Towards practical application of lanthanum ferrite catalysts for NO reduction with H₂

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• 作者：Stefania Furfori ; Samir Bensaid ; Nunzio Russo ; Debora Fino
• 关键词：Selective catalytic reduction of NO ; Perovskite ; Palladium ; Hydrogen
• 刊名：Chemical Engineering Journal
• 出版年：2009
• 出版时间：15 November 2009
• 年：2009
• 卷：154
• 期：1-3
• 页码：348-354
• 全文大小：615 K

文摘

A series of perovskite-type catalysts (LaFeO₃, La_0.8Sr_0.2FeO₃, Pd/La_0.8Sr_0.2FeO₃, La_0.8Sr_0.2Fe_0.9Pd_0.1O₃, La_0.7Sr_0.2Ce_0.1FeO₃, Pd/La_0.7Sr_0.2Ce_0.1FeO₃ and La_0.7Sr_0.2Ce_0.1Fe_0.9Pd_0.1O₃) has been prepared by the solution combustion synthesis method and fully characterized by XRD, BET, FESEM and TPD/R analyses. The performance of these catalysts towards the NO reduction mechanism by H₂ has been evaluated in a temperature-programmed reaction apparatus (TPRe) in the absence and in the presence of oxygen. The catalysts have been studied in the 25–350 °C temperature range, and significant catalytic activities were measured at 150–250 °C. Among the catalysts screened, La_0.8Sr_0.2Fe_0.9Pd_0.1O₃, showed the best performance. Hence, it was deposited directly over a ceramic honeycomb monolith by in situ SCS, tested in a lab-scale test rig, then submitted to the specific ageing protocol (thermal treatment at 500 °C for 96 h) in the presence of water vapour and sulfur dioxide, two potentially deactivating species present in diesel exhaust gases, and it showed a good compromise between satisfactory catalytic activity and stability. A mechanistic analysis is presented concerning the relationship between the observed activity and the reducibility of the B site, determined through TPR experiments. Some final conclusions are drawn on the perspective of the practical application of the investigated aftertreatment route for diesel exhaust gases.