NiCx/Ni-foam discovered as a promising high-temperature WGSR catalyst

Abstract

Water gas shift reaction (WGSR) is urgently calling for an alternative to the Fe-Cr catalyst. Ni-based catalysts are taken into consideration but remain challenging because of their high methanation activity. Here we report a highly active and selective NiCx/Ni-foam catalyst with clearly detectable Ni3C phase, facilely obtainable by endogenous growth of NiC2O4 onto a Ni-foam and subsequent H2-reduction treatment. The preferred catalyst with high content of NiCx is capable of converting 63.6% or 94.3% CO at 350 °C or 400 °C with trace or < 0.8% CH4 formation for a feed gas with H2O/CO/Ar molar ratio of 4/1/9, and is stable for at least 110 h. It is experimentally and theoretically unveiled that the Ni3C facilitates the dissociative activation of H2O and favors CO to form carboxylate species (favorable for CO2 formation) rather than active Ni(CO)n intermediates for CH4 formation thereby enabling the catalyst with high WGSR activity and selectivity.