Effects of penta-coordinated Al3+ sites and Ni defective sites on Ni/Al2O3 for CO methanation

Engineering sophisticated structure of Al2O3 and controlling the structure of counterpart metal active sites remain challenges to achieve a high catalytic-performance in heterogeneous catalysis. Herein, we present a confinement strategy to stabilize homogeneous Ni by penta-coordinated Al3+ anchoring sites in Al2O3. This approach is involved in using a metal-organic framework as host to load Ni2+ ions, by the aim of producing a confined Ni/Al2O3 catalyst after a standard calcination. Metal-support interaction between Ni and Al2O3 was tailored to be medium to avoid the formation of inactive NiAl2O4, which favors the generation of more available Ni active sites accessible to the reactants. The resultant Ni/Al2O3 exhibited superior catalytic performance in comparison with the control Ni/Al2O3 in CO methanation owing to the presence of defective sites on sufficient Ni-0 surface. Furthermore, the presence of oxygen vacancies on Al2O3 and hydrogen spillover contributed toward excellent coke resistance properties in the reaction.