Inclusion of Ceria in Alumina- and Silica-Based Aerogels for Catalytic Applications

Abstract

Ceria-alumina (CeAl) and ceria-silica (CeSi) catalytic aerogels were prepared. Cerium undergoes rapid changes in oxidation state, which makes it a good oxygen-storage component for automotive catalysis applications. The high surface area and thermal stability of alumina- and silica-based aerogels render them attractive catalyst platforms. Co-precursor (for CeAl and CeSi) and impregnation (for CeSi) synthetic approaches were employed, followed by rapid supercritical extraction (RSCE) to yield aerogels. Physical characterization (bulk density, surface area, FTIR, XRD, and SEM/EDX) was performed on the as-prepared aerogels, after heat treatment (calcining), and after catalytic testing in a testbed that simulates aspects of catalytic converter conditions. The aerogels have low densities (≤0.1 g/cm3) and relatively high surface areas (ca. 100 m2/g for CeAl, ≥400 m2/g for CeSi). Microcrystalline CeO2 is observed in heat-treated and catalytically tested aerogels. CeSi aerogels show catalytic activity toward CO and NO; at high temperature, CeAl aerogels act as three-way catalysts.