Baoyu Wang,Mingrui Li,Songdang Zhang,Hongguo Wu,Yuhe Liao,Hu Li
Finite size effect is closely correlated with heterogeneous catalytic activity and selectivity as reducing the metal to a few nanometers, but may suffer from deficient active sites for cascade reactions. Here, a type of dual-size heterogeneous N-doped cobalt catalysts (Co SAs-NPs /NC(n)) with the coexistence of Co single-atoms (Co-SAs) and Co nanoparticles (Co-NPs) were prepared for efficient synthesis of benzimidazoles (up to 91% yield) from 2-nitroanilines and bio-based alcohols via cascade hydrogen transfer-dehydrogenative cyclization. Experimental results and density functional theory calculations suggested that the bio-alcohol dehydrogenation mainly occurs at Co-SAs sites, while Co-NPs sites remarkably facilitate the subsequent reduction of nitro species, indicating the synergistic effect between Co-SAs and Co-NPs in the coupled hydrogen transfer process. The Co SAs-NPs /NC(0.25) catalyst can be recycled and applied to a wide range of substrates (28 examples). This catalytic approach based on the metal size effect opens a new route for the direct upgrading of biomass feedstocks involving multiple reactions.
Hongzhen Luo,Tairan Zhou,Rui Zhang,Qianyue Yang,Xinyan You,Shijie Wang,Jiabin Wang,Fang Xie,Rongling Yang
Efficient production of second-generation biofuels (bioethanol and biobutanol) from renewable lignocellulosic biomass holds strategic importance and aligns with sustainability objectives. However, it poses a persistent long-term challenge because of the biomass recalcitrance. Therefore, development of mild, environmentally friendly biomass pretreatment methods is a critical concern. To this end, in this study, a ternary deep eutectic solvent (DES) was synthesized with choline chloride , succinic acid , and glycerol at a molar ratio of 1:0.5:0.5. The ternary DES pretreatment largely enhanced glucan digestibility of corn stover (CS) to 94.7 % which was 4.60-fold to untreated CS. Mechanism of improved enzymatic efficiency of DES-pretreated CS was revealed by characterization methods such as SEM, XRD, and FTIR technologies. In addition, adding 1.0 % H 2 SO 4 to the ternary DES further increased enzymatic hydrolysis yield to nearly 100 %. Subsequently, the H 2 SO 4 -assisted DES-pretreated CS was used as substrate to produce C2-C4 bioalcohols (ethanol and butanol) by microbial fermentations. The results indicate that 46.6–49.2 g/L ethanol could be obtained by S. cerevisiae under separate hydrolysis and fermentation (SHF), and simultaneous saccharification and fermentation (SSF) strategies. Meanwhile, up to 11.9 g/L butanol was achieved from CS hydrolysate by Clostridium acetobutylicum with fed-batch mode. Finally, an artificial microbial consortium by co-culturing C. acetobutylicum and S. cerevisiae was developed which efficiently co-produced 12.4 g/L biobutanol and 5.7 g/L bioethanol from CS hydrolysate. Overall, this study provides a sustainable and green pretreatment technology that deconstruct lignocellulose and possess universality to produce various low-carbon bioalcohols by microbial fermentations.
危险品化学品经营许可证（带存储）