Effects of Increasing Alkali Catalysts Concentration on Hydrogen Gas Yield during the Supercritical Water Gasification of Food Waste

Abstract:

Supercritical water gasification (SCWG) of food waste was carried out to investigate the effects of increasing alkali catalysts (NaOH, KOH, Ca (OH)₂, Na₂CO₃, NaHCO₃ and K₂CO₃) concentration on hydrogen yield. Food waste containing twenty-eight different Chinese food items was gasified at a temperature of 400°C (held for 10mins) and pressure of 24MPa. The basicity of the reacting medium was an underlying factor influencing the effects of the different alkali catalysts concentrations on the hydrogen yield. In this study, KOH generally had the highest catalytic effects on hydrogen yield. Additionally, increasing the concentration of alkali catalysts significantly suppressed the CO₂ content in the product gases. Suppression of CO₂ by NaOH and KOH was due to their catalytic effects during the water gas shift reaction (WGSR) in order to increase the hydrogen yield. Suppression of CO₂ by carbonates on the other hand was due to their catalytic effects on the methanation reaction, thereby hindering the WGSR and resulting in lower hydrogen yields. Finally, increasing NaOH concentrations was very effective to decarbonize the product gas of the various reactions. This study seeks to discriminate the effects of increasing alkali catalysts concentration on hydrogen yield during the SCWG of food waste.

• Periodical: Advanced Materials Research (Volumes 1073-1076)
• Pages: 905-910
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1073-1076.905
• Online since: December 2014
• Authors: Basil Amuzu-Sefordzi*, Jing Yu Huang
• Keywords: Alkali Catalysts, Carbon-Dioxide, Food Waste, Hydrogen, Supercritical Water Gasification

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