Compressed isobutane as a solvent of heavy hydrocarbons

Abstract

This research provides solubility data required for environmental applications involving the extraction of heavy hydrocarbons with compressed gases. Dibenzothiophene (DBT), 2-nitrophenyl disulfide (NPDS), and tetramethylthiuram disulfide (TTDS) have been selected as model compounds for this type of pollutants and isobutane as compressed gas. The solubilities obtained at 367-413 K and 3.9-7.5 MPa, expressed as solute mole fractions, were in the ranges 0.025-0.106 for DBT, 1.2 3 10 24 26.3 3 10 24 for NPDS, and between 2.7 3 10 24 and 1.8 3 10 23 for TTDS. They were compared to other pollutants solubilities (anthracene and carbazole). From the comparison, the following solubility order was established: DBT > anthracene > carbazole > TTDS > NPDS. Furthermore, when comparing these isobutane solubilities to those in propane and CO 2 , they were found to be about one and two magnitude orders larger, respectively. Results obtained were explained considering solvent density, solute vapor pressure, and interactions between solutes and solvent. Peng-Robinson equation was used to correlate the data and a good fitting attained.