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Hysteresis and Multiple Steady States in Catalytic CSTRs in Series


In the simulation below, each continuous stirred tank reactor (CSTR) contains the catalyst in Reactor Lab, Web Labs, Lab 2, Dynamic diffusion and reaction in a porous solid catalyst. Conditions here are at the default conditions in Lab 2 with Model 2 kinetics, except this Κflow is smaller (0.014) to obtain higher conversion. Dimensionless variables are defined in Lab 2 info. The steady-state rate is the average dimensionless turnover frequency.

Each CSTR can exhibit two steady states at the same reactant concentration over a range of concentration because of the coupling between diffusion resistance in the isothermal porous catalyst and the self-inhibiting reaction. This four-reactor system can exhibit more than two multiple steady states at some concentrations.

Perform experiments to determine the ranges of reactant concentration over which multiple steady states are obtained in this lab. How many multiplicities can you find?

You can change the reactant concentration in the feed by moving the range slider or by typing a value between 0 and 1 in the input field, then hit the Enter/Return key or click out of the field. The dynamic response is determined only by the fluid space time in this lab, with the catalyst specified to be at pseudo-steady-state, whereas surface as well as fluid dynamics are present in Lab 2. When a steady state is reached, points are added to the second and third plots below. See this journal paper for a related physical system with experimental data (opens in new tab).

Enter reactant feed concentration:

Select reactor for SS conversion display: