Design And Synthesis Of Hollow Materials Confined Transition Metal Catalysts For Catalytic Oxidation Desulfurization Of Fuel

With the increasing demand for sustainable development,stringent limits have been put on the amount of sulfur species in fuel due to the environmental problems caused which was generated by burning of sulfur oxides(SO_x),the main energy source in the production process of society.At present,the main industrial desulfurization method is hydrodesulfurization(HDS),which can remove the vast majority of sulfur-containing compounds in the oil,but it is still difficult to remove thiophene sulfide,and HDS technology requires high temperature and pressure reaction conditions.Therefore,it is necessary to find a desulfurization technology with high desulfurization performance for thiophene and its derivatives to make up for the deficiency of HDS.Oxidative desulfurization(ODS)had aroused widespread concern because of its mild reaction conditions and high sulfur removal efficiency.In this paper,a series of heterogeneous catalysts were designed and synthesized using the confined hollow material as the support and the transition metal as the active center.The catalytic oxidation desulfurization performance of these catalysts for the activation of hydrogen peroxide(H₂O₂)or oxygen(O₂)was investigated.The properties of the catalysts were analyzed and discussed through a series of characterization methods,and described from the following three aspects:1.The molybdenum phosphomolybdic acid was connected to the template by ion exchange,and then coated with silica.Finally,the molybdenum oxide containing the defect is fixed to the inner surface of hollow silica by calcination in nitrogen atmosphere,and the hollow silica confined Mo O_x catalyst(Mo O_x/HS)is synthesized.The prepared catalyst was used in the catalytic oxidation desulfurization reaction system of activated hydrogen peroxide.The influence of different reaction conditions on the catalytic reaction system was investigated,and the optimal reaction conditions were obtained.n(O/S)=3,T=50^oC,0.01g of Mo O_x/HS desulfurization efficiency could achieve 100%at the reaction condition of reaction of 60 min,and achieve deep desulfurization effect.The sequence of removal efficiency of different sulfur-containing substrates was as follows:DBT>4-MDBT>4,6-DMDBT.The results of interference experiments showed that the catalyst had good anti-interference ability and was suitable for desulfurization of oil with low olefin content.Mo O_x/HS still had good catalytic performance after being recycled for 5 times.The investigation of reaction mechanism shows that·OH played a major role in the reaction,and DBT was oxidized to DBTO₂ under the action of Mo O_x/HS and H₂O₂.2.A hollow mesoporous silica nano-sphere confined cobalt molybdenum binary transition metal catalyst(Co-Mo/HMNS)with mesoporous structure was formed by hydrothermal synthesis using Si O₂ as template and introducing HPMo and Co(acac)₃through dissolution and regeneration.The catalyst prepared was used in the catalytic oxidation desulfurization reaction system of activated air.The influence of different reaction conditions on the catalytic reaction system was explored,and the optimal reaction conditions were obtained.When T=120^oC,the desulfurization efficiency of0.01g Co-Mo/HMNS could reach 100%within 3 h of reaction time.The order of removal effect of different sulfur-containing substrates was:DBT>4-MDBT>4,6-DMDBT.Co-Mo/HMNS still had good catalytic performance after 8 cycles.The investigation of reaction mechanism showed that O₂^·-played a major role in the reaction,and DBT was oxidized to DBTO₂ under the action of Co-Mo/HMNS and O₂.3.Monatom Cr was loaded onto carbon nanotubes by wet impregnation method,and then calcined by annealing in nitrogen atmosphere to obtain carbon nanotube confined Cr monatom catalyst(Cr/CNT(1%)).The catalyst prepared was used in the catalytic oxidation desulfurization reaction system of activated air.The influence of different reaction conditions on the catalytic reaction system was investigated,and the optimal reaction conditions were obtained.When the loading capacity was 1%and T=120^oC,the desulfurization efficiency of 0.01 g Cr/CNT(1%)could reach 100%within 4 h.The order of removal effect of different sulfur-containing substrates was:DBT>4-MDBT>4,6-DMDBT.The catalyst has good cyclic performance and still has good catalytic performance after 8 times of cyclic use.The study of reaction mechanism showed that O₂^·-played a major role in the reaction,and DBT was oxidized to DBTO₂ under the action of Cr/CNT(1%)and O₂.