Question 1) The gas phase reaction (A→ B+C) must be carried out in a fixed-bed tubular reactor using a solid catalyst in a spherical shape of 0.4 cm in diameter. The reactor must operate isothermally at 573 K and an inlet pressure of 1 atm. The reaction is first order and the reactor is fed with pure A at a molar flow of FA0-1 g-mol/s. The internal diameter of the reactor must be 2.54 cm.It is known: -The reaction on the surface of the catalyst is of the type r₁=kCA.; -The particle density gp=2 g/cm3; -The porosity of the bed gl= 0.40.-This reaction, when carried out using the catalyst in powder form, obtained a speed of R 1 10-3 g-mol/g-cat.s, at a temperature of 573 K and pure reagent A at a pressure of 1 atm .-Consider that the reactor is being operated under conditions free from resistance to external mass transfer to the particle.-The effective molecular diffusivity in the gas phase (DAB) to solve this exercise must also be considered constant with the temperature and composition DAB=2.0 10-4 cm2/s.We ask: a) Make the differential mass balance, in steady state, for one of the reactants inside an infinite plate of porous catalyst. Non-dimensionalize the resulting differential equation, so that the Thiele modulus appears. b) Sketch an effectiveness factor curve versus Thiele’s modulus. Show, on this curve, the regions where the diffusional resistance in the pores is negligible (which is the controlling stage in this case?) and where this resistance is the controlling stage (the asymptotic region). Calcule: 1) O valor do modulo de Thiele; 2)O valor do fator de efetividade; 3) O comprimento do reator para se obter a conversão na saída do reator XA=0,8.
Question 1) The gas phase reaction (A→ B+C) must be carried out in a fixed-bed tubular reactor using a solid catalyst in a spherical shape of 0.4 cm in diameter. The reactor must operate isothermally at 573 K and an inlet pressure of 1 atm. The reaction is first order and the reactor is fed with pure A at a molar flow of FA0-1 g-mol/s. The internal diameter of the reactor must be 2.54 cm.
It is known: -The reaction on the surface of the catalyst is of the type r₁=kCA.; -The particle density gp=2 g/cm3; -The porosity of the bed gl= 0.40.
-This reaction, when carried out using the catalyst in powder form, obtained a speed of R 1 10-3 g-mol/g-cat.s, at a temperature of 573 K and pure reagent A at a pressure of 1 atm .
-Consider that the reactor is being operated under conditions free from resistance to external
-The effective molecular diffusivity in the gas phase (DAB) to solve this exercise must also be considered constant with the temperature and composition DAB=2.0 10-4 cm2/s.
We ask:
a) Make the differential mass balance, in steady state, for one of the reactants inside an infinite plate of porous catalyst. Non-dimensionalize the resulting differential equation, so that the Thiele modulus appears.
b) Sketch an effectiveness factor curve versus Thiele’s modulus. Show, on this curve, the regions where the diffusional resistance in the pores is negligible (which is the controlling stage in this case?) and where this resistance is the controlling stage (the asymptotic region).
Calcule: 1) O valor do modulo de Thiele; 2)O valor do fator de efetividade; 3) O comprimento do reator para se obter a conversão na saída do reator XA=0,8.
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