Hydrogen Generation from Wood Chip and Biochar by Combined Continuous Pyrolysis and Hydrothermal Gasification

Hydrothermal gasification (HTG) experiments were carried out to extract hydrogen from biomass. Although extensive research has been conducted on hydrogen production with HTG, limited research exists on the use of biochar as a raw material. In this study, woodland residues (wood chip) and biochar from wood-chip pyrolysis were used in HTG treatment to generate hydrogen. This research investigated the effect of temperature (300-425 degrees C) and biomass/water (0.5-10) ratio on gas composition. A higher temperature promoted hydrogen production because the water-gas shift reaction and steam-reforming reaction were promoted with an increase in temperature. The methane concentration was related positively to temperature because of the methanation and hydrogenation reactions. A lower biomass/water ratio promoted hydrogen production but suppressed carbon-monoxide production. Most reactions that produce hydrogen consume water, but water also affects the water-gas shift reaction balance, which decreases the carbon-monoxide concentration. By focusing on the practical application of HTG, we attempted biochar treatment by pyrolysis (temperature of heating part: 700 degrees C), and syngas was obtained from hydrothermal treatment above 425 degrees C.

Automated summary

The study found that increasing temperature can promote hydrogen production in hydrothermal gasification, while a lower biomass/water ratio may be conducive to hydrogen production and suppress the formation of carbon monoxide.