The Study Of Selective Oxidation Of Alcohols To Corresponding Aldehydes

The photocatalyst In2S3was prepared by hydrothermal method,and also was themultiplex photocatalyst BN/In2S3. Then we study the mechanism of the selective oxidationof alcohols to the corresponding aldehydes. And the photocatalytic activity andmorphology were detected by XRD, DRS, BET, SEM, TEM, and PL. Benzylalcohol,p-methoxybenzyl alcohol, p-chlorobenzyl alcohol,p-fluorobenzyl alcohol,p-nitrobenzyl alcohol and cinnamyl alcohol were chosen as the materials for selectiveoxidation to study the activity of the photocatalyst under the visible illumination. Theconversion and the selectivity of benzyl alcohol in different solvent such asbenzotrifluoride,toluene, aceonitrile and water were also tested in the paper. From theexperimental results, In2S3(Eg=1.96eV) displays a ball-like structure of varying sizes withdiameter around1～3μm. For selective oxidation of benzyl alcohol, when illuminationtime is4h, the conversion reaches to41.5%, and the selectivity is99.8%. BN can adsorpthe holes produced from the catalyst, which can reduce the electron-hole recombination. Sowhen illumination time is2h, the conversion reaches to42.4%, and the selectivity is90%for BN(7wt.%)/In2S3. For different aromatic alcohols, the selectivity of the reactionshould be as follows: benzyl alcohol≈p-methoxybenzyl alcohol> p-chlorobenzyl alcohol> p-fluorobenzyl alcohol> p-nitrobenzyl alcohol. The selectivity of benzaldehydedecreases with the rise of solvent’s polarity (water> aceonitrile> toluene) because of thesolubleness of O-O bands in the polar solution, and benzotrifluoride can dissolve moreoxygen, so benzotrifluoride is the most suitable solvent for selective oxidation of alcohols to corresponding aldehydes under visible light irradiation. O2and OH are the importantoxidizing agents in the photocatalytic process for In2S3, either O2is the importantoxidizing agent for BN/In2S3.