Thermal Characteristics of Biomass Pyrolysis Oil and Potential Hydrogen Production by Catalytic Steam Reforming

In order to facilitate the further processing and utilization of biomass pyrolysis oil, the chemical composition and thermal properties of biomass pyrolysis oil from pyrolysis of rice husk were investigated. The chemical composition analysis revealed that the pyrolysis oil contained a large amount of oxygenated compounds, i.e., acid, ketones, and phenols. Thermal degradation behaviors and kinetics of pyrolysis oil were investigated at different heating rates (5, 20, 35, and 50 °C min^-1) under N₂ and air atmospheres by TG. Pyrolysis oil decomposition mainly experienced three stages in either N₂ or air atmosphere, and the corresponding activation energies vary with the degree of conversion. Py-GC/MS analysis of the pyrolysis oil reveals that ketones and aromatics are the main pyrolysis products of biomass pyrolysis oil. When the temperature increased from 600 to 700 °C during Py-GC/MS analysis, the content of ketones increased while the content of aromatics decreased. Subsequently, the feasibility of catalytic steam reforming of pyrolysis oil to produce renewable hydrogen was performed in a fixed-bed reactor with a NiO/ceramic foam catalyst. The effects of calcination temperature and metal content on the hydrogen yield were investigated. It is indicated that higher calcination temperature and loading content lead to the aggregation and sintering of NiO particles. A maximum hydrogen yield of 105.28 g H₂ kg^-1 pyrolysis oil (up to 81.1% of the stoichiometric yield) was obtained at a reaction temperature of 700 °C, S/C ratio of 1, and NiO loading content of 3.54%.