Abstract: The hydrogen desorbed at high temperature (high-temperature hydrogen) over the hydrogen reduced catalyst Ni/La2O3/α-Al2O3 was observed by H2 temperature-programmed desorption. Kinetic experiments show that the activity of the reforming reaction is initially increased with the amount of high-temperature hydrogen in Ni/La2O3/α-Al2O3 and finally reaches a constant value due to the in situ generation of the high-temperature hydrogen. Pulse results indicate that the high-temperature hydrogen in Ni/La2O3/α-Al2O3 is prone to form CHx species with high x values, which has higher activity for the reaction of CHx with CO2. The Ni/La2O3/α-Al2O3 catalyst with plenty of high-temperature hydrogen can increase the x values of CHx species and decrease the activation energy for the reaction between CHx and CO2, leading to a higher reaction rate. The addition of La2O3 on the Ni/α-Al2O3 catalyst promotes the reverse water-gas shift reaction and slightly improves the activation of CO2. La2O3 also increases the amount of high-temperature hydrogen and its stability, resulting in higher x values of CHx species and improving the reforming reaction rate.

Key words: high-temperature desorbed hydrogen, nickel-based catalyst, lanthana, methane reforming reaction, initial rate