The preparation and photocatalytic activity of Ag-Pd/g-C3N4 for the coupling reaction between benzyl alcohol and aniline

Abstract

In this study, the carrier g-C3N4 was prepared by melamine, and the Ag-Pd/g-C3N4 catalyst was synthesized by the NaBH4 reduction method. Different characterization techniques, including SEM, TEM, XRD, UV–vis DRS, XPS, photoluminescence spectra (PL) and BET, were employed to investigate the morphology and optical properties of the as-prepared samples. The Ag-Pd/g-C3N4 catalyst was used for the synthesis of imine from a benzyl alcohol and aniline. The results show that when the total loading of Ag and Pd is 2 wt%, and the mass ratio of Ag and Pd is 1:1, the activity of the catalyst is the highest (The highest conversion of aniline is 86.7% and the product selectivity is >99%.). The reaction is optimized by changing the type of solvent, the type and amount of base, the type of catalyst, and the amount of reactants. The optimal reaction conditions are 6 ml of n-hexane, 1.4 mmol of Cs2CO3, 50 mg of the Ag-Pd/g-C3N4 (2 wt%, 1:1), and 2:1 mol ratio of benzyl alcohol and aniline. Under optimal reaction conditions, alcohol derivatives and amine derivatives were investigated to determine the suitable range of the catalyst for alcohols and amines. Then, the effects of different light intensities and wavelengths on the reaction were explored. Additionally, the catalyst's recycling ability was tested, and it was found to be relatively stable. The effect of reactive groups on the mechanism shows that the reaction is mainly achieved by the synergy between h+, e− and ·O2−.