Hirose, S., Miyairi, Y., Katsube, F., Yuuki, K. et al., "Newly Developed Cordierite Honeycomb Substrate for SCR Coating Realizing System Compactness and Low Backpressure," SAE Technical Paper 2012-01-1079, 2012, doi:10.4271/2012-01-1079.
Ammonia Selective Catalytic Reduction (SCR) and Lean NOx Trap (LNT) systems are key technologies to reduce NOx emission for diesel on-highway vehicles to meet worldwide tighter emission regulations. In addition DeNOx catalysts have already been applied to several commercial off-road applications. Adding the DeNOx catalyst to existing Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) emission control system requires additional space and will result in an increase of emission system back pressure. Therefore it is necessary to address optimizing the DeNOx catalyst in regards to back pressure and downsizing.Recently, extruded zeolite for DeNOx application has been considered. This technology improves NOx conversion at low temperature due to the high catalyst amount. However, this technology has concerned about strength and robustness, because the honeycomb body is composed of catalyst. A zeolite catalyst supported by a ceramic honeycomb structure resolves the strength and robustness issues. Also the honeycomb structure offers higher geometric surface area (GSA), a key characteristic for higher NOx conversion.Cordierite substrates with a honeycomb structure are a historically proven technology used for a variety of applications (gasoline, diesel, LDV, HDV, Non-Road) over the past 30 years. Cordierite substrates have been used widely for three-way catalyst (TWC) and DOC as well as ammonia SCR and LNT for several decades. However, today's DeNOx catalyst technologies require higher catalyst loading to ensure very high conversion efficiencies at lower temperature. Conventional cordierite substrate has not been optimized for high catalyst loadings for DeNOx catalysts applications. By modifying cordierite substrate material properties for high catalyst loadings, lower pressure drop and retention of high NOx conversion efficiency can be offered.In this investigation, the performances of newly developed cordierite substrates with material properties adjusted to address high catalyst loadings and in various geometrical configurations were compared to conventional substrate technology. The performance evaluation includes NOx conversion, pressure drop performance, as well as durability and material strength evaluation. The paper will discuss the opportunities this newly developed material provides in regards to compactness and low pressure drop while maintaining high NOx conversion efficiency.