Fishery waste valorization: Sulfated ZrO(2) as a heterogeneous catalyst for chitin and chitosan depolymerization

Chitin and chitosan are abundant unique sources of biologically-fixed nitrogen mainly derived from residues of the fishery productive chain. Their high potential as nitrogen-based highly added-value platform molecules is still largely unexploited and a catalytic way for their valorization would be strongly desirable within a biorefinery concept. Here we report our results obtained with a series of heterogeneous catalysts in the depolymerization of chitosan and chitin to acetylglucosamine. Copper catalysts supported on SiO(2), SiO(2)–Al(2)O(3), SiO(2)-ZrO(2), ZrO(2) and the corresponding bare oxides/mixed oxides were tested, together with a sulfated zirconia system (ZrO(2)-SO(3)H) that revealed to be extremely selective towards glucosamine, both for chitosan and chitin, thus giving pretty high yields with respect to the values reported so far (44% and 21%, respectively). The use of a heterogeneous catalyst alone, without the need of any additives or the combination with a mineral acid, makes these results remarkable.