| The research & development of renewable clean energy is becoming the focus in the worldwide, due to the "oil crisis" and the environmental and climate problems brought by the use of fossil fuels. Hydrogen, because of its cleanness, efficiency, safety and sustainability, is the most promising candidate in this area. In 2002, Dumesic reported aqueous-phase reforming of polyols (a kind of biomass derivatives) to produce hydrogen, which realized zero emission of CO2 and connected the hydrogen with renewable biomass resources.In this dissertation, ethylene glycol, the simplest polyol molecule, was chosen as reactant. The effect of supports and preparation methods of supported platinum catalysts on aqueous-phase reforming of ethylene glycol was investigated. And the reaction mechanism was discussed through the variation of reaction and characterization results of catalysts.The supports ofγ-Al2O3,δ-Al2O3 andα-Al2O3 were obtained through calcination of AlOOH at different temperatures. After impregnation with Pt, the catalysts were evaluated by aqueous-phase reforming of ethylene glycol. The results showed that the catalytic activities decreased in order of Pt/α-Al2O3> Pt/δ- Al2O3> Pt/γ- Al2O3. The yield of hydrogen reached 452μmol·min-1·gCat-1 at the condition of 225℃,29.0 KPa and 6 ml/h of ethylene glycol solution (volume percentage of ethylene glycol was 10%) with 1% Pt/α-Al2O3. The characterization of XRD, H2-TPR, TEM-EDX, CO chemisorption and XPS evidenced that no chlorinated platinum species was presented on Pt/α-Al2O3, which favored the improvement of the dispersion of surface species and avoided the sintering of Pt. Furthermore, the strong interaction between Pt andα-AI2O3 with less surface hydroxyl groups led to the formation of platinum species with low oxidation state. As a result, the combination of the above arguments was assumed to be the reasons for the higher catalytic activity of Pt/α-Al2O3.Iorn oxide supports with different surface area and phase composition were prepared by using evaporation-induced self-assembly method, hard template method, thermal solid decomposition method and precipitation method. The study on aqueous-phase reforming of ethylene glycol with Pt/Fe-0 catalysts indicated that the interaction between Pt and support would be influenced by Si or C reminded in iron oxide supports, which consequently inhibited the activity of catalysts. The results showed that Fe3O4 with large surface area should be a good choice of iorn oxide supports.Water-gas shift reaction, aqueous-phase reforming of methanol and ethylene glycol were carried out on Pt/Al-O, Pt/Fe-0 and Pt/Ce-O, respectively. For aqueous-phaes reforming of ethylene glycol, the catalytic activities decreased in order of Pt/Al-O> Pt/Fe-O> Pt/Ce-O. While, it changed as Pt/Ce-O> Pt/Fe-O> Pt/Al-O for water-gas shift reaction. Moreover, all the activities for aqueous-phase reforming of ethylene glycol were higher than those for aqueous-phase reforming of methanol. Therefore, the catalytic activity of aqueous-phase reforming of ethylene glycol did not involve any relationship with the activity of water-gas shift reaction or the catalyst capacity for C-C bond breakage. This conclusion was also confirmed by the study on Pt/γ-Al2O3, Pt/δ-Al2O3, Pt/α-Al2O3 and Ce-doped Pt/Al-0 catalyst. The H2-TPR and ethylene glycol-TPD of Pt/γ-Al2O3 and Pt/α-Fe2O3 and diffuse reflectance infrared Fourier transform spectroscopy of ethylene glycol on Pt/γ-Al2O3, Pt/δ-Al2O3 and Pt/α-Al2O3 revealed that the breakage of O-H bond in ethylene glycol and the removal of surface bicarbonate or formate species should be the crucial steps in aqueous-phaed reforming of ethylene glycol.
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