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Technology

The electrochemically responsive heterogeneous catalyst described in this invention is made up of an electrically conductive matrix and a conformal coating containing an electrochemically active catalytic molecule. For example, a heterogeneous catalyst for the Michael addition of methyl vinyl ketone (MVK) and ethyl-2-oxycyclopentane carboxylate (E2OC) -- a reaction used in steroid synthesis -- can be made by coating a porous carbon fiber matrix with polyvinylferrocene (PVF). Ferrocene (Fc) has no catalytic activity, per se, but its oxidized form, ferrocenium (Fc+), catalyzes the addition reaction.

To control the rate of the reaction, a voltage is applied to the carbon fiber matrix to create a localized oxidative environment, which in turn oxidizes Fc into Fc+ to increase catalytic activity. The proportion of Fc to Fc+ depends on the magnitude of the voltage applied, allowing the reaction rate to be continuously modulated over a range. The additional flexibility this method provides over binary-switching catalytic schemes is useful in situations including selectivity control in complex reaction networks or thermal regulation of exothermic reactions. Since this responsive catalysis system relies on redox switching of the catalytic compounds instead of structural changes to the matrix, it maintains a constant volume and is resistant to catalyst leaching, making it well-suited for use in fixed-bed flow reactors.