Key factors to develop hybrid photoactive materials based on mesoporous carbon/TiO2 for removal of volatile organic compounds in air streams

Abstract

The performance of a series of Adsorbent-Photocatalyst Hybrids (APHs) based on graphitized mesoporous carbons and TiO2, for the photooxidation of formaldehyde and trichloroethylene in gas phase has been studied. TiO2 was incorporated to different carbonaceous materials including a commercial mesoporous carbon, Starbons with different hydrophobicity and micro-mesoporosity and activated carbon. However, the actual performance of the APHs is strongly affected by the nature of the carbonaceous material and the synthesis route selected to prepare the carbon/TiO2 hybrids. The results obtained show the importance of the preparation route for the optimum distribution of the TiO2 nanoparticles on the porous carbon and the influence on its photocatalytic properties. The photocatalysts prepared via mechanical mixing exhibit higher activity than those synthetized by incipient wet impregnation. The hybrid based on the hydrophobic Starbon ST-800 and TiO2 achieved total removal of formaldehyde at high gas flow, improving by a 15 % the degradation rate of bare TiO2, without formation of undesired by-products. Moreover, in the case of the organochloride compound, both the reaction rate and the selectivity to CO2 were promoted over ST-800/TiO2, being the most photoactive material of the series with a great stability over reaction time.