An ecologically benign catalytic system consisting of superbase and saccharide was developed for CO2 chemical fixation with epoxides under metal-free and halide-free conditions. Because of the synergistic effect played by superbase and saccharide on the activations of CO2 and epoxide, the reaction could be performed with good activity and selectivity. A possible catalytic mechanism of the hydrogen-bonding of saccharide and activation of the carbon atom by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was proposed. The process is a simple, biocompatible, and ecological route for CO2 chemical fixation into high-value chemicals.
Weiguo Cheng;Fei Xu;Jian Sun;Kun Dong;Congkai Ma;锁江 张
It was found for the first time that glycine, L-serine, and L-proline can form aqueous biphasic systems (ABS) with a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]). The related mutual coexistence curve data are reported.
Jianmin Zhang;Yanqiang Zhang;Yuhuan Chen;锁江 张
Journal of Chemical & Engineering Data
Ionic liquids (ILs)/polymer composite membranes show great potential for CO2 separation. The main challenge is to select the appropriate combination of ILs and polymer in a limited time and cost. In this work, the microstructure, interactions and dynamic properties of a series of systems of 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]) and 1-butyl-3-methylimidazolium tetracyanoborate ([bmim][B(CN)4] composited with poly(vinylidene fluoride) (PVDF) with increasing ionic liquids (ILs) content were studied by molecular dynamics simulations for understanding the composite membrane at the molecular level. The radial distribution functions show that ILs aggregation is formed in the PVDF matrix, and the aggregation region continuously expands and finally becomes ionic channels with increased ILs content to 50 wt %. The weakest cations-anions interaction of [bmim][B(CN)4] and the strongest interaction of PVDF-[B(CN)4] as well as the weakest aggregation of [bmim][B(CN)4] are favorable for forming the continuous ionic channels in PVDF matrix for CO2 diffusion. The increased self-diffusion coefficients of PVDF after the addition of ILs, which originates from the strong interaction of ILs-PVDF and the broken hydrogen bond network among PVDF chains, facilitate the transportation of CO2 among PVDF chains. Moreover, the free energy of solvation, Henry's law constant and self-diffusion coefficients for CO2 in three ILs/PVDF systems suggest that [bmim][B(CN)4]/PVDF composite membrane possesses better CO2 separation performance.
Tao Song;Xiaochun Zhang;Yonggang Li;Kun Jiang;锁江 张;Xiangmei Cui;Lu Bai
Industrial & Engineering Chemistry Research
Zheng Yong;Lu Xingmei;锁江 张
Freezing points of aqueous solutions of HOEtpyBr, HOEtmimBr, AmimCl, EtOMmimCl, EmimDep, and EmimAc were measured using a modified Beckmann apparatus with automatic data logging. The ionic liquids (ILs) in this study exhibited features similar to those of inorganic salts in depressing the freezing point of water. On the basis of the cryoscopic behavior recorded, the solid phases formed at higher IL contents were presumed to be hydrates of the form IL·nH2O. The HOEtpyBr+H2O and HOEtmimBr+H2O systems formed simple eutectic systems. The eutectic points were found to be at a water mole fraction of 0.617 and 219.841 K in the first system and at a water mole fraction of 0.657 and 202.565 K in the second system. Water activities in aqueous IL solutions were predicted by COSMO-RS and COSMO-SAC and compared to water activities derived from the experimentally determined freezing points. The COSMO-RS predictions were closer to the experimental water activities than the COSMO-SAC predictions. The experimental results indicate that the freezing points of IL+H2O systems are affected by the nature of both cations and anions. However, according to the COSMO-RS excess enthalpy prediction results, the anions have a relatively higher influence than cations on the IL+H2O interaction.
Yanrong Liu;Anne S. Meyer;Yi Nie;锁江 张;Yongsheng Zhao;Philip L. Fosbøl;Kaj Thomsen
Journal of Chemical & Engineering Data
Conventional microsized and nanosized secondary battery electrodes inevitably suffer from poor rate capability and low tap density, respectively. Inspired by a multipolar neuron consisting of a centric micron-soma and multiple divergent nanodendrites, we propose a smart electrode design based on a two-dimensional (2D) multiscale synergistic strategy, for addressing both of the above problems. As a proof of concept, multiple Zn-doped Co-based regional-nanoarrays are grown on one Co-doped Zn-based micron-star in a 2D mode via a facile one-pot liquid-phase process, serving as a representative neuron-mimic anode for lithium-ion batteries. The 2D assembly well retains the tap density advantage derived from the micron-star subunit. Combined analysis of three-dimensional tomographic reconstruction, Li-storage kinetics, and in situ transmission electron microscopy reveal a smart electrochemical behavior similar to a neuron working mechanism, which significantly enhances rate capability as compared to the single micron-star subunit. A mutual-doping effect also benefits high-rate lithium storage as verified by density functional theory calculations. As expected, superior reversible areal capacity (2.52 mA h cm-2), high long-term capacity retention (<0.024% loss per cycle over 800 cycles after initial 5 cycles), and enhanced rate capability (1 order of magnitude higher than the microsized electrode) are obtained, accompanied by considerable high-temperature endurance.
