Selectivity Changes in Electrochemical Reaction Sequences by Modulated Potential Control

Abstract

Electro-organic reactions typically involve the electrochemical generation of a reactive intermediate which may participate in further chemical or electrochemical reactions. It is possible to effect the product distribution in such branched reaction networks by modulating the electrode potential. Reaction rate calculations under electrokineticcontrolled conditions for four reaction mechanisms, each involving an electrogenerated intermediate, are presented for step-and sinusoidal-potential modulation. The results show that reactor operating conditions unobtainable under steady potential control are possible. The cycle-averaged selectivity and yield of selected products may be significantly increased at the stationary state in comparison to those at an identical production rate but under dc conditions. The effect of modulation is frequency dependent; for some reaction sequences, the reaction trend at low frequency may be opposite than that at high frequency. The relative rates of a chemical reaction in parallel with an electrochemical reaction, both involving the intermediate, are more sensitive to potential modulation than either two parallel chemical or electrochemical reactions. Mass transfer limitations dampen the results of modulation. Reactor performance increases under modulated potential (or current) control possibly may be significant enough to make an electrochemical processing route economically viable. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 147.188.128.74 Downloaded on 2014-11-16 to IP Vol. 131, No. 6 ELECTROCHEMICAL REACTION SEQUENCES 1305

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