Ti-grafted MIL-101 as hydrophilic catalyst for efficient oxidative desulfurization of dibenzothiophene with hydrogen peroxide

Abstract

Ti-containing porous materials are extensively studied in liquid-phase oxidative desulfurization (ODS) to obtain low-sulphur fuel, these materials displayed excellent ODS performance co-operating with organic oxidants but relatively poor ability with H2O2, which is a green and cheap oxidant widely used in industrial process. To overcome this challenge, we reported a H2O2 compatible ODS catalyst Ti-MIL-101 by treating MIL-101 with TiCl4 in dehydrated CH2Cl2. The results of N2-absorption, UV–vis, IR and XPS indicated that Ti species were mainly confined in mesopore cages of MIL-101 in the form of isolated and oligomeric octahedral Ti which were grafted to Cr centres of MIL-101 by Cl bridge. Moreover, wettability studies further suggested this catalyst possessed good affinity with water-based substance. As a result, Ti-MIL-101 exhibited efficient ODS ability in the oxidative reaction of DBT with H2O2 compared with that with organic oxidant. In model fuel, sulphur content was reduced to less than 10 ppmw from 1000 ppmw within 30 min at 333 K and the corresponding TOF value over Ti-MIL-101 reached 16.8 h−1. This outstanding catalytic ability might be the result of the synergy between the distinct active Ti species and the good surface affinity of Ti-MIL-101. Ti-containing metal–organic frameworks were prepared for oxidative desulfurization of obstinate sulphur compounds with H2O2. This catalyst displayed highly efficient activity in ODS of DBT. The sulphur content was reduced from 1000 ppmw to less than 10 ppmw in 30 min, corresponding TOF number reached 16.8 h−1. This outstanding catalytic result could be attributed to the superior affinity between catalyst and oxidant.