Extractive desulfurization of model diesel fuel in a micro-channel contactor using deep eutectic solvents (DESs)

In the present study, the extractive desulfurization of model diesel fuel (i.e., dibenzothiophene (DBT) in n-decane) has been investigated using different deep eutectic solvents (DESs) in a micro-channel device. Eight different DES were synthesized using polyethylene glycol 200 (PEG200) and propionic acid (Pr) as hydrogen bond donor (HBD) in combination with four different hydrogen bond acceptor (HBA). The sulfur removal, slug length, specific interfacial area, and volumetric mass transfer coefficient were investigated for different examined DESs. In this regard, the hydrodynamic of the two-phase flow was captured using a camera and microscope. The remarkable sulfur removal of 62.16% and 75% was achieved using triethylamine/PEG200 with molar ratio of 1:3 (TEA/PEG200 [1:3]) and triethylamine/Pr with molar ratio of 1:3 (TEA/Pr [1:3]) in the residence time of 3.125 s, respectively. The highest sulfur removal in the micro-channel was 78.28% using TEA/Pr [1:3], which was achieved in the residence time of 25 s. The maximum value of the volumetric mass transfer for the extraction of DBT was 0.6097 s(-1) using TEA/Pr [1:4] at a flow rate of 0.96 mL/min. It was found that the achieved sulfur removal in the micro-channel with very low residence time is comparable with the sulfur removal in the batch extraction with high operating time.