Modulating The Geometric And Electronic Structure Of Vanadium Based Supported Catalysts For Aerobic Oxidative Desulfurization

The presence of sulfur-containing substances in oil products,especially aromatic hydrocarbon sulfides,poses great challenges to the ecological environment and public health.They are important factors that hinder the achievement of“carbon peak”by2030 and force the traditional energy industry to improve fuel efficiency and transition to new energy.Therefore,reducing the sulfur compound content in fuel to produce ultra clean fuel oil,known as“sulfur-free”fuel oil（sulfur content<3.0μg/g）is imperative.At present,the main technology for producing ultra clean fuels is hydrodesulfurization,but with the increasingly strict national environmental standards（national VI B sulfur content<10μg/g）,resulting in a sharp increase in energy and hydrogen consumption during the hydrogenation process.With the adjustment of China’s energy structure and the implementation of the“dual carbon plan”,“Reducing oil and increasing chemicals,reducing oil and increasing specialty”will become the development trend of the refining industry.The Catalytic Oxidation Desulfurization（CODS）technology has attracted widespread attention and in-depth research from researchers due to its excellent desulfurization efficiency,mild reaction conditions,lower production costs,and the final product being polar sulfone compounds with high added value as pharmaceutical intermediates.In this paper,based on the supported metal oxides,three different types of vanadium-based catalysts were constructed by controlling the geometric and electronic structure of the active components of the catalyst.The effects of the geometric and electronic structure of the catalyst on the adsorption and activation of oxygen molecules and the ultra-deep CODS performance of sulfur compounds were studied.The main conclusions are as follows:Firstly,a series of VO_x with different VO_x NPs sizes（17-27 nm）were constructed using an intercalation domain limiting strategy.The ultra-deep CODS performance of VO_x/BNNS@TiO₂-y（y=1,2,3）heterogeneous catalysts for dibenzothiophene（DBT）and its derivatives was investigated.The experimental results indicated that the size of VO_x particles decreased first and then increased with the increase of TiO₂ doping.VO_x/BNNS@TiO₂-2 catalyst exhibited the highest CODS performance due to its excellent VO_x dispersion,excellent redox performance,and abundant active oxygen species,achieving a DBT conversion rate of 93.7%at 130℃and 60 min.The kinetic fitting results indicated that the DBT CODS reaction was a quasi-first order kinetic process,and the subsequent oxidation product was dibenzothiophene sulfone（DBTO₂）.Based on the paramagnetic results,the reaction mechanism of the catalyst in the CODS process was proposed.Secondly,due to the simultaneous changes in VO_x particle size and TiO₂ support in the previous catalyst system.Therefore,in this chapter,a series of VO_x/TiO₂-y（y=1,2,3）catalysts with different particle sizes of VO_x nanocrystals（3.0-10 nm）were constructed by controlling the proportion of citric acid/ethylene glycol to maintain the carrier TiO₂ unchanged.The effects of VO_x particle size on O₂ adsorption,activation,DBT and its derivatives ultra-deep CODS performance were investigated.The research results indicated that as the size of VO_x particles gradually decreased,the CODS performance of VO_x/TiO₂ catalysts gradually improved.When the particle size of VO_xwas～3.0 nm,the VO_x/TiO₂-1 catalyst achieved 100%conversion of DBT and generated corresponding DBTO₂ within 120℃and 80 min.The kinetic fitting results indicated that the oxidation reaction of DBT was a quasi-first order kinetic process,and the reaction mechanism of CODS process was proposed based on the paramagnetic results.Finally,a series of VO_x/TiO₂ catalysts with different crystal planes of TiO₂ loaded V single atoms and VO_x clusters were designed and controllable through a"top-down"strategy.The effects of TiO₂ crystal planes,V single atoms and VO_x clusters on O₂ sub adsorption,activation,and ultra-deep CODS performance of 4,6-DMDBT were systematically studied.The experimental data showed that the synergistic effect between the crystal plane of TiO₂,V single atoms,and VO_x clusters significantly promoted the CODS activity of vanadium-based catalysts.The VO_x/TiO₂-{001}catalyst could achieve 100%conversion of 4,6-DMDBT at 120℃and 60 min,and performance tests had been conducted on real diesel,achieving a conversion rate of93.6%.Meanwhile,the kinetic fitting results indicated that the 4,6-DMDBT CODS reaction was a quasi-first order kinetic process,and the final oxidation product was a highly valuable 4,6-dimethyldibenzothiophene sulfone（4,6-DMDBTO₂）sulfone substance,achieving deep utilization of resources and proposing the reaction mechanism of the catalyst in the CODS process.In conclusion,the geometry and electronic structure of vanadium based supported catalysts significantly affect the CODS performance of the catalysts.The research results provide theoretical guidance for the design and construction of catalysts with ultra deep oxidation desulfurization performance.