The Pseudoadiabatic Operation (PO) of a fixed-bed catalytic reactor is an operating regime in which the temperature profile is monotonically increasing with the axial coordinate. It can be achieved in co-currently cooled reactors where the heat transfer fluid is a non-boiling liquid. This mode of operation has intrinsic advantages with respect to the hot-spot temperature profile usually experienced by packed bed units for exothermic reactions, such as better control of the temperature distribution and much less parametric sensitivity.;The PO was demonstrated experimentally for the first time in a pilot-plant-scale unit converting methanol to hydrocarbons.;Theoretical developments of the PO concept are also summarized in the present report. It was shown that the transition between PO and hot-spot operation occurs through an intermediate regime, and this was also confirmed by the experiments.;Based on mathematical simulations of the reactor, analytical a priori criteria for the determination of the operating regime were obtained. Comparison of the PO reactor with countercurrently cooled units showed remarkable advantages of the novel concept.;The experimental reactor used in this study was 2 cm in diameter and 2 m long, and it utilized a ZSM-5-class zeolite catalyst. It was observed that Pseudoadiabatic temperature profiles were consistently obtained, and that the Pseudoadiabatic Operation was compatible with high methanol conversions (80 to 100%). Under these conditions, the quality of the hydrocarbon products was satisfactory, the liquid fraction having a RON of 95-97.;The reactor throughput was comparable with that of existing methanol conversion processes.;Finally, it was verified that the process was flexible enough to provide different product distributions under the operating conditions tested
