Abstract:Because wet biomass such as residues from food industry or sewage sludge usually contains plenty of protein and fattiness, the experiments of glycine and glycerin gasifications in supercritical water were conducted, in which glycine and glycerin were used as the model compounds of protein and fattiness, respectively. The product characteristics of glycine and glycerin gasifications, the catalytic mechanism of alkali compound such as sodium carbonate, were investigated with coupled relation between reaction temperature and reaction time. The results show that glycine and glycerin gasification efficiencies could reach more than 95.8%, the gas produced was a hydrogen-enriched fuel gas, in which hydrogen molar fraction can be higher than 55%, hydrogen yield could be up to 4.14 mol•mol^-1_glycineand 5.08 mol•mol^-1_glycerin, respectively. Liquid after reaction could be reused not only because it was clear and transparent but also that because both the Chemical Oxygen Demand (COD) and pH value indexes were met the quality standard of domestic water formiscellaneous use. Sodium carbonate could increase hydrogen yield and COD removal efficiency of liquid products. The catalytic effect of addition amount of 0.1% mass concentration was better than that of 0.2%. Sodium carbonate increased the hydrogen yield of glycine gasification probably by accelerating the decarboxylation reaction of formic acid, which is a glycine hydrolysate, not by the water-gas shift reaction. Sodium carbonate would inhibit the hydrogen yield of glycerin gasification and COD removal efficiency, the reasons are required to investigate in detail.
Keywords:supercritical water;glycine;glycerin; gasification;hydrogen