Reactor internal combustion exchanger for endothermic reaction in a fixed bed.

An exchanger-reactor (1) comprising: - an enclosure (2) - means of distributing a load through a catalytic zone in fixed bed (10), - collecting means (6) of the effluent from the catalytic zone (10 ), - heating means of the catalytic zone (10), wherein said collecting means (6) include ducts passing through the catalytic zone (10) from side to side, said ducts distributed being in the catalytic zone and interposed between the heating means, and wherein the heating means of the catalytic zone are contained in sheaths (8) immersed in part in the catalytic zone (10), the sheaths (8) open at one end and closed at the other, the open end fixed to an upper tube plate (21) delimiting the collection chamber (19) located above the catalytic zone (10) being, said heating means comprising at least one combustion zone (13 ) located in the proximi ties of the catalytic zone, means for supplying said combustion zone (13) with oxidant gas mixture (15) and a gaseous fuel (17), and means for evacuating the gaseous effluent from the combustion (14).