CO 2 capture and regeneration properties of MgO-based sorbents promoted with alkali metal nitrates at high pressure for the sorption enhanced water gas shift process

Hwang, Byung Wook; Lim, Jeong-Hyeon; Chae, Ho Jin; Ryu, Ho-Jung; Lee, DoYeon; Lee, Joong Beom; Kim, Hana; Lee, Soo Chool; Kim, Jae Chang

doi:10.1016/j.psep.2018.02.008

Cited by 41 publications

(13 citation statements)

References 30 publications

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“…Harada et al 23 and other researchers 20,32,33 have argued that the molten layer of nitrates acts primarily as a diffusion medium for CO2, allowing for an improved contact between MgO and the gaseous reactant. While carbonation on bare MgO produces a rigid, monodentate carbonate layer impermeable for gaseous reactants, in nitrate-promoted MgO the molten layer dissolves CO2 and, owing to the high concentration of oxygen (O 2-) ions in the nitrate melt, carbonate (CO3 2− ) ions form rapidly 23 leading in turn to the fast formation of MgCO3.…”

Section: Introductionmentioning

confidence: 99%

CO₂ Uptake and Cyclic Stability of MgO-Based CO₂ Sorbents Promoted with Alkali Metal Nitrates and Their Eutectic Mixtures

Pozzo

Armutlulu

Rekhtina

et al. 2019

ACS Appl. Energy Mater.

114

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CO2 capture and storage (CCS) is a technological solution to stabilize or even reduce the atmospheric concentration of the greenhouse gas CO2, to mitigate climate change. In this context, MgO is a promising solid CO2 sorbent, as the energy penalty sorbent regeneration is comparatively small, but it requires the addition of promoters, typically alkali metal nitrates, to yield acceptable kinetics. Under operating conditions, the promoters are in a molten state. The main objectives of this work are (i) to assess experimentally the validity of different reaction mechanisms for the CO2 uptake of promoted MgO that are currently debated in literature and (ii) to elucidate the processes that lead to sorbent deactivation. Our experimental results support the mechanism in which the dissolution of MgO in the molten nitrate promoter is the rate-limiting step for carbonation. We were able to establish a direct correlation between the solubility of MgO in the promoter and the initial rate of carbonation. In addition, a systematic study of a large number of promoter compositions (mixtures of LiNO3, NaNO3, KNO3) indicate that promoters with a lower melting point exhibit higher CO2 uptakes, presumably due to their lower viscosity and, thus, higher ion mobility at a given temperature. Concerning the cyclic stability of promoted MgO, a decay of its CO2 uptake with number of carbonation/calcination cycles is ascribed only partially to sintering. Instead, the surface migration of the promoter was identified as an at least equally relevant deactivation mechanism. Importantly, it was also found that the CO2 uptake of the deactivated sorbent can be restored to a large extent with a simple hydration step.

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Section: Introductionmentioning

confidence: 99%

CO₂ Uptake and Cyclic Stability of MgO-Based CO₂ Sorbents Promoted with Alkali Metal Nitrates and Their Eutectic Mixtures

Pozzo

Armutlulu

Rekhtina

et al. 2019

ACS Appl. Energy Mater.

114

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“…However, these modified MgO particles with increased specific surface area have achieved only limited success [20]. Increasing the pressure may increase the reaction rate, but this is problematic for practical applications [21]. Alternatively, the use of steam can improve the CO 2 sorption rates of MgO due to the formation of Mg(OH) 2 , [22].…”

Section: Introductionmentioning

confidence: 99%

Structural and kinetic analysis of CO2 sorption on NaNO2-promoted MgO at moderate temperatures

