CuWO₄ Series Photocatalytic Oxidation Desulfurization Catalysts

The sulfur dioxides（SOx）produced by combusting sulfur compounds in fuels have become one of more and more serious environmental problems.Therefore,deep desulfurization technology has become one of the hot subjects nowadays.In this paper,CuWO₄ was introduced into the preparation of SBA-15molecular sieve using CuWO₄ as the active component to prepare CuWO₄/SBA-15 photocatalytic oxidation desulfurization catalyst.CuWO₄-TiO₂ composite photocatalytic desulfurization catalyst was synthesized by hydrothermal method using CuWO₄ and amorphous TiO₂.The samples were characterized by XRD,N₂ adsorption and desorption,FTIR,UV-vis,SEM,EDS and TEM.The photocatalytic performance of the catalysts was investigated by using dibenzothiophene（DBT）and dodecane as simulate diesel and photocatalytic oxidation desulfurization（PODS）reaction as probes.The reusability of the catalyst was investigated,and the mechanism of PODS was deduced.The specific research contents and results are as follows:（1）Due to the small specific surface area of CuWO₄,the catalytic performance is poor in practical photocatalytic reaction.SBA-15 is an excellent carrier with a large specific surface area and pore size.Therefore,CuWO₄ is the active component and SBA-15 is the carrier.CuWO₄ was introduced during the preparation of SBA-15 to synthesize CuWO₄/SBA-15 catalyst.By characterization,the catalyst has a two-dimensional hexagonal pore structure,which is still a single mesoporous structure,retains the wheat spike shape of SBA-15 molecular sieve,CuWO₄ is uniformly dispersed on the molecular sieve,and CuWO₄/SBA-15 is illuminated by light compared with CuWO₄.The increase in post-carriers increases the oxidation performance.The PODS performance of CuWO₄/SBA-15 catalyst was investigated.The desulfurization effect of CuWO₄/SBA-15（x）（x is the mass ratio of CuWO₄to silica）was analyzed.In the PODS reaction,the specific surface area of CuWO₄ is increased in the reaction,so the active site of CuWO₄/SBA-15（x）is also increased,and the pores of SBA-15 are favorable for the diffusion of DBT.When the O/S molar ratio is 10,the ratio of the agent to the oil（v/v）is1:1,the amount of the catalyst（mass percentage）is 3%of the simulated oil mass,and the CuWO₄/SBA-15（0.07）catalyst is used when the light is 2h.The desulfurization rate can reach 93.2%,which is obviously higher than that of CuWO₄ and SBA-15.It proves that the new catalyst has good photocatalytic performance.After repeated 6 times of PODS reaction,the desulfurization rate is still close to 90%,which proves that the catalyst has good stability.The reactive groups of the catalyst are h⁺and·OH.（2）If the electrons generated by the excitation of CuWO₄ are not effectively migrated to the outside world,then it does not exhibit good activity in the application.To solve this problem,CuWO₄ is combined with TiO₂,and TiO₂ has better light.Catalytic activity is one of the most commonly used catalysts,but its photogenerated electron-hole pairs are easy to conform,and its forbidden band width is wide,while CuWO₄ has a narrow band gap,and the two are combined to prepare a novel CuWO₄-TiO₂catalyst.CuWO₄-TiO₂ enhances the absorption intensity of the catalyst in the ultraviolet region,so that its absorption in the ultraviolet region is significantly better than that of CuWO₄ and TiO₂,and also has light absorbing properties in the visible region,and effectively suppresses photogenerated electron-hole pairs.The combination improves the utilization of light by the catalyst.The PODS properties of CuWO₄-TiO₂（x）（x is the mass ratio of CuWO₄ and TiO₂）catalysts were investigated.When the O/S molar ratio is 10,the ratio of agent to oil（v/v）is 1:1,the amount of catalyst（mass percentage）is 1%of simulated oil mass,and when irradiated for 2 h,CuWO₄-TiO₂（x=0.02）catalyst Its desulfurization rate can reach92.9%,the desulfurization effect is better than that of CuWO₄ and TiO₂,and it has good photocatalytic performance.The PODS reaction was repeated 6times,and the desulfurization rate was still close to 90%,which proved that the catalyst had good stability.It was found by capture experiments that the reactive groups were h⁺and·O₂^-.