Synthesis of ionic-liquid-functionalized UiO-66 framework by post-synthetic ligand exchange for the ultra-deep desulfurization

Abstract

Ionic Liquids (IL) has been recently immobilized into the pores of metal-organic framework materials (MOFs) to prepare heterogeneous catalyst. However, the IL@MOFs composites are generally prepared by impregnation method, which is unstable in polar solvents. So, we design a new strategy to immobilize IL, and a novel Fenton-like catalyst [mim(CH2)3COO]FeCl4@UiO-66 has been prepared based on the post-synthetic ligand exchange (PSLE) between MOFs and monocarboxylic functional IL. The [mim(CH2)3COO]FeCl4@UiO-66 was exploited to act as an efficient heterogeneous catalyst for dibenzothiophene (DBT) oxidation in a biphasic system using H2O2 as the oxidant. Based on optimal conditions, the DBT removal efficiency reached up to 99.1%. Moreover, the heterogeneous catalyst had a good thermal and chemical stability, and the DBT removal efficiency still exhibited over 95% after 6 recycle runs. It is worth noting that the high DBT removal efficiency could be attributed to the synergistic effect between adsorptive and oxidative desulfurization, where [mim(CH2)3COO]FeCl4@UiO-66 is both an adsorbent and a catalyst.