Hyperbranched polyethyleneimine towards the development of homogeneous and highly porous CuO-CeO2-SiO2 catalytic materials

Abstract A novel templating strategy for the development of composite nanoporous CuO/CeO 2 /SiO 2 materials with advanced properties and significant thermal stability is proposed in this work, for potential use in automotive catalysts. The synthetic process is based on the dual role of low cost hyperbranched polyethyleneimine (PEI) acting both as a reactive template to control the formation of a siliceous porous network and as a metal chelating agent to facilitate the incorporation of finely dispersed CuO/CeO 2 nanoparticles into the silica matrix. Direct Ce(III)/Cu(II) introduction into the reaction mixture or post-synthetic impregnation of a preformed hybrid organic/inorganic xerogel was employed. Materials properties were assessed by means of XRD, SEM, TEM, N 2 adsorption, TPR and XPS techniques. Final Cu loading was determined by a novel UV–Vis spectroscopic method. Activity tests were performed under stoichiometric, O 2 -deficient and O 2 -rich conditions simulating realistic exhaust environment. Catalytic performance was found to be strongly depended on the employed synthetic pathway. The CuO/CeO 2 /SiO 2 composites prepared by direct introduction, exhibited enhanced structural characteristics (BET ≈ 680 m 2 /g), high homogeneity, superior oxidation performance and notable thermal stability, with great potential for use in automotive aftertreatment systems.