Membrane Permeability Map

This graph shows the relation between reaction rate (expressed as the Damkohler number, Da) and the permeability of the membrane. B is the dimensionless heat release.The ranges of membrane permeability for which the membrane reactor did better than the plug-flow reactor were obtained from the trajectories that passed through the upper left quadrant of the reactor performance plane. The trajectories gave lower and upper limits on the membrane permeability range over which the MR would have an advantage. These quantities are plotted in the figure shown on the right to delineate the MR-favorable regions. For each value of B, two curves are shown, the upper full one corresponding to the upper limit on membrane permeability and the lower dashed curve corresponding to the lower limit on membrane permeability. Below the lower limit, the conversion of the MR was too low for it to compete with the PFR, due to the low supply of reactant A. Above the upper limit, the supply of reactant A was too high, leading to a loss in selectivity and giving yield below that of the PFR once more. As the heat-of-reaction parameter B increased, the MR-favorable region extended to lower values of Da, and over a wider range of permeability. In particular, the lower limit on permeability decreased with higher B, since the higher temperatures in the reactor allowed the conversion level to be maintained at lower levels of A.