Nanocast LaNiO3 Perovskites as Precursors for the Preparation of Coke-Resistant Dry Reforming Catalysts

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• 作者：Mahesh Muraleedharan Nair ; Serge Kaliaguine ; Freddy Kleitz
• 刊名：ACS Catalysis
• 出版年：2014
• 出版时间：November 7, 2014
• 年：2014
• 卷：4
• 期：11
• 页码：3837-3846
• 全文大小：492K
• ISSN：2155-5435

文摘

Dry reforming of methane is gaining great interest owing to the fact that this process efficiently converts two greenhouse gases (CH₄ and CO₂) into synthesis gas (CO + H₂), which can be further processed into liquid fuels and chemicals. Herein, a perovskite-derived nanostructured Ni/La₂O₃ material is reported as an efficient and stable catalyst for this reaction. High-surface-area LaNiO₃ perovskite precursor is first synthesized by the method of nanocasting using ordered mesoporous silica SBA-15 as a hard template. The resulting nanostructured perovskite was found to possess high specific surface area as obtained from the BET method (150 m² g^鈥?). The reduction behavior of the nanocast perovskite was monitored by performing the temperature-programmed reduction of hydrogen (TPR-H₂). It has been found that the complete destruction of perovskite structure occurs below 700 掳C, leading to the formation of highly dispersed Ni⁰ in La₂O₃, as observed in the XRD pattern of the material after reduction. Similar behavior was observed for the LaNiO₃ perovskite synthesized using the conventional citrate process. However, the specific surface area of the former material was found to be much higher than that of the latter (50 m² g^鈥?), which obviously resulted from the mesoporous architecture of the nanocast LaNiO₃. It was found that the nanostructured Ni/La₂O₃ obtained from the reduction of the nanocast LaNiO₃ exhibited high activity for the conversion of the reactant gases (CH₄ and CO₂) compared to the catalyst obtained from conventional perovskite, under the reaction conditions used in the present study. Particularly, no coke formation was observed for the mesoporous catalyst under the present conditions of operation, which in turn reflects the enhanced stability of the catalyst obtained from the nanocast LaNiO₃. The improved performance of the nanostructured catalyst is attributed to the accessibility of the active sites resulting from the high specific surface area and the confinement effect leading to the stabilization of Ni nanoparticles.

Keywords:

dry reforming; nanocasting; perovskites; coke resistance; high surface area; synthesis gas; mesoporous