Assessment of kinetic model for ceria oxidation for chemical-looping CO2 dissociation

Abstract

Chemical looping technologies are identified as to have a great potential for CO2 capture and fuels synthesis. Oxygen carriers are the fundamental component of a chemical looping process, and the choice of stable and efficient carriers with fast redox kinetics is the key for the successful design of the process. Hence, understanding the reaction kinetics is of paramount importance for the selection of an appropriate oxygen carrier material. This work provides a method for kinetic model selection based on statistical approach to identify the reaction mechanism. The study experimentally investigates the oxidation kinetics of CeO2- by CO2 and applies a statistical method for the selection of the best-fitting kinetic model for the reaction. The kinetic study is performed in the temperature range of 700-1000 o C with CO2 concentration between 20-40% in the feed. The measured peak rates of CO production on ceria were influenced both by temperature and concentration of reactant, showing a marked increase with the temperature and CO2 fraction, from 13.25 ml/min/g at 700 o C and 20% CO2 in feed to 46.08 ml/min/g for 40% CO2 and 1000 o C. The total CO production showed more influence of temperature than CO2 concentration, with a maximum CO yield of 33.66 ml/g at 1000 o C and 40% CO2. The identification of the oxidation kinetic model is performed by fitting different reactions models to the measured reaction rates and statistically comparing them using Residual sum of squares (RSS), Akaike information criterion (AICc) and the F-test for the selection of the best-fitting one. Models corresponding to the nucleation and grain growth reaction mechanism provided a good fit of the data, with the Sestak-Berggren (SB) model showing the best approximation of the measured rate of reaction with evaluated activation energy of 78.5 kJ/mol for the CO2 oxidation.

Assessment of integration of methane-reduced ceria chemical looping CO2/H2O splitting cycle to an oxy-fired power plant

“…The authors compared the different reaction models to experimental data (CO 2 oxidation of reduced ceria in an atmosphere of H 2 at a temperature range of 700-1100 o C) by curve fitting, followed by statistically comparison using the Residual sum of squares (RSS), Akaike information criterion (AICc) and the F-test methods. The Sestak-Berggren (SB) model which is a nested category model of nucleation and grain growth was found to fit best to the experimental data of the CDS reaction together with an activation energy of 79.1 ± 6.5 kJ/mol being obtained [32].…”

“…This is due to the fact that the SS models, essentially lumped parameter models with a minimal level of detail about the reaction mechanisms, does not account for the transient phenomena occurring during the CDS reactions. Farooqui et al [32] in another recent study, tried to further this limitation for identification of the proper kinetic model for the CDS reaction. The authors compared the different reaction models to experimental data (CO 2 oxidation of reduced ceria in an atmosphere of H 2 at a temperature range of 700-1100 o C) by curve fitting, followed by statistically comparison using the Residual sum of squares (RSS), Akaike information criterion (AICc) and the F-test methods.…”

Simulation of two-step redox recycling of non-stoichiometric ceria with thermochemical dissociation of CO2/H2O in moving bed reactors – Part I: Model development with redox kinetics and sensitivity analysis

“…The oxidation kinetics for ceria for H2O and CO2 splitting have been investigated by several research groups (Ackermann et al, 2015;Arifin and Weimer, 2018;Farooqui et al, 2018). The initial reduction state of the sample has been reported to strongly influence the subsequent oxidation reaction.…”

“…Numerous thermochemical cycles have been proposed comprising multiple steps. Of them the two-step redox oxide pair systems have shown great potential for synthetic solar fuel generation (Farooqui et al, 2018). These thermochemical cycles operate on the principle of transition between higher valence oxidized (MeOoxd) and lower valence reduced (MeOred) form of the oxide of a metal having multiple oxidation states (Agrafiotis et al, 2015).…”

Techno-economic and exergy analysis of polygeneration plant for power and DME production with the integration of chemical looping CO2/H2O splitting

“…One intriguing approach to recycle exhaust gas within the power plant and hence produce chemicals in addition to power is through the chemical looping (CL) technology [19,20]. Chemical looping technology for CO2/H2O splitting usually utilizes metallic oxygen carriers to convert the thermochemical energy into chemical energy [21]. Both thermally driven cycles (by concentrated solar power) or by fuel reduction (by methane) are feasible alternatives [22].…”