Hydrogen production from glycerol over nickel catalysts supported on Al2O3 modified by Mg, Zr, Ce or La
Hydrogen production from glycerol over nickel catalysts supported on Al2O3 modified by Mg, Zr, Ce or La
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DOI：
10.1007/s11244-008-9060-9
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发表时间：
2008-07-01
影响因子：
3.6
通讯作者：
Fierro, J. L. G.
中科院分区：
文献类型：
--
作者：
Iriondo, A.;Barrio, V. L.;Fierro, J. L. G.
研究了Ce、Mg、Zr和La改性的氧化铝负载镍催化剂上甘油液相（水相重整，APR）和气相（水蒸气重整SR）重整制氢反应。通过程序升温还原和XPS分析的催化剂的表征揭示了重要的结构效应：（i）Mg在镍和氧化铝之间的插层，其抑制氧化铝并入镍相，（ii）Ni和Zr相之间的紧密接触，以及（iii）La和Ce离子与NiO相的紧密表面相互作用。在这项工作中研究的样品的催化活性清楚地表明，不同的催化剂功能进行水相和气相蒸汽重整甘油。对于甘油的水相重整反应，在Ni/Al（2）O（3）负载型催化剂上添加Ce、La和Zr可提高甘油的初始转化率。结果表明，催化活性的差异与Ce和La对Ni相的修饰或Ni和Zr之间的紧密相互作用所引起的几何效应有关。尽管镍催化剂在运行的初始时间显示出高的APR活性，但所有样品都显示出与载体无关的重要的失活速率，该失活速率在操作几小时后使催化剂失活。APR后的催化剂表征表明，活性金属Ni在反应过程中的氧化是所观察到的失活的主要原因。在甘油蒸汽重整反应中，添加Ce、La、Mg和Zr作为Ni基催化剂的助催化剂可以提高氢气的选择性。活性的差异被解释在增强方面：表面镍浓度（Mg），激活蒸汽（Zr）和稳定性的镍相在反应条件下（Ce和La）的能力。
Hydrogen production from glycerol reforming in liquid (aqueous phase reforming, APR) and vapor (steam reforming SR) phase over alumina-supported nickel catalysts modified with Ce, Mg, Zr and La was studied. Characterization of catalysts by temperature programmed reduction and XPS analyses revealed important structural effects: (i) the intercalation of Mg between nickel and alumina that inhibited the alumina incorporation to nickel phases, (ii) the close contact between Ni and Zr phases and, (iii) the close surface interaction of La and Ce ions with NiO phases. The catalytic activity of the samples studied in this work clearly indicated the different catalyst functionalities necessary to carry out aqueous-phase and vapor-phase steam reforming of glycerol. For aqueous phase reforming of glycerol, the addition of Ce, La and Zr to Ni/Al(2)O(3) improves the initial glycerol conversions obtained over the Ni/Al(2)O(3) supported catalyst. It is suggested that the differences in catalytic activities are related with geometric effects caused by the decoration of Ni phases by Ce and La or by the close interaction between Ni and Zr. In spite that nickel catalysts showed high APR activities at initial times on stream, all samples showed, independently of support, important deactivation rates that deactivate the catalysts after few hours under operation. Catalysts characterization after APR showed the oxidation of the active metallic Ni during reaction as the main cause of the observed deactivation. In the case of the glycerol steam reforming in vapor phase, the use of Ce, La, Mg and Zr as promoters of Ni based catalysts increases the hydrogen selectivity. Differences in activity were explained in terms of enhancement in: surface nickel concentration (Mg), capacity to activate steam (Zr) and stability of nickel phases under reaction conditions (Ce and La).