Au-Pd nanoparticles enfolded in coil-like TiO2 immobilized on carbon fibers felt as recyclable nanocatalyst for benzene oxidation under mild conditions

Abstract

Carbon fiber felt (CFF) is considered as a stable carbonaceous support for different applications such as absorbents and catalysts. Herein, a novel method for preparation of Au-Pd/CFF@TiO2 catalysts is presented. Structure, morphology, and performance of the novel nano-catalyst were characterized during different stages of their fabrication by means of structural, chemical and optical techniques. The results demonstrated that, compared with the other products, the Au-Pd/CFF@TiO2 composite pyrolyzed at 450 °C had the highest thermal and mechanical stability, as well as better textural features. It showed good catalytic activity in oxidation of benzene-to-phenol by hydrogen peroxide (25%) as eco-friendly oxidant under mild thermal conditions. The influence of different parameters on the oxidation process, such as reaction temperature, amounts of catalyst, oxidant/substrate molar ratio and condensation temperature, was investigated to optimize the catalyst. At the optimum set of conditions, the Au-Pd/CFF@TiO2-450 showed the values of yield and selectivity for phenol as the main product as high as 46% and 100%, respectively. The catalyst maintained its activity after eight cycles and thus looks very promising for direct conversion of benzene to phenol under mild conditions.