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[oldwhpsian]

Hello friends!

 

Quick question, it seems rather simple but I can't wrap my head around it. I'm doing some experiments in the lab. Initially I was trying to determine a kinetic expression for a heterogeneous reaction. Soon I realised that I was seeing a constant reaction rate regardless of inlet concentration. This didn't make sense to me, until I realised that the concentration rage is extremely narrow (13 uM to 0), and so I'm happy to assume that the rate will be constant across these concentrations.

 

I have a value for k, which I found by plotting the reactant concentration against catalyst weight (i.e. catalyst mass seen by the reactive mixture). Plotting [conc] vs weight gives me a straight line with a slope of -0.2, which should be the k that I am looking for, correct? Assuming what I'm doing can be reduced down to zero-order kinetics.

 

The trouble comes in when I consider the material flows. I was using 1g of catalyst bed and a liquid flow of 25 mL/min. Obviously, the liquid flow will affect the residence time and in turn the rate. How do I determine a rate constant, k, that accounts for variable flows?

 

I hope this makes sense.

 

Regards!