120 / 2023-06-20 22:20:14

Partial oxidation of coal mine gas over Ni/Al2O3 catalyst for hydrogen production

coal mine gas; partial oxidation; hydrogen; Ni/Al2O3; catalyst

To investigate the reaction performance of Ni/Al₂O₃-catalyzed partial oxidation of gas to hydrogen, a series of Ni/Al₂O₃ catalysts were prepared by impregnation method, and the catalytic performance was evaluated with the help of U-shaped tubular fixed-bed reactor and BET, XRD, H₂-TPR, NH₃-TPD characterization. The results show that the Ni/Al₂O₃-catalyzed partial oxidation of gas for hydrogen production can be divided into two stages based on the reaction temperature, i.e., complete oxidation below 650 °C and partial oxidation from 650 to 900 °C. At the reaction temperature of 750 °C, the H₂ yield gradually increased from 35.44% to 55.84% with the increase of Ni loading, while the CH₄ conversion increased and then decreased with the inflection point of 8% Ni loading. The reason for the experimental result is that the surface phase NiO is the active phase in the catalytic partial oxidation of gas to hydrogen, and when the Ni loading increases from 5% to 15%, the reduction difficulty of NiAl₂O₄ in the catalyst is weakened; NiO transforms from amorphous to surface phase and then to bulk phase; meanwhile, the excessive free state NiO covers part of the active sites of the catalyst. It was also found that the roasting temperature of the catalyst affected the activity of the catalyst by influencing the interaction force between NiO and Al₂O₃.