Balancing Ni0 and Ni2+ on γ-Al2O3 for Efficient Steam Methane Reforming

Graphical The key role of Ni valence state on the catalytic SMR performance of Ni/Al 2 O 3 is reported. Ni 0 /Ni 2+ ratio on Ni/Al 2 O 3 is individually regulated by changing the reduction temperature while maintaining the states of nickel particles and support. A deep understanding is gained on how the Ni valence state of Ni/Al 2 O 3 affects the catalytic SMR performance. Steam methane reforming (SMR) is the most mature technology for hydrogen production in industry, and alumina supported nickel (Ni/Al 2 O 3 ) is the most widely used catalyst. Herein, the key role of Ni valence state on the catalytic SMR performance of Ni/Al 2 O 3 is reported. The ratio of Ni 0 /Ni 2+ on Ni/Al 2 O 3 is individually and effectively tuned by changing the reduction temperature after wet impregnation. Catalytic performance of Ni/Al 2 O 3 is greatly dependent on the surface concentration of Ni 0 and Ni 2+ . The catalyst reduced at 675 °C possesses balanced Ni 0 and Ni 2+ sites and exhibits superior catalytic performance, on which 60 % of methane is stably converted at 600 °C. CH 4 -TPD and CO-TPD profiles demonstrate that appropriate Ni 0 /Ni 2+ ratio can promote the adsorption of CH 4 and inhibit the moderate-strength adsorption of CO, which leads to increased SMR activity and selectivity.