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Résumé :
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Four metal―organic frameworks (MOFs) are synthesized using two different metal centers and two different organic ligands, viz., Cu3[C6H3(CO2)3]2 (Cu-BTC), Cu[O2C―C6H4―CO2] (Cu-BDC), Cr(OH)[O2C―C6H4―CO2] (Cr-BDC), and Cr3F(H2O)3O[C6H3(CO2)3]2 (Cr-BTC). Their adsorption behaviors for thiophenic sulfurs in model diesel oils are systematically investigated at mild temperatures and follow the order Cu-BTC > Cr-BDC > Cr-BTC ≫ Cu-BDC. Meanwhile, the adsorption capacity of different sulfur compounds follows the order dibenzothiophene (DBT) > benzothiophene (BT) > 3-methylthiophene (3-MT). The MOFs adsorption mechanism is regarded as a combined effect of many factors involving appropriate framework structure, suitable pore size and shape, and exposed Lewis acid site matching the S-compound to be adsorbed. The difference in adsorptive activity among the organosulfurs is mainly ascribed to their π-electron number and the electron density on the S-atom. Finally, the used MOF can be easily regenerated by solvent washing and recycled at least five times.
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