Question

- The gas phase oxidation of nitric oxide is given as; 2NO+ O2 --> 2NO2

?rO2 = k(CNO)^2 (CO)^2 kmoles/m3 .h

The feed stream containing 9% NO, 8% O2, 1% NO2 and 82% N2 is fed to an isothermal PF reactor with a rate of 10000 m3 /h at 450oC and 2 atm. The reaction rate constant is given as 0.7x104 (kmoles/m^3 )^-2 h^-1

a) Setup a stoichiometric table and express the concentration of each species in the reaction as a function of conversion by evaluating all constants.

b) Calculate the reactor volume in order to achieve 5 moles of NO2 per mole NO in product stream

Answer 1

solution

the reaction is

rate of reaction

as we know that volume fraction is eqaul to the mole fraction

from the reaction given in the question we observed that that two moles of NO needs one mole of O₂ to form two moles of NO₂

let the the conversion of O₂ be X

species	reactant stream(moles)	product sream(mole remains)
NO	900	900-2*800X=900-1600X
O2	800	800-800X
NO2	100	100+2*800X = 100+1600X
N2(Inert)	8200	8200

solution B

according to the question the product sream contains five moles of NO₂ and one mole of NO

from the reaction above two moles of NO gives two moles of NO₂ to acheive the given condition feed should contain six moles of NO to form five moles NO₂ and one mole of NO

X_A = 5/6 = 83.33%

the performance equation of PFR is

.

here A is NO

-r_A= K(C_A0)²(1-X_A)²(0.5*C_A0*X_A)²

when we put the value of rate of reaction and integrate the term by putting the limits the result is in determinant or diverges because we put the rate of reaction of oxygen we have to put rate of reaction of NO

so some more data

reaction rate constant

reaction rate expression for NO if reaction is not elementry reaction