The Study On Structure-activity Relationship Between The Carrier Structure And The Oxidative Desulfurization Performance Of Heteropoly Acid

Fuel oil is one of the most important fossil fuel,it will produce sulfur compounds in the combustion process,which will cause serious air pollution and endanger human health.In recent years,countries around the world have legislated strict laws on the sulphur content of fuel products.Reducing the sulfur content of fuel oil has become a very urgent need.The oxidative desulfurization process is a mild and environmentally friendly desulphurization technology,which has attracts people's attention gradually.As for the development of the oxidation desulfurization technology.The most important thing is to develop efficient catalysts.The main problem are:?1?The catalyst is difficult to recycle,resulting in low recovery efficiency of the catalyst.?2?Most of the molecular sieve catalyst support currently used are expensive,the active component should have a high loading to achieve high catalytic activity,which further increase the cost of catalyst.Therefore,research on cheap,highly efficient recyclable catalyst,while reducing the loading of active components has becomes an urgent problem to be solved.Aiming at the above problems,this paper mainly researches on the following three parts:?1?By using a natural vermiculite material?VMT?,treated with hydrogen peroxide to get expansion,followed by acid treatment to remove the metal components.Lamellared structure,large surface area were proved by scanning electron microscopy?SEM?and nitrogen absorption curve?BET?.The HPW/aEVM catalyst was prepared after loading of phosphotungstic acid?HPW?on the support.Under experimental conditions,the conversion for DBT was almost 100%.After 7 cycles,the catalytic activity decreased from99.95%to 98.06%.This result may be due to the limitation of HPW by the interlayer pore structure.?2?The acid treatment process of expanded vermiculite will produce a lot of Mg²⁺,Al³⁺ion.In the previous literature,the Mg²⁺and Al³⁺ion can be used to prepare Layered Double Hydroxide?LDH?.Based on this,the LDH was used as the support for the oxidative desulfurization process.Previous studies have found that pure MgAl-LDH can't obtain a good desulfurization effect due to it's smaller specific surface area.By the modification of sodium dodecyl benzene sulfonate?SDBS?,the morphological structure of the LDHs has a significant change,as well as an increasement of surface area.The HPW/MgAl-LDH-DBS catalyst was obtained by impregnation of HPW and applied to the oxidative desulfurization reaction.After 15 cycles,the conversion of DBT only decreased from 99.89%to 95.73%.?3?By using a carbon material rich in nitrogen,assisted by ultrasonic to prepare a low HPW loading and well dispersed HPW/NOLC catalyst.The X-ray photoelectron spectroscopy?XPS?analysis shows there are four types of nitrogen on the surface:Pyridine nitrogen,graphite nitrogen,pyrrole nitrogen and pyridine nitrogen.Moreover,the content of graphene increased with the HPW loading.The EDS test shows HPW is highly dispersed on the NOLC surface.And the low loading content of HPW was also proved by ICP-AES test.The low loading and high dispersion of HPW on the support was achieved by ultrasound-assisted method and the use of material rich in nitrogen and oxygen.