Clean and effective catalytic hydrolysis of bagasse waste to small-molecular compounds over a hydrothermally stable Ru/La(OH)3

Abstract

Ruthenium/lanthanum hydroxide (Ru/La(OH)3), a hydrothermally stable catalyst, was prepared and used for catalyzing hydrolysis of bagasse, a sugar industry waste, to small-molecular compounds under low initial H2 pressure (IHP 0.2 MPa, 5% H2 in 4 MPa H2 and N2 mixture) at 240 °C. Neither oligomers nor char was formed and bagasse was almost completely converted into soluble portion (SPCH, 59.1 wt%) and gaseous products by the catalytic hydrolysis (CH). Obviously different from the methanol-soluble portion and ethanol-soluble portion from the bagasse methanolysis and ethanolysis, in total 104 organic compounds were detected in SPCH, among which alkyl-substituted phenols & benzenepolyols (38.8%), alkoxy-substituted phenols (22.2%), ketones (15.1%), and carboxylic acids (12.2%) are dominant according to the analysis with a gas chromatograph/mass spectrometer (GC/MS). Based on the analysis with a quadrupole exactive orbitrap mass spectrometer, heteroatom-containing compounds, especially oxygenates, are predominant in the SPs, while more species including smaller molecular fragments, can be identified in SPCH, which is consistent with the analysis with GC/MS. In addition, the catalytic hydroconversion of phenethoxybenzene over Ru/La(OH)3 further confirms that appropriately raising the temperature and reducing the IHP facilitate the formation and transfer of active H∙. In one-pot, clean and effective conversion of bagasse with low H2 consumption and in a green solvent can be achieved through this strategy.