Preparation And Modification Of Molybdenum-based Catalyst And Its Catalytic Performance For Thiophrne Hydrodesulfurization

With the rapid development of our society,human pay more attention on green energy.To produce the oil with lower sulfur content,it is essential for us to improve Hydrodesulfurization reaction performance.Molybdenum disulfide—a transition mental sulfide has ben focus on due to its special chemical and physical characteristics.It plays an important role in hydrodesulfurization of gasoline and diesel and electrochemical hydrogen evolution.In this paper the catalyst of Co-Mosystem was successfully modified to obtain a catalyst with improved performance.The HDS performance of the catalyst before and after modification was studied from two aspects:cobalt-doped molybdenum disulfide modified in different atmospheres and sodium borohydride modified.The morphological changes and catalytic mechanism of the catalyst before and after modification were studied in detail by TEM,XRD,XPS etc.The specific contents of this work are as follows:The first part:the catalyst with Co-doped molybdenum disulfide dispersed was produced by simple hydrothermal synthesis method and then roast at low temperature in different atmospheres（hydrogen and oxygen）.TEM,XRD,XPS and other characterization methods were used to analyze the elemental valence state,sample morphology and surface crystal structure of the three catalysts before and after atmosphere control.the results of XRD show that the lattice spacing of the（002）crystal face of the material is increased and the peak width is narrowed after the atmosphere control,which shows that the crystallinity of the（002）crystal face of molybdenum disulfide is increased due to the atmosphere control.XPS results show that the active phase content of the catalyst after hydrogen treatment increases.Raman characterization results show that the catalyst treated by hydrogen atmosphere produces 1T-MoS₂.And the EPR test results show that the sulfur vacancy content of the catalyst treated with atmosphere is more than that of the untreated catalyst.The thiophene hydrodesulfurization performance of the catalyst was tested.The results showed that the catalyst treated with hydrogen and oxygen showed better hydrodesulfurization performance than the untreated catalyst,which proved the effectiveness of atmosphere control.The influence of sulfur vacancy content on thiophene adsorption energy of catalyst was studied by DFT calculation.The calculation results showed that the catalyst with more sulfur vacancy content had stronger adsorption energy and more stable adsorption.The second part:Cobalt-doped molybdenum disulfide catalyst was synthesized by simple hydrothermal synthesis method,and sodium borohydride was added to modify it during the synthesis process.The catalyst before and after sodium borohydride modification was characterized by TEM,XRD and XPS,and the morphology,electronic valence distribution and crystal structure of the catalyst surface were analyzed.The XRD test results showed that the catalyst modified by sodium borohydride had Co₉S₈crystal phase,which could play a synergistic role with the CoMoS active phase to jointly promote the hydrodesulfurization reaction.Raman results show that most of the catalysts without sodium borohydride are 2H-MoS₂,while the catalysts modified by sodium borohydride have 1T-MoS₂,and 1T-MoS₂exposes more active sites,which will be beneficial to the hydrodesulfurization performance of the catalysts,so the catalysts modified by sodium borohydride show better hydrodesulfurization performance.