Gas/liquid oligomerization reactor comprising transverse internals

A gas/liquid reactor for oligomerization of gaseous ethylene which can contain a liquid phase and a gas headspace, said reactor comprising:

• a reaction chamber (1) of elongated shape along the vertical axis;
• a means for introduction of gaseous ethylene (2), located in a lower part of the reaction chamber;
• a means for withdrawal (5) of a liquid reaction effluent, located in the lower part of the reaction chamber;
• a means for bleeding off (4) a gaseous fraction, located at a top of said reactor;
• wherein:
• said chamber (1) comprises at least two transverse internals (11) positioned over at least a part of a section of the chamber (1) of said reactor so as to increase residence time of the gaseous ethylene in the liquid phase;
• each of said internals exhibiting at least one opening (12) with a hydraulic diameter between 21 and 500 mm;
• and
• said opening (12) or the sum of the openings for an internal occupying between 20% and 80% of the total surface area of a cross section of the reaction chamber on which said internal is located.