Methanol synthesis in a forced unsteady-state reactor network

Abstract The feasibility of carrying out the low-pressure methanol-synthesis process in forced unsteady-state conditions, using a network of three catalytic fixed bed reactors with periodical change of the inlet position, has been investigated; advantages and limitations in comparison with the previously proposed reverse-flow reactor have been highlighted. The effect of the main operating parameters—inlet temperature, switching time, inlet flow rate—has been studied. A cyclic-steady-state condition and auto-thermal behaviour are possible; nevertheless, they are attainable only for switching times varying in two narrow ranges. Out of these regions, complex steady-states of high periodicity, where conversion is low, or extinction of the reactors occur. For low values of the switching time, the establishing of optimal temperature profiles along the network allows higher conversions than in the reverse flow reactor. Furthermore, the performances of the network are weakly affected by wash-out, the removal of unconverted gas in correspondence of switching, which is in intrinsic disadvantage of reverse flow operation.