No abstract

The selective hydrogenolysis of 5-hydroxymethylfurfural (HMF) platform molecule to 2,5-dimethylfuran (DMF) has attracted increasing attention due to its broad range of applications. However, HMF, with multiple functional groups, produces various byproducts, hindering its use on an industrial scale. Herein, a bimetallic Pt-FeOx/AC catalyst with low Pt and FeOx loadings for selective HMF hydrogenolysis to DMF was prepared by incipient wetness impregnation. The structures and properties of different catalysts were characterized by XRD, XPS, TEM, ICP-OES and Py-FTIR techniques. The addition of FeOx enhanced Pt dispersion and the Lewis acidic site density of the catalysts, and was found to be able to inhibit C=C hydrogenation, thereby im-proving DMF yield. Moreover, the presence of Pt promoted the reduction of iron oxide, creating a strong interaction between Pt and FeOx. This synergistic effect originated from the activation of the C–O bond over FeOx species followed by hydrogenolysis over the adjacent Pt, and played a critical role in hydrogenolysis of HMF to DMF, achieving a yield of 91% under optimal reaction conditions. However, the leaching of Fe species caused a metal–acid imbalance, which led to an increase in ring hydrogenation products.

To investigate the influence of dilute acid pickling on pyrolysis behavior and product distribution during rape straw (RS) pyrolysis, HCl, HF, and HCl + HF were selected. Proximate and ultimate analysis, ICP-AES, SEM, and BET were employed to examine the composition and the physicochemical properties of the biomass. It is found that the alkali and alkaline earth metals (AAEMs) in RS were obviously removed by acid pickling, especially HCl. Fixed bed pyrolysis data showed that liquid product increased from 37.48 wt % (RS) to 42.24 wt % (RS-HCl), 48.03 wt % (RS-HF), and 47.20 wt % (RS-HCl + HF). The relative content of main compounds in bio-oil were identified by GC/MS. Sugars increased from 1.43% (RS) to 25.27% (RS-HCl), 19.00% (RS-HF), and 19.78% (RS-HCl + HF). Particularly, D-allose, which has been widely used in the field of healthcare, increased dramatically. It is proposed that the removal of AAEMs promoted the depolymerization of cellulose or hemicellulose, resulting in increased sugars. Current results provide greater feasibility using bio-oil as raw material in biorefinery process.