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

The Ni-H is proved to be formed in Ni/alpha-Al2O3 Corresponding to the high temperature desorbed H in its H-2-TPD. Ni-H can be generated in Ni/alpha-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 degrees C. Kinetic experiments show that the activity of the reforming reaction is initially increased with the amount of Ni-H in Ni/alpha-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/alpha-Al2O3 is prone to form CH, 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. (c) 2005 Elsevier B.V. All rights reserved