Noémie Perret

The chemical valorization of lignocellulosic biomass is of fundamental importance for the sustainable production of chemicals. Among them ethylene and propylene glycols are useful products that can be obtained from lignocellulose using heterogeneous catalysts. It has been reported that catalysts composed of supported Ni and W carbides promote this transformation. We intend in this article to bring new insights by reporting a deep investigation of Ni‐W x C/AC (x=1 or 2) materials, including the preparation modes, the comparison of the surface species composition and their impact on the catalytic cellulose hydrogenolysis into ethylene and propylene glycol. The composition of materials obtained by the preparation mode consisting in the co‐impregnation of W and Ni on the carbon support was influenced by the amount of W and Ni. It appears that a catalyst composed of 5 wt% Ni and 30 wt% of W allowed the formation of a material presenting only the W 2 C phase and two alloys Ni 3 W 17 and Ni 6 W 6 C. The preparation mode consisting in forming W x C phases on the carbon support before Ni impregnation allowed the selective formation of W 2 C/AC or WC/AC depending on the carburization conditions. The catalyst prepared by the co‐impregnation showed the most important synergetic effect between Ni and W sites leading to high yields into ethylene and propylene glycol from cellulose, hemicellulose or pine wood. In addition, this catalyst showed a much higher stability with a good reusability.

This study describes the use of novel Cu/ZnO/ZnAl 2 O 4 /PAAH (PAAH=polyacrylic acid) hybrid nanomaterials for glycerol hydrogenolysis. Their elaboration by sol‐gel process either in one step or in two steps allowed to modulate their structural properties in terms of specific surface area, Lewis acidity, sizes and dispersion of copper nanoparticles. The presence of PAAH and aluminium during the synthesis particularly showed benefits in terms of dispersion and metal‐support interaction. The characterization of the catalyst surfaces in composition and size of the copper nanoparticles allowed to establish structure‐reactivity relationships. Their optimization allowed to reach remarkable conversions up to 96 % with selectivity towards 1,2‐propanediol of 83 %. A recyclability study also showed a possible reuse of these catalysts after a reactivation step.