Selective photocatalytic oxidation of benzyl alcohol to benzaldehyde by using metal-loaded g-C3 N4 photocatalysts

Replacement of traditional thermal synthesis of fine chemicals by selective photocatalysis can lead to more environmental friendly processes, carried out at milder conditions, using ambient temperature, atmospheric pressure, with more ecological and economic solvents such as water. Because benzaldehyde (BAL), as fine chemical building block, has an enormous range of applications in pharmaceutical, fragrance and agricultural industries, we analyzed its route of synthesis by the photocatalytic oxidation of benzyl alcohol (BA). In this work, we used graphitized-carbon nitride (g-C3N4) as photocatalyst for the selective synthesis of benzaldehyde from benzyl alcohol. The solid matrix of the photocatalyst was modified by loading different metals such as Au, Ru, Pd, Pt, Ir, Ag and Rh. Conversion, yield and selectivity were compared against benchmark commercial photocatalyst P25 TiO2 (by Evonik). The influence of the physical-chemical nature of the medium, by means of the pH, on the efficiency of the photocatalytic process was also evaluated. The 1 wt.% Ru/g-C3N4 photocatalyst had the best compromise between conversion (73%) and selectivity (72%) for a 4 h of irradiation time using 390 nm activation by a light emitting diode source and it proved to be stable up to 3 consecutive runs. (C) 2016 Elsevier B.V. All rights reserved.