One-pot synthesis of NiCo/MgAl2O4 catalyst for high coke-resistance in steam methane reforming: Optimization of Ni/Co ratio

Abstract

NiCo bimetallic catalysts based on the support of a MgAl2O4 defect spinel (Mg/Al < 1/2) were developed as catalysts for steam methane reforming (SMR) in the present study. Catalysts were synthesized by the one-pot evaporation-induced self-assembly (EISA) method followed by exsolving of active components under reduction conditions. The optimum Co contents were found to be 5 wt% in NiCo-MgAl2O4 for the SMR catalysts with high activity and coking resistance. To understand the key parameters, the physicochemical properties of the catalysts were investigated by multiple analyses. Ni and Co were simultaneously exsolved from the A-site in the MgAl2O4 support after reduction, which led to formation of Ni-Co alloy with strong metal-support interaction. Co highly influenced the oxidation state of Ni where the relative concentration of Ni0 was highest (37.6 %) for NiCo5 (5 wt% of Co). Through SMR reaction tests and Raman and thermogravimetric (TG) analyses, it was clearly confirmed that the addition of Co in NiCo-MgAl2O4 enhances for catalytic efficiency and coke resistance. Our findings are highly applicable to the development of more robust and optimized catalysts, particularly in light of the future hydrogen economy and the related and increasing demand for small-scale SMR for distributed hydrogen production.