Catalyst design of Pt/TiO2 microsphere for benzene oxidation under microwave irradiation

Abstract

Pt/TiO2 microspheres with sea-urchin like structures were prepared by sequential processes including the preparation of TiO2 by a hydrothermal method and the preheating of the TiO2, the deposition of Pt nanoparticles on the TiO2 surface, followed by post heating in O2/N2 and H2. The TiO2 and Pt/TiO2 catalysts were characterized by XRD, Raman, SEM, TEM and N2 adsorption studies. The average diameter of TiO2 microspheres was about 250 nm. The TiO2 microspheres were composed of TiO2 nanoparticles with the size of 20−30 nm. Pt particles with the size of 3 nm were highly dispersed on the TiO2 microsphere by liquid phase adsorption of colloidal Pt particles. The heating of TiO2 at 300 °C before and after the Pt deposition did not change the size of TiO2 microsphere and reduced the surface area from 238 to 137 m2 g−1. The Pt/TiO2 microsphere exhibited higher catalytic activity for benzene oxidation than Pt/TiO2 P25 under normal outer heating, whereas pristine TiO2 exhibited almost no activity. Activated carbon was used as a catalyst with a mixture of Pt/TiO2 microspheres when performing the catalytic reaction under microwave heating. The mixture of Pt/TiO2 and activated carbon showed higher benzene oxidation activity under microwave irradiation than under normal external heating. The mixture was applied to benzene adsorption-catalytic oxidation combined processes.