High specific surface area LaFeCo perovskites-Synthesis by nanocasting and catalytic behavior in the reduction of NO with CO
High specific surface area LaFeCo perovskites-Synthesis by nanocasting and catalytic behavior in the reduction of NO with CO
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DOI：
10.1016/j.apcatb.2009.04.004
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发表时间：
2009-08-17
影响因子：
22.1
通讯作者：
Urquieta-Gonzalez, E. A.
中科院分区：
文献类型：
--
作者：
de Lima, R. K. C.;Batista, M. S.;Urquieta-Gonzalez, E. A.
LaFe1-xCOxO_3钙钛矿的合成采用传统方法或纳米铸造法。纳米铸造包括使用二氧化硅Aerosil 200和碳源制备微介孔碳模。然后在800℃下对钙钛矿进行碳浇注，并用X射线衍射仪、氮气吸附、红外光谱、热重/差热分析、扫描电子显微镜和透射电子显微镜对其进行了表征。N-2吸附表明，尽管纳米钙钛矿的比表面积(SSA)提高了30-50m(2)/g，但并没有显示出明显的颗粒内孔隙率。而透射电子显微镜、X射线衍射仪和Rietveld细化数据表明，固相颗粒至少由97wt%的钙钛矿相和小于100 nm的团聚体组成，团聚体由约6 nm的微晶组成。TGA/DTG结果表明，在钙钛矿形成过程中，碳被氧化，从而消除了模板效应，促进了烧结的发生，从而限制了SSA的增加。纳米钙钛矿在还原NO方面比未铸造钙钛矿更活跃，这归因于其SSA的增加，从而允许暴露更多可访问的活性部位。然而，钙钛矿成分和杂质的存在会降低织构性能的改善效果。纳米钙钛矿还表现出很高的热稳定性和催化稳定性，证实了它们作为所研究反应的催化剂的潜力。(C)2009爱思唯尔B.V.保留所有权利。
LaFe1-xCOxO3 perovskites were conventionally or nanocasting synthesized. The nanocasting involved the preparation of a micro-mesoporous carbon mould using a Silica Aerosil 200 and a carbon source. Then, perovskites were carbon cast at 800 degrees C. The solids were characterized by XRD, N-2 sorption, FTIR, TGA/DTG, SEM and TEM. N-2 sorption evidenced that the nanocast perovskites did not show significant intraparticle porosity in despite of their enhanced (30-50 m(2)/g) specific surface area (SSA). Nevertheless, TEM images, XRD and Rietveld refinement data showed that the solids are constituted at least by 97 wt% of perovskite phase and by agglomerates smaller than 100 nm constituted by crystallites of about 6 nm. TGA/DTG results demonstrated carbon oxidation during the perovskite formation, thus eliminating the template effect and facilitating the occurrence of sintering, which limited the SSA increase. The nanocast perovskites were more active in the reduction of NO than the uncast ones, behavior that was attributed to the increase in their SSA that allows the exposure of a higher number of accessible active sites. However, the perovskite composition and the presence of impurities can reduce the effect of the improvement of the textural properties. The nanocast perovskites also showed high thermal and catalytic stability, corroborating their potential as catalysts for the studied reaction. (C) 2009 Elsevier B.V. All rights reserved.