Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
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Fundamental Research Funds for the Central Universities[DUT21YG113/DUT22YG213/DUT22YG116]
No full textData-driven identification of coherent structures in gas-solid system using proper orthogonal decomposition and dynamic mode decomposition
No full textSpatiotemporal coherent structures are critical in quantifying the hydrodynamics of dense gas-solid flows. In this study, two data-driven methods, proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD), are applied to identify and characterize the dominant spatiotemporal coherent structures in a bubbling fluidized bed. It is found that (i) with the same number of modes (or coherent structures), POD captures more defined energy than DMD; (ii) the main coherent structure of POD is symmetric and confirms the existence of bubble-emulsion two-phase structure; (iii) the coherent structures with a frequency of 0 Hz in DMD analysis can construct the mean flow field more reasonably than POD; and (iv) POD reconstructs the transient flow fields more accurately with the same number of modes. This study offers insights into the coherent structures in gas-solid systems
In-situ fabrication of Si/FeSi2@C NPs with volume control effect by fluidized bed chemical vapor deposition as anode materials
No full textSilicon (Si) has been proven to be the most potential anode material for the next-generation lithium-ion batteries (LIBs) because of its superior theoretical capacity (similar to 4200 mAh g-1). However, the huge volume changes, unstable solid-state interphase (SEI) layers, and large internal stresses upon the lithiation process severely limit the practical application for commercial LIBs anodes. Herein, we fabricate the carbon-coated Si/FeSi2 nanoparticles (Si/FeSi2 @C NPs) with volume control effect by fluidized bed chemical vapor de-position (FBCVD) method to solve the above-mentioned problems. These 15 min-Si/FeSi2 @C NPs and 30 min-Si/FeSi2 @C NPs show excellent Li+ storage capacity in the first cycle (2705.9/3039.1 mAh g-1 and 2645.9/2984.2 mAh g-1) with high Initial Coulombic Efficiency (ICE) of similar to 89.0% and 88.7%. In-situ TEM characterization demonstrates that the carbon coating layer and inert FeSi2 phase enable a small volume variation, only similar to 37.8%, revealing the effective volume expansion control effect, and generating thin SEI layers. Besides, the perfect structure of Si/FeSi2 @C NPs makes this material a great improvement in rate performance.(c) 2022 Elsevier B.V. All rights reserved
The effect of the active carbonyl groups and residual acid on the ammonia adsorption over the acid-modified activated carbon
No full textEfficient ethylene/ethane separation by rare earth metal-containing ionic liquids in N,N-dimethylformamide
No full textMetal-containing ionic liquids (MILs) have been considered as promising solvents for ethylene/ethane (C2H4/ C2H6) separation. With multiple 4f and 5d empty electronic orbitals, special electronic configuration and abundant electron energy levels, rare earth elements have potential to be great electron acceptor of C2H4. Herein, a new strategy of rare earth metal ionic liquids (REMILs), 1-butyl-3-methylimidazolium tri-fluoromethanesulfonate containing erbium ([Bmim][TFO]/Er(TFO)3) in N, N-dimethylformamide (DMF) was exploited to separate C2H4/C2H6 for the first time. The complexation between Er3+ and C2H4 and interactions in absorbents were adopted to achieve fast and selective C2H4 absorption. The physical properties of the absorbents were measured and studied firstly. The addition of 20 wt% DMF in REMILs was optimized with a decrease in viscosity of 6-7 times at 293 K. The absorption parameters, such as Er3+ concentration, temperature and regeneration of absorbents were also investigated systematically. The results showed that the selectivity of C2H4/ C2H6 was enhanced with increasing Er3+ concentration. The solubility of C2H4 in [Bmim][TFO]/Er(TFO)3 + 20 wt% DMF was 0.95 mg/g with C2H4/C2H6 selectivity of 10 (at 303 K, 0.1 MPa), much higher than that of conventional ILs. The interaction energy (Delta E) of Er3+-C2H4 was more negative than Er3+-C2H6 through density functional theory (DFT). Furthermore, the rare earth absorbents exhibited excellent reversibility after five cycles. In summary, this work provides a potential method for efficient separating C2H4/C2H6 via REMILs in DMF solution
Selective extraction and separation of REEs from NdFeB magnets scrap using co-chlorination and water leaching
No full textAn approach of co-chlorination followed by water leaching to achieve the selective extraction of rare earth elements (REEs) from NdFeB magnets scrap (scrap) was studied. Co-chlorination refers to the synergistic effect of direct and indirect chlorination reactions. The feasibility of direct and indirect chlorination was explored from both theoretical and practical standpoints. The transformation between NdCl3 and NdOCl during the chlorination roasting process was discovered by X-ray diffraction (XRD) analysis combined with Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) as well as chemical analysis. The formation of NdOCl was prevented by regulating FeCl3 center dot 6H(2)O dosage, chlorination temperature and chlorination time, then the negative impact from the hydrolysis of NdOCl was avoided. As a result, the complete chlorination of REEs was successfully achieved by using co-chlorination and water leaching. The results showed that 96.51% REEs and 64.29% Co can be synchronously extracted into the leaching solution under appropriate conditions. After the separation of REEs and iron, 92 wt% iron oxide was obtained. This work offers an effective method for recovering REEs from NdFeB magnets scrap
Temperature dependence of deposition behavior and corrosion resistance of zinc coatings electroplated on copper substrates from ethaline electrolyte
No full textElectrodeposition of zinc (Zn) coatings on copper (Cu) substrates was conducted from choline chloride-ethylene glycol-based deep eutectic solvent under the temperatures varying from 323 to 343 K. The electrochemical behavior of Zn ions on Cu electrodes at different temperatures was studied through cyclic voltammetry and chronoamperogram testing. The obtained results illustrate that the electrodeposition of Zn coatings is a diffusion-controlled quasi-reversible process with an instantaneous two-dimensional nucleation and growth mechanism. The crystal structure and chemical composition analysis demonstrates that the electrodeposition from ChCl-EG-ZnCl2 system is an effective strategy to achieve a Zn coating with high crystallinity and purity. The surface morphological analysis further reveals that the electroplated coatings are stacks of flake Zn grains. The dependence of the deposition behavior and quality of electroplated Zn coatings on temperature was studied systematically. The growth behavior of Zn grains is enhanced with increasing the temperature, but too high a temperature inevitably leads to the undesired coarsen microstructure instead. On the basis of the polarization curves and EIS testing results, the temperature was optimized at 333 K to obtain a Zn coating with superior corrosion resistance in 3.5 wt% NaCl solution to that of Zn coatings electroplated at other conditions