Fundamental Understanding of the Interaction of Acid Gases with CeO₂: From Surface Science to Practical Catalysis

Acid gases including CO₂, SO₂, and NO_x are ubiquitous in large-scale energy applications including heterogeneous catalysis. The adverse environmental and health effects of these acid gases have resulted in high interest in the research and development of technologies to remove or convert these acid gases. The main challenge for the development of these technologies is to develop catalysts that are highly efficient, stable, and cost-effective, and many catalysts have been reported in this regard. CeO₂ and CeO₂-based catalysts have gained prominence in the removal and conversion of CO₂, SO₂, and NO_x because of their structural robustness and redox and acid-base properties. In this article, we provide a brief overview of the application of CeO₂ and CeO₂-based catalysts for the removal of CO₂, SO₂, and NO_x gases with an emphasis on the fundamental understanding of the interactions of these acid gases with CeO₂. The studies summarized in this review range from surface science using single crystals and thin films with precise crystallographic planes to practical catalysis applications of nanocrystalline and polycrystalline CeO₂ materials with defects and dopants. After an introduction to the properties of CeO₂ surfaces, their catalytic properties for conversions of different acid gases are reviewed and discussed. The surface atomic structure, oxygen vacancies, and surface acid-base properties of CeO₂ play vital roles in the surface chemistry and structure evolution during the interactions of acid gases with CeO₂ and CeO₂-based catalysts.