Non-catalytic supercritical water gasification of cedar tree trunk: influencing factors and kinetics

To achieve carbon peak and neutrality targets, biomass supercritical water gasification (SCWG) technology, as a promising renewable energy utilization technology, provide an effective way. The cedar tree trunk, as one kind of low-cost and widely available biomass material, was chosen in this study which could make a contribution to achieving the aforementioned goals. This paper explored the influence of different operation factors (reaction temperature: 600–750 °C, residence time: 0–10 min, feedstock concentration: 2.5–10 wt%, particle size: unfiltered-300 mesh) on the non-catalytic gasification results of cedar tree trunk powder through a quartz tube reactor. Under the conditions of 700 °C, 3 min and 2.5 wt%, the carbon gasification efficiency reached the maximum value of 61.88 %. Then, based on the experimental data of the quartz tube reactor, a kinetic model of non-catalytic SCWG of cedar tree trunk powder was established. The theoretical fitting value of the model was in good agreement with the experimental value. The gas reaction rate analysis showed that the primary routes of H₂ production mainly concluded the pyrolysis reaction, steam-reforming reaction and water-gas shift reaction; the pyrolysis reaction and the steam reforming reaction were the main sources of CO; most CH₄ and CO₂ was from the pyrolysis reaction. The water-gas shift reaction (WGS) dominated in later reaction stage.