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SSCI-VIDE+CDFA+ADO:MET:NES:FRAInternational audienc

This article reports a detailed study on the reactivity of levulinic acid and cellulose with 1-butene and iso-butene for the catalytic formation of sec- and tert-butyl levulinates. The influence of catalyst type and various solvent conditions have been investigated to assess the potential of a sustainable transformation. A very simple and efficient procedure was discovered by using reusable Amberlyst-15 in the absence of solvent to form, from levulinic acid and iso-butene, tert-butyl levulinate (70 % yield), a compound very difficult to prepare by other means. sec-Butyl levulinate (66 % yield) was obtained by using Amberlyst-15 in γ-butyrolactone as a biosourced solvent. The original procedure was also extended notably by directly using cellulose as a reactant. In the presence of a catalytic amount of H SO , it was possible to form sec-butyl levulinate (19 % yield) from 1-butene in a more efficient way than by using the alcohol as an esterifying agent.

Recently, the photocatalytic conversion of glucose appeared as an environmentally friendly route to produce valuable molecules. However, the potential of this new route in comparison with the usual hydrothermal catalytic process remained questionable. In this paper, we compared the two routes using three commercial TiO 2 as catalysts in the same reactor. The TiO 2 superficial acidity and basicity were determined by calorimetry and FTIR of CO 2 , NH 3 and pyridine adsorption. Relationships between the acid-base properties, the TiO 2 glucose adsorption capacities measured in water and their photocatalytic or hydrothermal performances were proposed: while the photocatalytic performances could be linked to the catalysts' Lewis acid sites density and their glucose adsorption capacities, the hydrothermal performances were dependent of the catalysts' basic/acid sites balance. We highlighted that the conversion of glucose over TiO 2 was as efficient with the photocatalytic process at ambient temperature as with the hydrothermal process at 120°C. This underlines the potential of the photocatalytic route at the lab scale as regards to the milder experimental conditions involved.

The objective of the present work was to determine if wood sawdust can be used instead of isolated cellulose in the general solid‐acid‐catalyzed production of chemicals. The kinetics of model cellulose and pine‐wood sawdust liquefaction into lactic acid were determined in the presence of a solid Lewis acid, ZrW. The catalytic hydrolysis of pine wood was performed at 190 °C in a large‐scale batch reactor (2.5 L). Similar kinetic curves of lactic formation were obtained for cellulose and wood as substrates. Moreover, the initial lactic acid production rate of pine‐wood sawdust was higher than that of model cellulose, proving that, in spite of the presence of lignin/hemicellulose, the catalyst drives the transformation towards lactic acid formation. However, our results give also evidence of solid‐catalyst deactivation for both cellulose and wood substrates. This result indicates that if wood pretreatment can be bypassed, the bottleneck will be the solid‐catalyst regeneration and recycling.

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