Phase Transfer‐Catalyzed Fast CO<sub>2</sub> Absorption by MgO‐Based Absorbents with High Cycling Capacity

Zhang, Keling; Li, Xiaohong Shari; Li, Wei‐Zhen; Rohatgi, Aashish; Duan, Yuhua; Singh, Prabhakar P.; Li, Liyu; King, David L.

doi:10.1002/admi.201400030

Cited by 104 publications

(186 citation statements)

References 18 publications

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“…(1), which exhibits the dolomite covered by the molten NaNO 3 during its activation. The previous investigation has indicated that the molten NaNO 3 provides a liquid channel and facilitates the diffusion of ions in the solid reaction . However, the decomposition of pure NaNO 3 and the decomposition of NaNO 3 over 0.20Na‐SiO 2 have indicated that the dispersive NaNO 3 and the accumulated NaNO 3 could result in different diffusion rates of ions.…”

Section: Resultsmentioning

confidence: 99%

Affecting mechanism of activation conditions on the performance of NaNO₃‐modified dolomite for CO₂ capture

Yang

Zhao

Xiao

2015

Asia-Pacific J Chem Eng

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The affecting mechanism of activation conditions on the performance of NaNO 3 -modified dolomites for CO 2 capture was conducted combined with the activation tests and the CO 2 absorption tests. The weight loss during activation was determined by the combined effects of the NaNO 3 content, activation temperature, and activation atmosphere, for their combined effects on the ion diffusion. Moreover, the greater weight loss during activation did not elicit a corresponding increase in CO 2 absorption ability of the activated absorbents. CO 2 absorption activity tests indicated that the sample 0.20Na-dol activated at 500°C in N 2 showed the best cyclic CO 2 absorption ability. The underlying mechanism was then analyzed based on the results of the Brunauer-Emmett-Teller, X-ray diffraction, and Raman analysis of the absorbents. The results indicated that the different CO 2 absorption abilities might be due to the two kinds of molecular arrangements between the MgO and CaCO 3 grains obtained during activation.

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Section: Resultsmentioning

confidence: 99%

Affecting mechanism of activation conditions on the performance of NaNO₃‐modified dolomite for CO₂ capture

Yang

Zhao

Xiao

2015

Asia-Pacific J Chem Eng

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“…Additional advantages with MgO include high specific surface area and high pore volume [12][13][14]. The conversion of MgO to MgCO 3 is believed to be limited kinetically, rather than thermodynamically [15,16], and the intrinsically high lattice enthalpy restrains MgO from achieving a fast reaction with CO 2 [17]; moreover, the rigid carbonate "shell" would inhibit CO 2 molecules from accessing more deeply into the MgO structure [18]. These factors mean that MgO has an extremely low capacity of 0.24 mmol•g -1 at 200 °C using the unmodified material [15].…”

Section: ͳǥmentioning

confidence: 99%

“…A MgO• KNO 3 composite exhibits a maximum capacity of 3.2 mmol•g -1 at 325 °C in a pure CO 2 stream [27]. Zhang et al synthesized a composite of MgO and NaNO 3 (80:20 by mass) via ballmilling, with the observation that the CO 2 sorption rate was greatly enhanced, leading to a maximum capacity of 15 mmol•g -1 at 375 °C and 1 bar of CO 2 [18]. A mesoporous MgO prepared using a supercritical drying process was found to be promoted by double sodium salts (NaNO 3 and Na 2 CO 3 ) and exhibited a sorption capacity of 12.7 mmol•g -1 at 325 °C in a dry CO 2 stream and 11.5 mmol•g -1 at 275 °C in a wet CO 2 stream [14].…”

Section: ͳǥmentioning

confidence: 99%

“…The melting point for NaNO 3 and NaNO 2 are 308 and 271 °C, respectively [30]. It has been concluded that alkali metal nitrates in molten/pre-molten state can serve as an effective phase transfer catalyst (PTC) promoting the gas-solid reaction between CO 2 and MgO [18]. A sorbent with higher capacity and faster kinetics is still highly probable, since the maximum MgO conversion in the open literature is < 85% [14,16,28,29,31].…”

Section: ͳǥmentioning

confidence: 99%

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Mesoporous MgO promoted with NaNO3/NaNO2 for rapid and high-capacity CO2 capture at moderate temperatures

