负载型Pt催化剂上生物质水相重整制氢

Hydrogen Production by Aqueous-Phase Reforming of Biomass over Supported Pt Catalysts

制备了Al2O3,活性炭(AC),氢型超稳Y分子筛(HUSY)和SiO2负载的Pt催化剂.采用N2物理吸附、感应耦合等离子体原子发射光谱和H2化学吸附等手段对催化剂进行了表征,并考察了它们在甘油水相重整反应中的催化性能.重点研究了Pt/AC催化剂上不同多元醇、葡萄糖和其它可溶性糖的水相重整制氢反应.结果表明,在甘油水相重整制氢反应中,负载Pt催化剂的活性在低温(503K)以Pt/AC,Pt/HUSY,Pt/SiO2和Pt/Al2O3的顺序递增,然而在高温(538K)却以Pt/SiO2,Pt/HUSY,Pt/AC和Pt/Al2O3的顺序递增.在载体为酸性的催化剂Pt/Al2O3和Pt/HUSY上有利于烃的生成;在多元醇水相重整制氢反应中,产物氢的选择性和产率随碳数增加而降低;在葡萄糖水相重整制氢反应中,产物氢的选择性和收率随其浓度增加而降低,烃选择性在葡萄糖浓度为4.6%时最高,这与葡萄糖的缩合和降解等副反应有关.果糖比葡萄糖更难发生水相重整制氢反应.与低级糖麦芽糖和葡萄糖相比,在多糖淀粉的重整制氢反应中氢选择性和收率较高.

Pt catalysts supported on Al2O3, activated carbon （AC）, HUSY, and SiO2 were prepared and characterized by N2 physisorption, inductively coupled plasma atomic emission spectrometry, and H2 chemisorption. The catalytic performance of these catalysts for H2 production by aqueous-phase reforming （APR） of glycerol was studied. In addition, the reforming of different reactants such as polyols, glucose, and other soluble saccharides was also investigated. It was found that the activity of the supported Pt catalysts for the reforming of glycerol increased in the order Pt/AC 〈 Pt/HUSY 〈 Pt/SiO2 〈 Pt/Al2O3 at 503 K; however, the activity increased in another order Pt/SiO2 〈 Pt/HUSY 〈 Pt/AC 〈 Pt/Al2O3 at higher temperature （538 K）. Pt catalysts supported on acidic supports such as Al2O3 and HUSY tended to increase hydrocarbon formation. The H2 selectivity and production rate for the reforming of polyols decreased with increasing carbon number. The H2 selectivity and yield for the reforming of glucose decreased when the glucose concentration increased, while selectivity for hydrocarbon showed a maximum at glucose concentration of 4.6%, which was ascribed to the condensation and degradation reactions. Fructose is less readily reformed to H2 than glucose. Higher H2 selectivity and yield were obtained by reforming of polysaccharide starch compared with those obtained by reforming of disaccharide maltose and monosaccharide glucose.