Search Results

The reduction of NOx from Diesel Engines or Lean-burn Gasoline Engines is a major issue in automotive catalysis. Over the last several years, many solutions to remove NOx under lean operating conditions have been considered. Attention is now focused on two main technologies: (i) Selective Catalytic Reduction using ammonia as reductant (urea SCR) and (ii) NOx-Storage Catalyst (NSC). This paper deals with materials for NOx storage catalysts. Even if the fresh NSC shows high efficiency, its durability is low due to a fast deactivation of the active sites [1,3]. This problem relates to a drastic sintering of the materials after ageing, especially during the regeneration and the desulfation [3, 4 and 5]. Moreover, the current materials are sensitive to SOx poisoning [1,3, 4]. In this paper, modified Ba-alumina oxides used as NOx-Storage materials have been investigated. These oxides contain high Ba loading (such as 20 wt% Ba) and are thermally stable.

New doped zirconia with high thermal stability and high sulfur resistance have been developed for Diesel Oxidation Catalysts (DOC). The present work is focused on rare earths-doped zirconia and base metal-doped zirconia which are preferred carriers of precious metals to improve catalytic performance and durability.

A new generation of hybrid zirconia oxides with high thermal stabilities has been developed. These new materials, covering a wide range of compositions, are investigated as carriers of precious metals for Diesel Oxidation Catalysts (DOC). In this paper, we show that they can be advantageously used for both Pt and Pd-based technologies to improve catalytic performance and possibly durability. Indeed, rare earths doped zirconia containing 60 wt% ceria used as Pd carrier show early light-off activity which is promising for reduced cold start emissions.

Diesel Particle Filters (DPFs) using a fuel-borne catalyst to assist filter regeneration provide a uniquely advantaged DPF technology. More than 5 million diesel passenger cars in the market today are equipped with this after-treatment system. Based on this extensive field experience, improvements have been made to the durability and maintenance requirements of this technology, and the total system cost has been optimized. Recently, a new fuel-borne catalyst, Eolys Powerflex™ (named new Fe-based FBC) has been developed to provide solutions that comply with current Euro 5 and forthcoming Euro 6 requirements that take into account both regulated emissions and optimization of CO₂ emissions. This paper presents the benefits of this optimized product. The soot oxidation activity of this new Fe FBC has been tuned to ensure fast and complete regeneration at low temperature and very low dosing rates in the fuel, thus reducing ash accumulation and improving the overall system durability.

Since Euro 5 standard, Diesel Particulate Filter (DPF) technology has been widely introduced in Europe and Fuel Borne Catalysts (FBC) provide a powerful solution to achieve regeneration in all driving conditions. Ongoing new emission regulation constraints of Euro 6.b (2014) and forthcoming Euro 6.c standard in 2017, that will reduce the gap between emissions during homologation and in real driving conditions, will demand the support of optimized FBC formulated with Deposit Control Additive (DCA). This paper presents the impact on DPF regeneration performance of advanced FBC with a sharp particle size distribution of reduced nanoparticle size diameter. Small particle size FBC gives enhanced DPF regeneration, allowing regeneration at lower temperature (i.e. improving fuel economy) but also lower dosing rates in fuel. Thus, this implies reduced filter ash content and an extended maintenance interval.