Processes and Balances
Reactors, Conversion & Yield
13 min · 2 worked examplesFree
Batch or continuous, stirred or tubular, and the difference between converting reactant and actually getting product.
After this lesson you can
- Tell conversion, selectivity and yield apart
- Choose between batch and continuous
- Say what a catalyst does and does not change
Three measures
Three numbers describe a reactor and they are constantly confused.
Conversion is the fraction of the limiting reactant consumed. Selectivity is the fraction of what reacted that became the product you wanted, rather than a by-product. Yield is the product of the two, how much of what you fed became what you wanted.
High conversion with poor selectivity is a bad reactor. You have used up the feedstock and made something you now have to separate and dispose of, which costs twice.
Often the best operating point is deliberately low conversion with excellent selectivity, with the unreacted feed recycled. That is why the mass balance lesson comes first: recycle is what makes a low-conversion reactor economic.
In the full lesson
- Three measures
- Reactor types
- Catalysts in practice
Free with an account. Read it, work the examples, answer the questions, then build it in the simulator.