Diesel Particulate Filtration and Combustion in a Wall-Flow Trap Hosting a LiCrO₂ Catalyst

Abstract

This paper concerns the development of an innovative LiCrO2 catalyst (synthesis, characterization, mechanistic analysis, and aging). This catalyst already showed appreciable activity at 300 °C toward the catalytic combustion of soot even under loose contact conditions. Furthermore, its limited sensitivity to hydrothermal aging in the presence of SO2 at 650 °C demonstrated a favorable result for its possible application in catalytic traps for diesel particulate removal from car exhaust gases. In this perspective, an in situ combustion synthesis method was tailored to the preparation of a LiCrO2−catalyzed trap based on a SiC wall-flow monolith. Engine bench tests on this catalytic trap (trap loading and regeneration inducing a temperature increase by the catalytic combustion of suitably postinjected fuel) showed that the presence of the catalyst in the wall-flow trap enabled both a more complete regeneration and a 2-fold reduction of the regeneration time compared to the case of a noncatalytic trap, with the consequent saving of postinjected fuel.

Secondary nanoparticle emissions during diesel particulate trap regeneration

“…Preliminary studies concerning the catalytic activity towards diesel soot and the mechanism of the CoCr 2 O 4 and LiCrO 2 have been carried out in our laboratories and the results have been well described in literature [13][14][15]. Figure 1 compares the results obtained with non-catalytic, the LiCrO 2 and the CoCr 2 O 4 SiC wallflow monoliths.…”

“…Tests carried out on an engine bench described in [13] and equipped with a Scanning Mobility Particle Sizer (SMPS), showed a different behaviour of the two catalytic wall-flow concerning the emission of secondary nanoparticles (<20 nm) during regeneration. The analysis of different operating and sampling conditions on this phenomenon is here discussed.…”

Electronic structure and magnetism in the frustrated antiferromagnetLiCrO2: First-principles calculations

“…The nickelates, LiNiO 2 , NaNiO 2 , AgNiO 2 , Ag 2 NiO 2 have been also subject of numerous studies, mostly because of their magnetic properties coupled with interesting structural transformations. However, chromates, such as LiCrO 2 , NaCrO 2 , and KCrO 2 , despite their potential use for rechargeable batteries[1] and as catalists [2] have been studied experimentally only sporadically [3,4,5,6,7,8], and no first principle calculations, to the best of my knowledge, have been reported so far.In this paper I report all-electron full-potential electronic structure calculations for LiCrO 2 . In agreement with the experimental findings, the magnetic interaction in-plane is found to be strongly antiferromagnetic.…”

Structured Catalysts for Soot Combustion for Diesel Engines

“…The aqueous phase is rapidly brought to boil, the precursors mixture ignite and the synthesis take place in situ. This method has been applied to deposit catalysts as perovskites or spinels, as La0.9K0.1Cr0.9O3 [47,48], LiCoO2 [49,50] and LaCr0.9O3 [51] over ceramic monoliths.…”