Iwasaki, K., "Catalyst Performance of Monolith-Type Diesel Particulate Filter having Microgear-Design based on Asymmetric Hexagonal Channel Geometry," SAE Int. J. Fuels Lubr. 10(2):2017, doi:10.4271/2017-01-0926.
The diesel particulate filter (DPF) has been used in the automobile industry for around a decade. As a key technology for emissions control the DPF design needs to be increasingly optimized to expand its function to deal with any emission not just particulate matter (PM). NOx emission regulations need to be met as well as CO2 targets through minimizing any fuel penalty. Cost is extremely important to deliver an effective after-treatment catalyst. Aluminum titanate and cordierite-based material DPFs are very cost effective in part because their properties allow monolith-manufacturing. Furthermore, geometrical design of the DPF channel structure can contribute to multi-functionalization of the DPF to provide further advantages. Square and asymmetric square-designed channel structures have been utilized on current after-treatment DPF systems. Additionally, asymmetric hexagonal-designed channel technology has recently been shown to provide lower backpressure and higher ash-capacity for longer DPF lifetime usage. A key concept is to increase the geometric surface area on the inlet channels of a DPF for soot and ash-loading. Asymmetric hexagonal channels can have 1.3 times higher surface area. For further functionalization of emissions control technology it can be advantageous to increase the catalyst loading on the DPF, for instance, Selective Catalytic Reduction (SCR) catalyst coatings. Herein, a unique higher surface area design named as microgear-shaped channels has been developed. Catalyst performance and filter substrate testing using hot-gas bench systems have been validated. Thanks to its higher geometric surface area the microgear design can contact soot particles more effectively and soot combustion could be improved. In addition, HC and NO oxidation performance carried out on engine dynamometer testing showed improved activity.