Kinetic study on the CH4/CO2 reforming reaction: Ni–H in Ni/α-Al2O3 catalysts greatly improves the initial activity

The Ni–H is proved to be formed in Ni/α-Al2O3 corresponding to the high temperature desorbed H in its H2-TPD. Ni–H can be generated in Ni/α-Al2O3 either by the hydrogen reduction above 500 °C or during the in situ CH4/CO2 reforming reaction and it can also be eliminated by the treatment above 900 °C. Kinetic experiments show that the activity of the reforming reaction is initially increased with the amount of Ni–H in Ni/α-Al2O3 and finally it reaches one constant value due to the in situ regeneration of Ni–H. Pulse results indicate that Ni–H in Ni/α-Al2O3 is prone to form CHx species with higher x value, which have higher activity for the reaction with CO2. The catalysts with plentiful Ni–H show higher reaction rate and lower apparent activation energy (77 kJ/mol versus 143 kJ/mol) than those of the catalyst without Ni–H for the pulse of CO2 after CH4.

Ni–H in Ni/α-Al2O3 (B) confirmed by H2-TPD shows a higher initial rate of CH4/CO2 reforming reaction involving higher CO2 rate for the pulse of CO2 after CH4 pulse. The rate of Ni/α-Al2O3 without Ni–H (C) finally reaches a constant value due to the in situ formation of Ni–H. It bridges the hydrogen storage metal and catalytic activity of CH4/CO2 reforming reaction. Figure optionsDownload as PowerPoint slide