A new solid-liquid-liquid reactor has been developed in order to simultaneously benefit from the advantages of both the catalytic activity and molecular sieve properties of the zeolites, the superior performances of concentration gradient reactors for positive order consecutive chemical reactions and the extraction of an intermediate target product by a solvent with countercurrent flows. The first reaction experimented with, was the acido-catalyzed dehydration of the hexoses into 5-hydroxymethylfurfural. The study was divided in two parts : (1) laboratory tests in a 0.3-liter batch reactor where mordenites were found to be the most selective catalysts, (2) chemical engineering studies : first, hydrodynamic tests where the systems tested ([water . hexose . zeolite]-methylisobutylketone) enable large through-put capacities, second, chemical tests in a stainless steel pulsed column of 25 mm in diameter and 8220 mm in height. Simultaneously, same simulations have been executed on a software designed by CEA for liquid-liquid extractions and modified by introducing chemical reactions.