ReaxFF Simulations of Lignin Fragmentation on a Palladium-Based Heterogeneous Catalyst in Methanol–Water Solution

Abstract

The interaction of fragments derived from lignin depolymerization with a heterogeneous palladium catalyst in methanol-water solution is studied by means of experimental and theoretical methodologies. Quantum chemistry calculations and molecular dynamics simulations based on the ReaxFF approach are combined effectively to obtain an atomic level characterization of the crucial steps of the adsorption of the molecules on the catalyst, their fragmentation, reactions, and desorption. The main products are identified, and the most important routes to obtain them are explained through extensive computational procedures. The simulation results are in excellent agreement with the experiments and suggest that the mechanisms comprise a fast chemisorption of identified fragments from lignin on the metal interface accompanied by bond breaking, release of some of their hydrogens and oxygens to the support, and eventual desorption depending on the local environment. The strongest connections are those involving the aromatic rings, as confirmed by the binding energies of selected representative structures, estimated at the quantum chemistry level. The satisfactory agreement with the literature, quantum chemistry data, and experiments confirms the reliability of the multilevel computational procedure to study complex reaction mixtures and its potential application in the design of high-performance catalytic devices.

Transforming the Accuracy and Numerical Stability of ReaxFF Reactive Force Fields

“…Moreover, ReaxFF is significantly less costly than DFTB or neural network potentials . Noteworthy applications of ReaxFF include the study of combustion and fuels chemistry, − heterogeneous catalysis, − nanotechnology, − enzymatic reactions, high-energy materials, − and aqueous phase chemistry, − among others.…”

A combination of experimental and computational methods to study the reactions during a Lignin-First approach

“…From a theoretical point of view, we simulated the catalytic processes inside the Pd/C reactor by means of classical reactive molecular dynamics simulations in the methanol-water mixture used in the experiments after parametrizing all the interactions of the whole species present in the system against quantum chemistry calculations [30]. All the molecular components, their structure, dynamics and reaction mechanisms were satisfactorily reproduced.…”

Modeling Diffusion in Functional Materials: From Density Functional Theory to Artificial Intelligence

“…Such processes can span long periods of time (>1 ns) and are not yet accessible to ab initio levels of theory. Therefore, the use of reactive force fields in the study of diffusion and transport mechanisms should be of utmost importance for a smarter, simulation‐based design of batteries, fuel cells, and catalysts among other advanced functional materials.…”