Metallurgical Transactions B

, Volume 23, Issue 4, pp 493–503 | Cite as

Kinetics of solid state reaction between barium carbonate and cupric oxide

  • S. G. Acharya
  • S. K. Bhatia
  • H. S. Shankar
Solid State Reactions

Abstract

The kinetics and equilibrium of the solid state reaction between barium carbonate and cupric oxide have been examined thermogravimetrically. The reaction rate is found to be dominated by effects of nucleation and diffusion of carbon dioxide produced. A mathematical model incorporating these effects, along with considerations of heat transfer, is found to satisfactorily correlate the conversion-time data. The reaction is found to follow the stoichiometry BaCO3 + CuO ⇌ BaCuO2 + CO2 although at temperatures above 1123 K, some evidence of BaO is also seen through X-ray diffraction. In the pelletized samples, incomplete conversion is noticed indicative of pore closure effects leading to transport limitations. The latter is also independently confirmed by porosity and surface area measurements. Data on the reaction equilibrium are also obtained and, in conjunction with Van’t Hoff’s relation, are used to obtain a correlation for the endothermic heat of reaction as a function of temperature.

Nomenclature

C

concentration of CO2 in product layer

C0

external bulk concentration of CO2

C*(T)

equilibrium concentration at temperatureT

C*0

C*(T0), equilibrium concentration at bulk temperature

D(T)

effective diffusivity at temperatureT

Dc

D(Tc), effective diffusivity at core temperature

Ds

D(Ts), effective diffusivity at surface temperature

D0

D(T0), effective diffusivity at bulk temperature

H

Ds/kgR0

h

heat-transfer coefficient

ΔH(T)

heat of reaction at temperatureT

ΔHc

ΔH(Tc), heat of reaction at core temperature

k

nucleation rate constant

kg

mass-transfer coefficient

ks

thermal conductivity of solid

Ke

equilibrium constant

n

constant, Eq. [7]

PCO2

partial pressure of carbon dioxide

r

radial position in pellet

rc

core radius

rs

pellet radius at any time

R0]

initial pellet radius

Rg

ideal gas constant

S

external surface area of pellet

t

time

T

temperature

T0

bulk temperature

Tc

core temperature

Ts

surface temperature

V

pellet volume

X

conversion

z

ratio of volume of product pellet to that of reactant pellet

Greek symbols

α

Eq. [17]

βc

Eq. [18]

ξ

r/R0

ξc

rc/R0

ξs

rs/R0

λ

ks/hR0

ψ

C/C*0

ψ

C*(Tc)/C*0

ψ0

C0/C*0

ρ

molar density

θ

T/T0

gqc

Tc/T0

θs

Ts/T0

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Copyright information

© The Minerals, Metals & Materials Society and ASM International 1992

Authors and Affiliations

  • S. G. Acharya
    • 1
  • S. K. Bhatia
    • 1
  • H. S. Shankar
    • 1
  1. 1.Department of Chemical EngineeringIndian Institute of TechnologyPowai, BombayIndia

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