摘要:
研究了Cu/ZrO2催化剂在乙醇水蒸气重整反应中的催化性能。用常规沉淀法、醇凝胶法制备了ZrO2载体；用浸渍法或共沉淀法制备了Cu/ZrO2催化剂。考察了ZrO2载体的制备方法以及Cu/ZrO2的制备参数对催化剂性能的影响。采用BET、XRD、TEM及XRF等方法对催化剂的比表面积、孔容、晶相、表面形貌以及活性组分等进行了表征。同时，制备并比较了Ni/ZrO2、Cu/10MgO-90ZrO2和Cu/10CaO-90ZrO2催化剂的性能，考察了活性组分Cu、Ni的差异以及ZrO2载体的影响。在Cu/ZrO2催化剂(Cu的质量分数为8%)上，500 ℃~600 ℃乙醇转化率达到98%~100％、H2选择性为2.0~2.6（摩尔比）。 Cu/ZrO2与Ni/ZrO2机械混合有助于H2选择性的提高。在催化剂载体中添加MgO、CaO碱性物质可以使H2选择性提高1.3倍~2.0倍。浸渍法制备的Cu/ZrO2催化剂的性能优于共沉淀法。
Abstract:
Recently, much attention has been attracted by hydrogen preparation from bio-ethanol. Cu-based and ZnO based catalysts have been widely applied for the investigations of hydrogen preparation from methanol or ethanol. ZrO2 has shown unique behavior as a catalyst support in many reactions owing to its acid-base property and redox property. ZrO2 supported Cu catalysts are expected to be effective catalysts in the hydrogen preparation by steam reforming of ethanol. In this paper, the catalytic performance of Cu/ZrO2 catalysts in the steam reforming of ethanol was investigated. ZrO2 supports were prepared by precipitation and alcogel methods. Supported Cu catalysts were prepared by impregnation method. The physical properties of ZrO2 support and Cu/ZrO2 catalysts, such as specific surface areas, pore volume, crystal phase and so on, were characterized by BET, XRD, TEM and XRF. The reaction was carried out in a fixed-bed reactor at 300 ℃～700 ℃ and atmospheric pressure. The effluent of the reactor was analyzed with an on-line gas chromatograph (gas phase products) and an off-line gas chromatograph (condensed products). The reaction results revealed that Cu/ZrO2 possesses relatively high activity in the steam reforming of ethanol. The influences of preparation parameters, such as catalyst components, Cu loadings, supports, preparation methods and calcination temperatures of supports, on the catalytic performance were examined. The catalytic performances of Ni/ZrO2, Cu/10MgO-90ZrO2 and Cu/10CaO-90ZrO2 were compared with Cu/ZrO2. The results showed that high conversion of ethanol and high selectivity of H2 produced by ethanol steam reforming could be obtained over Cu/ZrO2 catalysts. The H2 production could be enhanced by the addition either of Ni promoter or of base oxides, such as CaO or MgO, to the Cu/ZrO2 catalyst. The optimum Cu loading was about 8% by weight and the catalytic performance of Cu/ZrO2 prepared by impregnation was much better than that prepared by co-precipitation. The ethanol conversion reached 98%~100% over 8%Cu/ZrO2 catalyst at 500 ℃~600 ℃ while the selectivity of H2 kept at about 2~2.6(mol ratio).
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