Green Synthesis Of MIL(Cr,Fe) And Its Adsorptive Desulfurization Performance

MIL series materials are an important branch of MOFs(metal-organic framework materials)and have attracted much attention due to their advantages such as a large surface area and pore volume,diverse structures and fascinating physicochemical properties.At present,the hydrothermal method is the most common method for the synthesis of MIL series materials.These synthetic processes have to suffer from problems involving low autoclave availability,high cost and environmental pollution resulting from the addition of large amounts of solvents.Therefore,a facile,high-yield and green synthetic route is urgently needed.On the other hand,the adsorption desulfurization(ADS)was considered as one of promising petroleum desulfurization methord because of its low-energy consumption and simple operation.Due to their high specific surface area and porosity,unique structure and high stability,MIL series materials are expected to be excellent adsorbents for ADS.Based on this,this project studied the solvent-free green synthesis and the ADS performance of MIL series materials.Firstly,MIL-100(Fe),one of the MIL series materials,was successfully prepared using the solvent-free green synthesis method.Under this synthetic system,optimal synthesis conditions for preparing MIL-100(Fe)were optimized by adjusting different synthesis parameters.More importantly,this approach can produce MIL-100(Fe)with a high product yield of 93% in a short crystallization time.In addition,it is demonstrated that MIL-100(Fe)prepared using this method as a heterogeneous catalyst is very active in the acetalization of benzaldehyde with methanol and can still maintain high catalytic activity after five runs.Meanwhile,the ADS performance of obtained MIL-100(Fe)was tested and the adsorption amount of dibenzothiophene(DBT)was 12.1 mg S/g.Second,MIL-53(Cr),another material in the MIL series,was prepared using a solven-freet green synthesis method.The ADS performance(for DBT)of MIL(Cr)series materials with the same metal center ions and different structures were systematically evaluated.The effects of adsorption conditions(including the amount of adsorbent,temperature,initial sulfur content,and type of sulfide)on the performance of the adsorbent ADS were studied in detail.Among the four MIL(Cr)materials,MIL-53(Cr)showed a better ADS performance(86.4 mg S/g).In addition,MIL-53(Cr)can remove the model oil with a sulfur content of 500 ppm until its sulfur content is almost zero.Finally,MIL-53(Cr)has poor reusability due to the strong interaction between MIL-53(Cr)and DBT.Thus,the regeneration method of MIL-53(Cr)adsorbent was studied in detail.It was found that the polar solvent extraction and vacuum heat treatment regeneration methods were effective.The regenerated adsorbent afforded more than 95% of the initial adsorption capacity after the fifth run and the structure of the adsorbent still remained intact after regeneration.