The process operating parameters effect on the extractive ability of some extractants to gasoline fraction dearomatization

Abstract

In the article considers the extraction dearomatization of a straight-run gasoline fraction using polar solvents – dimethyl sulfoxide and ethylene glycol. The relevance of the study is determined by tightening environmental requirements for the content of aromatic hydrocarbons in motor fuels (Technical Regulation TR CU 013/2011) and the need for high-quality pyrolysis feedstock. The presence of aromatic compounds in pyrolysis feedstock leads to a decrease in the yield of target olefins and contributes to equipment coking, which makes the task of dearomatization particularly important. Based on a comparative theoretical analysis of existing dearomatization methods – hydrogenation, adsorption, and extraction – the advantage of extraction as a physical separation method is substantiated. Unlike catalytic hydrogenation, in which the aromatic ring is destroyed, extraction allows selective extraction of aromatic hydrocarbons without changing their chemical structure. The process does not require expensive noble metal catalysts and constant hydrogen consumption, is carried out at atmospheric pressure and moderate temperatures, which ensures its low energy intensity. The extraction method is environmentally friendly, does not produce greenhouse gas emissions, and does not require disposal of spent catalysts. An important advantage is the possibility of simultaneous production of two commercially valuable products: a dearomatized raffinate suitable for use as high-quality pyrolysis feedstock, and a high-aromatic extract – valuable feedstock for petrochemical synthesis. It has been theoretically shown that water added to the extraction system acts as an effective selectivity modifier. For a dipolar aprotic solvent, water increases system polarity and selectivity through hydrogen bonding, however, its excess reduces the solvent capacity.