Py-GC/MS characterization of a wild and a selected clone of Arundo donax, and of its residues after catalytic hydrothermal conversion to high added-value products.

Two analytical procedures based on gas chromatography and mass spectrometry were used to study the compositions of a wild population and a selected clone (Torviscosa) of giant reed (Arundo donax L.), one of the most promising biomass both in terms of energy and fine chemicals production. Gas chromatography/mass spectrometry (GC/MS) was used to characterize and quantitatively determine the monosaccharide composition. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), using hex- amethyldisilazane (HMDS) as a derivatising agent, was used to characterize the lignocellulosic polymers. Analytical pyrolysis was also used to study the composition of residues left after the catalytic hydrolysis used to convert cellulose to levulinic acid and hemicellulose to furfural. GC/MS allowed us to determine the monosaccharide composition and polysaccharide content of the giant reed samples, highlighting that there was no significant difference between the wild population and the selected clone. GC/MS also highlighted that the giant reed leaves have a higher percentage (roughly 60%) of polysaccharide material than the stalks, which contain approximately 50%. Py-GC/MS, following the disappearance of the pyrolysis products of polysaccharides, showed that 150 ◦ C and 190 ◦ C are the best temperatures to obtain the complete catalytic conversion of hemicellulose and cellulose, respectively. Analytical pyrolysis also highlighted that in the course of catalytic hydrother- mal conversion a partial depolymerisation of lignin was obtained. In particular, the formation of lignin units containing free phenol groups via the cleavage of the ��-aryl ether bonds was demonstrated. The presence of these free phenols in the lignin network suggests the possible exploitation of lignin residues as antioxidant components or in high value biopolymer industries rather than the traditional use as low-value fuel for energy production.