Catalytic pyrolysis of biomass with Ni/Fe-CaO-based catalysts for hydrogen-rich gas: DFT and experimental study

The H2-rich gas produced by biomass pyrolysis with Ni-based catalysts were studied by DFT, thermodynamic simulation, and pyrolysis experiment. The complex reaction between volatiles of biomass pyrolysis was clarified through DFT calculation. The results proved that the Ea of key reactions for H2 production on Ni-Fe/CaO surface were lower than that on NC, which facilitates to produce H2. The order of the Ea of the rate determining step on Ni-Fe/CaO surface is toluene cracking reaction < water-carbon reaction < Boudouard reaction < methane steam reforming reaction < methane dry reforming reaction < water gas shift reaction, indicating water gas shift reaction is the key control reaction. When the temperature is 650 ℃, Ni-Fe/CaO can effectively adsorb CO2 to break the thermodynamic equilibrium of the water gas shift reaction and promote the forward reaction to generate H2. Thermodynamic simulation and pyrolysis experiments determined that 650℃ and Ni-Fe/CaO are the most suitable reaction condition for H2 formation. Under this condition, the liquid yield of biomass pyrolysis decreased by 18.32% and the gas yield was increased by 26.27% compared to that of Ni /CaO. More importantly, the H2 yield was increased by 18.29% to 453.34 mL/g-biomass.