Polyethylene glycol-based deep eutectic solvents as a novel agent for natural gas sweetening.

Jiyad N Aldawsari,Inas M Alnashef,Idowu A Adeyemi,Mohamed K Hadj-Kali,Emad Ali,Abdelbasset Bessadok-Jemai,Esmaiel Jabbari

doi:10.1371/journal.pone.0239493

Abstract

Deep eutectic solvents (DESs) have received significant attention as potential extracting agents in recent years due to their favorable characteristics including low cost, easy preparation and environmentally safe starting materials. Experimentally screening for highly efficient DESs meeting various requirements for natural gas sweetening remains a challenging task. Thus, an extensive database of estimated Henry’s law constants (Hi) and solubilities (xi) of CO2 in 170 different DESs at 25°C has been constructed using the COSMO-RS method to select potential DESs. Based on the COSMO-RS study, three DESs, namely tetrabutylammonium bromide (TBAB)+polyethylene glycol (PEG-8) (on a molar basis 1:4), TBAB+octanoic acid (OCT) (1:4), and methyltriphenylphosphonium bromide (MTPB)+PEG-8 (1:10), were chosen for further experimentation up to 2 bar at 25°C using a vapor-liquid equilibria (VLE) apparatus. Reliable thermophysical properties were determined experimentally, and a detailed equilibrium-based model was developed for one of the glycol-based DESs (i.e., TBAB+PEG-8 (1:4)). This information is an essential prerequisite for carrying out process simulations of natural gas sweetening plants using ASPEN PLUS. The simulation results for the proposed DES were compared to those of monoethylene glycol (MEG). Here, we find that the aqueous TBAB+PEG-8 (1:4) solvent shows ~60% lower total energy consumption and higher CO2 removal when compared to those using the MEG solvent.

Highlights

The global climate has witnessed severe changes in the last decade primarily due to greenhouse gases released by the combustion of coal, oil, and natural gas (NG) [1]
To inspect the accuracy of COSMO-RS predictions of the solubilities of carbon dioxide gas, 58 different types of Deep eutectic solvents (DESs) (S10 Table in S1 File) representing different types of salts, hydrogen bond donors (HBDs), and molar structures from the open literature as solvents, and CO2 was chosen as the model gas for evaluation
Molecular and process simulations were developed in Polyethylene glycol-based deep eutectic solvent as a novel agent for natural gas sweetening order to screen, design and evaluate process parameters for the system of carbon capture from the sour gas

Summary

Introduction

The global climate has witnessed severe changes in the last decade primarily due to greenhouse gases released by the combustion of coal, oil, and natural gas (NG) [1]. The energyrelated CO2 emissions are expected to increase during the decade according to the World Energy Outlook (WEO) [4]. This outlook predicts an accelerated increase in the consumption of NG as an alternative, less-polluting fuel based on emission requirements. Polyethylene glycol-based deep eutectic solvent as a novel agent for natural gas sweetening established by environmental regulatory agencies [4, 5]. There is an urgent need for technologies that can better utilize NG and improve the process to meet regulatory standards

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Conclusion