Denitrogenation of Light Hydrocarbon Fractions with Natural Deep Eutectic Solvents Using Commercial Extraction Equipment

Hydrophilic deep eutectic solvents are actively positioned as efficient extractants for removing heterocyclic compounds from light hydrocarbon fractions. Of particular interest is the subclass of natural deep eutectic solvents (NaDESs), since they contain substances of exclusively natural origin. However, these processes have not been systematically studied to date in extraction equipment. To study the process of countercurrent extraction of pyridine, quinoline, and indole from a model solution of light hydrocarbon fractions using commercial equipment, a series of NaDESs based on citric and malic acids, xylitol, and water was used for the first time in this work. The high extraction capacity of these NaDES was demonstrated in laboratory experiments, and the extraction mechanism was determined. A detailed study of the efficiency of extraction of heterocycles with varying process conditions allowed us to move on to studying the process using extractors of the mixer–settler type. From the model solution of light hydrocarbon fractions, pyridine, quinoline, and indole were removed to concentrations <1 ppm by countercurrent extraction using a cascade of six mixer–settlers.