Process for the controlled oligomerization of butenes

A process for the dimerization of isoolefins, the process comprising:

• feeding an oxygenate reaction modifier and a hydrocarbon feed to a fixed bed reactor containing an oligomerization catalyst, the hydrocarbon feed comprising isobutene and a secondary feed comprising butanes;
• reacting isobutene in the fixed bed reactor at oligomerization conditions to form a reaction effluent comprising reaction modifier, isobutene dimers, unreacted isobutene, any oxygenate high-boiling reaction byproducts formed, as well as butanes;
• without componential separation, feeding the reaction effluent to a second fixed bed reactor containing an oligomerization catalyst;
• reacting the unreacted isobutene in the second fixed bed reactor at oligomerization conditions to form additional isobutene dimers, recovering a second reaction effluent comprising reaction modifier, isobutene dimers, any oxygenate high-boiling reaction byproducts formed, as well butanes;
• without componential separation, feeding the second reaction effluent to a catalytic distillation reactor having a reactive distillation zone comprising an oligomerization catalyst;
• concurrently within the catalytic distillation reactor:
• reacting unreacted isobutene in the second reaction effluent to form additional isobutene dimers;
• separating the dimers and any oxygenate high-boiling reaction byproducts, recovered as a bottoms fraction, from the isobutane and n-butanes, and any unreacted isobutene, recovered as an overheads fraction;
• recycling the overheads fraction to the hydrocarbon feed.