Isothermal reactor

Isothermal reactor for carrying out exothermal or endothermal heterogeneous reactions comprising:

• a substantially cylindrical outer shell with longitudinal axis,
• at least one catalytic bed extending in the shell and comprising opposite perforated side walls respectively for the inlet of a gaseous flow of reactants and for the outlet of a gaseous flow comprising reaction products, and
• a heat exchange unit immersed in said at least one catalytic bed and crossed by a heat exchange fluid,
• wherein said at least one catalytic bed is delimited laterally by said opposite perforated side walls, wherein a first and a second interspace is defined between said shell and said perforated side walls, and in that said heat exchange unit comprises at least one succession of heat exchangers arranged substantially parallel to each other and substantially parallel to the direction in which said at least one catalytic bed is crossed by said gaseous flow of reactants.