Catalysis Today 176 (2011) 309–313 Contents lists available at ScienceDirect Catalysis Today jou rn al h om epage: www.elsevier.com/locate/cattod Supported transition metal-oxide catalysts for HC-SCR DeNO x with propene Denis Worch, Wladimir Suprun, Roger Gläser ∗ Institute of Chemical Technology, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany a r t i c l e i n f o Article history: Received 2 September 2010 Received in revised form 30 November 2010 Accepted 2 December 2010 Available online 11 January 2011 Keywords: DeNOx SCR Hydrocarbon Propene Mixed-oxide catalyst a b s t r a c t The selective catalytic reduction of nitrogen oxides by hydrocarbons (HC-SCR DeNO x ) on supported mixed-oxide catalysts is a promising technology for the treatment of exhaust gases from spark-ignition engines. In this work, the SCR of NO with propene on catalysts with Fe-, Cu-, V- and Ce-oxides supported on Al 2 O 3 , phosphated Al 2 O 3 or SAPO-11, was investigated. As shown by their temperature-programmed reduction-profiles, the catalysts’ behaviour for NO conversion depends mainly on the redox properties of the supported metal oxide. The acidic properties of these catalysts assessed by temperature-programmed reduction of ammonia can be neglected for NO x conversion. Catalysts prepared by sol–gel synthesis are more active for NO x conversion than catalysts prepared by wet impregnation. Probably, this is due to smaller metal oxide particles on the support surface in catalysts from sol–gel synthesis compared to those prepared by excess solution impregnation. Catalysts containing CuO x show highest NO conversion (at 350 ◦ C), CeO x - and FeO x -containing catalysts show moderate NO conversion (at 350–450 ◦ C), whereas VO x - and FeO x -containing catalysts favor total oxidation of propene already at low temperature. © 2011 Elsevier B.V. All rights reserved. 1. Introduction NO x are environmental pollutants that are made responsible, e.g., for the formation of ozone in the troposphere and the pro- duction of acid rain. The most promising method to reduce NO x under excess oxygen conditions is the selective catalytic reduction of NO x (SCR-DeNO x ). For instance, hydrocarbons [1], hydrogen [1], urea [2], ammonia [1], and oxygenates [3] were studied as reducing agents. In the presence of excess oxygen, a conventional three-way catalyst (TWC), which is commonly used for emission reduction in spark-ignition engines, is ineffective in reducing NO x . That is why, inter alia, supported mixed-oxide catalysts have attracted much attention as potential candidates for the catalytic removal of NO x from lean-burn and diesel exhaust gases under excess oxygen con- ditions. Numerous works published over the last decade focused on investigations of SCR mechanism, the search for new catalysts and the use of different reducing agents. Of particular note are the works of the research group of Burch [1,4] for their pioneering research in investigating the detailed mechanism of HC-SCR over several catalysts such as Ag/Al 2 O 3 . Recently, supported transition metal oxides were found to be highly active for NO x reduction by NH 3 . The use of NH 3 causes high costs due to the necessary safety technology during trans- port and storage, damages by corrosion as well as the costs for the reducing agent itself. However, hydrocarbons and oxygenates ∗ Corresponding author. Tel.: +49 3419736301. E-mail address: roger.glaeser@chemie.uni-leipzig.de (R. Gläser). are ingredients of off-gases. Lower hydrocarbons (C 1 –C 4 ), higher hydrocarbons, gasoline, diesel fuel and alcohols (C 1 –C 4 ) have all been investigated as reducing agents [1,5–7]. To develop more cost effective catalysts, supported transition metals or metal oxides of, e.g., Fe, Cu, Ce, Ni, V, Mn, may be used for catalytic NO x decompo- sition [8]. Up to date, many catalysts such as the zeolite Cu-ZSM-5 [9], Ag/Al 2 O 3 [4], supported rare-earth oxides [10], La–Mn–Ba- perovskites [1] and supported noble metals [8] were studied for HC-SCR. Most of them are not active in the low-temperature region (<400 ◦ C), except noble metal catalysts. The main requirement for HC-SCR catalysts is high catalytic activity in low temperature region (<400 ◦ C). Most catalysts for HC-SCR DeNO x show high activity in higher temperature region (>400 ◦ C), which is then also limited by the total oxidation of the reducing agent. Recently, Suprun et al. [11] investigated HC-SCR DeNO x in the presence of CH 4 over sulphated zirconium oxides doped with different metal oxides and found for the investigated mesoporous materials that catalytic activity increases with higher acid site density. These catalysts were mainly active in a temperature region of 400–500 ◦ C. On the other hand, deactivation is a significant drawback, especially when real feeds are used, i.e., in the presence of water and/or SO 2 [12]. The goal of this work was to study the performance of Fe-, Cu-, V- and Ce-oxide supported on Al 2 O 3 , phosphated Al 2 O 3 or SAPO-11 prepared by either sol–gel synthesis or excess solution impregna- tion, catalysts for HC-SCR of NO in the presence of propene and excess oxygen. Additionally, the role of the nature of the support and of added acidic components (phosphoric acid) on the catalytic activity and their resistance towards hydrothermal treatment were 0920-5861/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.cattod.2010.12.008