RuNi/MMO Catalysts Derived from a NiAl-NO3-LDH Precursor for CO Selective Methanation in H2-Rich Gases

CO selective methanation (CO-SMET) is a promising method for deep CO removal from H2-rich gases. In this study, a series of RuNi/MMO catalysts are prepared using the support MMO-N derived from NiAl-NO3-LDHs, which was prepared from NiAl-CO3-LDHs via an acid–alcohol ion-exchange reaction. The prepared catalysts were characterized by XRD, SEM, TEM, XPS, H2-TPR, CO-TPD, CO2-TPD, NH3-TPD, and TG. The RuNi/MMO-N catalyst demonstrated excellent CO-SMET performance, successfully reducing the CO to less than 10 ppm with a selectivity greater than 50% in a reaction temperature window ranging from 180 °C to 260 °C. Compared with similar catalysts derived from NiAl-CO3-LDHs, the exceptional CO-SMET capability of the RuNi/MMO-N catalyst is suggested to be associated with a more effective hydrogen spillover, a larger number of electron-rich Ni sites, and a higher density of acid sites on the surface of RuNi/MMO-N, which are conducive to CO adsorption and the inhibition of CO2 methanation.