RuNi/TiZr-MMO Catalysts Derived from Zr-Modified NiTi-LDH for CO-Selective Methanation

CO-selective methanation (CO-SMET) is an efficient hydrogen-rich (H₂-rich) gas purification technology for proton exchange membrane fuel cells. It is vital to develop suitable catalysts with good low-temperature activity for CO-SMET reactions. In this study, RuNi/TiZr_x-mixed metal oxide (RuNi/TiZr_x-MMO) catalysts with different molar ratios of Zr/Ti, derived from a Zr-promoted NiTi-layered double hydroxide (NiTi-LDH) precursor were successfully prepared using the co-precipitation and wet impregnation methods. The RuNi/TiZr_0.2-MMO catalyst possesses higher catalytic performance in a lower temperature window of 180-280 °C, which can reduce the CO concentration to be below 10 ppm. The characterization results obtained from XRD, BET, SEM, TEM, XPS, TPR, and TPD suggest that the addition of ZrO₂ increases the surface area of the catalyst, improves the dispersion of metallic nanoparticles, increases the reducibility of Ni species on the RuNi/TiZr_0.2-MMO catalyst's surface, and enhances the adsorption and activation ability of CO, resulting in remarkable catalytic performance at lower reaction temperatures. Moreover, the RuNi/TiZr_0.2-MMO catalyst demonstrated long-term catalytic stability and carbon resistance.