Preparation Of Tungsten Trioxide Photocatalysts For Photocatalytic Benzylamine Oxidation

Photocatalytic organic systhesis has received extensive attention and research in recent years.Traditional semiconductor catalysts,such as titanium dioxide,are limited by their band gaps and underutilize visible light.Therefore,finding a new material with a suitable band gap,stable physical and chemical properties,and a response to visible light is one of the effective ways to solve this problem.As a common semiconductor oxide,tungsten trioxide have the following characteristics:the band gap is about 2.6 e V,it can utilize 14%of sunlight,and it has good chemical and thermal stability,which makes it become one of the candidates for current photocatalytic materials.However,the study has found that tungsten trioxide also has some disadvantages such as,electron-hole recombination and low conduction band,which affects its photocatalytic efficiency and applications.Therefore,a great vision has come toward the development of a novel visible light-driven WO₃-based photocatalysts which can promote the separation of photogenerated electrons and holes.So,this paper takes WO₃as the main research object,and synthesized a series of tungsten trioxide and copper supported composites by hydrothermal method and impregnation reduction method.Because the Transition metal copper is cheape and available,which can be used as a co-catalyst to improve catalytic performance.In addition,it has been previously reported that copper and its copper salts can catalyze the oxidation of benzylamine,so we choose copper loading to improve the above problems and study their photocatalytic performance.The main research contents and research results are as follows:（1）Cu/WO₃was synthesized using sodium tungstate as a precursor by hydrothermal method and immersion reduction method,and the effect of copper nanoparticles with different mass ratios on the photocatalytic activity of benzylamine were studied.Experiments show that when the loading of Cu is 0.5 wt%,the catalytic efficiency is optimal,and the conversion rate can reach about 96%,which is more than four times that of pure WO₃.The improvement of the catalytic activity of the composite catalyst mainly comes from the synergy between the two.（2）Prepare the catalyst by the same method as above.Tetraethyl silicate was added to synthesize silica.After HF etching,mesoporous tungsten trioxide（m WO₃）is obtained.Then the metal Cu nanoparticles were supported on the m WO₃support by dip reduction method.Under mild conditions,the 1.0 wt%Cu/m WO₃catalyst can achieve 93%benzylamine conversion and high selectivity in 4 h.This is because m WO₃enlarges the specific surface area and active site of the catalyst,and the addition of Cu weakens the recombination of electron-hole pairs,which improves the photocatalytic efficiency.