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Quantitative analysis of CO 2 hydrate formation in porous media by proton NMR
Author(s) -
Zheng Jianan,
Yang Lei,
Ma Shihui,
Zhao Yuechao,
Yang Mingjun
Publication year - 2020
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16820
Subject(s) - hydrate , clathrate hydrate , chemistry , stoichiometry , porous medium , porosity , mineralogy , chemical engineering , organic chemistry , engineering
Abstract Gas hydrate is a nonstoichiometric crystal compound formed from water and gas. Most nonvisual studies on gas hydrate are unable to detect how much water is converted to hydrates, and thus, the hydrate stoichiometry calculations are inaccurate. This study investigated the CO 2 hydrate formation process in porous media directly and quantitatively. The characteristics of the time‐variable consumption of hydrate formation indicated a two‐stage formation, hydrate enclathration and continuous occupancy. The enclathration stage occurred in the first 20 min of the formation when considerable heat is released. The continuous occupancy stage lasted longer than the hydrate enclathration because the empty cages in previously formed hydrates would also be occupied. The higher formation pressures can accelerate water consumption and increase cage occupancy. The compositions of completely formed CO 2 hydrates at 2.7, 3.0, and 3.3 MPa and 275.15 K were determined as CO 2 ·6.90H 2 O, CO 2 ·6.70H 2 O, and CO 2 ·6.49H 2 O, respectively.