Analysis of intermediate product yield in distributed-feed nonisothermal tubular membrane reactors

A comparative study of yield to intermediate products obtained from the dis tributed-feed membrane reactor (MR) and the conventional cooled-tube plug-f low reactor (PFR) is presented. The nonisothermal, nonadiabatic one-dimensi onal pseudohomogeneous reactor model was used. The analysis is presented in terms of the usual dimensionless groups (Damkohler number (Da), heat of re action parameter, Stanton number (St), etc.) and delineates regions of para meter space where the membrane reactor gives improved yield with no higher maximum temperature. Optimal conditions for the PFR usually lie on or close to the boundaries between either pseudo-adiabatic operation (PAO) or hot-s pot operation (HSO), and runaway operation. Results show that when compared under optimal operating conditions and at t he same catalyst volume, reactant feed rate, temperature and pressure, the membrane reactor performance is better than that of the PFR only over restr icted regions of parameter space. In general, distributed feed is preferred at higher Da, and under conditions of high heat release or lower cooling r ates. The distributed-feed reactor performance can be enhanced by a mixed-f eed strategy, or by slightly increased inlet temperature. (C) 2001 Elsevier Science B.V. All rights reserved.