Aqueous Phase Reforming of Bio-Derived Organic Compounds
Sadashiv M. Swami and Martin Abraham. Chemical & Environmental Engineering Department, University of Toledo, Nitschke Hall, Room # 3048,, Toledo, OH 43606
Hydrogen is receiving more attention than ever before as a future energy alternative owing to the recent global efforts to reduce the dependence on fossil fuel and carbon-based emissions. Currently, research is being focused on the conversion of renewable energy sources such as biomass. However, the existing technologies available for conversion of biomass and biomass derived materials are based on high temperature (500-800°C) steam and autothermal reforming, both of which are energy-intensive. The aqueous phase reforming is being conceived as an alternative technology for hydrogen generation. APR is carried out at relatively low temperature (225 -250°C) and moderately high pressure (400-600 psig). Since reaction is carried out in liquid phase, the energy required for evaporation of fuel and water is saved. Another advantage of using APR is very low levels of CO obtained in product gases (ppm level compared to ~ 10 % CO obtained in steam reforming processes). Aqueous phase reforming of ethanol has been evaluated at 250°C and 600 psig using 5 % Pt on Al2O3 catalyst to provide a baseline for catalyst and reactor development. The pH of feed solution has been determined as a critical parameter affecting catalyst performance and stability. Experiments in a continuous flow packed bed reactor revealed the possibility that reactions were mass transfer limited because of the low flow rates and low diffusivity of the reacting molecules in the liquid phase. H2 yields were found to be in the range of 10%, lower than that predicted from equilibrium calculations. Current research is focused improving catalyst design to increase hydrogen production.