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

Abstract

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 TiO 2 activated under UV-A radiation. The impact of ethanol concentration, of the nature of TiO 2 (rutile, anatase or mixture), of the photodeposition 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 TiO 2 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 photodeposition 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 H 2 .

Tandem Photooxidation/Acetalization of Alcohols to Acetals/Ketals with Sulfur‐doped Carbon Nitride

“…Therefore, only recently avoiding the use of acids, green solid photocatalytic systems have increasingly been employed to catalyse such transformations in tandem fashion [12,17,22–25] . Also, photocatalytic conversion of aldehyde to acetal with ethanol using TiO 2 and other photocatalysts has shown significant promise [23,25–27] . Nikitas et al.…”

“…[12,17,[22][23][24][25] Also, photocatalytic conversion of aldehyde to acetal with ethanol using TiO 2 and other photocatalysts has shown significant promise. [23,[25][26][27] Nikitas et al showed that thioxanthenone photocatalysts efficiently catalyzed the acetalization of aldehydes using a household lamp. [16] Similarly, Subramanian et al achieved chemoselective acetalization with Ni (II) complexes under neutral conditions.…”