ABSTRACT
Furthermore, the model proposed for rs can be modified by separating the effect of true surface area, temperature, and partial pressure of gas species on k' (T. PG), by using the power law:
k'(T,pG) = k(T)AsPu = k(T)A8y'af/' (15.38) where (m2 /g) is the pore surface per unit mass of the solid, YG is !he mole fraction of species G in the gas phase, p is the total pressure, and n is the power law constant to be determined experimentally. For most gas-solid reactions the dependence of the reaction rate constant on pressure could be lineaL i.e., n = 1. The rate expression /c(T) [g/(h · m2 · atmn] in Eq. (8.38) would be a function of temperature in the Arrhenius form,
I T) -To/ RT K(~ = Ap,se ( 8.39) which reduces rs to the form
dxjdt -EjRT rs = 1 _ x = f(x)As,oA, se YGP (8.40)
where Ap,s is the pre-exponential coefficient [g/(h · m2 • atm)], E is the activation energy mol), and R is the universal gas constant [8.31 J /(K · mol)].
