Viability of Clathrate Hydrates as CO₂ Capturing Agents: A Theoretical Study

Abstract

Capture and sequestration of green house gas CO(2) is a major challenge for scientists and identifying right materials for this purpose is a task of outstanding importance. Through reliable computational studies, we have demonstrated that the clathrate cages (5(12), 4(3)5(6)6(3), 5(12)6(2), 5(12)6(4), and 5(12)6(8)) have a great potential to store CO(2). All the considered clathrates and their CO(2) inclusion complexes are optimized at B3LYP/6-31G(d) level of theory. The impact of DFT-D, M05-2X, and MP2 functionals on interaction energy were tested using various basis sets. Although different functionals and basis sets show variation in absolute IE values, the trend is consistent and does not depend on the level of the calculations. Dispersion was found important for these complexes and DFT-D shows comparable IE values with MP2 functional. The optimum and maximum cage occupancy for all the considered cages were tested on the basis of quantum chemical calculations. The maximum cage occupancy for all five considered cages (5(12), 4(3)5(6)6(3), 5(12)6(2), 5(12)6(4), and 5(12)6(8)) is one, two, two, two, and seven CO(2) molecules, respectively, and the optimum cage occupancy is one, one, one, two, and five CO(2) molecules, respectively. Thus, 5(12)6(8) cages can host up to 7 CO(2) molecules, resulting in about 32 wt %, which makes them highly promising materials.

Replacement micro-mechanism of CH4 hydrate by N2/CO2 mixture revealed by ab initio studies

“…However, these methods are based on the decomposition of the hydrates by external stimulations, which may lead to geological disasters such as earthquakes and submarine landslides [11][12][13][14]. Alternatively, the CO 2 replacement technique has been widely studied as an economically viable and environmentally friendly production method [15][16][17][18], which also provides a way to store CO 2 for a long term [19,20]. Although the replacement reaction will significantly depend on the experimental conditions [15,21], experimental studies have suggested that at least 60% of CH 4 can be recoverable through the direct injection of CO 2 into CH 4 hydrate layers [22][23][24].…”

C–C Stretching Raman Spectra and Stabilities of Hydrocarbon Molecules in Natural Gas Hydrates: A Quantum Chemical Study

“…49 Molecular quantum-chemical computations, where the guest molecules and the cages from the hydrate structures are represented by cluster models, is an efficient way to study host-guest interactions. 30-31, 40-41, 44, 49-52 However, in earlier studies it has been seen that unreasonable deformations of the models of water cavities in some cases occur, 53 and some water cage structures have been optimized with the oxygen atoms fixed. 54 This behavior can be avoided by employing a proper low-energy H-bond network.…”

Structure and stability of multiply occupied methane clathrate hydrates

“…Clathrate hydrates have attracted great attention, because they can serve as a possible source of energy [6][7][8] and as a potential medium for gas storage and transportation [9][10][11]. Therefore, an improved understanding of their structural stability is important for many technology applications, e.g., estimating potential effects of hydrates on global climate change [5,12], preventing hydrate blockages in pipelines [13][14], and promoting hydrate formation in gas storage [15][16][17].…”