Preparation Of Au-supported Graphitic Phase Carbon Nitride Catalysts And Its Catalytic Performance For Oxidative Esterification Of Aldehydc

Ester is a vital chemical raw material with significant applications and commercial significance.Synthetic ester is primarily produced on a large industrial scale by condensation of aldol between acid and alcohol in the presence of strong sulfuric acid.This technology,however,has numerous drawbacks,including high energy consumption,a hazardous environment,and rapid corrosion of equipment.In recent years,several researchers have advocated one-step oxidative esterification of aldehydes as a suitable alternative to the classic ester production procedure.The creation of green and efficient catalysts is a key link in the implementation of the new process.Being a noble metal,Au has strong oxidation esterification catalytic capabilities,and g-C₃N₄ is extensively utilized as a green carrier.In this paper,Au was loaded on g-C₃N₄ for a catalytic oxidation esterification reaction,and the catalytic performance was investigated.The influence of carriers prepared by different methods on the catalytic performance was also studied.The main research contents are as follows:1.Three alternative approaches were used to create g-C₃N₄.To catalyze the oxidation esterification of benzaldehyde,an Au catalyst was loaded via urea deposition and precipitation.XRD,SEM,TEM,BET,FT-IR,XPS,and CO-DRIFTS were used to investigate the support and catalyst.Choose the best catalyst influence on reaction kinetics and cycle stability tests while also investigating the benzaldehyde oxidation optimal reaction conditions of the esterification process.Because of the two-dimensional planar structure of g-C₃N₄,Au is equally dispersed,with particle sizes ranging from3-4 nm.Simultaneously,the existence of g-C₃N₄ surface imperfections provides an active site for Au loading.By electron transfer,Au and g-C₃N₄ improve the performance of activated oxygen.Under the influence of reactive oxygen species,Au⁰ serves as the primary adsorption site,causing the reaction to proceed more favorably.2.As raw materials,bimetallic precursors and urea were employed to create bimetallic doped modified graphitic phase carbon nitride support MZn-g-C₃N₄（M=Ce,Co,Mn,Al）.To examine the oxidative esterification reaction activity of benzaldehyde,an Au/MZn-g-C₃N₄ catalyst was synthesized via urea deposition and precipitation.XRD,SEM,TEM,BET,FT-IR,XPS,and CO DRIFTS were used to examine the catalysts,and the best Au/Ce Zn-g-C₃N₄ catalyst was chosen for kinetic analysis and cyclic stability testing.Not only may metal doping modify the shape and surface area of g-C₃N₄,but it can also control the electrical environment of the catalyst.As adsorption sites,Au⁰ and Au^δ+have synergistic effects with lattice oxygen and oxygen vacancy.Electron transfer to lattice oxygen activates it,which improves oxygen activation and the adsorption of the reaction substrate,hence improving catalytic performance.