Experimental, simulation and process design of hydrogen production from biomass-based products co-gasification in supercritical water

Abstract

The research explored the most effective combination of ethanol and glycerol for producing hydrogen through supercritical water co-gasification. The experiments were conducted at different temperatures (500–700 °C), space time (1.75–3.5 min), feedstock concentrations (10–25 g Carbon/L), and with the use of different alkali-based catalysts (NaOH, Na2CO3, KOH, and K2CO3). The findings revealed that under optimized conditions of 700 °C, 1.75 min, and 25 g Carbon/L, an H2 yield of 63.75 mol/kg was achieved using a carbon mass ratio of 25:75 for ethanol and glycerol, along with Na2CO3 as the catalyst. Furthermore, detailed thermodynamic simulations (GAMS and TeS software) were carried out to understand how the gaseous products varied with different feed compositions and operational conditions. These simulations demonstrated the predictive capabilities of the proposed thermodynamic models, especially in the presence of catalysts. Additionally, a comprehensive process design for scaling up hydrogen production through supercritical water co-gasification was developed and optimized using Aspen Plus. The inclusion of a heat recovery unit and recycle stream led to a substantial reduction in both feedstock solution heating and product cooling duties by 84.4 % and 81.7 % respectively, as well as a decrease in freshwater consumption.