Programmable Catalysts

Overview

We propose a new paradigm of heterogeneous catalysis whereby the catalyst changes with time in a predetermined manner (i.e., program) to control surface chemistry for faster, more selective catalysis.  This class of forced dynamic catalysis is constructed on three parts:

  • Catalytic Resonance Theory:  A relationship between the timescales of elementary surface steps and the catalytic turnover frequency exhibiting enhanced catalytic rates beyond the Sabatier limit
  • Catalyst Perturbation:  Synthetic heterogeneous catalysts that can manipulate the adsorption enthalpy and/or entropy via electronic or physical stimulation (e.g., light, potential, physical force)
  • Dynamic Catalyst Optimization:  The complexity of surface reactions combined with the capability for applying complex surface perturbation waveforms (i.e., catalyst programs) requires advanced strategies and fundamental principles to improve either overall rate, product selectivity, or conversion relative to equilibrium

1. Catalytic Resonance Theory

CRT

The dynamic variation of catalyst enthalpy and entropy provide a unique approach to enhancing the rate, selectivity, and extent of catalytic conversion.  By oscillating a catalyst with optimal amplitude and frequency (>1 Hz), catalytic rates can be achieved over three orders of magnitude above the Sabatier maximum 

More information:

Publications

  • "Principles of Dynamic Heterogeneous Catalysis:  Surface Resonance and Turnover Frequency Response," ACS Catalysis, 2019, 9(8), 6929.  LINK
  • "Catalytic Resonance Theory: SuperVolcanoes, Catalytic Molecular Pumps, and Oscillatory Steady State" Catalysis Science & Technology. 2019, 9, 5058. LINK
  • "Catalytic Resonance Theory: Parallel Reaction Pathway Control" Chemical Science. 2020, 11, 3501.  LINK
  • "The Catalytic Mechanics of Dynamic Surfaces: Stimulating Methods for Promoting Catalytic Resonance"  ACS Catalysis, 2020, 10(21), 12666.  LINK
  • "Catalytic Resonance Theory: Negative Dynamic Surfaces for Programmable Catalysts" Chem Catalysis 2022, DOI:  10.1016/j.checat.2021.12.006 

2. Catalytic Condenser (Perturbation)

Chemicals on a catalyst surface can be perturbed by electronically manipulating the electron/hole density of the catalyst surface.  Within a 'catalytic condenser' example below, an alumina/graphene active bilayer undergoes oscillating applied bias (VCAT), allowing it to shift its strength of acidity with time. Reaction occurs when electrons have been depleted, and desorption of products proceeds under the least acidic condition.  More information is available here:  

Catalytic Condenser Dauenhauer Minnesota