Reactor for multiphasic reactions

A reactor for multiphasic reactions which comprises a body manufactured in a single part which comprises a plurality of parallel tubes is provided. The parallel tubes are arranged for containing a catalyst and also for circulation of reactant in contact with the catalyst and wherein the internal diameter of such tubes is less than 4 mm. A reaction unit which comprises a reactor, a housing, inlets and outlets and a preheater is also provided. Methods for manufacturing such reactor are also provided.