In situ growth of ceria nanofibers on cordierite monoliths for diesel soot combustion

Abstract

The direct in situ growth of CeO2 nanofibers was performed by hydrothermal synthesis on cordierite monoliths for the diesel soot combustion reaction. They were characterized by SEM (Scanning Electron Microscopy), XRD (X-Ray Diffraction), LRS (Laser Raman Spectroscopy), textural analysis and adherence test. The mechanical stirring during the synthesis was essential to obtain the desired nanofibers, as well as a homogeneous coverage throughout the monolith with a very good anchoring to the substrate. The CeO2 nanoarray monolithic catalyst exhibited a catalytic oxidation activity similar to that obtained for bare CeO2 fibers (temperature of maximum soot combustion rate, TM = 428 °C). Raman in situ experiments along with kinetic analysis indicated that the amorphous fraction of carbon burned more easily than the graphitic fraction. Successive reaction runs indicated that the nanoarray of CeO2 fibers partially deactivated, especially after 800 °C. However, TM was 477 °C, being this last value about 100 °C lower than the non-catalytic soot combustion temperature.