Preparation Of PTA-MOF Hybrids And Their Performance In Adsorb-oxidizing Thiophenic Sulfur

In order to resolve the difficulties of eliminating thiophene and its derivatives intraditional hydrodesulfurization (HDS), new porous material MIL-101was selected tocombine with phosphotungstic acid (PTA) in this research. A lot of energy was spentto study the adsorption property of virgin MIL-101and hybrids over thiophenic sulfur.Meanwhile, considering the adsorption property of MIL-101, the synergistic effectbetween MIL-101and PTA was also investigated during the adsorb-oxidativedesulfurization process.Firstly, the hybrid materials PTA@MIL-101and PTA/MIL-101were synthesizedthrough either one-pot synthesis or post-modification, relatively. In the preparation ofPTA@MIL-101, PTA was introduced into the reaction system directly, while PTAwas impregnated into obtained MIL-101through post-modification. Test resultsillustrated that the pore volume and specific surface area of both two kinds of hybridsare decreased. And among them, PTA@MIL-101decreased relatively low.Secondly, in this study, desulfurization efficiency of both MIL-101and hybridswere detected by using the mixture of n-octane and dibenzothiophene (DBT) as rawmaterial. In addition, after comparing with a common zeolite Na-Y, the adsorptionkinetic, adsorption isotherm and reuse stability of the optimal adsorbents were alsostudied. According to the adsorptive dynamics results, the adsorption amount of sulfurover MIL-101and hybrids were larger than Na-Y. Furthermore, the equilibriumadsorption capacity of2PTA@MIL-101illustrated that the direct introduction of PTAinto MIL-101during synthesis resulted in a10.7%increment compared with MIL-101.However, porous hybrid adsorbent1PTA/MIL-101prepared via post-modificationmethod exhibited lower adsorption capacity than virgin MIL-101. In the isothermaladsorption experiments, the theoretical maximum adsorption capacity (Q0) of2PTA@MIL-101is136.5mg S/g adsorbent,4.2times of MIL-101. Even incompetitive adsorption between aromatic compounds which possess strong affinitywith MOFs, and DBT,2PTA@MIL-101and MIL-101remained their effectiveness inremoval of DBT in the system.Finally, catalytic activity of PTA-dispersed MIL-101in the oxidation of DBTwas explored. During the experiment, the conversion of DBT changing with reaction time, H2O2concentration, catalyst dosage and the content of aromatics in model fuelwere also measured. The results showed that the supported PTA performed better thanhomogeneous PTA. Meanwhile, the catalytic activity changed with the loadingamount of PTA in an order of1PTA/MIL-101>2PTA/MIL-101>0.2PTA/MIL-101.In addition, the result also demonstrated that TBHP cannot act as oxidant as H2O2inthis reaction system. The conversion of DBT was98.1%with the O/S molar ration50and12.5mg catalyst/mL solution. The introduction of aromatics including benzeneand p-xylene reduced the conversion of DBT very slightly. And as the content ofbenzene and p-xylene increased to15%(vol.), the conversion of DBT only decreased3.5%and7.9%, respectively.