Both value-added utilization of agricultural waste to prepare catalytic materials and selective conversion of biomass-based carbonyl compounds are hot topics. Herein, sugarcane bagasse ( SB ), a main by-product of cane sugar manufacturing industry, was directly assembled with HfCl 4 and methanesulfonic acid (MSA) via a one-step hydrothermal method for scalable preparation of Hf-containing coordination complex (Hf@ SB -MSA). Characterization results revealed that the coordination between Hf 4+ and phenolic hydroxyl, alcohol hydroxyl, carboxyl groups in SB resulting in the formation of Lewis acid (LA) and Lewis base (LB) sites, while sulfonic group in MSA providing Brønsted acid (BA) sites. The cooperative role of LA, BA and LB in Hf@ SB -MSA delivered prominent catalytic performance for catalytic transfer hydrogenation (CTH) of levulinic acid (LvA) to γ-valerolactone (GVL) with isopropanol as solvent and H-donor at mild reaction conditions (GVL yield was up to 99.1%). Heterogeneity and recycling experiments further revealed the good recyclability of Hf@ SB -MSA, which can be easily separated from the reaction mixture by filtration and repetitively used at least five reaction runs without an obvious loss of activity. More gratifyingly, Hf@ SB -MSA also displayed superior universality for the CTH of various carbonyl compounds to their corresponding alcohols with yields up to 90%.
Yixin Cai,Liming Liu,Huafeng Tian,Zhennai Yang,Xiaogang Luo
Adsorption and desorption behaviors of tetracycline hydrochloride by activated carbon-based adsorbents derived from sugar cane bagasse modified with ZnCl2were investigated. The activated carbon was tested by SEM, EDX, BET, XRD, FTIR, and XPS. This activated carbon exhibited a high BET surface area of 831 m2g−1with the average pore diameter and pore volume reaching 2.52 nm and 0.45 m3g−1, respectively. The batch experimental results can be described by Freundlich equation, pseudo-second-order kinetics, and the intraparticle diffusion model, while the maximum adsorption capacity reached 239.6 mg g−1under 318 K. The effects of flow rate, bed height, initial concentration, and temperature were studied in fixed bed adsorption experiments, and adsorption data were fitted with six dynamic adsorption models. The results of characterizations and the batch experiments were analyzed to study the adsorption and desorption mechanisms. Tetracycline hydrochloride and activated carbon were bonded together by π–π interactions and cation–π bonds. Ethanol was used as an eluent which bonded with 10 hydrogen bond acceptors on tetracycline hydrochloride to form a complex by hydrogen bonding to achieve recycling.Keywords:adsorption;desorption;mechanism;sugar cane bagasse;activated carbons;tetracycline
Chun Chang,Xin Liu,Shuo Zang,Kai Fu,Zhen Ma,Xiaoyang Zheng,Huijuan Tian,Zhining Li
Xylose residue (XR), a waste product from the xylose industry, is currently primarily used for incineration, animal feed, and cultivation substrates, representing a significant waste of resources. Due to its rich cellulose content, this study demonstrates the valorization of XR into methyl/ethyl levulinate (ML/EL) under high-solid conditions catalyzed by sulfate, through an integrated approach combining experimental and DFT investigations. Under the same optimized conditions (catalyst loading: 6 g/200 mL, 180 °C, 2 h), an increase in the solid content of XR from 15 % to 30 % in methanol, catalyzed by CuSO 4 , enhanced the ML concentration by 58 % (46.73 → 74.06 g/L), though at the expense of a 20 % yield reduction (24.89 → 19.84 wt%). Analogous trends were observed in ethanol systems catalyzed by Al 2 (SO 4 ) 3 under identical conditions (EL: concentration +60 % (26.0 → 41.59 g/L), yield −19 % (22.96 → 18.64 wt%)). DFT simulations revealed that Brønsted-Lewis acid synergy (e.g., Cu(CH 3 OH) 2 + , Al(CH 3 OH) 4 3+ , and Fe(CH 3 OH) 3 3+ ) governed catalytic performance. The Brønsted-to-Lewis acidity hierarchy (Al 3+ > Fe 3+ > Cu 2+ ) correlated with metal electronegativity but was predominantly modulated by ligand electron transfer. Fukui function analysis highlighted distinct electronic behaviors of H + and Cu 2+ , enabling cooperative catalysis that shifted the rate-limiting step from initial dehydration (39.87 and 39.13 kcal/mol) to glucoside-fructoside isomerization (33.87 and 35.87 kcal/mol). These insights underscore the superiority of bifunctional catalysts in reducing energy barriers and optimizing reaction pathways. By integrating process intensification with acid-site engineering, this work establishes a strategy to reconcile yield-concentration trade-offs in high-solid biomass conversion, offering a scalable route for sustainable levulinate production.
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