The effect of synergistic amino acids-ionic liquids in methane hydrate inhibition by COSMO-RS application

Gas hydrates solid deposition in pipelines has caused critical flow assurance issues especially in the transportation of hydrocarbons. The gas hydrates occurrence can be mitigated via mechanical and chemical methods; however, the latter are found to be more feasible. Ionic liquids have received considerable attention due to their dual function capabilities in the inhibition of hydrates. Amino adds have also demonstrated potentials as hydrate inhibitors due to their inherent zwitterion interaction characteristics. With these attributes demonstrated by both ionic liquids and amino acids, their synergistic performances in the prevention of hydrate formations were investigated in this research. Due to their unlimited number of cationic and anionic combinations, experimental testing is time consuming and associated with great cost. Hence, a pre-screening approach is applied to study the potential of these synergistic formulations to perform as hydrate inhibitors using COSMO-RS software. There are 91 synergistic amino adds-ionic liquids (AACILs) with combinations of ionic liquids as cations and amino acids as anions were studied in this research. However only the five most performing AACILs are highlighted in this manuscript. Choline aspartate was found to be the most performing synergistic AACIL due to its hydroxyl chain and hydrogen bonding affinity to water molecules, by showing the highest hydrogen bonding energy, EHB of -44.13 kcal/mol. When each cation was tested individually, it was revealed that choline achieved the highest Etas (-5554 kcal/mol). while tetrabutyl ammonium showed the lowest Etta (-0.278 kcal/mol). Besides that, aspartate with Elm of -38.60 kcal/mol became the most performing anion while serinate with E-HB of -2738 kcal/mol was taken as the least performing anion. The outcome of this research has provided critical understanding on the potential of AACILs as an alternative to the conventional methods of hydrate inhibition. (C) 2020 Elsevier B.V. All rights reserved.