08/19/2024
New Insights Into Exsolution Catalyst Fabrication Published
Catalysts made from solid materials are used to produce approximately 90 percent of industrially important chemicals. A key type of such catalysts consists of nano-sized metal particles finely dispersed on an oxide support.
The fabrication of such catalysts faces several critical challenges: the metal particles should neither be too large nor too close to each other, and they should maintain their dispersion even under extreme operating conditions to ensure that the often-expensive metals are used as efficiently as possible.
Recently, there has been significant interest in 'exsolution' as a straightforward way to address these challenges. Exsolution involves starting from a solid solution containing all necessary ingredients (with the metal dissolved within the oxide support), and then exposing this solution to specific environmental conditions to force the system to expel the metal as finely dispersed nano-sized particles on the support's surface. However, fundamental knowledge about why exsolution occurs, how it happens, and why it happens so quickly has been lacking.
Alexander Bonkowski, Dr. Matthew J. Wolf, and Prof. Roger A. De Souza, along with researchers from the Technical University of Darmstadt and the University of Bath, have published an article titled "A Single Model for the Thermodynamics and Kinetics of Metal Exsolution from Perovskite Oxides" in the Journal of the American Chemical Society, which fills this knowledge gap. In this publication, they propose a new, unified model addressing key questions for an important class of oxides known as perovskites.
Using state-of-the-art computational chemistry calculations, which were carried out on RWTH's high-performance computing facilities, they demonstrate that, under environmental conditions typically used during catalyst production, metal ions can be reduced to metal atoms while still inside the host material - a possibility that had not been previously considered. With this understanding of the exsolution process, optimizing the catalytic activity of exsolution systems will be facilitated and the development of new exsolution systems will be accelerated.
Source: RWTH Aachen University