Catalytic reforming of methane with carbon dioxide over nickel catalysts .1. Catalyst characterization and activity
Catalytic reforming of methane with carbon dioxide over nickel catalysts .1. Catalyst characterization and activity
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DOI：
10.1016/0926-860x(96)00065-8
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发表时间：
1996-08-01
影响因子：
5.5
通讯作者：
Vannice, MA
中科院分区：
文献类型：
--
作者：
Bradford, MCJ;Vannice, MA
研究了以氧化镁、二氧化钛、二氧化硅和活性碳为载体的镍催化剂上甲烷与二氧化碳的重整反应。载体对催化剂活性和积炭电阻率的影响在每种情况下都有明显不同。虽然在Ni/SiO_2催化剂上观察到了大量的丝状碳的形成(由透射电子显微镜和TPO证实)，但催化活性的初始损失可以忽略不计。Ni/C的催化活性与Ni/SiO_2相似，但没有形成丝状碳。与Ni/SiO_2催化剂相比，无论是Ni/TiO_2催化剂还是Ni/MgO催化剂，结焦现象都要少得多。Ni/Ti02催化剂中金属-载体相互作用(SMSi)很强的证据表明，大量对碳沉积具有活性的镍原子被活性TiOx物种的存在所钝化或去除。用透射电子显微镜直接测量晶格间距，可以鉴别出两个TiOx相和一个Ni5TiO7相。结果表明，Ni/MgO催化剂具有良好的活性和稳定性，可连续使用44h。化学吸附、X射线衍射和透射电子显微镜结果表明，形成了部分可还原的NiO-MgO固溶体，这似乎稳定了还原的镍表面，并提供了抗碳沉积的能力。
The reforming of methane with carbon dioxide was studied over nickel supported on MgO, TiO2, SiO2, and activated carbon. The influence of the support on catalyst activity and carbon deposition resistivity was markedly different in each case. Although considerable formation of filamentous carbon was observed over Ni/SiO2 (confirmed by TEM and TPO), there was negligible initial loss of catalytic activity. The catalytic activity of Ni/C was very similar to that of Ni/SiO2, but no filamentous carbon appeared to be formed. In contrast to Ni/SiO2, substantially less coking was observed over either the Ni/TiO2 or the Ni/MgO catalysts. Evidence of strong metal-support interaction (SMSI) in the Ni/TiO2 catalyst indicated that large ensembles of nickel atoms, active for carbon deposition, are deactivated or removed by the presence of mobile TiOx species. The identification of two TiOx phases and a Ni5TiO7 phase was made possible by direct measurement of crystalline d spacings with TEM. The Ni/MgO catalyst was both active and very stable for up to 44 h time on stream. Chemisorption, XRD and TEM results indicate the formation of a partially reducible NiO-MgO solid solution, which appears to stabilize the reduced nickel surfaces and provide resistance to carbon deposition.