Catalytic hydroconversion of a wheat straw soda lignin: Characterization of the products and the lignin residue

A wheat straw soda lignin was characterized and converted into gases and liquids under H2 pressure, at 350 °C over a supported NiMo sulfide catalyst, using tetralin as a hydrogen-donor solvent in a batch autoclave. The aim of this work was to evaluate the transformations occurring during the temperature increasing step to reach a pseudo-t0 and the impact of the catalyst presence in the mixture. A well-developed products separation protocol made possible to isolate and to characterize gases, organic liquid, lignin residue and solids (catalyst and char). A limited quantity of solids (or char) was produced however. As the lignin residue is one of the main intermediates of the lignin conversion pattern, the nature of this material has to be carefully determined. Thanks to several appropriate characterization techniques (GPC, NMR, FTIR), the conversion was followed and the lignin residue was compared to the initial lignin in order to understand the transformations occurring during the process.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Characterization of a wheat straw soda lignin (FTIR, GPC, 1D and 2D NMR) and lignin residue. ► Implementation of an experimental product recovery protocol leading to 98 wt% of mass balance after conversion. ► Hydroconversion into liquid (65 wt%) and gases (9.8 wt%) with a NiMo/Al2O3 catalyst. ► Qualitative analysis of the products in the liquid phase (2D-GC–MS).