Acetal photocatalytic formation from ethanol in the presence of TiO2 rutile and anatase.

The decomposition of ethanol, one of the most important biomass platform molecules, was investigated under green conditions, ambient temperature, atmospheric pressure and air for the synthesis of acetal in the presence of TiO2 activated under UV-A radiation. The impact of ethanol concentration, of the nature of TiO2 (rutile, anatase or mixture), of the photo-deposition of Pt under air or argon were all factors under investigation. Whatever the conditions and the nature of catalyst used, acetaldehyde was initially formed before reacting with ethanol to form acetal, a promising fuel additive. However, the subsequent generation of acetal differs depending on the conditions and the nature of catalyst. In the absence of a noble metal, rutile TiO2 leads to an increase in acetal formation at equivalent acetaldehyde formation. This behavior is discussed considering the acidic and basic properties of rutile and anatase phases together with H+ generated under UV. In the presence of Pt, under air or Ar, the acetal formation begins at a lower concentration of acetaldehyde due to the in-situ photo-deposition of Pt. However, whereas acetal formation is similar for Pt/anatase and Pt/rutile phase under air, under Ar, less acetal is generated on Pt/rutile in agreement with the production of more H2.

Coupling of photocatalysis and catalysis using an optical fiber textile for room temperature depollution.

Herein, we investigate the interplay between a photocatalyst (TiO2) and a catalyst (Pt/TiO2 and Pt/CeO2) for the oxidation of formaldehyde and toluene at room temperature. A luminous textile is used as support and as light source for the photocatalyst. Our results indicate that the presence of the catalyst and the photocatalyst increases the catalytic performance for the oxidation of formaldehyde, while the photocatalytic performance for toluene oxidation decreases. The overall performance (toluene and formaldehyde degradation) of the system can be optimized with respect to the choice of support for the catalyst (e.g. TiO2 or CeO2), the quantity of Pt used, and the ratio between the catalyst and photocatalyst. In addition, different configurations of the photocatalyst and the catalyst on the textile are studied: under leaching and flow-through gas streams, catalyst and photocatalyst deposition on the same and opposite site of the textile are tested. The performance of the system can be optimized by adapting a configuration where the gas stream goes through the textile, while the deposition side of the catalyst and/or photocatalyst with respect to the gas stream is of minor importance.