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41.
Chao Yang Jianrui Feng Yelong Zhang Qifeng Yang Peihao Li Tobias Arlt Feili Lai Junjie Wang Chaochuang Yin Wei Wang Guoyu Qian Lifeng Cui Wenjuan Yang Yanan Chen Ingo Manke 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(44)
Potassium‐ion batteries (KIBs) have come into the spotlight in large‐scale energy storage systems because of cost‐effective and abundant potassium resources. However, the poor rate performance and problematic cycle life of existing electrode materials are the main bottlenecks to future potential applications. Here, the first example of preparing 3D hierarchical nanoboxes multidimensionally assembled from interlayer‐expanded nano‐2D MoS2@dot‐like Co9S8 embedded into a nitrogen and sulfur codoped porous carbon matrix (Co9S8/NSC@MoS2@NSC) for greatly boosting the electrochemical properties of KIBs in terms of reversible capacity, rate capability, and cycling lifespan, is reported. Benefiting from the synergistic effects, Co9S8/NSC@MoS2@NSC manifest a very high reversible capacity of 403 mAh g?1 at 100 mA g?1 after 100 cycles, an unprecedented rate capability of 141 mAh g?1 at 3000 mA g?1 over 800 cycles, and a negligible capacity decay of 0.02% cycle?1, boosting promising applications in high‐performance KIBs. Density functional theory calculations demonstrate that Co9S8/NSC@MoS2@NSC nanoboxes have large adsorption energy and low diffusion barriers during K‐ion storage reactions, implying fast K‐ion diffusion capability. This work may enlighten the design and construction of advanced electrode materials combined with strong chemical bonding and integrated functional advantages for future large‐scale stationary energy storage. 相似文献
42.
For the investigation of fluid dynamics from computed tomography (CT) images, an evaluation method was developed that enables data acquisition directly from the recorded CT images. A segmentation algorithm was implemented in Matlab to assign every component a specific gray value. A comparison of weight experiments with CT scans and following segmentation demonstrates the good accuracy of this method. The liquid holdup in different Mellapak 500.Y packings was determined through CT measurements and compared to predictive correlations from the literature. Three‐dimensional visualizations of short packing sections enable an evaluation of the liquid distribution and the flow morphology of the liquid in the packing. The common assumption of an evenly wetted packing surface with a constant liquid film thickness could not be proved. 相似文献
43.
The micelle‐water partition coefficients of reactants, products, and catalyst ligands are predicted using UNIFAC‐IF and COSMO‐RS. It is demonstrated that both models represent a reasonable tool for preliminary screening of the micellar systems for a specific continuous reaction process supported by micellar enhanced ultrafiltration (MEUF). The model reaction is the hydrogenation of itaconic acid and its derivatives (dialkyl esters) in the presence of a rhodium‐based catalyst. The effect of the size and nature of the surfactant head group and tail is explored for nonionic and ionic surfactants. The high partition coefficients of the catalyst ligands indicate that no catalyst leakage is expected in MEUF. Based on the concentration dependence of the calculated partition coefficients, the solubilization capacity of micelles is estimated. 相似文献
44.
V. Mokrushin D. Assenbaum N. Paape D. Gerhard L. Mokrushina P. Wasserscheid W. Arlt H. Kistenmacher S. Neuendorf V. Göke 《化学工程与技术》2010,33(1):63-73
This paper presents an extensive study on the feasibility of ionic liquids (IL) for the extractive distillation of propene‐propane mixtures. A new experimental method for express screening of non‐volatile entrainers was elaborated. A series of ILs and their mixtures were screened at ambient temperature and low pressures. The screening results show that every tested IL turns a low boiler propene into a high boiler and the alkene‐to‐alkane separation factor can be as low as 0.28. The solubility and separation efficiency can be tuned by adjusting the chemical structures of the ions forming the IL. It was found that shortening of the alkyl substituents of the imidazolium ions leads to a decrease in capacity and to an increase in the separation factor. Interestingly, ILs containing nitrile functionalities in either the cation or the anion showed, in our experiments, enhanced separation ability combined with still good capacities. From our thermodynamic measurements, [EMIM][[B(CN)4] was proved to be the most promising candidate. Binary mixtures of ILs were also tested and resulted in separation factors and capacities between the values for the individual ILs. For the most promising candidates, also autoclave measurements at elevated temperatures and pressures were carried out. These experiments indicate that the separation ability decreases with growing temperature and loading. In general, our study definitely proves the high potential of ILs to act as entrainers in the extractive distillation of propene‐propane mixtures or for the separation of any other low‐boiling alkene‐alkane mixture. 相似文献
45.
