(297a) A Detailed Mechanism of Solar Thermochemical Carbon Dioxide Splitting With CeO2

Currently ceria is a favored material within the concentrated solar power fuels community. The kinetic mechanisms responsible for ceria’s catalytic activity have been studied in great detail at lower temperatures and under numerous chemical environments. However, there is a critical gap in the knowledge base of ceria’s oxidation kinetics under conditions appropriate for solar thermochemical processes. An understanding of the mechanistic pathway and a detailed engineering model of the oxidation step is necessary to develop accurate computational models for the design and optimization of concentrated solar receiver reactors.

In this work, we focus on ceria mediated CO₂ splitting process as a case study, and apply a solid state numerical approach and a micro-kinetic analysis that separates experimental artifacts from material-specific fuel production behavior; yielding high quality fits to experimentally determined CO production rates over the entire reaction time domain. The results of this study show that the CO₂ splitting reaction is a complex surface phenomenon where temperature-dependent site blocking and mechanism transition occurs at the different oxidation temperatures.