(462e) Polarization Enables Brønsted Acid Catalysis at Mild Thermochemical Conditions

Industry has long employed high temperatures and pressures to increase reaction rates, but interfacial electric fields have also been employed to promote catalysis. Our group has recently demonstrated that Brønsted acid catalytic rates are highly dependent on these interfacial fields, but previously employed methods of polarization do not allow for high catalyst surface areas and loadings, general control of catalyst potential (E_cat), or engender deleterious side reactivity (Fig. 1A). These drawbacks prevent the general implementation of polarized Brønsted acid catalysis at scale. In this work, we develop and employ a polarized slurry reactor to allow for high active site loadings and general control of E_cat, thereby realizing scaled polarized Brønsted acid catalysis. This reactor design further enables Brønsted acid catalytic activity at lower temperatures and E_cat than under typical thermochemical and electrochemical conditions (Fig. 1B).

We first measure the rate-potential scaling for the dehydration of 1-methylcyclopentanol over 5% phosphotungstic acid on carbon (PTA/C), a known quantity on both 2D and 3D manifolds, in a polarized slurry reactor and show an identical rate-potential scaling to this previously studied system. We then utilize the reactor’s high catalyst loadings in tandem with the strong E_cat dependence of Brønsted acid catalysis to promote the acylation of anisole over PTA/C at room temperature, achieving reactions rates which exceed that of the same catalyst without polarization 45°C higher in temperature. Finally, we leverage these same reactor characteristics to promote the Brønsted acid catalyzed isomerization of olefins at near-room temperature, highlighting the breadth of reactivity achievable with this reactor design.

Altogether, these results further demonstrate that E_cat is a powerful control handle for Brønsted acid catalysis which enables thermochemical transformations at significantly milder conditions when paired with reactor designs that harness this property.