Preparation of 2D WO3 nanomaterials and their catalytic performance during the synthesis of imines under visible light irradiation

Abstract In this work, 2D WO3 photocatalysts were successfully prepared by a hydrothermal method with different methods, different pH values and different calcination temperatures. The morphology, crystal structure, composition, and chemical properties of the as-prepared samples were systematically investigated by multiple techniques (XRD, XPS, SEM, TEM, UV–vis DRS, BET, and PL). Imines were synthesized from aniline and benzyl alcohol over WO3 under visible light irradiation. The catalysts and reaction conditions were optimized. The results showed that the catalytic performance of WO3 (hydrochloric acid method, pH=1, and calcination temperature=400 °C) was the best. The conversion reached 75.9 %. After five cycles, the catalyst performance was stable and the morphology did not change. Analysis of the active species showed that the amination reaction was mainly realized by the synergistic action between h+ and OH. Visible light irradiation can lower the activation energy of the amination reaction. A possible reaction mechanism was proposed.