Jia Yu;Yanlei Wang;Long Kong;Shimou Chen;锁江 张
The combination of ionic liquids (ILs) and metal organic frameworks (MOF) as a new type of hybrid ionic conductor has raised extensive concern. Novel solid electrolytes with high ionic conductivities and good cycle performance have been successfully synthesized by loading ILs into nanoarchitectures of MOF materials. In this work, two highly conductive ILs, 1-ethyl-3-methylimidazolium thiocyanate ([Emim][SCN]) and 1-ethyl-3-methylimidazolium dicyanamide ([Emim][DCA]), were embedded into the pores of MIL-101 via an effective soaking-volatilizing method. Using this method, a series of IL@MIL-101 composites with different IL contents were obtained. The effects of IL amount on pore volume, stability, morphology, and conductivity were investigated. The results showed that the conductivity of the composites improved with increasing the amount of ILs. When the pores of MIL-101 material are fully filled with [Emim][SCN], the ionic conductivity of the composites can reach up to 6.21 × 10-3 S·cm-1 at 150 °C under a N2 atmosphere, which is higher than traditional solid electrolytes. And the activation energy of this sample is estimated to be 0.18 eV, which is as low as other IL@MOF conductive composites. It is noteworthy that the IL@MOF hybrid composites can be regarded as promising ionic-conductors due to the value of high conductivity and low activation energy.
Qiuxia Xu;Xiangping Zhang;Shaojuan Zeng;Lu Bai;锁江 张
ACS Sustainable Chemistry and Engineering
A continuous process for methacrolein production was constructed by filling w/o Pickering emulsions in a column reactor. Ionic liquid (IL-[HDEA]Ac) with secondary amine was designed to catalyze propionaldehyde condensation with formaldehyde through the Mannich reaction. Emulsion droplets encapsulated with IL aqueous solution were stabilized with modified SiO2 nanoparticles and dispersed in cyclohexane, which could be observed as numerous reactors. The properties of SiO2 stabilizer, such as wettability, surface groups, and the effect on interfacial tension were investigated. The characteristics of emulsion influenced by stabilizer properties and content were systematically studied. The droplet size, IL concentration and liquid hourly space velocity were optimized. The droplets were evaluated at 0.5 hr−1 for 150 hr without IL leakage and obvious activity decreasing, indicating the excellent stability of the emulsion system. The continuous process showed a 1.25-fold enhancement in catalysis efficiency and less equipment compared to batch process.
Hui Zhao;Ran Ran;Lei Wang;春山 李;锁江 张
Nitrogen-coordinated single-atom catalysts (SACs) have emerged as a frontier for electrocatalysis (such as oxygen reduction) with maximized atom utilization and highly catalytic activity. The precise design and operable synthesis of SACs are vital for practical applications but remain challenging because the commonly used high-temperature treatments always result in unpredictable structural changes and randomly created single atoms. Here, we develop a pyrolysis-free synthetic approach to prepare SACs with a high electrocatalytic activity using a fully -conjugated iron phthalocyanine (FePc)–rich covalent organic framework (COF). Instead of randomly creating Fe-nitrogen moieties on a carbon matrix (Fe-N-C) through pyrolysis, we rivet the atomically well-designed Fe-N-C centers via intermolecular interactions between the COF network and the graphene matrix. The as-synthesized catalysts demonstrate exceptional kinetic current density in oxygen reduction catalysis (four times higher than the benchmark Pt/C) and superior power density and cycling stability in Zn-air batteries compared with Pt/C as air electrodes.
Peng Peng;Lei Shi;Feng Huo;Chunxia Mi;Xiaohong Wu;锁江 张;中华 向
Although ionic liquids (ILs) are efficient solvents for dissolving cellulose, long time dissolution (for example ≥24 h) could lead to cellulose degradation, especially at high temperatures (for example ≥130 °C), limiting the use of ILs in the cellulose industry. On the premise of sufficient dissolution, inhibiting cellulose degradation in 1-butyl-3-methylimidazolium chloride [C4mim]Cl, 1-ethyl-3-methylimidazolium chloride [C2mim]Cl and 1-allyl-3-methylimidazolium chloride [Amim]Cl at 130 °C was achieved by the addition of amino acids. The results show that the cellulose regeneration rate increased from 0.00% to 90.02% at 130 °C for 24 h when 1.25 wt% of l-arginine was added to [C4mim]Cl. It is concluded that l-arginine can form an intermolecular hydrogen bond with one of the three ipsilateral hydroxyls of cellulose, which prevents the cation [C4mim]+ or anion Cl- from simultaneously forming three hydrogen bonds with the three ipsilateral hydroxyls of cellulose, successfully inhibiting cellulose degradation. This work expands the application of ILs in the cellulose industry.
Jiming Yang;兴梅 吕;Xiaoqian Yao;Yao Li;Yongqing Yang;Qing Zhou;锁江 张