Study On Reaction Process Of Hydrogen Production From Biomass Gasification In Supercritical Water

A set of experimental apparatus was set up to produce hydrogen from biomassgasification in supercritical water (SCW). Moreover, the apparatus have been improved to fitfor higher temperature and pressure, which extends the range of operating conditions.Using glucose as a model compound of biomass, the effects of high temperature andcatalysts on the experiment were studied in this paper. The composition of gas production wasanalyzed by GC900A gas chromatography. The method for the qualitative analysis of liquidproduct was also determined. The possible reaction pathway and mechanism were proposedbased on the analysis result of the liquid product, which will provide basis for furtherresearch.First of all, the effects of operating parameters on hydrogen production from the biomassgasification in SCW were validated according to the relevant literatures. It is found thattemperature is the main affecting factor in experiment. Both the content of hydrogen and theconversion ratio of the gas increase with the temperature rising. Besides, the effect ofcatalysts (base catalysts only) on the experiment was also studied. The catalysts can improvethe gas composition effectively, and enhance the content of hydrogen in the gas phase. It isfound that base catalysts can promote the reactions of ring-opening and isomerization for thecyclic compounds.It is the key to the investigations on reaction pathway and mechamnism to analyze theliquid product. According to relevant literatures and the results of the experiments in thiswork, the methods of liquid processing and analyzing were determined: Most composition inthe liquid product was qualitatively analyzed by gas chromatograph-mass spectrum (GC/MS)using temperature programmed. Glucose, used as feedstock, had started to decompose whenthe temperature was below 300℃, and had completely decomposed to generate hydrogen,carbon monoxide, methane, carbon dioxide, and amount of liquid production at elevatedtemperature. Hydrogen is the main composition of the gas product, followed by carbonmonoxide and carbon dioxide.The possible reaction pathway and mechanism for hydrogen production from biomassgasification in SCW was proposed based on the comprehensive analysis of gas and liquidproduct, and the theoretical basis for improving the process of hydrogen production frombiomass gasification in SCW was provided. In addition, hydrogen production from the gasification of original biomass (such assawdust) and other organic materials in SCW was also studied in this paper. At theseconditions, hydrogen had also been successfully obtained. Compared with the result ofglucose gasification, it shows that original biomass is gasified well in this set of apparatus,which indictates the apparatus can be used for the research on hydrogen production from solidpowder feedstock.