Removal of benzothiophenes from model diesel/jet oil fuel by using pervaporation process: Estimation of mass transfer properties of the different membranes and dynamic modeling of a scale-up batch process

Abstract

Removal of benzothiophenes is a crucial step in order to reduce sulfur content in transportation fuels up to the desired levels. In this study, pervaporation process is investigated for the removal of benzothiophenes from model diesel/jet fuels (benzothiophene/n dodecane mixtures). Values of different mass transfer parameters were estimated for different sulfur selective membranes by using reported experimental results. These parameters were then used to compare the membrane selectivity for benzothiophene. Polyimide membrane prepared from 2,3,5,6-tetramethyl-1,4-phenylenediamine showed the highest selectivity (1.99) towards benzothiophene at 393 K feed temperature. Membrane selectivity towards benzothiophene increased with increasing feed temperature for all membranes.Later, a mathematical model was developed for a scale-up batch pervaporation unit. The model was simulated to reduce the sulfur concentration from 303 PPM mole to 30.3 PPM mole in 100 liters of model diesel/jet fuel by using a 5 m2 spiral wound module. Simulations showed that all membranes are able to reduce the sulfur content up to the desired limit (303 PPM mole to 30.3 PPM mole). Polyimide/POSS hybrid membrane took 11.17 h to reduce sulfur concentration; however, the product recovery was low (7.05%). Moreover, polyimide membranes synthesized from 2,3,5,6-tetramethyl-1,4-phenylenediamine gave the highest product recovery 35.81% and took 21.33 h to reduce the sulfur concentration.