Coupled Systems For Selective Oxidation Of Aromatic Alcohols To Aldehydes And Reduction Of Nitrobenzene Into Aniline Of Composite Photocatalyst

The CdS/g-C3N4composite photocatalyst was prepared by hydrothermalmethod using Cd(CH3COO)2·2H2O, TAA and C3H3N6as precursor, a coupled system ofselective oxidation of benzyl alcohol to benzaldehyde and reduction of nitrobenzene intoaniline was realized using CdS/g-C3N4composite as a photocatalyst under visible lightillumination. The structure and optical properties of CdS/g-C3N4composite photocatalystwere investigated by X-ray powder diffraction (XRD), UV-vis diffuse reflectancespectroscopy (DRS), scanning electron microscopy (SEM), transmission electronmicroscopy (TEM) and nitrogen adsorption-desorption (BET). Through the Conversion,Yield and Selectivity on selective oxidation of benzene methanol, p-methoxybenzylalcohol, p-fluorobenzyl alcohol, p-chlorobenzyl alcohol and cinnamyl alcoholand reduction of nitrobenzene into aniline under visible light to verify the photocatalyticactivity, in addition the relationship between the electron and hole in the process ofselective photocatalytic oxidation reduction has been further explored. The results showedthat10%of the CdS/g-C3N4photocatalytic selective oxidation of alcohols to aldehydes andreduction of nitrobenzene into aniline optimal effect. Under illumination for4h, theconversion of benzyl alcohol and the yield of benzaldehyde are about48.0%and44.6%,and the conversion of nitrobenzene and the yield of aniline are about49.2%and26.0%,respectively. It demonstrates that selective oxidation of aromatic alcohol into aromaticaldehyde by direct holes oxidation, and reduction of nitrobenzene into aniline by directelectrons reduction. This experiment also studied the experimental solvent (BTF, toluene,acetonitrile and water) to the reaction system, the results show that when BTF as a solvent,selective of alcohol and nitrobenzene were the highest than others.The solvent order: BTF>toluene> acetonitrile> Water. Eliminating agents (oxalic acid and CCl4) photocatalystexperiments further confirmed the photocatalytic mechanism of selective photocatalyticoxidation of alcohols is works by the h+, nitrobenzene reduction is achieved through the e-.