A Novel Alkali-Catalyzed Alpha-Alumina DPF with High Catalytic Activity and Durability

Abstract

A novel catalyzed diesel particulate filter (CDPF) consisting of an α-alumina DPF and an alkali-metal catalyst has been developed for the aftertreatment of diesel soot. The α-alumina DPF (Al-DPF) was fabricated in a multi-segmented structure to relieve the thermal stress caused by the relatively high thermal expansion coefficient of α-alumina. The thermal and physical properties of the Al-DPF were analyzed and compared with those of the commercially available cordierite- and SiC-DPFs. The fundamental properties of the Al-DPF, including its particle filtration efficiency, pressure drop, and thermal durability were comparable to those of the conventional DPFs. Furthermore, the soot oxidation activity of the alkali-catalyzed Al-DPF (AC-Al-DPF) was evaluated using a 2.2 L diesel engine test bench. The soot oxidation rate of the AC-Al-DPF was 3-fold higher than that of a conventional Pt/Pd catalyzed SiC-DPF even after thermal aging at 800 °C for 50 h. Several accelerated durability tests were also conducted to clarify the negative effects of sulfur poisoning and ash accumulation on the catalytic activity of the AC-Al-DPF. The AC-Al-DPF demonstrated considerable stability against both sulfur poisoning and ash accumulation, which indicated that the alkali-catalyzed α-alumina DPF could be applied as an effective tool for the emission control of diesel soot.

F2012-A04-028