Study On Catalyst For Production Of Hydrogen By Steam Reforming Of Methanol For Fuel Cell

With less and less fossil fuel on the earth and environment deteriorating, hydrogen energy becomes more and more important. Utilization of hydrogen energy mainly includes production, purification and use of hydrogen. Because of wild source and gentle reaction condition, hydrogen production from methanol is suitable to the preparation of portable hydrogen. Compared with other preparation method, hydrogen production from steam reforming of methanol has higher yield and lower CO concentration and is thought the most promising method used for the hydrogen preparation of fuel cell. Therefore the catalyst used for Steam Reforming of Methanol is key technology of methanol fuel cell.At present the catalysts used for hydrogen production of fuel cell by SRM mainly include noble metal catalyst and copper-based catalyst. Noble metal catalyst has excellent performance except for high price; copper-based catalyst has good low temperature activity and selectivity except for weak stability and fail to demand fuel cell. Ceria is used to promote Cu-ZnO/Al₂O₃ catalyst in research. Cu-ZnO-CeO₂/Al₂O₃ catalyst with excellent low temperature activity, selectivity and stability is prepared. Catalyst performance is valued on fixed bed reactor at atmosphere pressure ; the suitable composition, preparation and activation method of prepared catalyst is researched; modern analytical means are used to characterize catalyst structure. Main research results are as below:1. Different preparation method of Cu-ZnO/Al₂O₃ catalyst is compared over SRM. The performance of catalyst prepared by parallel current co-precipitation is better than that of the catalysts prepared by thermal decomposition and homogenous precipitation.2. Series of Cu-ZnO/Al₂O₃ catalysts are prepared by parallel current co-precipitation. When copper and Zinc's atom mass percent is 1 ∶ 1 and aluminum's atom mass concentration is 5-10% Cu-ZnO/Al₂O₃ catalysts have the best performance over SRM reaction. For example, a maximum methanol conversion of 90.51% , a CO₂ selectivity of 97.77%(mol) and a outlet CO concentration of dry-based gas of 0.56%(mol) are obtained at 220℃ over self-prepared Cu₄₅Zn₄₅Al₁₀ catalyst. Methanol is conversed completely at 240℃.3. The activation method is investigated over Cu₄₅Zn(45)Al₁₀ catalyst. Suitable baked temperature is 500℃; Suitable reduction gas is mixed gas of methanol and water.4. Ceria promoted Cu-ZnO/Al₂O₃ catalysts display higher activity and alike CO₂selectivity. When Cerium's atom mass percent is 5-20% catalysts have best catalytic performance. The optimum reaction conditions of Cu36Zn36AlsCe2o catalyst are as follows: reaction temperature is 230²50°C, ratio of water to methanol is 1.0-1.4, methanol liquid weight space velocity is 1.5².5h"\5. A methanol conversion of 90% and a outlet CO concentration of dry-based gas of 0.2%(mol) are obtained at 250 °C over Cu42.75Zn42.75Al9.5Ce5 during stability experiment. Those performance basically demand hydrogen production of fuel cell on vehicle.6.Characterization means, including TG-DTA, ICP, XRD, SEM, EDX, are utilized to optimize catalysts' composition, preparation and activation method. Ceria promoted function is because that Ceria promote copper to disperse on catalyst's surface, hinder copper particle to agglomerate and sinter, keep active material firmly exist during reaction.