Selective catalytic hydroconversion of bagasse-derived bio-oil to value-added cyclanols in water: Through insight into the structural features of bagasse

The chemical structures of bagasse and residue (RBE) from bagasse ethanolysis (BE) were characterized with multiple direct tools. According to solid-state 13C nuclear magnetic resonance (SS 13C NMR) analysis, the aromatic carbon content in bagasse is 21.1%, while ‘Oxy-methylene’ (28.2%) and ‘Oxy-methine’ (45.7%) are the most abundant among the aliphatic carbons. X-ray photoelectron spectrometric analysis shows that the oxygen atoms mainly exist in >C-O- moieties of bagasse, which is consistent with SS 13C NMR, thermogravimetric, and Fourier transform infrared semi-quantitative analyses, while the >C-O- moieties in RBE are obviously reduced, indicating that the >C-O- bond cleavage should be the major reaction during BE. Based on the analysis with a gas chromatograph/mass spectrometer, a series of alkyl-substituted phenols & benzenepolyols (39.85%), alkoxybenzenes (ABs, 3.02%), alkoxyphenols (APs, 11.29%), ketones (12.66%), and ethyl alkanoates (13.64%) were detected in ethanol-soluble portion (ESP) from BE. Interestingly, in one-pot, the total relative content of cyclanols in the selective hydroconverted ESP is as high as 69.18% over Ru/lanthanum hydroxide (Ru/La(OH)3) in water, suggesting that ABs and APs are converted to cyclanols via highly selective demethoxylation over Ru/La(OH)3, while many -OH groups are retained. The high yields of cyclanols demonstrate the potential for the selective hydroconversion of bagasse-derived bio-oil to value-added cyclanols.