Zhao

et al. 2018

Chemical Engineering Journal

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A series of mesoporous MgO samples with different morphologies were synthesized through a simple hydrothermal treatment and NaNO 3 /NaNO 2 were used as promoters to enhance CO 2 capture capacity at an intermediate temperature range (200-400 °C). The effects of hydrothermal solution pH and content of promoters were examined to determine the optimal synthesis conditions. The influence of operational temperatures, CO 2 partial pressure, and performance over repeated cycles was investigated and the reaction mechanism was discussed. The mesoporous MgO promoted by NaNO 3 /NaNO 2 exhibited a CO 2 capture capacity as high as 19.8 mmol•g-1 at 350 °C in the presence of 0.85 bar of CO 2 within only 50 min. A "three-stage" reaction process was proposed based on a detailed sorption kinetics study, namely Stage I: initiating interactions between CO 2 and exposed MgO; Stage II: generation and accumulation of Mg 2+ and CO 3 2-; and Stage III: fast carbonation. Gradual deterioration of sorbents was found over the first 5 cycles followed by stable regenerability in the 5-15 th cycles. A kinetic study of the 15 th cycle suggests that the deactivation of sorbents inhibited the accumulation of Mg 2+ and CO 3 2in Stage II and suppressed the carbonation in Stage III. A range of characterizations were undertaken revealing the morphology and structure of both fresh and regenerated sorbents. The results confirmed that, other than the sintering effect due to phase transition, the transformation of MgO skeleton is also an important contributor to the gradual deactivation of the sorbents over the first 5 cycles. More severe sintering effect under harsh decarbonation conditions suppressed the stability of the sorbents over cycles.

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“…Xiao et al 11 reported that a K-promoted double salt MgO sorbent had the highest sorption capacity, 8.6 wt% in a 100% CO 2 environment. 14 Liu et al 15 developed a Cs-doped MgO based sorbent using the wet impregnation method with a maximum sorption capacity of 8.3 wt% at 300 1C. During multiple cycle tests, the CO 2 sorption capacity was maintained at 15 wt% in a 100% CO 2 environment.…”

Section: Introductionmentioning

confidence: 99%

Promoting alkali and alkaline-earth metals on MgO for enhancing CO₂capture by first-principles calculations

Kim

Han

Lee

et al. 2014

Phys. Chem. Chem. Phys.

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Developing next-generation solid sorbents to improve the economy of pre- and post-combustion carbon capture processes has been challenging for many researchers. Magnesium oxide (MgO) is a promising sorbent because of its moderate sorption-desorption temperature and low heat of sorption. However, its low sorption capacity and thermal instability need to be improved. Various metal-promoted MgO sorbents have been experimentally developed to enhance the CO2 sorption capacities. Nevertheless, rigorous computational studies to screen an optimal metal promoter have been limited to date. We conducted first-principles calculations to select metal promoters of MgO sorbents. Five alkali (Li-, Na-, K-, Rb-, and Cs-) and 4 alkaline earth metals (Be-, Ca-, Sr-, and Ba-) were chosen as a set of promoters. Compared with the CO2 adsorption energy on pure MgO, the adsorption energy on the metal-promoted MgO sorbents is higher, except for the Na-promoter, which indicates that metal promotion on MgO is an efficient approach to enhance the sorption capacities. Based on the stabilized binding of promoters on the MgO surface and the regenerability of sorbents, Li, Ca, and Sr were identified as adequate promoters among the 9 metals on the basis of PW91/GGA augmented with DFT+D2. The adsorption energies of CO2 on metal-promoted MgO sorbents for Li, Ca, and Sr atoms are -1.13, -1.68, and -1.48 eV, respectively.

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Phase Transfer‐Catalyzed Fast CO₂ Absorption by MgO‐Based Absorbents with High Cycling Capacity

Cited by 104 publications

References 18 publications

Affecting mechanism of activation conditions on the performance of NaNO₃‐modified dolomite for CO₂ capture

Affecting mechanism of activation conditions on the performance of NaNO₃‐modified dolomite for CO₂ capture

Mesoporous MgO promoted with NaNO3/NaNO2 for rapid and high-capacity CO2 capture at moderate temperatures

Promoting alkali and alkaline-earth metals on MgO for enhancing CO₂capture by first-principles calculations

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Phase Transfer‐Catalyzed Fast CO2 Absorption by MgO‐Based Absorbents with High Cycling Capacity

Cited by 104 publications

References 18 publications

Affecting mechanism of activation conditions on the performance of NaNO3‐modified dolomite for CO2 capture

Affecting mechanism of activation conditions on the performance of NaNO3‐modified dolomite for CO2 capture

Mesoporous MgO promoted with NaNO3/NaNO2 for rapid and high-capacity CO2 capture at moderate temperatures

Promoting alkali and alkaline-earth metals on MgO for enhancing CO2capture by first-principles calculations

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Phase Transfer‐Catalyzed Fast CO₂ Absorption by MgO‐Based Absorbents with High Cycling Capacity

Affecting mechanism of activation conditions on the performance of NaNO₃‐modified dolomite for CO₂ capture

Affecting mechanism of activation conditions on the performance of NaNO₃‐modified dolomite for CO₂ capture

Promoting alkali and alkaline-earth metals on MgO for enhancing CO₂capture by first-principles calculations