Optimization of extractive desulfurization of Malaysian diesel fuel using response surface methodology/Box–Behnken design

•An extractive desulfurization technology was developed to reduce the sulfur content in HDS diesel.•Dimethylformamide was the most potential aprotic solvent in ambient extraction reactions.•Process optimization and parametric interaction-effect assessment by response surface method.•EDS technique has great potential to be economically and industrially used after HDS treating process particularly in ASEAN countries.

Systematic experiments were conducted to investigate the most appropriate extraction conditions for sulfur reduction. Initial extraction studies showed that DMF was the most potentially effective solvent. The influence of DMF to diesel ratios, extraction times and temperatures, addition of co-solvent, solvent mixtures, double extractions were explored. The use of co-solvent and solvent mixtures showed poor efficiencies of sulfur removal. A two-stage extraction with ratio of 1:1 (DMF/Diesel) was successfully removed over 88.0% of sulfur in diesel. Under Box–Behnken design, the model showed that maximum extraction ability was observed at 30 °C, 30 min and 1.0 of DMF/diesel ratio to achieved 67.5%.