Boosting diesel soot catalytic combustion via enhancement of solid(catalyst)-solid(soot) contact by tailoring micrometer scaled sheet-type agglomerations of CeO2-ZrO2 catalyst

Abstract

Solid(catalyst)-solid(soot) contact is a crucial factor in diesel soot catalytic combustion, and rationally optimizing solid(catalyst)-solid(soot) contact is a promising yet challenging pathway for improving catalytic diesel soot combustion performance. Here, we report a micrometer scaled sheet-type CeO2-ZrO2 soot oxidation catalyst. The nitrogen adsorption-desorption result indicates that soot particulates are barely able to enter into the inner pore of the catalyst (average pore size < 20 nm) due to the large size of filamentous soot agglomeration (reaching up to 1 μm). Thus the catalyst-soot contact mainly depends on the catalyst external surface and morphology. Electron microscope images confirm the presence of microsheet agglomerations of the prepared CeO2-ZrO2 catalyst, which is an advantage for enhancing the adherence of soot filaments on catalyst. Compared to common CeO2-ZrO2 particle catalyst, the CeO2-ZrO2 microsheet shows a remarkably higher macrolevel soot combustion performance. Interestingly, the single catalytic site activity (intrinsic activity) of CeO2-ZrO2 microsheet is not enhanced by the micro-structure. Thus the enhanced soot combustion efficiency could be ascribed to the improving of catalyst-soot contact. And therefore, this work suggests that constructing structured catalyst at micrometer level is an efficient way to improve the solid(catalyst)-solid(soot) contact efficiency and thereby boost the diesel soot combustion performance.