Abstract
The serious issues of energy shortage and greenhouse gas emission have
led to the development of coalbed methane (CBM) with new commercial
ramifications. A hydrate-based gas separation technology is introduced
to recover methane from CBM. However, the mechanism of hydrate
nucleation needs to be clear for enhancing the hydrate formation rate
and gas recovery efficiency. In this work, we studied, by means of in-situ
Raman spectroscopy, the microscopic characterizations of hydrates
forming in/around the initial gas–liquid interface in the case of CBM
and tetrahydrofuran (THF). It is found that the hydrates accumulate as a
film with horizontal crevices in the initial gas–liquid interface.
These crevices prevent the hydrate film from hindering gas–liquid
contact and limiting hydrate formation. Raman spectroscopy results
illustrate that the initial gas–liquid interface shows a positive impact
on water aggregation, and that the holding gas molecules stay stably
with the water molecules. Nitrogen molecules encage into the cavities of
THF hydrates along with methane molecules. For the interface and
hydrate layer, water aggregation is evaluated by the Raman intensity
ratio of hydrogen-bonded water (BW) and free water (FW) without any
hydrogen bonds, abbreviated as IBW/IFW. A value of IBW/IFW higher than 0.85 can symbolize the occurrence of hydrate nucleation in the interface and help assess the hydrate formation.
Original language | English |
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Journal | ACS Omega |
Volume | 6 |
Issue number | 51 |
Pages (from-to) | 35467–35475 |
DOIs | |
Publication status | Published - 2021 |
Keywords
- Gas hydrate
- Tetrahydrofuran
- Coalbed methane
- Interface
- In-situ Raman