Examining and Modeling Oxygen Uncoupling Kinetics of Cu-Based Oxygen Carriers for Chemical Looping with Oxygen Uncoupling (CLOU) in a Drop Tube Fluidized Bed Reactor

Means, Nicholas C.; Burgess, Ward A.; Howard, Bret H.; Smith, Mark W.; Wang, Ping; Shekhawat, Dushyant

doi:10.1021/acs.energyfuels.9b00338

Cited by 21 publications

(25 citation statements)

References 33 publications

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“…The reaction of C via combustion (eqs and ) or gasification (eqs and ) to form CO gas opens alternate CuO reduction pathways (eqs and ), increasing the overall CuO reduction rate. Kinetic constants of Arrhenius prefactor and activation energy for the CLOU reaction for CuO-based oxygen carriers have been recently reported by our group . Kinetic information for the reduction of CuO by CO is also available .…”

Section: Introductionmentioning

confidence: 87%

Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling

et al. 2019

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Chemical-looping combustion with oxygen uncoupling (CLOU) is a process using gaseous or solid hydrocarbon fuels and is a promising carbon capture and storage (CCS) technology. In CLOU, combustion of the fuel is achieved through the release of gaseous O2 from an oxygen carrier material such as CuO and is favored at high temperatures and low O2 partial pressures. The primary objectives of this study were to (1) compare values for the apparent rate constant k ov(T) for the overall rate of reduction of a CuO carrier, either alone or in the presence of coal char obtained from the pyrolysis of Powder River Basin (PRB) coal, and (2) develop and validate a computational fluid dynamics (CFD) model for the CuO/PRB coal char system based on known kinetics of the individual CuO and Cu2O reduction, combustion, and gasification reactions. Two oxygen carriers consisting of 20 wt % CuO/Al2O3 and 9 wt % CuO/Al2O3 were prepared by physical mixing and by incipient wetness impregnation (IWI), respectively. Kinetic analyses were conducted in the temperature range of 850–1100 °C. The CFD model typically reproduced experimental values of k ov(T) to within ±10%. The increase in k ov(T) caused by addition of only 0.075 g of PRB char per gram of CuO was modest at 1100 °C, but was more than 3-fold at 850 °C. Combustion and gasification of the coal char not only produced CO, opening another pathway for CuO reduction in addition to the CLOU reaction, but also resulted in the over-reduction of Cu2O to the undesired metallic Cu. Production of Cu metal increased with respect to char loading.

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Section: Introductionmentioning

confidence: 87%

Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling

et al. 2019

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“…As illustrated in Figure S1, the effects of nitrogen sweep flow rate, sample mass, and particle size on the solid conversion were investigated. The results show that an adequate purge gas velocity (≥40 mL·min –1 ) and a less loading mass (≤6 mg) lower the oxygen partial pressure around the particles, minimizing the reaction rate limitation due to the thermodynamic effects . In addition, the particles in the size range of 75–150 μm have a negligible internal mass-transfer resistance according to the law of additive reaction times .…”

Section: Reaction Kineticsmentioning

confidence: 97%

“…The results show that an adequate purge gas velocity (≥40 mL•min −1 ) and a less loading mass (≤6 mg) lower the oxygen partial pressure around the particles, minimizing the reaction rate limitation due to the thermodynamic effects. 51 In addition, the particles in the size range of 75−150 μm have a negligible internal mass-transfer resistance according to the law of additive reaction times. 52 Moreover, as discussed by a previous study, 53 the temperature difference between particles and the bed during redox reactions can be neglected for oxygen carrier particles with a small size.…”

Section: ■ Reaction Kineticsmentioning

confidence: 99%

Efficient Metal–Organic Framework-Derived Cu–Zr Oxygen Carriers with an Enhanced Reduction Reaction Rate for Chemical Looping Air Separation

Jin

et al. 2020

ACS Sustainable Chem. Eng.

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As a key to realize the chemical looping air separation (CLAS) process, CuO is a good oxygen carrier candidate because of its high oxygen transport capacity and excellent thermodynamic characteristics. However, it is hampered by easy deactivation during redox cycles. In this work, a Cu−Zr oxygen carrier is developed via a metal−organic framework (MOF) self-templated method to realize high redox reactivity and favorable thermal stability for the CLAS process. The physicochemistry property and reduction kinetics are investigated through isothermal redox cycles, material characterizations, and reduction kinetic modeling. Compared to the coprecipitated oxygen carrier (Copr.), the MOF-derived oxygen carrier (MOF-D) obtains a 35% faster average reaction rate at the temperature interval of 800−900 °C, especially a 60% reduction rate increase at 850 °C. This enhanced reaction rate is mainly ascribed to the lower intrinsic activation energy (126.3 kJ•mol −1 for MOF-D vs 157.3 kJ•mol −1 for Copr.) rather than the amount of active oxygen species. The oxygen-releasing mechanisms for the MOF-derived and coprecipitated oxygen carriers follow the nucleation and nuclei growth model with a transition of one-dimensional growth to two-dimensional nucleation at two temperature ranges (800−825 and 850−900 °C). This study offers a new route to develop an efficient oxygen carrier for the CLAS process.

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“…This model focuses on the oxygen uncoupling process and suits for oxygen uncoupling reaction. The oxygen uncoupling of OC is a typical solid-gas reaction, and the basic kinetic equation is given by [59][60][61]:…”

Section: Kinetic Analysismentioning

confidence: 99%

Understanding of the oxygen uncoupling characteristics of Cu Fe composite oxygen carriers for chemical-looping gasification

Wang

et al. 2021

Fuel Processing Technology

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Examining and Modeling Oxygen Uncoupling Kinetics of Cu-Based Oxygen Carriers for Chemical Looping with Oxygen Uncoupling (CLOU) in a Drop Tube Fluidized Bed Reactor

Cited by 21 publications

References 33 publications

Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling

Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling

Efficient Metal–Organic Framework-Derived Cu–Zr Oxygen Carriers with an Enhanced Reduction Reaction Rate for Chemical Looping Air Separation

Understanding of the oxygen uncoupling characteristics of Cu Fe composite oxygen carriers for chemical-looping gasification

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