Device for liquefying gaseous dihydrogen for offshore or onshore structure

A device for liquefying gaseous dihydrogen resulting from the evaporation of dihydrogen in the liquid state stored in at least one tank, the liquefaction device comprising at least one heat exchanger with a plurality of passes, at least one supply branch configured to bring at least a portion of the gaseous dihydrogen from the tank to a gaseous dihydrogen consumer, a part of the supply branch passing through the heat exchanger via a first pass inside which is disposed a catalyst involved in the conversion of the para isomer of the dihydrogen into ortho isomer of the dihydrogen, the liquefaction device comprising at least one cooling branch configured to liquefy at least a part of the gaseous dihydrogen, the cooling branch having at least one compression member, a portion of the cooling branch passing through the heat exchanger via a second pass disposed after the compression member, the second pass exchanging heat energy with the first pass in order to liquefy at least a part of the dihydrogen circulating in the cooling branch.