Hydrotreatment of Kraft Lignin to Alkylphenolics andAromatics Using Ni Mo and W Phosphides Supported on Activated Carbon

摘要

The conversion of lignin to biofuels and biobased chemicals is currently attracting a lot of attention. We here report on the valorization of Kraft lignin by a catalytic hydrotreatment using Ni, Mo, and W phosphide catalysts supported on activated carbon in the absence of an external solvent. Experiments were carried out in a batch setup in the temperature range of 400–500 °C and 100 bar initial H2 pressure. The synthesized catalysts were characterized by X-ray diffraction, nitrogen physisorption, and transmission electron microscopy. The lignin oils were analyzed extensively by different techniques such as GPC, GC-MS-FID, ¹³C NMR, and elemental analysis. Two-dimensional gas chromatography (GC×GC-FID) was applied to identify and quantify distinct groups of compounds (aromatics, alkylphenolics, alkanes, etc.). Mo-based catalysts displayed higher activity compared to the W-containing catalysts. The reaction parameters such as the effect of reaction temperature, reaction time, and catalyst loading were studied for two catalysts (15MoP/AC and 20NiMoP/AC),and optimized reaction conditions regarding yields of monomeric componentswere identified (400 °C, 100 bar H2 at RT, 10 wt %catalyst loading on lignin intake). The highest monomer yield (45.7wt % on lignin) was obtained for the 20NiMoP/AC (Ni 5.6 wt %, Mo 9.1wt %, P 5.9 wt %) catalyst, which includes 25% alkylphenolics, 8.7%aromatics, and 9.9% alkanes. Our results clearly reveal that the phosphidecatalysts are highly efficient catalyst to depolymerize the Kraftlignin to valuable biobased chemicals and outperform sulfided NiMocatalysts (monomer yield on lignin < 30 wt %).