Crystals
·
2017
·Vol. 7
·期 9
·275
·
IF 1.566
Yang Shu,Wenchao Yan,Haisong Wang,Jicheng Jiang,Deye Sun,Xiaodi Ma,Yongcheng Jin
A series of LiNi0.5Mn1.5O4(LNMO) samples were synthesized by adjusting the molar ratio of (NH4)2CO3to Na2CO3in a mixed precipitant for evaluating the effects of ammonia from (NH4)2CO3as a complexing agent and Na2CO3as a precipitant on the morphology and electrochemical performances of LNMO. In this research, a rapid precipitation method followed by hydrothermal treatment was used to prepare the precursors of LNMO, and different molar ratios (0:1, 1:2, 1:1, 2:1, 1:0) of (NH4)2CO3to Na2CO3were used for mixed precipitants. The test results revealed that the cathode material exhibits the best electrochemical performance when the molar ratio of (NH4)2CO3to Na2CO3is set at 1:2, displaying a specific discharge capacity of 129.4 mA h g−1at 0.5 C and a capacity retention of 82.3% after 200 charge–discharge cycles. In addition, it still shows a high rate performance with a discharge capacity of 112.7 mA h g−1at 10 C and 98.8 mA h g−1at 20 C, which is attributed to an accurate Ni/Mn ratio, smaller primary particle sizes and a porous spherical morphology.Keywords:rapid precipitation;hydrothermal treatment;mixed precipitants;spherical morphology
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2018
·
IF 4.439
Jiating Shen,Cheng Rao,Ziyang Fu,Xiaohui Feng,Jianjun Liu,Xueliang Fan,Honggen Peng,Xianglan Xu,Chao Tan,Xiang Wang
To gain fundamental understanding on the catalytic property of individual CuO for soot combustion, a series of CuO samples have been prepared with a simple precipitation method by using different Cu precursors and precipitants. Pure monoclinic CuO crystalline phase has been detected by XRD and Raman for all the samples. However, by changing the precursors and precipitants, the morphology and texture property of the CuO samples can be influenced. Furthermore, the redox property of the CuO catalysts can also be altered. Soot-TPR results have testified that four types of active sites with varied activity are present on the surface of all the samples, but only the two types of active sites that can be reduced by soot particles below 500 °C are believed to contribute effectively to soot combustion. It has been discovered that the surface oxygen mobility and abundance are the crucial factors to determine the soot combustion activity of CuO catalysts. Because of the optimal balance of these two factors, CuO-Cu(NO 3 ) 2 -Na 2 CO 3 , a CuO catalyst prepared by the combination of Cu(NO 3 ) 2 precursor and aqueous Na 2 CO 3 precipitant, displays the highest soot combustion activity among all the catalysts.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
MINERALS ENGINEERING
·
2022
·
IF 5.479
Xianping Luo,Xianqiang Yuan,Kunzhong He,Yongbing Zhang,Caigui Luo,Zishuai Liu,Hepeng Zhou
Impurity metal ions in ionic rare earth ores are similar to rare earth ions in terms of occurrences and similarities in properties. During the leaching operation, a large number of impurity ions enter the rare earth leaching solution, which makes the crystal form of the rare earth unstable or forms an amorphous flocculent precipitate. The commonly used ammonium bicarbonate (NH 4 HCO 3 ) precipitation crystallization process has low rare earth precipitation rate, long precipitation crystallization period, and high ammonia nitrogen content in precipitation wastewater. In this paper, the leaching solution obtained by ionic rare earth ore magnesium salt leaching-combined impurity removal process was taken as the research object, and the effects of precipitants, such as NH 4 HCO 3 , calcium oxide, sodium carbonate, and oxalic acid, on the preparation of crystalline rare earth precipitation were investigated through comparison. On the premise of determining the best rare earth precipitant, the effects of dosage, stirring speed, stirring time, and aging time on the preparation of crystalline rare earth precipitate were investigated further. The precipitation effects of different precipitation processes were studied systematically combined with SEM-EDS, laser particle size analysis, and other means to characterize the morphology of crystalline products. Results showed that when calcium oxide was used as a precipitant, the molar ratio was 2.5. After stirring at a constant speed of 200 r/min for 4 h and aging for 4 h, precipitates with good crystal appearance, smooth crystal surface and easy filtration were obtained. This process promoted crystal growth of rare earth precipitates, and the crystal grain size, which was beneficial to the improvement of the quality of rare earth products, increases significantly.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
