Mathematical modeling and parametric study of a dehydrogenation catalyst decoking process

• A kinetic model for decoking reaction of dehydrogenation catalyst is developed.
• A two-stage dynamic heterogeneous model is developed for regeneration process.
• Controlling the O2 concentration is the best strategy to prevent the catalyst sintering.
• The constant inlet O2 concentration of 5.5% reduces the regeneration duration by about 4 h.

The present study provides a dynamic mathematical model for a regeneration process of coked catalysts in a multi-tube fixed-bed reactor. Mass and energy conservation laws are applied to predict the temperature variation of gas and solid phases along the reactor length in two main stages: heating and coke burning. The kinetics of decoking is obtained by fitting the data taken from a pilot-scale reactor. The model results are compared with the experimental data taken from both a pilot-scale and a commercial-scale plant. The effect of operating parameters, including inlet gas flow rate, temperature, and composition on the reactor performance is studied. Controlling the O2 concentration is the best strategy to prevent the catalyst sintering. In order to reduce the regeneration process duration, two strategies are examined: constant and stepwise rising trend of inlet O2 concentration. Using the inlet O2 molar-fraction of 5.5% reduces the regeneration duration by about 4 h.

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