Ultrafast Desulfurization of Diesel Oil with Ionic Liquid Based PMoO Catalysts and Recyclable NaClO Oxidant

Abstract Sodium hypochlorite (NaClO) is a strong oxidant with facile electrochemical regenerability whereby a sustainable oxidative desulfurization (ODS) process of fuel may be viable. Here, a ultrafast deep ODS process was proposed by using ionic liquid (IL) catalyst and NaClO oxidant, and its catalytic mechanism was studied through GC-MS, FI-IR, and in-situ ESR technique. The results show that the IL with C16 alkyl groups makes the amphiphilic catalysts oil dispersible, and the catalytic activity of the imidazolium is higher than that of pyridinium and ammonium based IL catalysts. Dibenzothiophene (DBT) in model oil and real diesel can be oxidized completely within 30 min, and 99% of catalytic performance can be remained after 8 recycled uses. Under the catalysis of [C16MIM][PMoO], NaClO is firstly decomposed into radical oxygen species of •O2- and •OH that oxidize Mo=O of the catalyst to its peroxide form Mo(O2), whereby DBT was oxidized into DBTO2. The present ultrafast and sustainable ODS process is perspective for industrial application, and the oxidation mechanism revealed here is instructive for ODS of fuel and other catalytic oxidation reactions.