Ni stabilised on inorganic complex structures: superior catalysts for chemical CO2 recycling via dry reforming of methane
Ni stabilised on inorganic complex structures: superior catalysts for chemical CO2 recycling via dry reforming of methane
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DOI：
10.1016/j.apcatb.2018.05.051
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发表时间：
2018-11-15
影响因子：
22.1
通讯作者：
Reina, T. R.
中科院分区：
文献类型：
--
作者：
le Sache, E.;Pastor-Perez, L.;Reina, T. R.
由于处理温室气体（GHG）排放的迫切需要，CO2利用正在成为催化科学中一个吸引人的话题。在此，甲烷的干重整（DRM）代表了将CO2和CH4（两种主要的温室气体）转化为合成气的可行途径，合成气是化学合成中非常有价值的中间体。镍基催化剂是该反应经济可行的材料，但它们不可避免地表现出失活的迹象。在这项工作中，镍在焦绿石-钙钛矿结构中的稳定被报道为防止快速失活的可行方法。在不同的反应条件（温度和空速）下，研究了锆酸盐焦绿盐La2Zr2O7中不同负载量的Ni取代锆。煅烧和还原催化剂的XRD分析表明，在高Ni负载下，形成了与焦绿石结构La2Zr2-xNixO7-delta相对应的晶体相和La2NiZrO6钙钛矿相。使用这种配方策略限制了碳的形成，因此，我们最好的催化剂在低至600摄氏度的温度下对DRM表现出优异的活性，并且在连续运行350小时以上表现出很高的稳定性。Ni从氧化物结构中析出，导致小而分散的Ni团簇，可以解释性能的增强。
CO2 utilisation is becoming an appealing topic in catalysis science due to the urgent need to deal with greenhouse gases (GHG) emissions. Herein, the dry reforming of methane (DRM) represents a viable route to convert CO2 and CH4 (two of the major GHG) into syngas, a highly valuable intermediate in chemical synthesis. Nickel-based catalysts are economically viable materials for this reaction, however they show inevitable signs of deactivation. In this work stabilisation of Ni in a pyrochlore-perovskite structure is reported as a viable method to prevent fast deactivation. Substitution of Zirconium by Ni at various loadings in the lanthanum zirconate pyrochlore La2Zr2O7 is investigated in terms of reactant conversions under various reaction conditions (temperature and space velocity). XRD analysis of the calcined and reduced catalysts showed the formation of crystalline phases corresponding to the pyrochlore structure La2Zr2-xNixO7-delta and an additional La2NiZrO6 perovskite phase at high Ni loadings. Carbon formation is limited using this formulation strategy and, as a consequence, our best catalyst shows excellent activity for DRM at temperatures as low as 600 degrees C and displays great stability over 350 h of continuous operation. Exsolution of Ni from the oxide structure, leading to small and well dispersed Ni clusters, could explain the enhanced performance.