Evaluation of amino acid L-leucine as a kinetic promoter for CO2 sequestration as hydrate: A kinetic and morphological study
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING(2023)
摘要
Carbon capture and sequestration (CCS) are widely recognized as the most effective technology for reducing CO2 emissions and mitigating global climate change. Hydrate-based CO2 sequestration (HBCS) has emerged as a promising technology for long-term and stable CO2 storage. There are growing interests in employing hydro-phobic amino acids to enhance CO2 hydrate formation kinetics recently. However, there is still a lack of understanding of how amino acids promote CO2 hydrate effectively. In this study, we systematically investigate an environmental-benign kinetic promoter (L-leucine, L-Leu) varying from 0.05 to 2.00 wt% to enhance CO2 hydrate formation at an initial pressure of 5.5 MPa and temperature of 275.2 K. The results show that varying L-Leu concentration has limited effect on tind. The kickoff concentration of L-Leu in promoting CO2 hydrate kinetics is 0.30 wt%. 2.00 wt% L-Leu yields the optimal CO2 gas uptake of 62.17 +/- 0.78 mmol/mol with CO2 partition in the hydrate phase of 66 %. CO2 hydrate forms a layer at the gas-liquid interface and turns to be porous at CL-Leu above 0.30 wt% followed by a significant wall-climbing growth with rapid CO2 gas uptake. L-Leu precipitation occurs at CL-Leu above 1.00 wt% and leads to a decrease in final CO2 gas uptake in repeated experiments at CL-Leu = 2.00 wt%. A mechanism of L-Leu in promoting CO2 hydrate kinetics by adsorption on the surface at CL-Leu above 1.00 wt% is proposed. L-Leu is evaluated to be effective in improving CO2 hydrate kinetics. These findings provide insights for a novel environmental-benign CO2 hydrate kinetic promoter in HBCS application, which requires rapid CO2 hydrate formation and high CO2 gas uptake.
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关键词
CO2 hydrate,Kinetics,L-Leucine,Amino acid,CO2 hydrate morphology,Hydrate-basedCO2 sequestration
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