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Rapid CO₂ capture-to-mineralisation in scalable reactor

Lookup NU author(s): Ning ZhangORCiD, Professor Lidija Siller

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This is the authors' accepted manuscript of an article that has been published in its final definitive form by Royal Society of Chemistry, 2020.

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Abstract

CO₂ mineralisation is a process that can convert CO₂ into solid carbonates for permanent storage. Our multiphase flow process uses alkaline brine solution to capture gaseous CO₂ and form carbonate particles in a continuous tubular reactor. In this research, monoethanolamine (MEA) solution is utilised to synergistically boost CO₂ solubility in the brine while neutralising the acidification caused by brine chloride ions left in solution following precipitation of alkaline earth metals. In this study, relatively low concentrations of MEA, ranging from 0.036 to 0.33 M, were investigated over a temperature range from 303 K to 323 K; these are significantly milder conditions than those used in traditional CO₂ capture processes with MEA, which contributes to low energy demand of the process. Short residence time, in the order of few minutes, is made possible by the high gas-liquid surface area for mass transfer, and the rapid kinetics of aqueous phase carbonation reactions. Nickel nanoparticles (NiNPs) were tested as a catalytic additive to further accelerate the rate limiting step (CO₂ dissolution), by accelerating the CO₂ hydration reaction. Experimental results were used to develop and calibrate a one-dimensional time-dependent plug-flow model that incorporates transport and chemical speciation equations. The model is thus capable of predicting aqueous species and solid carbonate concentration, fluid pressure and gas slug size as a function of reactor length. These in turn yield carbonation conversion, total pressure drop, and provide mechanistic insight into the reactor processes that can be used for scale-up. The experimental and modelled results showed a good agreement for a wide range of conditions tested: effects of temperature, brine composition, MEA concentration, and gas-liquid flow ratio. Under optimum conditions, it was found that the reactor could achieve full conversion of calcium from the brine and CO₂ from the gas phase, thus proving to be an efficient process with high atom economy.

Publication metadata

Author(s): Zhang N, Santos RM, Siller L

Publication type: Article

Publication status: Published

Journal: Reaction Chemistry and Engineering

Year: 2020

Volume: 5

Issue: 3

Pages: 473-484

Print publication date: 01/03/2020

Online publication date: 21/01/2020

Acceptance date: 14/01/2020

Date deposited: 09/02/2020

ISSN (electronic): 2058-9883

Publisher: Royal Society of Chemistry

URL: https://doi.org/10.1039/c9re00446g

DOI: 10.1039/c9re00446g

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