Optimal extractive and reductive desulfurization process using sodium borohydride in situ generated via sodium metaborate electroreduction in ionic liquid

In order to lower desulfurization cost, the NaBH 4 preparation via NaBO 2 electroreduction was introduced into the integrated process of extraction and reductive desulfurization. Accordingly, a novel desulfurization method was developed where NaBH 4 can be recycled at the same time as desulfurization. The process of NaBH 4 preparation via NaBO 2 electroreduction was analyzed by cyclic voltammetry and the effect of pulse parameters on desulfurization efficiency was optimized by orthogonal experiments. Under optimal conditions desulfurization efficiency of more than 97 % was obtained for model fuel oil. Desulfurization mechanism and kinetics was probed. Results showed that the desulfurization of DBT should proceed over direct cleavage of C S bond and desulfurization reaction could be treated as pseudo-first-order reaction. Furthermore, the structures of original and recycled ionic liquids (ILs) were analyzed by nuclear magnetic resonance and the desulfurization performance of the recycled ILs was also investigated. Results showed that ILs maintained their original structures after regeneration and displayed good reusability. In summary, the novel desulfurization process is feasible and promising.