Hydrogen production from biomass combining pyrolysis and the secondary decomposition

An efficient method of hydrogen production from biomass was studied in this paper. The pyrolysis of biomass was combined with the secondary decomposition of gaseous intermediate for hydrogen-rich gas production, with the avoidance of N2 and CO2 dilution to the energy density of gaseous effluents. In order to acquire the optimum conditions for hydrogen generation, effects of operating parameters on this two-step decomposition of biomass were analyzed through simulation of thermodynamic equilibrium and experiments using Ni/cordierite catalyst. The results indicate that the operating parameters, including pyrolysis temperature 923 K, 18 min of residence time, the secondary decomposition temperature 1123 K and molar steam to carbon ratio 2, satisfy all the criteria for high hydrogen content and energy efficiency. Hydrogen content of above 60% and hydrogen yield of around 65 g/kg biomass were achieved with optimized conditions. The hydrogen-rich gas is preferred for potential utilization in downstream fuel cells for the implementation of distributed energy supply, and is also practical for pure hydrogen production.