The aqueous-phase heterogeneously catalysed isomerisation of bio-oil derived glyoxal is herein introduced as a novel route for the sustainable production of glycolic acid. While commercial ultra-stable Y zeolites displayed only moderate performance, their evaluation enabled to highlight the crucial role of Lewis acidity for the reaction. Gallium incorporation in these zeolites boosted the glycolic acid yield, but the best catalytic results were obtained over tin-containing MFI-type zeolites, reaching 91% yield of the desired product at full conversion. These materials comprised hydrothermally-synthesised Sn-MFI as well as a novel catalyst obtained by the introduction of tin in silicalite-1 by means of a simpler and more scalable method, i.e. alkaline-assisted metallation. In-depth spectroscopic characterisation of these systems uncovered a substantial similarity of the tin centres obtained by the top-down and bottom-up synthetic approaches. NMR spectroscopic studies gave evidence that the reaction follows a 1,2-hydride shift mechanism solely catalysed by Lewis-acid sites. The Sn-MFI analogue could be reused in 5 cycles without the need for intermediate calcination, did not evidence any tin leaching, and demonstrated suitable for utilisation under continuous-flow operation. Both tin-based zeolites exhibited remarkable performance also in alcoholic solvents, leading to the one-pot production of relevant alkyl glycolates.

The kinetics of the acid hydrolysis of arabinogalactans (AG) was studied isothermally in a batch reactor. AG was hydrolyzed with hydrochloric acid and the main parameters established were the acid concentration (pH), temperature and AG concentration. The hydrolysis rate increased with the acid concentration (pH) and temperature. Complete hydrolysis of AG to arabinose and galactose was achieved at 90°C and pH 1 without any further degradation of the sugars. A first-order kinetic model including two simultaneous reactions for the formation of arabinose and galactose was successfully fitted to the experimental data. The rate constants and activation energies were calculated from the model. The decrease of the average molecular weight was also explained by the model.

We disclose in this study a Ni 6 AlO x catalyst prepared by coprecipitation for the reductive amination of biomass-derived aldehydes and ketones in aqueous ammonia under mild reaction conditions. The catalyst exhibited 99% yield toward 5-aminomethyl-2-furylmethanol in the reaction of 5-hydroxymethyl furfural with ammonia at 100 °C for 6 h under 1 bar H 2 . The catalyst was further extended to the reductive amination of a library of aromatic and aliphatic aldehydes and ketones with a yield in the range 81–90% at optimized reaction conditions. Besides, 5-hydroxymethylfurfural could react with a library of primary and secondary amines with yields in the range 76–88%. The catalyst could be easily recycled and reused without apparent loss of activity in four consecutive runs.

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