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Journal of Applied Electrochemistry

, Volume 16, Issue 6, pp 851–866 | Cite as

Selectivity analysis in electrochemical reactors. II. Engineering models of a batch reactor with a complex reaction sequence

  • L. Weise
  • G. Valentin
  • A. Storck
Article

Abstract

This paper presents a mathematical model of a batch stirred-tank electrochemical reactor where a required cathodic reduction reaction is coupled with a complex reaction sequence between the reactant and the key product. The set of coupled, non-linear differential equations is solved numerically and simple dimensionless quantities characterizing the cell performance and selectivity are derived. The experimental results presented in Part I of this paper are found to be in excellent agreement with the model. In the particular case where the homogeneous chemical reactions may be neglected in the cathodic diffusion boundary layer, a simplified analytical expression of the process selectivity is proposed. This quantifies the effects of the operating conditions by means of a single dimensionless criterion.

Keywords

Boundary Layer Reduction Reaction Electrochemical Reactor Batch Reactor Cell Performance 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

Ae

electrode area

ae

specific electrode area

CA,CB,CC

molar concentrations of species A, B, C

CAS,CBS,CCS

bulk molar concentrations

CAO

initial concentration of species A

CA+,CB+

reduced concentrations (with respect toCAS-section 2)

CAO+,CBO+

reduced concentrations (with respect toCAO)

CBS*

=CBS/CAS

CAS, i+;CBS, i+

bulk concentrations in thei th reactor normalized with respect toCAO

DA,DB

molecular diffusion coefficients

DB+

=DB/DA

E

electrode potential

F

Faraday's constant

Ha0,Ha

Hatta numbers defined with respect toCAO orCAS

i

current density

iL

limiting current density

i*

dimensionless current density (Equation 6)

kci

chemical rate constants involved in scheme I

kc

chemical rate constant of scheme II

kd

mass transfer coefficient

K1,K2

dimensionless parameters defined in Equation 13

K

dimensionless parameter defined in Equation 17

N

impeller rotation speed

Qv

volumetric flowrate

ri

chemical reaction rate

RA

conversion factor of species A

S

product selectivity

T

temperature

t

time

t+

dimensionless time=t(kdae)

V

volume of catholyte

XA,XB,XC

molar fractions, i.e.CAS/CAO;CBS/CAO;CCS/CAO

y

coordinate perpendicular to the electrode

y+

reduced coordinate=y

ve

number of electrons involved in the reduction

τ

space time

Subscripts

f

final

L

limiting

0

initial (time=0)

S

in the bulk of the electrolyte

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References

  1. [1]
    L. Weise, G. Valentin and A. Storck,J. Appl. Electrochem. 16 (1986) 836.Google Scholar
  2. [2]
    R. C. Alkire and J. D. Lisius,J. Electrochem. Soc. 132 (1985) 1879.Google Scholar
  3. [3]
    P. V. Danckwerts, ‘Gas-Liquid Reactions’, Mc-Graw Hill, New York (1970).Google Scholar
  4. [4]
    J. C. Charpentier and G. Wild, ‘Absorption avec réaction chimique’, Technique de l'Ingénieur, J2640-12, Paris (1983).Google Scholar
  5. [5]
    W. H. Ray and J. Szekely, ‘Process Optimization’, John Wiley and Sons, New York (1983).Google Scholar
  6. [6]
    J. Villermaux, ‘Génie de la Réaction Chimique’, Technique et Documentation, Lavoisier, Paris (1982).Google Scholar

Copyright information

© Chapman and Hall Ltd. 1986

Authors and Affiliations

  • L. Weise
    • 1
  • G. Valentin
    • 1
  • A. Storck
    • 1
  1. 1.Laboratoire des Sciences du Génie ChimiqueCNRS-ENSICNancy CedexFrance

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