Catalytic oxidative desulfurization performance of immobilized NMP.FeCl3 ionic liquid on γ-Al2O3 support

•NMP.FeCl3/γ-Al2O3 was prepared as a novel recyclable supported catalyst for ODS system.•True immobilization of NMP.FeCl3 was confirmed by several characterization techniques.•A facilitated desulfurization was attained by the novel catalyst in a solvent free system.•99% of DBT was removed at the found optimal operating conditions of ODS.•Based on examination results, a plausible mechanism was proposed for desulfurization.

NMP.FeCl3 (NMP = N-methyl-2-pyrrolidone, C5H9NO) ionic liquid (IL) was effectively immobilized on γ-Al2O3 as a support and examined in the catalytic oxidative deep desulfurization (ODS) of BT, DBT and 4,6-DMDBT from model oil employing 30 wt.% H2O2 as the oxidant reagent. The supported catalyst was prepared via a simple wet impregnation and the effective immobilization of IL was confirmed by FTIR, SEM, EDS, XRD, BET and BJH analysis. The maximum efficiency of 99% was achieved for ODS of DBT using supported IL at the loading amount of 10 wt.%, H2O2/sulfur molar ratio of 4, temperature of 40 °C, and duration of 90 min. The use of support material in this study resulted in using a lower amount of IL in ODS process. The ODS reactivity of the thiophenic compounds changed in the order of DBT > 4,6-DMDBT ≫ BT. The catalyst was recycled for several times and showed no significant loss in the activity. Furthermore, based on GC-MS analysis of the products, desulfurization mechanism was surveyed and a reasonable pathway was proposed.