Catalytic pyrolysis of corncob with Ni/CaO catalysts for hydrogen-rich gas: Synthesis modes and catalyst/biomass ratios

Abstract

With the depletion of traditional fossil fuels, biomass has evolved as a new environmentally friendly and sustainable alternative energy source. Ni/CaO catalysts are promising for CO2 capture and biomass catalytic use. In this study, we examined four different synthesis modes for Ni/CaO catalysts: impregnation method, sol–gel method (citric acid complexation), sol–gel method with propionic acid modification and sedimentation method, and used the catalysts in the pyrolysis of corncob to produce hydrogen-rich gas at 600 °C. According to the results of the fixed-bed experiments, adding the propionic acid modification to the citric acid complexation boosted hydrogen generation by 24.93 vol.%. The global behavior of the catalysts synthesized by the different methods follows the order sol-Ni1/Ca7-P > sol-Ni1/Ca7 > sed-Ni1/Ca7≫imp-Ni1/Ca7-A. At a catalyst/biomass ratio of 2:1, the maximum H2 concentration of 84.45 ± 1.02 vol.% and H2 production of 26.84 ± 1.26 mmol/gbiomass were attained, as well as CO2 concentrations of just 2.08 ± 0.03 vol.%. The H2 production was about 20 times higher than without the addition of the catalyst. Optimizing the synthesis modes and catalyst/biomass ratio produced high-quality hydrogen-rich gas with a high H2 conversion of 88.95 ± 2.20 % and the energy efficiency of 52.73 %.