[NaDoume]

Hi everyone. I am a student. I just finished my  first design for a fixed (single) bed reactor . The reactor hosts an exothermic heterogeneous catalytic reaction whereby a gaseous inlet stream undergoes consecutive multi-step reactions to form liquid intermediary reactants/products. All components produced are desired. My first question is how is selectivity defined when all products are desired, as molar rate of product A over total inlet molar rate or molar rate product A over total effluent molar rate?
 
Also , as this is a very exothermic reaction which can potentially lead to thermal runaway and the product selectivity is extremely sensitive to temperature, I want to operate the reactor isothermally. I am aware that hot spot generation will cause a problem. I am not using a slurry reactor as the catalyst according to literature shows prolonged activity without deactivation. The reactor more suitable to the process I am guessing is a multi-tubular trickle bed reactor?
 
I've done extensive research and I cannot find any sources to read from. Is the principle behind design of multi tubular reactor essentially the same as that of heat exchangers?(with the exception of kinetics etc). Is there a source/book where you could redirect me to? Would the Ergun pressure drop equation be applicable for a multi-tubular reactor?
 
Thank you for your time

[curiouscat]

You can define selectivity any which way so long as you are clear about which particular definition you are using.

Try the book by Walas. Also the handbook by McKetta. Perry's Handbook is another good source. Rules of Thumb by Branan should also have good heuristics.

[NaDoume]

Thank you very much