METHOD FOR OLIGOMERISATION IN A CASCADE OF AGITATED GAS-LIQUID REACTORS WITH STAGED INJECTION OF ETHYLENE

The invention relates to a process for the oligomerization of ethylene, carried out at a pressure of between 0.1 and 10.0 MPa, at a temperature of between 30 and 200° C., in a cascade of N gas/liquid reactors in series, N being at least equal to 2, comprising a step of introducing a catalytic oligomerization system into at least the first reactor of the cascade, a step of bringing said catalytic system and an optional solvent into contact with ethylene by introducing said ethylene into the lower part of the reaction chamber of at least the first reactor of the cascade, for each reactor n, a step of withdrawing a liquid fraction in the lower part of the reaction chamber of the reactor n, the liquid fraction being separated into two streams: a first stream corresponding to a first, "main", part of the liquid fraction, which is conveyed to a heat exchanger for cooling; a second stream corresponding to the second part of the liquid fraction which constitutes the liquid feedstock of the following reactor n+1 in the cascade, a step of introducing said second part of the liquid phase withdrawn from the reactor n towards the reaction chamber of the following reactor n+1 in the direction of flow, a step of cooling said first part of the liquid fraction withdrawn from the reactor n in step c) by passing said first part of the liquid fraction into a heat exchanger in order to obtain a cooled liquid fraction, a step of introducing said liquid fraction cooled in step e) at the top of the reaction chamber of said reactor n, the steps a) to f) being carried out, unless indicated otherwise, for each reactor n of the cascade, n being between 1 and N. The invention also relates to a device of N stirred gas/liquid reactors in a cascade, enabling the oligomerization process to be carried out.