Effect of KOH on hydrogen production from lignite in a continuous supercritical water reactor

Hydrogen-rich gas production from Chinese Xiaolongtan lignite was performed in a continuous supercritical water reactor with feeding of coal water slurry. The effects of KOH/coal weight ratio, temperature and pressure on carbon gasification efficiency, product distribution and yields of gas were investigated. At KOH/coal weight ratio of 4.1% (600℃, 25MPa), carbon gasification efficiency reaches to 31.5%. The content of hydrogen in gas is 38.5% and its yield reaches to 239.1mL/(g daf coal). There is a notable increase in the yield of hydrogen with the elevation of reaction temperature. The yield of hydrogen increases from 53.0mL/(g daf coal) to 287.8mL/(g daf coal) when temperature increases from 500℃ to 650℃. The catalytic performance of KOH is distinct at higher temperature. The increase of pressure also has positive impact on yield of hydrogen.