Experimental study of a hydrophobic solvent for natural gas sweetening based on the solubility and selectivity for light hydrocarbons (CH4, C2H6) and acid gases (CO2 and H2S) at 298–353 K

Abstract

Henry’s constants of H2S, CO2, CH4, and C2H6 in a hydrophobic solvent (HPS) consisting of 2-fluorophenethylamine (2-FPEA)/4-methoxy phenol (MePhOH)/a mixture of polyethylene glycol dibutyl ether (Genosorb 1843) were determined to evaluate the potential use of the HPS for natural gas sweetening applications. In addition, the Henry’s constants of H2S, CO2, CH4, and C2H6 in an industrial solvent, promoted methyldiethanolamine (MDEA)/piperazine (PZ)/water, were also reported in this work. The gas solubilities were evaluated in the temperature range 298.15–353.15 K. The Henry’s constant of N2O in the HPS was also determined and used to differentiate the physical absorption of acid gases from the chemical absorption. The temperature-dependent Henry’s constant correlations of these gases were developed and used to determine the separation performance of the HPS in a simple absorber process simulation. The simulation results suggest that HPS can remove acid contaminants and achieve the targeted quality of natural gas for liquid natural gas (LNG) production. The HPS exhibits rather high CH4 and C2H6 absorption and, consequently, has low acid gas selectivity compared to the commercially available physical solvent. The acid gas selectivity can be optimized with the inclusion of a limited quantity of hydrophilic component to enhance acid gas solubility while still minimizing hydrocarbon solubility.