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[csandoval]

Hi, I'm a Chemical Engineering student and I have a question about the design of a packed bed tubular reactor for heterogeneous catalysis on steady-state. I'm using Matlab to solve the one-dimensional model with axial dispersion:

 

 

Where C_Ab is concentration, z is the length of the packed bed, D_AB is the dispersion, U is superficial velocity, r_A is the reaction rate and rho_b is the packed bed density.

 

I've been working on this a lot but I can't find the problem. Heres is the Matlab code just if you can help me. 

clear all; clc
%butanotiol+heptano
%T=25ºC


Deff=0.046E-8        %m2/s
ro_b=167.9400;      %kg/m3
L=4.27;                   %m
U=0.0024/0.327;     %m/s
k=4.68E-2                %m6/(mol*s*kg_cat)
Ca0=6.05;                %mol/m3


%ODE
z=0:0.000001:L;
z1=z';
y0=[Ca0; 0]
ode_react = @(z,y)react(z,y,U,Deff,ro_b,k);
[z,y]=ode15s(ode_react,z1,y0)
plot(z,y(:,1))
ylabel('Concentración Ca [mol/m3]')
xlabel('z   [m]')

function

function dy=react(z,y,U,Deff,ro_b,k)
dy = zeros(2,1);
dy(1)=y(2);
dy(2)=(U./Deff).*y(2)-k.*ro_b.*(y(1).^2)./Deff;
end

Thanks for everything.