Evaluate Catalyst Replacement Economics: Part 1 — Periodic Replacement


When is it time for fresh catalyst in your fixed-bed reactor? This article gives you the tools to determine the optimal replacement interval.

Catalysts play a key role in process design and operation in the refining and chemical industries, and their costs can be a significant factor in chemical value chains. The global catalyst market is worth about US$29 billion (1), $6.8 billion of which is in the refining industries (2).

Aged catalyst may not perform as well as fresh catalyst, in terms of its:

  • kinetic activity (ability to keep up with production demand)
  • selectivity to a desired product
  • physical stability, which can affect attrition and pressure drop.

Operating conditions can sometimes be modified to mitigate catalyst aging — for example, by raising operating temperature to maintain activity, or by changing feed compositions to improve selectivity. Increasing the recycle of unreacted raw material and removing unwanted components (and nonselective components that participate in side reactions) will increase operating costs.

As the performance of aged catalyst deteriorates, the process requires more raw material input and higher utility usage. Eventually, the process will reach equipment constraints and production will become limited.

Author Bios: 

Gary Sawyer, P.E.

Gary Sawyer, P.E., has more than 35 years of experience in the chemical industry, most of which has been supporting business and R&D decision analysis with process design, economic evaluations, and competitive technology assessments.  He was employed by Lyondell Chemical (formerly ARCO Chemical), and by Union Carbide prior to that.  He is now a consultant practicing as Process Evaluations LLC.  He holds a B.S. and M.S. degree in chemical engineering from Rensselaer Polytechnic Institute, and serves as an Industrial Consultant for the University of Pennsylvania....Read more

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