Efficient corn stover-derived metal-supported biochar catalyst for hydrogenation of xylose to xylitol

Abstract

Xylitol, one of the top twelve chemical building blocks, is commercially synthesized through the xylose hydrogenation reaction using a metal catalyst. Biochar has emerged as an eco-efficient catalyst support material. In this study, biochar derived from corn stover (BCS) was first used as a metal catalyst support material for xylose hydrogenation into xylitol. The catalyst was prepared by carbonizing corn stover (CS), impregnating the resulting biochar with metal, and reducing the metal-impregnated BCS. The catalyst characteristics were comprehensively explored. The Ru/BCS catalyst was employed in xylose conversion to xylitol at different process temperatures (100 – 160 °C), retention times (3 – 12 h), H2 pressures (2 – 5 MPa), and Ru contents (1 – 5 %). The highest xylitol yield (87.0 wt.%) and selectivity (91.6 %) were derived at 120 °C for 6 h under 4 MPa H2 using 5 % Ru. Interestingly, the Ru/BCS catalyst showed high stability under the promising process condition. Additionally, xylitol production from hydrolysates enriched with CS xylose was subsequently explored. On the other hand, the catalyst characterization results revealed that the superior catalytic efficiency of 5Ru/BCS was mainly due to the metal nanoparticles embedded in the biochar. Additionally, BCS proved to be an outstanding support material for a bimetallic hydrogenation catalyst (Ru-Ni/BCS). Therefore, these results indicate that BCS can be a competitive support material for metal hydrogenation catalysts, enhancing environmental friendliness and potentially being employed in industrial-scale xylitol production.