Cu and Co oxides supported on halloysite for the total oxidation of toluene

Abstract

This paper shows the chemical, structural and textural characterization of materials obtained from chemical modification of a clay mineral (halloysite) with species of Cu, Co and CuCo. The synthesized materials were characterized by elemental, structural and textural analyses using X-ray fluorescence (XRF), X-ray diffraction (XRD), temperature programmed reduction (H2-TPR), N2-adsorption and transmission electron microscopy (TEM). The catalytic performance was evaluated on the complete combustion of toluene, a model molecule of volatile organic compounds (VOCs). The characterization results showed the effective incorporation of chemical species of the metals used and the formation of copper oxides, cobalt oxides or mixed oxides as active phases of the catalysts. In addition, the XRD and TEM analyses indicated the structural and morphological conservation of the catalytic support (halloysite). The N2-adsorption analysis showed that, in general, the type of porosity is maintained and predominantly determined by the support, although a reduction in a specific pore population was detected. The catalytic activity tests showed excellent performance of the materials as catalysts of the studied reaction, and revealed a cooperative effect due to the simultaneous incorporation of copper and cobalt species: the catalysts containing copper and cobalt were substantially more active than the catalysts containing only one metal in the oxide phase.