Kinetics of Steam Gasification of Glucose as a Biomass Surrogate over Ni/Ce-Mesoporous Al₂O₃ in a Fluidized Bed Reactor

This study reports the kinetics of steam gasification of glucose as a biomass surrogate over a new Ni(x)/Ce-doped Al₂O₃ (x = 5, 10, 15, and 20 wt %) catalyst in a fluidized bed reactor. The presence of ceria plus successive nickel impregnation helped in conserving the catalyst's high surface area (i.e., 102 m²/g at 20 wt % nickel loading). Incorporation of ceria dopant suppressed coke formation during steam gasification of 15 wt % glucose in the fluidized bed reactor at 650 °C and 1 atm in the order Ni(20) < Ni(15) < Ni(10) < Ni(5)/Ce-doped Al₂O₃. The detailed kinetic model comprises reactant adsorption, surface reaction, and product desorption steps, involving the water gas shift reaction (WGS), steam reforming of methane (SRM), and reverse dry reforming of methane (RDRM). Ni(20)/Ce-doped Al₂O₃ with the best performance in terms of syngas production, and the least tendency for coking, was used for the kinetic studies (for T = 550-700 °C and t = 5-25 s). The results of the model simulation indicate that the rate of water gas shift was the highest (7.76 × 10^-2 mmol/g of cat.·s·bar²) followed by steam reforming of methane (4.13 × 10^-2 mmol/g of cat.·s·bar²) and then reverse dry reforming of methane (3.57 × 10^-2 mmol/g of cat.·s·bar²). The high reaction rates signify the suitability of the new Ni(x)/Ce-mesoporous Al₂O₃ catalytic system applied in this work. The modeling procedure could be applied conveniently for a different catalytic system in a similar reactor to obtain the necessary kinetic parameters.