Overview
Work in the Paolucci group focuses on computer simulations of chemical reactions at interfaces. Research areas include computational catalysis (understanding how current catalysts accelerate chemical reactions at the molecular level, and predicting the performance of potential new ones), and modeling of material synthesis and deactivation for both catalysts and other solid materials. The lab uses existing quantum and classical simulation methods and also develop new hybrid methods that bridge micro and macroscopic length scales through the use of techniques such as machine learning and Monte Carlo simulation. In addition, we work closely with experimental colleagues to validate models and test our predictions.
Ethylene Epoxidation
Ethylene epoxidation occurs under reaction conditions that cause significant modifications to the surface and subsurface of Ag catalysts. Further, catalyst selectivity is promoted by the addition of chlorine to the surface at fractional monolayer coverages, inducing even further reconstruction of the surface. The goal of our research is to determine the surface and subsurface structure during ethylene epoxidation, and how they influence the catalytic mechanism. To model surface reconstructions and subsurface diffusion of oxygen and chlorine on these dynamic surfaces we are using a combination of neural network forcefields and Monte Carlo simulations. Collaborators: Prof. David Flaherty (UIUC)
Synthesis of Complex Materials
Metal carbides have complex crystallization pathways and pass through metastable phases during synthesis, presenting challenges for designing carbides with specific phase and surface structures. We are employing quantum chemical calculations and surrogate machine learning models to better understand the connections between particle size, phase stability, and interphase transformations during synthesis. Collaborators: Prof. Jason Hicks (Notre Dame), Dr. Kirsten Winther (Stanford)
Zeolite Catalysis and Synthesis
Under some conditions metal cations in zeolites dynamically agglomerate and reduce to form nanoparticles in the nanoscale voids or the external surface of zeolite particles. In contrast, other conditions promote the oxidation and disintegration of metal nanoparticles to metal cations. The molecular details of the cation-nanoparticle interconversion mechanism are not well-understood. We are using quantum chemical calculations and reactive forcefields to understand how zeolite composition, gas conditions, and nanoparticle size influence the thermodynamics and kinetics of cation and nanoparticle interconversion. Collaborators: Prof. Rajamani Gounder (Purdue), Prof. William S. Epling (UVA)
Tandem Catalysis
This project explores the fundamental importance of hydrogen spillover on a multifunctional catalyst composed of metal particles coupled to metal oxide particles. Collaborators: Prof. Robert J. Davis (UVA)
Nitrogen-doped Carbon Catalysts
Earth-abundant single metal atom catalysts (SAC) kinetically trapped within the matrix of nitrogen-doped carbons (NC) have recently been demonstrated to have potential equivalent to that of precious metal catalysts for selective dehydrogenation of alkanes, aromatics, and alcohols. However, the molecular nature of the single atom active sites in metal nitrogen-doped carbon (M-NC) are not well-understood. Furthermore, typical synthetic M-NC SACs have a heterogenous distribution of metal sites, and the “active sites” are usually in the minority. To determine the molecular structure of catalytically active sites we are using a combination of DFT calculations, thermodynamic and kinetic modeling, and machine learning surrogate models to constrain the configurational search space. Collaborators: Prof. Robert J. Davis (UVA)