(509cv) Catalytic Resonance Theory: Negatively Correlated Linear Scaling Relationships for Overcoming the Sabatier Limit

Development of higher-performing catalysts is needed to move toward more energy-efficient synthesis of key chemicals. Dynamic catalysis, in which an oscillating external stimulus (e.g., electric field, strain) is used to drive temporal changes in the properties of the catalyst itself, has been proposed as a method for overcoming the Sabatier limit to increase catalyst activity or selectivity.^1,2 In this work, we extend the modeling of dynamic catalysis to chemistries in which the binding energies of key reaction intermediates change in opposite directions, i.e., those with scaling relationship slopes γ = ΔBE_B/ΔBE_A < 0, which have been recently predicted to exist under applied electric fields.³

We use a model A⇌B catalytic reaction to elucidate optimal dynamic parameters (e.g., waveform amplitude, frequency) for both increasing reaction rates and controlling reaction selectivity, and we further study how the properties of the catalyst-stimuli pair, parameterized into two scaling relationships, affect these results. We use microkinetic modeling to study rate in a differential conversion CSTR and selectivity in a batch reactor. For amplitudes U ≤ 1.2 eV and frequencies f ≤ 10⁴ Hz, reaction rates can be increased by 10x to over 10,000x above maximal static rate. Regarding selectivity, we find that the catalyst-stimulus pair is an additional determining factor of the dynamic steady-state conversion. In all cases, systems with higher waveform amplitudes and frequencies have the strongest driving effect. We also study the turnover efficiency² and find that rate enhancement can be maximized without decreasing turnover efficiency for this reaction class.

The findings of this study extend the applicability of dynamic catalysis to a wider set of chemistries and provide guidelines for experimental implementation of this novel catalyst enhancement method.

References:

[1] ACS Catal. 2019, 9(8), 6929.

[2] ACS Catal. 2020 10(21), 12666.

[3] ACS Catal. 2020, 10(21), 12867.