COSMO-RS: An ionic liquid prescreening tool for gas hydrate mitigation

Abstract

Recently ionic liquids (ILs) are introduced as novel dual function gas hydrate inhibitors. However, no desired gas hydrate inhibition has been reported due to poor IL selection and/or tuning method. Trial & error as well as selection based on existing literature are the methods currently employed for selecting and/or tuning ILs. These methods are probabilistic, time consuming, expensive and may not result in selecting high performance ILs for gas hydrate mitigation. In this work, COSMO-RS is considered as a prescreening tool of ILs for gas hydrate mitigation by predicting the hydrogen bonding energies (EHB) of studied IL inhibitors and comparing the predicted EHB to the depression temperature (Ŧ) and induction time. Results show that, predicted EHB and chain length of ILs strongly relate and significantly affect the gas hydrate inhibition depression temperature but correlate moderately (R=0.70) with average induction time in literature. It is deduced from the results that, Ŧ increases with increasing IL EHB and/or decreases with increasing chain length. However, the cation–anion pairing of ILs also affects IL gas hydrate inhibition performance. Furthermore, a visual and better understanding of IL/water behavior for gas hydrate inhibition in terms of hydrogen bond donor and acceptor interaction analysis is also presented by determining the sigma profile and sigma potential of studied IL cations and anions used for gas hydrate mitigation for easy IL selection.