Upgradation of Petroleum Streams from Middle Distillate Using Solvent Extraction with Organic Solvents

Abstract

This thesis describes the upgradation of middle distillate streams such as diesel and LCO via desulfurization and dearomatization using solvent extraction method. Chapter one describes the detailed literature survey on oxidative desulfurization and dearomatization of fuels via solvent extraction. Chapter two specifies the experimental procedures and the different physicochemical techniques used such as density, viscosity, refractive index, total sulfur and spectroscopic characterization techniques such as FTIR spectra for synthesized deep eutectic solvents named as DESs. Chapter three describes the results and discussion of all the experiments performed. This chapter explained the oxidation followed by extraction of two different diesel using the solvent NMP plus water and synthesized deep eutectic solvents at different temperatures. The heavier fraction of LCO named as HFLCO also performed for the extraction study. Among all the synthesized DESs tetraethylene glycol named as TetEG based DESs using methyltriphenyl phosphonium bromide named as MTTPBr and choline chloride as HBAs performed better desulfurization. The total sulfur was reduced to 92 ppm and 0.187 percent wt respectively for diesel I and diesel II at temperature 50 degrees centigrade using NMP plus water. The total sulfur and aromatic contents of HFLCO were reduced to 0.320 percent wt and 33 percent wt respectively using NMP plus water. The synthesized DES using MTTPBr with TetEG reduced the total sulfur content from 1400 ppm to 752 ppm in a model feed while on oxidation of diesel I and oxidized diesel II, the total sulfur was reduced to 257 ppm and 0.728 percent wt respectively from 532 ppm and 1.225 percent wt at 30 degrees centigrade. Thus DESs synthesized by using MTTPBr as HBA and TetEG as HBD based DES can be used as a suitable extraction solvent for sulfur removal at slightly low temperature to that used for the conventional solvents NMP and finds the best DESs which can be used as a suitable extraction solvent for sulfur removal.