Direct reduction of nickel catalyst with model bio-compounds

The effects of temperature and S/C on the reduction extent and kinetics of a steam reforming NiO/α-Al₂O₃ catalyst were systematically investigated using five bio-compounds commonly produced during the fermentation, pyrolysis and gasification processes of biomass (acetic acid, ethanol, acetone, furfural and glucose). Reduction was also performed with methane and hydrogen for comparison. Kinetic modelling was applied to the NiO conversion range of 0–50% using the Handcock and Sharp method. The two-dimensional nuclei growth model (A2) was found to fit very well except for glucose. For all the bio-compounds, the apparent activation energy of NiO reduction was between 30 and 40 kJ/mol. Their pre-exponential factors decreased in this order: CH₄ > ethanol ≈ acetone > acetic acid > furfural > glucose, probably due to the different activities of reducing species they produced. Optimal molar steam to carbon ratios for reduction kinetics were found between 1 and 2.