Mini Review on Application and Outlook of In Situ Raman Spectrometry in Gas Hydrate Research

Abstract

Natural gas hydrates have drawn much attention as a result of their considerable reserves, clean energy, and global distribution. Some new technologies, such as energy storage and transportation, gas separation, and desalination, have been developed via forming hydrates. The structure, composition, and cage occupancy of gas hydrates and kinetics of hydrate formation and dissociation are crucial in flow assurance and the applications mentioned above. In view of its dependable, efficient, and non-destructive features, in situ Raman spectroscopy is a typical and popular measuring technique in gas hydrates. In this mini review, the application and microscopic characterization using in situ Raman spectroscopy in the gas hydrate field were reviewed, including how to use Raman spectroscopy to identify the structure and molar composition of hydrate and how to offer in situ information on the kinetics of formation, decomposition, replacement, and molecular diffusion at the molecular level. The challenges and perspectives on future studies of in situ Raman spectrometry have been proposed.

Abnormal structural transformation of tetra-n-butyl ammonium chloride + Xe clathrates and its significance for clathrate-based Xe capture and storage

“…Raman spectroscopy is a non-destructive analytical method that allows for the examination of the structure and guest information of clathrates by observing the vibration modes of guest molecules. 53 However, because Xe is a monoatomic molecule, it cannot be detected by Raman spectroscopy. 17 In this study, the lattice vibration mode (O–O vibration mode) and O–H vibration mode of water were thus measured via in situ Raman spectroscopy to investigate the structural transition and formation of sI in the TBAC + Xe (3.3 mol%) + water system, according to the temperature changes at a constant pressure.…”

Comprehensive Review and Perspectives of CO2 Hydrate Storage in Subseafloor Saline Sediments: Formation, Stability, and Optimization Strategies

“…Specifically, using in situ measurements with these spectroscopic techniques offers real-time monitoring of hydrate formation and decomposition, which is a significant advancement over traditional methods. 148 Furthermore, the combination of Raman and FTIR techniques allows researchers to gather a more holistic understanding of both vibrational and rotational modes within a hydrate structure, something not possible with either technique alone. This dual-analysis approach enhances the understanding of the gas hydrate formation and the interactions within the nanostructured encapsulation.…”

Environmentally Sustainable Large-Scale CO2 Sequestration through Hydrates in Offshore Basins: Ab Initio Comprehensive Analysis of Subsea Parameters and Economic Perspective

“…Researchers have been working extensively to solve these mass transfer and thermodynamics barriers in the past few years using different additives. − Environmentally friendly additives such as biodegradable surfactants, amino acids, ionic liquids and natural nanoparticles now open up newer avenues among the research community. The in situ Raman spectroscopy, X-ray imaging, and molecular simulations help researchers to fundamentally understand CO 2 hydrates in sequestration conditions. − The long-term stability of hydrate, mechanical characteristics of hydrate-bearing sediments, and effect of sequestration conditions on hydrate formation and dissociation can be analyzed using the aforesaid techniques. Economic challenges such as carbon pricing, capital expenditure, unpredictable environmental policies and lack of transition will make large-scale storage in oceans difficult for both industries and government.…”