Development of MgMnO3-δ as an oxygen carrier material for chemical looping combustion

Hwang, Jong Ha; Baek, Jeom-In; Ryu, Ho Jung; Sohn, Jung Min; Lee, Kitae

doi:10.1016/j.fuel.2018.05.111

Cited by 19 publications

(3 citation statements)

References 24 publications

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“…Zhu et al showed that oxygen vacancies introduced by Ce doping contributed to the reactivity of syngas generation from CH 4 via hexaaluminate OC. Furthermore, the defective sites of perovskites were shown to serve as active sites for the breakage of H–O to generate H 2 in the steam methane re-forming process. , In terms of surface adsorption, Lee et al reported that the surface adsorption of CH 4 would be promoted by the oxygen vacancies on the surface of gadolinium-doped ceria (GDC). Zhao et al focused on Cu-based OCs and showed that the defective sites significantly benefit the sulfur-sensitive CuO adsorption and reaction with gaseous COS (the main sulfur-containing species in the in situ gasification chemical looping combustion process) .…”

Section: Introductionmentioning

confidence: 99%

Insights into Syngas Combustion on a Defective NiO Surface for Chemical Looping Combustion: Oxygen Migration and Vacancy Effects

2020

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A thorough theoretical analysis of vacancy effects on syngas combustion was conducted for the chemical looping combustion (CLC) process using NiO as an oxygen carrier (OC). A density functional theory (DFT) analysis was conducted to provide new insights into the effects of surface vacancies on OC behavior such as O migration, syngas adsorption, and syngas oxidation. The results showed that the vacancies are expected to promote the subsequent oxidation reactions, which might come from the lower state energies of the reactants, the syngas adsorption configurations on the defective surface. Furthermore, the proposed reaction mechanisms showed that the presence of the defective sites benefited the syngas oxidation by reducing the energy barriers of the CO and H2 oxidation reactions. In particular, H2 oxidation changed from a 3-step process on a perfect surface (i.e., without vacancies) to a 2-step process on a defective surface. Moreover, the CO oxidation reaction was shown to dominate the overall syngas oxidation process. In addition, the outward diffusion direction of oxygen migration was observed from the bulk side to the surface. The proposed CO and H2 reaction kinetics were validated against the experimental data using a DFT-based mean-field (MF) model. An electronic analysis was also performed to further support the intrinsic effects of surface vacancies obtained from the DFT analysis.

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Section: Introductionmentioning

confidence: 99%

Insights into Syngas Combustion on a Defective NiO Surface for Chemical Looping Combustion: Oxygen Migration and Vacancy Effects

2020

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“…For the combustion of coal, 95% of CO 2 was captured with 45.4% efficiency of a power production plant. The use of MgO as support for Mn-based OC was examined by Hwang et al 101 The OTC of 8.74 wt % was maintained during five redox cycles with methane as reducing gas. The XRD pattern showed that the phase and crystal structure remained unchanged.…”

Section: Copper Oxide (Cuo)mentioning

confidence: 99%

Recent Advances and Development of Various Oxygen Carriers for the Chemical Looping Combustion Process: A Review

Qasim

Ayoub

Ghazali

et al. 2021

Ind. Eng. Chem. Res.

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The amount of CO 2 in the atmosphere is rising due to the combustion of fossil fuels to fulfill the energy demand. The need to build cleaner and more efficient energy systems is motivated by the introduction of chemical looping combustion (CLC) as an alternative to conventional combustion by transferring oxygen. The transfer of oxygen from the air to fuel is carried out by a metal oxide known as an oxygen carrier (OC). For high fuel conversion and oxygen transport capacity, many efforts have been made for the preparation of an OC with minimal material cost. This review aims to summarize the recent advances and development of various types of OCs; particularly those developed within the previous five years are critically discussed in this paper. The main criteria for the selection of the OCs for CLC include their oxygen vacancies, oxygen transport capacities, costs, and tendencies over coke deposition, agglomeration, and attrition. OCs for CLC can be generally divided into single oxides, mixed oxides, natural mineral, spinel from mixed metal oxides, and perovskite. These have been critically discussed with their significance in CLC. The performances, advantages, and limitations of the OCs are presented and compared in detail.

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“…The redox reactivity of a composite oxygen carrier depends upon its chemical and physical properties, which include surface area, surface morphology, crushing strength, and crystalline species. 33 The BET surface area, crystalline species, and surface characteristics of the samples were measured by Quantachrome NOVA 1200e, Panalytieal PW 3040/60, and Zeiss ULTRA 55, respectively. The crushing strength (maximum force of breaking a particle) was determined with a press.…”

Section: Description Of the Experimental Detailsmentioning

confidence: 99%

Oxygen Uncoupling Property and Kinetics of a Copper Manganese Composite Oxygen Carrier in a Packed-Bed Reactor

Wang

Hua

et al. 2020

Energy Fuels

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Decreasing the reduction temperature of an oxygen carrier is the key to reduce energy consumption further and avoid the operational difficulties of chemical looping air separation (CLAS). The copper manganese composite oxygen carrier with zirconia as an inert binder, which has a relatively low temperature of oxygen uncoupling, was developed. In the packed-bed reactor, effects of several important operating parameters, viz., the feed gas rate, temperature, and inlet oxygen concentration, on the separation reactivity were discussed. At higher reaction temperatures, the reduction reactivity increases but the oxidation reactivity decreases. In comparison to a copper oxygen carrier, the equilibrium oxygen concentration of the copper manganese oxygen carrier is greatly enhanced. High gas flow rates can accelerate the separation reaction. In the reduction step, a lower oxygen concentration leads to a higher reduction reactivity. In the oxidation step, the higher oxidation reactivity requires higher oxygen concentrations. The oxygen uncoupling kinetics was determined by the lnln kinetic method. The separation activation energy was determined at 162.95 kJ mol–1, and the most likely mechanism function is the unreacted shrinking core model (R 2). The main compositions in fresh and oxidized composite oxygen carriers are Cu x Mn3–x O4 and ZrO2. After reduction, the active phase compositions are transformed into Cu x Mn2–x O2. The inert phase of ZrO2 is stable during the redox reaction. The repeated separation capability of the composite oxygen carrier over 20 consecutive redox cycles is high.

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Development of MgMnO3-δ as an oxygen carrier material for chemical looping combustion

Cited by 19 publications

References 24 publications

Insights into Syngas Combustion on a Defective NiO Surface for Chemical Looping Combustion: Oxygen Migration and Vacancy Effects

Insights into Syngas Combustion on a Defective NiO Surface for Chemical Looping Combustion: Oxygen Migration and Vacancy Effects

Recent Advances and Development of Various Oxygen Carriers for the Chemical Looping Combustion Process: A Review

Oxygen Uncoupling Property and Kinetics of a Copper Manganese Composite Oxygen Carrier in a Packed-Bed Reactor

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