Study On Preparation Of MOFs Matrix Composites And Their Oxidative Desulfurization Properties

With the increasing demand for energy,petroleum fuels are playing an important role in human life.However,fuel oil contains a large amount of organic sulfide,so the traditional hydrodesulfurization technology is difficult to remove the organic sulfide in fuel oil,while the oxidation desulfurization technology has a good development prospect with mild reaction conditions,simple operation and good effect on the removal of organic sulfide.It is very important to develop catalysts with high catalytic activity for oxidative desulfurization technology.Therefore,in this paper,MOF-808（Zr）was used as the support,and active species were introduced to prepare the oxidation desulfurization catalyst with excellent performance.In this paper,10～50%MoO_x/MC-808 composite was prepared by impregnation method and tube furnace method using MOF-808 as support and ammonium molybdate as precursor.The structure characteristics of MoO_x/MC-808 have been studied by XRD,FT-IR,Raman,XPS and UV-Vis DRS.The results show that electrons can be transferred from Zr-MOF to MoO₃ in the composite sintered at 400℃,and some MoO₃ can obtain electrons and convert to MoO₂,which then form heterostructures.MoO₂ enriched with free electrons（e^-）is favorable for H₂O₂ to break O-O bond and generate hydroxyl radical（·OH）.The main active substances in the process of oxidative desulphurization are·OH and e^-.Under the optimal experimental parameters（T=60℃,O/S=4）,the 40%MoO_x/MC-808-400 composite with40%MoOx loading capacity can achieve 98.9%desulfurization rate within 60 min.After 5cycles of experiments,the desulphurization rate decreased to 77.9%.In order to improve the desulfurization activity of MOF-808,MOF-808-D with abundant defect sites was prepared by hot ethanol treatment.On this basis,10～50%La/MOF-808-D composites were prepared by introducing lanthanum species.Through various characterization tests,lanthanum species were successfully introduced and highly dispersed.Acid-base potentiometric titration showed that compared with the defect site of MOF-808（0.151）,the defect site number of MOF-808-D（0.23）increased by 52%,while the defect site number of La/MOF-808-D was only 0.09.This is because La species occupied partial defect sites of MOF-808-D and generated La-O-Zr bonds and La-OH active centers,which improved the desulfurization performance of the catalyst.The experimental results show that under the experimental conditions of T=60℃and O/S=6,compared with the desulfurization rate of MOF-808（51.7%）and MOF-808-D-6（79.8%）,the desulfurization rate of 30%La/MOF-808-D-6 reaches 100%within 60 min,and after four cycles of experiments,the desulphurization rate decreased to 80.1%.