Influence of Pt location on BaCO₃ or Al₂O₃ during NO_x

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• 作者：Robert Bü ; chel ; Reto Strobel ; Frank Krumeich ; Alfons Baiker ; Sotiris E. Pratsinis
• 关键词：NO_x storage– ; reduction ; Pt/Ba/Al₂O₃ ; Flame spray pyrolysis ; Pt– ; Ba proximity ; Remote control ; Lean NO_x trap
• 刊名：Journal of Catalysis
• 出版年：2009
• 出版时间：25 January 2009
• 年：2009
• 卷：261
• 期：2
• 页码：201-207
• 全文大小：657 K

文摘

Catalysts for NO_x storage–reduction (NSR) were made selectively with Pt on either the Al- or the Ba-components without altering significantly the Al₂O₃ or BaCO₃ crystal sizes, Al/Ba weight ratio, specific surface area, porosity, and Pt dispersion using a two-nozzle flame spray pyrolysis (FSP) unit. The NO_x storage performance at 300 °C was best for Pt located near Al₂O₃ as it facilitates the oxidation of NO to NO₂ during the fuel lean period but the reduction rate during the subsequent short fuel rich period was much slower resulting in incomplete regeneration. This contributed to a gradual decrease of the NO_x conversion at increasing cycling. In contrast, Pt on BaCO₃ resulted in an initially lower NO_x storage rate but during ten storage–reduction cycles a stable NO_x conversion of about 50 % was reached. When using NO₂ instead of NO or higher NO_x oxidation-reduction temperatures (e.g. 350 °C) the Pt location did not affect the NSR performance of the Pt/Ba/Al₂O₃ catalysts.