Wang

Zhao

Clough

et al. 2019

Chemical Engineering Journal

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Alkali metal nitrate-/nitrite-promoted MgO sorbents are promising candidates for intermediate-temperature (200-500 °C) CO 2 capture. However, the structure-performance relationship and kinetic characteristics of NaNO 2-promoted MgO remain unclear. Here the effects of physical-chemical properties on the CO 2 sorption performance of NaNO 2-promoted MgO and the sorption kinetics were comprehensively studied to elucidate the detailed role of NaNO 2. Samples were characterized by X-ray diffraction, scanning electron microscopy, N 2 adsorption, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The sorption kinetics were obtained by isothermal thermogravimetry and elucidated using a double exponential model. Compared with pure MgO and NaNO 3-promoted MgO, NaNO 2-modified MgO had a lower initial sorption temperature and a unique bimodal sorption characteristic. Characterizations results revealed that such bimodal sorption

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“…Therefore, future studies of materials with well-defined pore structures would be very valuable to delineate accurately the effect of promoters while excluding effects due to differences in the pore structure and/or surface area. A second hypothesis concerning the carbonation mechanism of promoted MgO was proposed by Harada et al [133] and others [415], [432]. Here, it is argued that the molten promoter layer impedes the formation of a unidentate carbonate layer, which is CO2-impermeable, on the MgO surface.…”

Section: Mgo-based Sorbentsmentioning

confidence: 93%

CO2 capture using solid sorbents: Fundamental aspects, mechanistic insights and recent advances

Dunstan¹,

Donat²,

Bork³

et al. 2021

Preprint

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Carbon dioxide capture and mitigation forms a key part of the technological response to combat climate change and reduce CO2 emissions. Solid materials capable of reversibly absorbing CO2 have been the focus of intense research for the past two decades, promising stability and low energy costs to implement and operate compared to the more widely used liquid amines. In this Review, we explore the fundamental aspects underpinning solid CO2 sorbents based on alkali and alkaline earth metal oxides operating at mid- to high temperature: how their structure, chemical composition and morphology impact their performance and long-term use. Various optimization strategies are outlined to improve upon the most promising materials, and we combine recent advances across disparate scientific disciplines including materials discovery, synthesis, and in situ characterization to present a coherent understanding of the mechanisms of CO2 absorption both at surfaces and within solid materials.

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CO 2 capture and regeneration properties of MgO-based sorbents promoted with alkali metal nitrates at high pressure for the sorption enhanced water gas shift process

Cited by 41 publications

References 30 publications

CO₂ Uptake and Cyclic Stability of MgO-Based CO₂ Sorbents Promoted with Alkali Metal Nitrates and Their Eutectic Mixtures

CO₂ Uptake and Cyclic Stability of MgO-Based CO₂ Sorbents Promoted with Alkali Metal Nitrates and Their Eutectic Mixtures

Structural and kinetic analysis of CO2 sorption on NaNO2-promoted MgO at moderate temperatures

CO2 capture using solid sorbents: Fundamental aspects, mechanistic insights and recent advances

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CO 2 capture and regeneration properties of MgO-based sorbents promoted with alkali metal nitrates at high pressure for the sorption enhanced water gas shift process

Cited by 41 publications

References 30 publications

CO2 Uptake and Cyclic Stability of MgO-Based CO2 Sorbents Promoted with Alkali Metal Nitrates and Their Eutectic Mixtures

CO2 Uptake and Cyclic Stability of MgO-Based CO2 Sorbents Promoted with Alkali Metal Nitrates and Their Eutectic Mixtures

Structural and kinetic analysis of CO2 sorption on NaNO2-promoted MgO at moderate temperatures

CO2 capture using solid sorbents: Fundamental aspects, mechanistic insights and recent advances

Contact Info

Product

Resources

About

CO₂ Uptake and Cyclic Stability of MgO-Based CO₂ Sorbents Promoted with Alkali Metal Nitrates and Their Eutectic Mixtures

CO₂ Uptake and Cyclic Stability of MgO-Based CO₂ Sorbents Promoted with Alkali Metal Nitrates and Their Eutectic Mixtures