Controlling the dispersion of ceria using nanoconfinement: application to CeO2/SBA-15 catalysts for NH3-SCR

Abstract

Mesoporous silicas, such as SBA-15, with their high and inert surface area, constitute promising support materials for catalytic applications. However, loading the active phase onto porous materials to give high dispersion and even distribution is still a great challenge. In the presence of the template P123, ceria crystal growth can be controlled by nanoconfinement effects. We have applied in situ Raman, DRIFT, and DR UV-vis spectroscopies to elucidate the mechanism of template-assisted synthesis of ceria/SBA-15 catalysts for NH₃-SCR applications. The co-decomposition of P123 and cerium precursor shows a catalytic interaction, resulting in a change of ceria nucleation and growth behavior during the calcination process. Based on this knowledge, we have developed an improved catalyst synthesis by combining the nanoconfinement effects of P123 and the use of an inert atmosphere, resulting in an improved ceria dispersion on SBA-15 and superior NH₃-SCR performance. Our results highlight the significance of the calcination process for defining catalyst properties and the use of in situ spectroscopy for rational synthesis of supported catalysts.