Batch Aqueous-Phase Reforming of Woody Biomass

摘要

Aqueous-phase reforming (APR) is reported for the first time for the production of H_2 from actual biomass. The experiments are carried out in batch using a 100 mL Parr microreactor heated to 225℃. In this one-pot, two-step process, acid hydrolysis is used to break down the polymeric constituents of biomass to smaller soluble molecules and these species are reformed using a Pt/Al_2O_3 catalyst. The experiments show that increasing the acid concentration from 1% to 5% causes more than a 12-fold increase in H_2 concentration, with hydrogen being a minor product accounting for 18% of the noncondensable gas phase and CO_2 as the major product. In the presence of the Pt/Al_2O_3 reforming catalyst, both the selectivity and yield of hydrogen in the gas phase increase. This is accompanied by a noticeable decrease in carbon monoxide production, which is attributed to the activation of the water gas shift reaction catalyzed by platinum. Comparison with other feeds such as glucose, wastepaper, and ethylene glycol showed that the amount of hydrogen produced from biomass is of a comparable magnitude per gram of feed, although biomass yields more hydrogen per gram of carbohydrate than either glucose or wastepaper. Baseline experiments with only the catalysts in the absence of any biomass show no increase in the reactor system pressure when only water and helium are present, indicating that the observed hydrogen produced is sourced from the biomass.