A second-order irreversible gas-solid catalytic reaction 2A -> R is carried out isothermally in a packed bed reactor of height 3m and diameter 0.3m. The packed bed reactor can be treated as a CSTR. The reactor is filled with porous, 50mm diameter spherical catalyst pellets to give a bed voidage of 46%. In two trial runs, at the same temperature, the following data were obtained:
(a) Show that external mass transfer does not present a significant resistance under these reactor conditions.
(b) Determine the effectiveness factor and determine the reaction rate constant per unit area of catalyst surface.
Data:
Specific surface area 2.0 x 10^5 m^2 cat-surf/kgcat
Pellet density 1.2 x 10^3 kg/m^3 cat
Effective diffusivity of A in catalyst pellet 8.0 x 10^-7 m^3 gas/(mcat*s)
For a nth order GS catalytic reaction with sphere catalysts, φ = (R)/(3)√(((n+1)k_(es)C_(AS)^(E-1))/(2D_(el)))
1. A second-order irreversible gas-solid catalytic reaction 2A -> R is carried out isothermally in a packed bed reactor of height 3m and diameter 0.3m. The packed bed reactor can be treated as a CSTR. The reactor is filled with porous, 50mm diameter spherical catalyst pellets to give a bed voidage of 46%. In two trial runs, at the same temperature, the following data were obtained:
Run Volumetric Inlet concentration of A (kmol/m^3 gas) Exit concentration of A (kmol/m^3 gas) flow rate (m^3 gas/s)
1 0.0143 0.0360 0.025
2 0.025 0.025 0.0060
(a) Show that external mass transfer does not present a significant resistance under these reactor conditions.
(b) Determine the effectiveness factor and determine the reaction rate constant per unit area of catalyst surface.
Data: Specific surface area 2.0 x 10^5 m^2 cat-surf/kgcat Pellet density 1.2 x 10^3 kg/m^3 cat Effective diffusivity of A in catalyst pellet 8.0 x 10^-7 m^3 gas/(mcat*s)