Design of active NiCo2O4-δ spinel catalyst for abatement of CO-CH4 emissions from CNG fueled vehicles

Increasing number of CNG vehicles on road emits considerable amount of CO, a poisonous gas and CH4, a greenhouse-gas. Highly active and oxygen-deficient NiCo2O4- spinel and its individual metal-oxides were synthesized by calcination of precipitated/co-precipitated basic-carbonates followed by calcination under different strategies of stagnant air(s), flowing air(f) and reactive calcination(RC) for total oxidation of CO-CH4 mixture. The catalysts were characterized by XRD, XPS, BET surface-area, SEM-EDX and TEM. The performance order of the catalysts for the oxidation of CO-CH4 mixture was as follows: NiCoRC>NiCof>NiCos>Co-RC>Co-f>Co-s>Ni-RC> Ni-f>Ni-s. The pairing of Ni and Co in spinel-structure together with RC produced catalyst was oxygen-deficient highly active for total oxidation of the mixture at the lowest temperature of 350 degrees C. The NiCoRC was found stable under reaction-conditions for 50h at 350 degrees C and after four successive heating (350 degrees C)-cooling (35 degrees C) cycles besides accelerated-aging tests up to 600 degrees C. (c) 2018 American Institute of Chemical Engineers AIChE J, 64: 2632-2646, 2018