Synergetic effect of Cu and Mn oxides supported on palygorskite for the catalytic oxidation of formaldehyde: Dispersion, microstructure, and catalytic performance

Abstract

In this study, palygorskite (Pal), a natural nanorod-like clay mineral, is applied as the support of mixed Cu Mn oxides for formaldehyde (HCHO) oxidation, with focus on their dispersion, microstructure, and relative role during the catalytic oxidation. The composite material loaded with Cu Mn oxides retains the nanorod-like morphology of Pal, while the oxide particles in the size of 10–40 nm are well dispersed in the slit pores stacked by rods of Pal. Most of the Cu Mn oxides on Pal are with spinel structure, where Cu2+ ions occupy the tetrahedral sites and Mn3+ ions occupy the octahedral sites. The Pal-supported Cu Mn oxides achieves 90% CO2 generation at 207-258 °C, and displays better catalytic performance than solely supported catalyst. The presence of Cu obviously improves the reducibility of composite and the adsorption of HCHO, resulting in the acceleration of HCHO oxidation. The water resistance of composite catalyst also enhances with the increase of Cu content. Based on all these benefits, the catalytic performance of Cu Mn oxides on Pal can be optimized with an increase of Cu level.