Electrogenerative and Voltameiotic Processes

Langer, Stanley H.; Sakellaropoulos, G.P.

doi:10.1021/i260072a001

Cited by 26 publications

(8 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this case, electrogenerative oxi- dations occur below the oxygen or chlorine thermodynamic potential (49). Conventional oxidations operate well above these potentials.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Reactor Analysis: Selectivity of Multiple Competing Reactions

Sakellaropoulos

Francis

1979

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

An analysis of multiple competing reactions is presented for one or more reactants with arbitrary electrode kinetics. Criteria are established for selectivity enhancement and control and mr electrochemical reactor design based on electrode potential, temperature, conversion, and transport processes. The strongest effect arises from the potential, which can offset the selectivity dependence on other operating variables. Diffusion transport in porous electrodes can also improve reaction specificity, depending on kinetics. The role of reactor design on selectivity is examined ~or two extreme reactors with channel flow or with thorough mixing. The former operates under nonuniform current and selectivity distribution along the working electrode and may result in apparent limiting currents. Although discussion focuses on two irreversible paralml electroorganic reactions, results are also applicable to reversible, coupled or uncoupled reactions of ionic, dissolved, and gas-phase reactants at thin porous flow-by, gas-diffusion, thin-gap, and slurry electrodes.Reductions and oxidations of organic molecules in solution, in the presence of an electric potential field, yield a variety of important chemicals. Despite extensive mechanistic and exploratory studies (1-3), however, few electroorganic reactions have reached large scale application (4-6). This slow evolution of electrochemicaI processing has partly resulted from inadequate understanding of the coupling of complex chemical, kinetic, and physical steps or of the effect of cell design on reaction specificity and rate. The latter constitute basic parameters in process feasibility evaluation. In view of recent interest for industrial electroorganic processing (6-8) an examination of design criteria for electrochemical reactors (cells) is warranted.In this analysis we examine the rational choice of flow reactors, contact patterns, and operating conditions for optimal selectivity and rate control of competing organic electrocatalytic reactions. For a rational design, knowledge of the kinetic parameters, including the transfer coefficients, of each reaction is essential. The discussion here presents a methodology for a detailed kinetic characterization of coupled, simultaneous electrochemical reactions.Electrocatalytic processes are considered because of the unusual effects that the electrode material and its potential have on selective promotion of complex reaction paths (9). The development of efficient catalytic electrodes and cell configurations and the advent of novel, energy-saving schemes, such as electrogenerative catalytic processes (10, 11), are expected to improve the feasibility of conventional processes (7, 8).With parallel or competing reactions, one reactant may undergo reduction or oxidation via two or more different routes. This is particularly the case with electrocatalytic reactions, which involve surface adsorption on one or more active sites, possible reorganization of the reactant or a reaction intermediate, and surface reaction with one or several el...

show abstract

“…In this case, electrogenerative oxi- dations occur below the oxygen or chlorine thermodynamic potential (49). Conventional oxidations operate well above these potentials.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Reactor Analysis: Selectivity of Multiple Competing Reactions

Sakellaropoulos

Francis

1979

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The hydrogenation of simple alkenes, conventionally a heterogeneous catalytic process, has served as an oft-cited model system for investigating simple organic electrogenerative system operation (5,12). Figure 1 shows a representative cell configuration.…”

Section: Discussionmentioning

confidence: 99%

“…Ethylene partial pressure or hydrogen ion concentration was maintained constant at a constant positive potential while the other was varied under conditions where transport was not limiting. An order in each reactant could be determined from log i (5) log C TECk*j with the assumption of a simple exponential rate expression. Here, i is current, E is potential, C represents concentration of a specific reactant at the electrode, and Z1 is the order of reaction with respect to each reactant (13).…”

Section: Discussionmentioning

confidence: 99%

“…Earlier possibilities for electrogenerative syntheses were recognized but few were developed beyond academic speculation or patent claims (4,5). Now, the advances in fuel cell technology and electrocatalysis stimulated by the world energy and raw material situation provide some special opportunities for investigating electrosynthesis of organic chemicals not only without a power source but with concurrent electricity generation.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electrogenerative and related processes

Langer¹,

Card²,

Foral³

1986

Pure and Applied Chemistry

View full text Add to dashboard Cite

A number of organic electrogenerative processes are described and explained by reviewing various aspects of studies associated with them. Electrogenerative hydrogenation, dehydrogenation, halogenation, and oxidation of alcohols are discussed together with possibilities for process improvement. Hydrogenation is used as a model for reviewing studies which correspond to the conventional ones of organic chemistry. The oxidation of ethanol vapor to acetaldehyde is used as an illustration of a potentially viable electrogenerative process. Generated electricity is a byproduct in electrogenerative processing and a useful indicator of the rate of reactant consumption. However, product selectivity may be lost where generation of high currents becomes the major consideration.

show abstract

“….. Electrochemical processes can be devised to conserve energy, generally by replacing the sacrificial electrochemical reaction with another that operates at a lower voltage. Langer and Sakellaropoulos (1979) have suggested that such processes be called voltameiotic (meiotic is Greek for decreasing); i.e., processes in which the overall electrolytic cell working voltage is reduced by altering the reaction at one electrode.…”

Section: The Electrochemical Deliglfil'ication Of Plant Materialsmentioning

confidence: 99%