Ethanol partial photoxidation on Pt/TiO2 catalysts as green route for acetaldehyde synthesis

Heterogeneous photocatalytic partial oxidation of ethanol was studied over different Pt/TiO2 as an alternative green process for acetaldehyde production. The catalysts were synthesized through the photodeposition of Pt over sol–gel TiO2 with platinum loads of 0.5 and 1 wt.%. The effect of some experimental conditions during photodeposition, such as deposition time and Pt loading, was investigated. A short deposition time at 0.5 wt.% Pt nominal loading led to small average particle size of platinum (2–3 nm) homogeneously distributed all over the TiO2 surface. Ethanol partial oxidation was tested in a gas–solid photocatalytic fluidized bed reactor at high illumination efficiency, using different reaction temperatures. Activity results have been correlated with characterization results of the different samples. Platinized samples prepared with short deposition times showed high conversion levels and high selectivity to acetaldehyde. Materials prepared at longer times, 120 min, showed selectivities >98%, although with lower ethanol conversion. Sample with 1 wt.% Pt loading prepared with 15 min deposition time combined a good compromise between a relevant ethanol conversion and a very high selectivity to acetaldehyde at a selected reaction temperature of 80 °C, with an acetaldehyde yield higher than 80%, which make of this catalyst a good candidate for acetaldehyde production by photocatalysis.