Molecular behavior of hybrid gas hydrate nucleation: separation of soluble H₂S from mixed gas

Abstract

hydrate technology; kinetics; mixed gas; gas separation; separation efficiency; molecular dynamic simulation.

Molecular Simulation on Hydrate Nucleation in the Presence of Initial Ih Ice and Nanobubble

“…After a long induction time, the hydrate structure appeared and the location of the incipient hydrate cluster was close to the nanobubble. This phenomenon is consistent with our previous research …”

Hydrate Nucleation in Water Nanodroplets: Key Factors and Molecular Mechanisms

“…Given that H 2 S is the guest species that is primarily responsible for the initial hydrate cage formation in the current conditions, our further detailed analyses of nucleation mechanisms will focus on pure-H 2 S guest systems. The quantitative analysis of the cage formation, as shown in Figure for sys-L at 250 K, is consistent with previous studies focusing on the formation of gas hydrates in bulk aqueous solutions. ,,,,,, For std cages, in good agreement with previous studies, ,,,,, 5 12 cages usually appear first and tend to predominate the std-cage population, followed by 5 12 6 2 , then 4 1 5 10 6 2 , 5 12 6 3 , and 4 1 5 10 6 3 cage, with 5 12 6 4 and 4 1 5 10 6 4 cages being rare. Moreover, as apparent in Figure , other CC cages also form (see panel A), as the formation of the nucleus proceeds, and singly occupied non-std cages initially predominate in the system but then decrease in proportion. ,, Similar observations of cage populations and proportions were observed in the other systems and conditions explored.…”

“…The ratio of 5 12 /5 12 6 2 in this structure is around 2, which is considerably large than the 1/3 ratio of the unit cell for the sI hydrate structure, which consists of two 5 12 cages and six 5 12 6 2 cages. These cage distributions and the relatively amorphous structure of the hydrate clusters obtained in this study are otherwise very comparable to those of previous bulk-phase studies. ,,,,, Consequently, both sI and sII motifs can be found in the incipient hydrate structure, as shown in Figure B.…”

“…These cage distributions and the relatively amorphous structure of the hydrate clusters obtained in this study are otherwise very comparable to those of previous bulkphase studies. 13,25,26,66,67,85 Consequently, both sI and sII motifs can be found in the incipient hydrate structure, as shown in Figure 8B.…”

“…All molecular models are rigid in this study. The model parameters for all species have been widely used in hydrate-related studies, ,,,− ,,− and more details are provided in Table S1. The temperature was controlled using a Nosé-Hoover thermostat with a time constant of 2.0 ps, and the pressure was controlled using an isotropic Parrinello-Rahman barostat with a time constant of 4.0 ps .…”