Thin multi-stage catalytic reactor with internal heat exchanger, and use thereof

A reaction vessel that is elongated substantially along a substantially vertical axis, comprising at least two stages in the vertical direction, in which at least one endothermic or exothermic catalytic reaction is carried out, comprising:

• at least one catalytic reaction zone (12a, 12b) per stage (6, 7) and extending substantially along the axis of the vessel;
• means (2) for introducing at least one reaction fluid to a stage adapted for substantially transverse fluid movement over substantially the whole vertical extent of the reaction zone;
• means for introducing catalyst into the reaction zone and means for extracting catalyst from the reaction zone;
• at least one means (5a) for heat exchange with the reaction fluids, located inside the vessel between two successive reaction zones;
• means (6) for transporting reaction fluids from one stage to another connected firstly to a heat exchange means and secondly to the reaction zone;
• means for recovering reaction fluids downstream of the last stage;
• the thickness of each reaction zone being determined to limit the variation in temperature in said zone and the heat exchange means being adapted to adjust the temperature of the reaction fluids entering the reaction zone to a level substantially at most equal to that of the temperature of the reaction fluids entering the preceding zone.