State-of-the-art and challenges in theoretical simulations of heterogeneous catalysis at the microscopic level

Abstract

Theoretical simulations of systems that represent heterogeneous catalysts constitute one of the main tools in the research for new catalytic materials. Theory plays a role in the three stages of the development ladder: characterisation, understanding and prediction. Due to the complexity of the computational methods, there is a strong need to integrate different models and cover the relevant scales in heterogeneous catalysis. This requirement constitutes an important drawback as scientists need training in several aspects of the problem including chemical, physical and engineering views of the modelling while keeping the experimental and industrial interests and needs in perspective. Here we present some of the latest developments in the field of theoretical simulations at the microscopic level while illustrating suitable examples that show how theory can shed light on several aspects of characterisation, activity, selectivity and long-term stability.

Lattice mismatch as the descriptor of segregation, stability and reactivity of supported thin catalyst films

“…Coating/shell bears the catalytic function and can consist of a single catalytically active metal or a multi-metal phase, which can further boost the catalytic performance. 11,12 While a clear border between the bulk and surface is difficult to draw, some studies have shown that many properties of a solid are close to those of bulk already three layers below the surface. 13 Concerning practical applications, a catalyst must have high activity and stability under operating conditions.…”

Density functional theory simulations of complex catalytic materials in reactive environments: beyond the ideal surface at low coverage

“…As methodological aspects and challenges of quantum calculations for heterogeneous catalysis have been the object of previous perspectives, 43,44 we focus here on the need to take into account the complexity in the molecular models to reach chemical relevance for current or future industrial catalysts. We highlight first-principles studies performed in our group, which have recently addressed this high degree of complexity of the catalytic system under the following reaction conditions:…”

“…Most commonly used types of models for heterogeneous catalysts have been detailed in previous perspectives. 43,44 In brief, the system can be modelled either by clusters of finite numbers of atoms or by ideal infinite surfaces within periodic boundary conditions. The cluster approach consists of the simulation of a piece of a particle (representing the active phase) from ten to several tens of atoms.…”

How Theoretical Simulations Can Address the Structure and Activity of Nanoparticles

“…The drawback of this simplification is the addition of an unknown exchangecorrelation term to the energy. DFT energies are usually taken as the reference for more sophisticated approaches, such as medium field theories, or schemes that describe larger time and length scales suitable to be compared to experiments in both Materials Science and Catalysis [8]. The accuracy and efficiency of DFT-based methods depend on several technical choices [9], including the particular exchange-correlation functional, the basis set for the expansion of the Kohn-Sham (KS) orbitals and the algorithms employed to solve the KS equations.…”