Promotion of the Water-Gas-Shift Reaction by Nickel Hydroxyl Species in Partially Reduced Nickel-Containing Phyllosilicate Catalysts

The role of surface hydroxyl species generated by partially reduced Ni‐containing phyllosilicate structures (Ni/SiO2P) in promoting the water‐gas‐shift (WGS) reaction and methane suppression was investigated. To analyze the effect of the surface hydroxyl species, Ni/SiO2P catalysts reduced at various temperatures were employed. All the Ni/SiO2P catalysts showed enhanced catalytic performances and methane suppression compared to the conventional Ni/SiO2 catalyst. As revealed by diffuse‐reflectance infrared Fourier transform spectroscopy (DRIFTS), methane suppression could be attributed to the inhibition of the formation of nickel subcarbonyl species, and the promotion of WGS activity was attributed to the involvement of surface hydroxyl species (Ni−OH, 3626 cm−1, and Si−OH, 3740 cm−1). The Ni/SiO2P catalyst reduced at 600 °C showed exceptionally superior performance to the other catalysts in the water‐gas‐shift reaction in terms of turnover frequency (2.79 s−1) and hydrogen formation rates (492.63 μmol H2 g−1 s−1) at 375 °C. Reduction required: Surface hydroxyl species in partially reduced Ni‐containing phyllosilicate structures (Ni/SiO2P[600]) render these structures superior to conventional Ni/SiO2 in the water‐gas‐shift reaction, and methane formation is suppressed by the inhibition of subcarbonyl nickel species.