Kinetic study of semiclathrate hydrates formed with CO2 in the presence of tetra-n-butyl ammonium bromide and tetra-n-butyl phosphonium bromide. (1st December 2020)

• Record Type: Journal Article
• Authors: Wang, Yan; Zhong, Dong-Liang; Englezos, Peter; Yan, Jin; Ge, Bin-Bin
• Is Part Of: Energy. Volume 212(2020)
• Publication Date: 2020-12-01
• Subjects: Gas hydrates -- Semiclathrate hydrate -- CO2 capture -- Subcooling -- Formation kinetics; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2020.118697
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: The kinetics of semiclathrate hydrates formation with CO2 in the presence of tetra- n -butyl ammonium bromide (TBAB), tetra- n -butyl phosphonium bromide (TBPB), and TBAB + TBPB were investigated. The experiments were conducted at the stoichiometric concentration of TBAB hydrate (2.57 mol%) and three subcoolings (Δ T = 6 K, 9 K, and 12 K) with the initial pressure fixed at 2.8 MPa. It was found that adding TBPB into the TBAB solution can promote hydrate nucleation, and this promotion effect at a lower subcooling (Δ T = 6 K) was stronger compared to that at higher subcoolings (Δ T = 9 K and 12 K). The gas consumption obtained in TBAB, TBPB, and TBAB + TBPB solutions decreased with the increase of subcooling, despite the increase of the rate of hydrate growth. At a given subcooling, gas consumption (CO2 uptake) in TBAB + TBPB solutions was greater than that in TBAB and TBPB solutions, indicating that hydrate formation kinetics and the CO2 storage capacity were improved in the TBAB + TBPB solution. The largest gas consumption was obtained at Δ T = 6 K in the TBAB + TBPB solution, which was 28.7% and 17.2% larger than those obtained in TBAB and TBPB solutions, respectively. Therefore, a mixture of TBAB + TBPB is a promising option to improve the kinetics of semiclathrate hydrate formation with CO2 . Highlights: The images of TBAB, TBPB, and TBAB + TBPB semiclathrate hydrates formed with CO2 were reported. CO2 consumption decreased with the increase of subcooling from 6 to 12 K. The kinetics and CO2 storage capacity of semiclathrare hydrate was improved in TBAB + TBPB solutions. A mixture of TBAB + TBPB is preferable for the design of a hydrate-based gas separation process of CO2 capture.