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The development of efficient heterogeneous catalysts for upgrading CO2, a greenhouse gas, and glycerol (Gly), an untapped biomass resource, into glycerol carbonate (GC) remains a challenge. Herein, 1,8‐diazabicyclo[5.4.0] undec–7–ene (DBU)–based poly (ionic liquid)s (PILs) were constructed for the one–pot synthesis of GC from CO2, Gly, and propylene oxide. Among them, P−DVB−DBUVBI–1 exhibited the best catalytic performance, achieving a GC yield of 90 % under optimal reaction conditions (100 °C, 6 h). The PIL catalyst was easily recovered and reused, as demonstrated by stable activity over five cycles. Density functional theory calculations showed that owing the strong positive charge delocalization ability of DBU onium, DBU–based PILs exhibit high nucleophilicity, which is the key to their efficient catalytic performance in the one–pot reaction. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 on catalyst surfaces is hindered by the inefficient mass transfer of CO2 in aqueous solutions. In this study, we employed an electrochemical reduction approach to fabricate a hydrophobic three-dimensional nanoporous silver catalyst with a plastron effect, aiming to enhance the CO2 diffusion. The resulting catalyst exhibited an exceptional performance with the FECO peaking at 95% at −0.65 V (vs. RHE) and demonstrated remarkable stability during continuous electrolysis for 48 hours. Control experiments, together with Tafel analysis, EIS measurements, and contact angle results, confirmed that the notable enhancement of performance was attributed to the hydrophobic porous structure that facilitated efficient storage and rapid mass transfer of low-solubility CO2 gas reactants. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) have been extensively studied for lignin extraction from lignocellulosic biomass due to their easy synthesis, selective lignin dissolution, high recyclability, and other benefits. In this study, lignin in poplar wood was extracted using DESs composed of malic acid (Mal) and choline chloride (ChCl). A two-step treatment approach using DESs was proposed in order to enhance the lignin separation capability of DESs under mild conditions and achieve cellulose purification. The impacts of the Mal/ChCl molar ratio, reaction temperature and time on lignin extraction were examined. 75.3% of lignin was separated from poplar wood using Mal/ChCl (2 : 1) DESs at 120 °C for 4 h. Notably, after two-step DES treatments, 86.9% of lignin was removed, and the delignification efficiency was 21.7% higher than that by one-step treatment at the same temperature and time. Also, the lignin dissolved in DESs was regenerated and characterized by Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), and heteronuclear single quantum correlation (HSQC) spectroscopy. The results suggested that the regenerated lignin has low molecular weight with the β-O-4′ bond eliminated, which could be beneficial for the subsequent modification and development of lignin-based biofunctional materials. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) have the advantages of low cost, non-toxicity, and biodegradability for the catalytic conversion of fructose to 5-hydroxymethylfurfural (5-HMF). However, the efficient separation of 5-HMF from DESs is essential and challenging for its high-value utilization. In this study, the efficient separation of 5-HMF from eight carboxylic acid-based DESs was achieved by four cycles of extraction using tetrahydrofuran (THF) with an overall extraction efficiency of more than 80.0% (30 °C). Besides, the addition of 1 mol L−1 NaCl solution can significantly improve the extraction efficiency from 30.0% to 42.0%. In addition, the process of recovery and reuse of the extractant was proved to be quite effective, in which the purity of 5-HMF in the recovered product and the amount of THF in the recycled extractant can reach up to 90.0% and 97.0%, respectively. Finally, a thorough procedure for the preparation, separation, and recovery of 5-HMF was carried out to assess the viability of the optimized separation and recovery process. The results reveal outstanding extraction efficiency (77.9%), excellent yield of 5-HMF (63.3%), and high purity of 5-HMF in the final product (86.0%). This work expands the range of possible uses for 5-HMF by demonstrating an efficient and environmentally friendly method for separating and recovering 5-HMF while ensuring the reuse of the extractant. [ABSTRACT FROM AUTHOR]

An ideal strategy for the management of greenhouse gas carbon dioxide (CO2) and surplus industrial product-glycerol (Gly) is to convert them into the valuable glycerol carbonate (GC). However, conventional conversion processes rely on high CO2 pressure and reaction temperature. In this work, a series of easily prepared protic ionic liquids (ILs) were studied for the one-pot synthesis of GC using CO2, Gly, and styrene oxide (SO). A 94% yield of GC was obtained with the catalysis of 1,8-diazabicyclo[5.4.0]undec-7-enenium iodide (HDBUI) under atmospheric pressure at 45 °C. Experimental results and density functional theory (DFT) calculations suggest that the high catalytic activity of HDBUI is attributed to the strong nucleophilicity and substrate activation afforded by the synergistic effect of the protic HDBU+ cation and I− anion. In addition, high GC yields were also obtained when simulated flue gas and crude Gly were used as substrates. [ABSTRACT FROM AUTHOR]