical looping, overcomes the limitations of oxygen storage capacity of oxygen carriers and enables the reaction to proceed under relatively mild conditions. In this study, we designed a high-performance carbon-storage catalyst (Ni-Co/Al2O3) for chemical looping conversion of CH4 and CO2 to H2 and CO. The physico-chemical characterizations suggested that the Co alloyed with Ni could result in larger active metal particles and simultaneously benefit the bending of carbon deposits toward the periphery of the active sites, avoiding the quick deactivation of catalysts due to the encapsulation of the active sites by carbon deposits and generating a higher carbon capacity (23.59 vs. 14.08 mol/kg). In addition, the alloying of Co with Ni could weaken the graphitization of carbon deposits, thus facilitating the carbon elimination and catalyst regeneration in the CO2 conversion step, strongly improving the cycling stability during long-term testing.