Consider the following reactions taking place in a CSTR: species decomposes by three simultaneous reactions to form three products—one desired, , and two undesired, , and ,

,

,

.

These are called the Trambouze reactions [1]. Here and with and are the reaction rates and rate constants, respectively, and is the concentration of species .

The selectivity of species is given by the ratio ,

the reactor residence time is , the CSTR is operated at an effluent concentration of species , , that maximizes the selectivity of the desired product , the feed stream contains only species at a concentration equal to 1, and the initial concentrations of species , , and are taken equal to zero, with . The optimum effluent concentration of reactant , , and the time plot of the reactor start-up are shown for values of time and that are set by the user.