It seems that you are working with a stiff system. In chemical engineering context, it means that very fast dynamics are coupled with very slow dynamics. For example, in a reaction, Temperature and Concentration may not change at a comparable rate. Generally, the rate of change of temperature is very low compared to that of composition or concentration.
So consider using 'ode15s' instead of 'ode45'.
I tried and it worked. However, there are a few other errors in your code. They may be minor ones.
Can you please upload the corrected code once you are done? I am somewhat interested in such models.
Best Wishes
