ABSTRACT Selective Catalytic Reduction (SCR) of NO x using reductants such as urea continues to be of high interest to meet impending regulations. Vanadia supported on anatase titania is a well-established catalyst for stationary and heavy- duty-diesel truck deNO x applications. However, traditional anatase titania-based materials are regarded to have limited thermal stability in the most demanding applications such as those where the SCR catalyst is located downstream of a regenerating DPF, in which the catalyst could be exposed to very high temperatures. More recently, state-of-the-art titania-based vanadia catalysts have shown good cold-start performance and are capable of surviving accelerated aging treatments of up to 64 hrs at 670°C [ 1 ], good performance in a configuration upstream of a DOC/DPF [ 2 ], good low temperature NO x conversion on par with Cu-zeolite SCR catalysts and superior resistance to sulfur poisoning [ 3 ]. We report here new, highly engineered titania-based materials with substantially improved stability and/or activity compared to the state-of-the-art commercial titania-based vanadia SCR catalysts. New synthetic approaches were used to prepare catalyst support materials that are predominantly anatase TiO 2 in composition. The thermal and hydrothermal stabilities of the new materials were characterized using a combination of x-ray powder diffraction with Rietveld Refinement, transmission and scanning electron microscopies, and N 2 porosimetry. Vanadia-loaded catalysts in powder form were thermally- or hydrothermally-aged and evaluated for NO conversion activity and selectivity in model-gas bench-scale reactors using NH 3 as the reductant, and were compared to commercial titania-based vanadia powders. The new materials fall into two classes. In the first, the materials exhibit substantially improved thermal stability, anatase phase stability and higher porosity, while exhibiting deNO x activity comparable to commercial materials. In the second class, the activity and stability of the new materials can be tuned to yield higher deNO x activity, particularly after exposure to high temperatures, while maintaining crystal phase stability and porosity at least as good as that of state- of-the art commercial titania-based vanadia catalysts. In a bench test under severe conditions that simulate lifetime catalyst exposure, no detectable vanadium is lost from the new catalysts to the vapor phase. The new, highly engineered materials should provide the catalyst formulator with new options to achieve robust and active SCR systems. INTRODUCTION The selective catalytic reduction (SCR) of nitrogen oxides produced during combustion processes using reductants such as NH 3 has been a commercially successful technology for over 30 years [ 4]. Over the last several years there has been extensive development of SCR catalysts for mobile-source applications. Titania-based vanadia catalysts have been employed widely on a commercial basis in stationary-source applications for many years, and more recently in heavy duty diesel mobile-source applications [ 5]. Recent SAE papers on titania-based vanadia catalysts have shown that these catalysts offer good cold-start performance, and are capable of surviving accelerated aging treatments of up to 64 hrs at 670°C [ 1], good performance in a configuration upstream of a DOC/DPF [ 2] and superior resistance to sulfur poisoning [ 3]. However, it is commonly accepted that the main limitation of titania-based vanadia catalysts is a relative lack of thermal durability relative to zeolite-based catalysts [ 6]. The titania New Titania Materials with Improved Stability and Activity for Vanadia-Based Selective Catalytic Reduction of NOx 2010-01-1179 Published 04/12/2010 David Monroe Chapman, Guoyi Fu, Steve Augustine, Mark Watson, Jennifer Crouse, Lubov Zavalij and Dale Perkins-Banks Millennium Inorganic Chemicals Copyright © 2010 SAE International SAE Int. J. Fuels Lubr. | Volume 3 | Issue 1 643