Iranica Journal of Energy and Environment (Jan 2012)
Effect of Reaction Temperature and Type of Catalyst on Hydrogen Production in Supercritical Water Gasification of Biomass
Abstract
The aim of this study was to investigate the feasibility of hydrogen production from sugarcane bagasse by supercritical water gasification (SCWG) at low temperature and in presence of alkali catalyst. Experiments were carried out in a batch autoclave reactor at 400 °C and 9% solid content. Effect of reaction time and alkali catalyst on gas yield, gas composition, carbon gasification efficiency (CGE) and hydrogen gasification efficiency (HGE) were investigated. Influence of reaction time on gas yield and composition as well as on CGE was found to be insignificant. Extending the reaction time even up to 4 h could not cause an attractive conversion of bagasse. In the presence of catalysts (K2CO3, KHCO3, NaHCO3 and NaOH), sugarcane bagasse was partially gasified in SCW and hydrogen-rich gas containing CO2 as the main carbon compound was produced. Among the implemented catalysts, K2CO3 was identified to be the most effective for improvement of HGE. Use of the catalyst under our experimental conditions, the maximum HGE of 19% was achieved; however the highest CGE occurred with KHCO3. Results showed that feed to catalyst ratio of 2 was high enough to reach the greatest possible gasification of hydrogen at 400 °C and 45 min. More CGE and HGE would be possible only by increasing the temperature, pressure and/or reaction time.
