The maximally attainable productivity of perforated monolithic bed reactors has been compared to that of the traditional packed bed of spheres for the case of laminar flow conditions and first-order isothermal reaction kinetics. Using the E number established in Part 1, it could be shown in a very condensed, yet fully quantitative way that the maximal gain in total reactor productivity which can be obtained by switching from the tortuous pore system of the packed bed of spheres (large flow resistance) to the straight-running flow-through pores of a perforated monolithic bed (minimal flow resistance) typically is 25-40%. Much larger gains in total productivity can be obtained by using highly open-porous beds. Whether this high porosity is achieved using a perforated monolithic bed, a packed bed of hollow extrudates or a structured fibre-mesh bed is then only of secondary importance. The E number also allows to quantify the potential gain and the range of applicability of the more advanced reactor designs proposed in the past years (e.g., the parallel passage reactor). It could now be shown that the productivity gain of these advanced concepts can even amount up to a factor of 100. As these gains are to be realized in beds with ultra-small flow-through pores, the present study also provides a strong quantitative argument for the current research on (micro-)structured reactor beds. (C) 2003 Elsevier Ltd. All rights reserved.