Design Of Molybdenum-Based Metal-Organic Framework And Its Derived Catalysts In Application Of Oxidation Desulfurization Of Fuel Oil

The wide use of motor vehicles has not only brought convenient transportation,but also caused a lot of pollution.A large amount of SO_xwill be discharged into air through exhaust gas because the fuel used by motor vehicles contains sulfides.In order to realize the sustainable development of green energy and protect the lucid waters and lush mountains for future generations,we need to conduct energy transition from fossil fuel to clean energy sources and realize reutilization.Among them,the cleaning and transition of fuel oil is mainly desulfurization treatment.At present,various countries have put forward standards for the sulfur content in fuel oil.For example,China’s national VI stipulates that the sulfur content in fuel oil should limit tp no more than 10ppm.Up to now,there are many desulfurization methods,among which oxidative desulfurization has the advantages of mild reaction conditions and high desulfurization efficiency,so it has attracted much attention.In recent years,metal organic framework materials（MOFs）have been widely used in the field of catalysis.In this paper,a series of Mo MOFs were designed and synthesized,and their derived catalysts were used to activate hydrogen peroxide（H₂O₂）for oxidative desulfurization.It mainly includes the following three systems:1.A series of Mo-MOFs were prepared by simple hydrothermal reflux method with imidazole and its derivatives as organic skeleton and MoO₃ as metal node.The activity of oxidative desulfurization was tested by using H₂O₂ as an oxidant and ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate（[Omim]PF₆）as an extractant.The results showed that under the reaction conditions of m（catalyst）=0.01 g,V（model oil）=5 m L,V（[Omim]PF₆）=1 m L,T=60°C,O/S=3,the desulfurization rate of dibenzothiophene（DBT）from model oil can reach 99.4%in 12 min.In addition,the catalyst had a good cycle performance.When the reaction time is 60 min,it can cycle stably for 20 times.2.Although Mo MOF in the previous chapter has high catalytic performance,it uses more expensive ionic liquids,MoO₂ was uniformly anchored in nitrogen doped carbon nanotubes to prepare the catalyst MoO₂@U-CNT by calcination in argon atmosphere by using Mo-MOF as molybdenum source,urea as nitrogen dopant and dispersant and carbon nanotubes as a carrier.The doping amount of nitrogen and the particle size of MoO₂ can be regulated orderly via adjusting the amount of urea.The oxidative desulfurization performance of the catalyst was investigated by using catalyst MoO₂@U-CNT to activate H₂O₂.The results showed that under the reaction conditions of m（catalyst）=0.01 g,V（model oil）=5 m L,T=50°C,O/S=3,the desulfurization rate of DBT from model oil can reach 99.6%in 30 min,and there was no need to used ionic liquids.After circulating stably for 8 times,the desulfurization rate of the catalyst could still reach 99.7%,indicating its good cycle performance.In addition,in the reaction system,not only the sulfides in the fuel can be perfectly removed,but also the reaction products can be recovered through simple separation.3.In order to further increase the specific surface area of the catalyst and reduce the cost of the catalyst.Mo-MOF was evenly dispersed in calcium citrate by PEG-200 with Mo-MOF as molybdenum source and calcium citrate as carbon source.The composite material of porous carbon uniformly loaded with amorphous MoO₃ was prepared by calcination in argon atmosphere.The oxidative desulfurization activity of model oil was tested by using H₂O₂ as oxidant.The results showed that under the reaction conditions of m（catalyst）=0.005 g,V（model oil）=5 m L,T=60°C,O/S=3,the desulfurization rate of DBT from model oil（DBT）could reach 99.1%in 20 min.After circulating stably for 9 times,the desulfurization rate of the catalyst could still reach 99%,indicating its good circulation effect.Through mechanism exploration,it was found that the main active substance of the reaction was hydroxyl radical,and the main product was DBTO₂.In addition,in this work,not only the sulfide in the fuel could be completely removed,but also the reaction products can be recycled through simple separation.