Reduction kinetics of hematite as oxygen carrier in chemical looping combustion

Su, Mingze; Ma, Jinchen; Tian, Xin; Zhao, Haibo

doi:10.1016/j.fuproc.2016.05.015

Cited by 45 publications

(33 citation statements)

References 29 publications

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“…During the last years, most of the research on kinetics of low-cost oxygen carriers for the iG-CLC process was focused on Febased materials. Most of the kinetic studies that can be found in literature on Fe-based oxygen carriers refer to synthetic materials (supported or unsupported Fe 2 O 3 ) [18][19][20][21][22][23][24][25][26]. Most of these studies consider the reduction from Fe 2 O 3 not only to Fe 3 O 4 , which would be the most interesting for iG-CLC purposes [27], but also the further reduction to FeO /Fe.…”

Section: Introductionmentioning

confidence: 99%

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Mendiara

Abad

Gayán

et al. 2019

Chemical Engineering Journal

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The in-situ Gasification Chemical Looping Combustion (iG-CLC) process allows combustion with inherent CO 2 capture. In this process, the oxygen for combustion is commonly supplied by a solid oxygen carrier based on a metal oxide thus avoiding direct contact between fuel and air. The oxygen carrier circulates between two reactors. In the fuel reactor, the fuel is oxidized to CO 2 and H 2 O while the oxygen carrier is reduced. In the air reactor, the reduced oxygen carrier is regenerated in air. Ilmenite has been widely used as a low-cost oxygen carrier for the iG-CLC process, and it can be taken as a reference material. Recently, the Tierga iron ore has been identified as a promising candidate for further scale-up of the process due to the higher combustion efficiency achieved compared to the results using 2 ilmenite. Modelling of the iG-CLC process with Tierga iron ore as oxygen carrier is a key step to determine the potential of this material. In order to model the iG-CLC process it is necessary to know the reactivity of both oxygen carrier and fuel used. In this paper, the kinetic determination for the reduction and oxidation reactions of the Tierga ore is presented.Reaction orders close to unity were obtained for the main reducing gases, i.e. H 2 , CO and CH 4 , as well as O 2 . The activation energy values obtained were 81.1±7, 76.1±6 and 257±14 kJ/mol for H 2 , CO and CH 4 , respectively. The activation energy for oxidation was determined as 18.4±05 kJ/mol. In addition, a simple method is used for a comparison of the performance of different oxygen carriers based on their kinetics.

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Section: Introductionmentioning

confidence: 99%

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Mendiara

Abad

Gayán

et al. 2019

Chemical Engineering Journal

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“…Besides, the conversion rate of CaSO 4 in the experiment with lime addition was larger than that without lime addition. It should be noted that the conversion rate of CaSO 4 showed the same value in the oxidation period, because the reaction rate was controlled by the oxygen aeration rate (Su et al, 2016). The improvement of the conversion rate may be attributed to the catalysis of lime on the water-gas shift reaction (Teyssié et al, 2011).…”

Section: Effect Of Temperaturementioning

confidence: 85%

Effect of Lime Addition to CaSO 4 Oxygen Carrier in Chemical Looping Combustion

Ding

Zhang

Guan

et al. 2018

Braz. J. Chem. Eng.

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“…The chemical looping concept (CLC) can be applied in many heterogeneous catalytic processes, such as chemical products generation by the chemical looping selective oxidation and CO 2 reduction and utilization by the reverse water–gas shift chemical looping . Fe-based materials are widely used as an oxygen carrier in chemical looping because of their inexpensiveness and large reserves. − Ilmenite has been used in different scale chemical looping units such as 10 kW th , 30 kW th , 50 kW th , 100 kW th , and 1 MW th chemical looping pilots and demonstrated its acceptable reactivity, good stability, and low attrition rate. In recent years, iron ores have shown promising performance for the chemical looping processes with different fuels. − It was found that the iron ore materials have high reactivity and can achieve high combustion efficiency. − In the design and operation of a chemical looping process, the circulation rate and bed inventories of the Fe-based oxygen carrier are very important parameters and determined by the redox kinetics of the oxygen carrier .…”

Section: Introductionmentioning

confidence: 99%

A First-Principles Microkinetic Rate Equation Theory for Heterogeneous Reactions: Application to Reduction of Fe₂O₃ in Chemical Looping

Cai

Liu

2021

Ind. Eng. Chem. Res.

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How to couple the microscale surface reactions with the macroscale kinetic phenomenon and achieve a firstprinciples-based kinetics prediction is an unsolved problem in the field of chemical looping. This study proposes a first-principlesbased theoretical model to calculate the heterogeneous reduction kinetics of an Fe 2 O 3 oxygen carrier in chemical looping. At the atom scale, the surface reaction mechanism of H 2 with Fe 2 O 3 is investigated on the basis of density functional theory (DFT) calculations. The energetic data, frequency, and atomic structure obtained from DFT calculations are introduced into transition state theory (TST) to calculate the reaction rate constants. At the grain scale, a rate equation theory is developed and used to couple the surface reaction with the bulk diffusion of lattice oxygen, and the reaction mechanism and reaction rate constants obtained from DFT and TST are introduced into the rate equations to predict the reduction kinetics of Fe 2 O 3 . The theoretical prediction is validated by experimental data from thermogravimetric analysis, and it is demonstrated that the first-principles-based microkinetics rate equation theory can provide an accurate prediction of the reduction kinetics of Fe 2 O 3 oxygen carrier in chemical looping.

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Reduction kinetics of hematite as oxygen carrier in chemical looping combustion

Cited by 45 publications

References 29 publications

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Effect of Lime Addition to CaSO 4 Oxygen Carrier in Chemical Looping Combustion

A First-Principles Microkinetic Rate Equation Theory for Heterogeneous Reactions: Application to Reduction of Fe₂O₃ in Chemical Looping

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Reduction kinetics of hematite as oxygen carrier in chemical looping combustion

Cited by 45 publications

References 29 publications

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Effect of Lime Addition to CaSO 4 Oxygen Carrier in Chemical Looping Combustion

A First-Principles Microkinetic Rate Equation Theory for Heterogeneous Reactions: Application to Reduction of Fe2O3 in Chemical Looping

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A First-Principles Microkinetic Rate Equation Theory for Heterogeneous Reactions: Application to Reduction of Fe₂O₃ in Chemical Looping