Chemical looping technologies are identified as to have an excellent 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 to 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 a statistical approach to identify the reaction mechanism. The study experimentally investigates the oxidation kinetics of CeO2-d 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¿°C with a CO2 concentration between 20 and 40¿vol% in the feed. The measured peak rates of CO production on ceria were influenced both by temperature and concentration of reactant. The total CO production was more influenced by the temperature than by CO2 concentration, with a maximum CO yield of 33.66¿ml/g at 1000¿°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 the 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 an evaluated activation energy of 79.1¿±¿6.5¿kJ/mol for the CO2 oxidation.

Peer Reviewed