Best oral presentation award

Here is a summary of the presentation:

Glycols as ethylene glycol (EG) and propylene glycol (PG) cover a wide range of applications, in particular for the polymer industry or as synthesis precursors. To date, these compounds are produced from fossil resources. The possibility to obtain polyols on a large scale from renewable biomass, in particular from lignocellulosic biomass, is therefore of particular importance in the context of the development of biorefineries. However, the production of low carbon number polyols starting from complex molecules with a high molecular weight is challenging in view of the complexity of the reaction pathway involving cascading reactions that require various catalytic sites.

As example, the formation of EG or PG from cellulose implies three consecutive reactions: (1) hydrolysis of polysaccharides to sugars by Brønsted acidity, (2) retro-aldol condensation of sugars by Lewis acidity and (3) hydrogenation of low carbon number polyols. An innovative catalysts designed by our group [1] containing nickel tungsten carbides supported on carbon (5%Ni-30%W2C/AC) is able to conduct the proper reactions successively due to the catalytic synergy between both sites W2C and the Ni17W3 alloy. The reactions are typically carried out in water at 160-250°C, under 60-100 bar of H2, giving yields between 40 to 80 mol% of glycols accompanied by various intermediates (as hydroxyacetone) or side products (as mannitol) coming from parallel reactions that compete with the main pathway (Fig. 1) [2]. The comprehension of the reaction pathways involved in the transformation of cellulose to glycols is then required to enhance the glycols productivity. For that, the catalytic conversion of glucose in the presence of 5%Ni-30%W2C/AC was done with regular sampling over time and the main intermediates compounds were identified and quantified by HPLC-RID-UV in order to study the kinetic of reaction. A design of experiments with the variation of parameters (stirring, temperature, pressure, concentration) has been performed to acquire sufficient experimental data in order to build a consistent kinetic model by computational method. This model will integrate reaction and diffusion for different stages of the reaction allowing the understanding of the mechanisms involved in the transformation of lignocellulosic biomass to polyols.

Figure 1: Reaction pathways from glucose to polyols.

For more information about the project : https://catremo.cnrs.fr/

[1] F. Goc, T. Epicier, N. Perret, F. Rataboul, Preparation of Carbon-Supported Tungsten Carbides: Comparative Determination of Surface Composition and Influence on Cellulose Transformation into Glycols, ChemCatChem. 15 (2023) e202201496.

[2] N. Ji, T. Zhang, M. Zheng, A. Wang, H. Wang, X. Wang, J.G. Chen, Direct Catalytic Conversion of Cellulose into Ethylene Glycol Using Nickel-Promoted Tungsten Carbide Catalysts, Angew. Chem. Int. Ed. 47 (2008) 8510–8513 ; R. Ooms, M. Dusselier, J.A. Geboers, B. Op de Beeck, R. Verhaeven, E. Gobechiya, J.A. Martens, A. Redl, B.F. Sels, Conversion of sugars to ethylene glycol with nickel tungsten carbide in a fed-batch reactor: high productivity and reaction network elucidation, Green Chem. 16 (2014) 695–707.