During the past years a growing number of scientists and engineers have investigated ionic liquids because of their outstanding advantages in several areas. Their unique physical properties and specific chemical behavior make these liquids very interesting for new and innovative applications. For commercial implementation ionic liquids have to meet a number of requirements. For use in high pressure applications they should have a low compressibility, an adjustable gas solubility and a superior lubricating ability. A screening of the relevant parameters was conducted in several experimental setups built for these purposes. Most of these parameters were also examined under long term conditions with regard to real process conditions and safety guarantee in possible high pressure applications. A major application is the compression of oxygen using ionic liquid as operating fluid. Besides, there are many more applications where the superior chemical and physical properties of ionic liquids are of high potential benefit. 相似文献
46.
47.
Metal hydrides are considered as promising candidates for hydrogen storage as they exhibit higher energy densities than compressed gas storage storages. This study represents a theoretical thermodynamic analysis of metal hydride‐based hydrogen storage systems, focusing mainly on the energy demand to operate the storage system and the resulting efficiency. The main energy demand occurs during hydrogen release. This energy demand is composed of three contributions: the heat required to heat the hydride up to desorption temperature, the heat of reaction and the work of compression to reach the targeted outlet pressure. A sensitivity analysis was performed to demonstrate the impact of several parameters, for example, heat of reaction and hydrogen uptake on the energy balance. The most influential parameter is the heat of reaction. The hydrogen uptake does not have a noticeable influence as long as it is not too low. Several possibilities to improve the efficiency of the storage system are discussed (heat integration and the application of a heat storage system). Heat integration can significantly improve the overall efficiency, whereas the application of a heat storage system does not seem realistic. Compared with other hydrogen storage technologies, metal hydrides can feature higher efficiencies than low‐temperature hydrogen storage concepts, for example, liquefied or cryo‐adsorbed hydrogen. The efficiencies of a metal hydride storage system are similar to those reached with a system based on liquid organic hydrogen carriers. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
48.
49.
Simulated Countercurrent Chromatography. This paper reviews simulated countercurrent chromatography, a separation process that has received only little attention. In contrast to standard batchwise operated chromatography, a periodical mode of operation is used. The feed and collection lines are shifted along the column, thus simulating countercurrent operation of the liquid phase and the stationary solid phase. As a result, higher product yield and higher product purity are obtained. At the same time the amount of solid phase and solvent phase required in comparison to discontinuous chromatography is reduced. Industrial applications have been developed since 1964 by Universal Oil Products (UOP). Large scale separation processes in the petrochemical and the sugar industries are already in operation. On the bench scale this process is used to separate biotechnological products and pharmaceuticals. The need to solve difficult separation problems (isomeric or racemic mixtures, biomolecules, polymers) will encourage further developments. Together with improved process-simulation tools and process control, simulated countercurrent chromatography will be established as a powerful separation technique with widespread industrial applicability. 相似文献
50.
A. Schrder K. Wippermann T. Arlt T. Sanders T. Baumhfer H. Marktter J. Mergel W. Lehnert D. Stolten I. Manke J. Banhart 《Fuel Cells》2013,13(3):371-379
Water evolution, distribution, and removal in the cathodes of a running direct methanol fuel cell were investigated by means of synchrotron X‐ray radiography. Radiographs with a spatial resolution of around 5 μm were taken every 5 s. Special cell designs allowing for through‐plane and in‐plane viewing were developed, featuring two mirror‐symmetrical flow field structures consisting of one channel with the through‐plane design. Evolution and discharge of water droplets and the occurrence of water accumulations in selected regions of the channels were investigated. These measurements revealed a nonuniform distribution of water in the channels. Both irregular and periodic formation of water droplets were observed. In‐plane measurements revealed, that the droplets evolve between adjacent carbon fiber bundles of the gas diffusion layer. The water distribution within the channel cross‐section fits very well to the pressure difference between cathode channel inlet and outlet. The quick discharge of water droplets causes sudden decreases of the pressure difference up to 4.5 mbar. 相似文献