Reaction Discovery in Porous Materials Using Periodic Nanoreactor Molecular Dynamics

Area of Science:

• Computational Chemistry
• Materials Science
• Chemical Engineering
• Heterogeneous Catalysis

Background:

• Catalytic processes are crucial for energy-efficient molecular transformations.
• Porous materials like zeolites are vital in heterogeneous catalysis due to their unique structures and high surface areas.
• Understanding reaction networks in zeolites is key to optimizing catalytic applications.

Purpose of the Study:

• To investigate the reaction network of selective catalytic reduction (SCR) of NO over copper-exchanged chabazite zeolites.
• To develop and apply a periodic ab initio nanoreactor molecular dynamics (NMD) approach for autonomous reaction discovery.
• To elucidate the formation mechanisms of both desired and undesired products in SCR reactions.

Main Methods:

• Periodic ab initio nanoreactor molecular dynamics (NMD) simulations.
• Autonomous discovery of reaction pathways using automated reaction detection.
• Refinement of reaction paths with free energy corrections via phonon spectrum computation.

Main Results:

• Autonomous discovery of established and novel reaction pathways for SCR of NO.
• Identification of a water-assisted tautomerization mechanism for N2 formation.
• Discovery of a new radical-driven pathway leading to N2O formation.
• Observation of reactivity involving Brønsted acid sites within the zeolite framework.
• Construction of a comprehensive reaction network detailing product formation.

Conclusions:

• The NMD approach effectively elucidates complex reaction networks in heterogeneous catalysis.
• New mechanistic insights into SCR side-reactions, including N2 and N2O formation, were gained.
• The study demonstrates the versatility of NMD for agnostic reaction discovery in advanced catalytic systems.