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Effect of Organic Matter on CO2 Hydrate Phase Equilibrium in Phyllosilicate Suspensions
journal contribution
posted on 2014-06-17, 00:00 authored by Taehyung Park, Daeseung Kyung, Woojin LeeIn
this study, we examined various CO2 hydrate phase equilibria
under diverse, heterogeneous conditions, to provide basic knowledge
for successful ocean CO2 sequestration in offshore marine
sediments. We investigated the effect of geochemical factors on CO2 hydrate phase equilibrium. The three-phase (liquid–hydrate–vapor)
equilibrium of CO2 hydrate in the presence of (i) organic
matter (glycine, glucose, and urea), (ii) phyllosilicates [illite,
kaolinite, and Na-montmorillonite (Na-MMT)], and (iii) mixtures of
them was measured in the ranges of 274.5–277.0 K and 14–22
bar. Organic matter inhibited the phase equilibrium of CO2 hydrate by association with water molecules. The inhibition effect
decreased in the order: urea < glycine < glucose. Illite and
kaolinite (unexpandable clays) barely affected the CO2 hydrate
phase equilibrium, while Na-MMT (expandable clay) affected the phase
equilibrium because of its interlayer cations. The CO2 hydrate
equilibrium conditions, in the illite and kaolinite suspensions with
organic matter, were very similar to those in the aqueous organic
matter solutions. However, the equilibrium condition in the Na-MMT
suspension with organic matter changed because of reduction of its
inhibition effect by intercalated organic matter associated with cations
in the Na-MMT interlayer.