Assessing Viability of Soybean Oils to Remove Hydrogen Sulfide from Natural Gas

Abstract

A combination of in silico and benchtop experiments was implemented to assess how soybean oils could remove hydrogen sulfide (H₂S)—a corrosive and toxic impurity—from natural gas. The development of hydraulic fracturing (i.e., fracking) in the United States has increased both the use of and interest in natural gas, but natural gas extracted via fracking is often highly concentrated with H₂S. The present work is a proof-of-concept study to evaluate the viability of conventional and high-oleic soybean oils to extract H₂S. The conductor-like screening model for real solvents (COSMO-RS) was used to predict the partition coefficient (Kₘₒd) of the target molecule (H₂S) between the liquid (soybean oil) and gas phases. These predicted Kₘₒd values were below 0.0005 at temperatures ranging from 10 to 100 °C at atmospheric pressure; Kₘₒd values approaching 0 are indicative of near-complete removal of the H₂S from the gas. Experiments showed Kₑₓₚ values below 0.2 in biphasic gas/oil systems at residence times <15 min. Isotherm models demonstrated the saturation limits of the soybean oils as compared with water and heptane. This proof-of-concept study employs a novel use of soybean oils as biosolvents for sweetening natural gas, and they have potential for high-impact application in soybean and natural gas industries.