IONICS
·
2019
·Vol. 26
·期 1
·127-139
·
IF 2.289
Zeng Tianbiao,Zhang Chuhong
The precursor synthesis of the LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) is usually operated in NaOH/NH 3 ·H 2 O aqueous system, and the pH value and the liquid feeding rate need strict control. Herein, a simple synthesis method was investigated without pH and liquid feeding rate control by using urea as the precipitation agent. The relationship of the metal ions’ concentration to the homogeneity of the precursor was studied in detail. To decrease the lattice disordering ratio and increase the reversible capacity of the NCA, polar CTAB molecules were added into the CO(NH 2 ) 2 /H 2 O system. The lattice disordering ratio of the NCA was decreased and the integral electrochemical performances were improved. The stable reversible capacity of the battery in 0.1, 0.5, 1, 2, 3, 4, and 6 C can reach to 188, 173, 167, 162, 152, 143, and 125 mAh g −1 . It is expected that the simple synthesize method may provide some inspiration to the NCA cathode research.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Jian-ming Gao,Bo Wang,Wenjie Li,Li Cui,Yanxia Guo,Fangqin Cheng
Preparation of inorganic polymer coagulants from circulating fluidized bed (CFB) fly ash is one of the most significant value-added and environment-friendly approaches. Nevertheless, CFB fly ash presents relatively low solubility in acidic systems, which limits its utilization efficiency. In this paper, enhanced metal leaching from CFB fly ash using combined HCl-H 2 SO 4 leaching process for polymeric aluminum ferric chloride sulfate (PAFCS) preparation was proposed. PAFCS with the different molar ratios of Al 3+ /SO 4 2− and Al 3+ /Fe 3+ were prepared from as-obtained leaching liquors and characterized by SEM, XRD, FTIR, and coagulation experiments. The leaching efficiencies of Al and Fe in CFB fly ash were up to 96.75% and 97.64% by combined HCl-H 2 SO 4 leaching process. The optimal molar ratios of Al 3+ /SO 4 2− and Al 3+ /Fe 3+ for the turbidity and UV 254 removal were 10:1 and 10:1, respectively, due to the three-dimensional chain-net structure and the highest [Al + Fe] b content. When applied to biochemical effluent of coking wastewater treatment, PAFCS exhibited excellent removal performance on both humic acid-like and fulvic acid-like matters. The resultant flocs of PAFCS presented the largest recovery factor (R f = 0.37) and strength factor (S f = 0.79) in contrast with PAC and PAFC. This work provides a novel and high-efficient Al and Fe leaching strategy from CFB fly ash to prepare Al-Fe coagulant.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Nanomaterials
·
2016
·
IF 1.758
Yongli Zhang,Shujuan Dai,Yanbo Zhou,Kai Lin
Fe-Co-Ce composite catalysts were prepared by coprecipitation method using CO(NH2)2, NaOH, NH4HCO3, and NH3·H2O as precipitant agents. The effects of the precipitant agents on the physicochemical properties of the Fe-Co-Ce based catalysts were investigated by SEM, TEM, BET, TG-DTA, and XRD. It was found that the precipitant agents remarkably influenced the morphology and particle size of the catalysts and affected the COD removal efficiency, decolorization rate, and pH of methyl orange for catalytic wet air oxidation (CWAO). The specific surface area of the Fe-Co-Ce composite catalysts successively decreased in the order of NH3·H2O, NH4HCO3, NaOH, and CO(NH2)2, which correlated to an increasing particle size that increased for each catalyst. For the CWAO of a methyl orange aqueous solutions, the effects of precipitant agents NH3·H2O and NaOH were superior to those of CO(NH2)2 and NH4HCO3. The catalyst prepared using NH3·H2O as the precipitant agent was mostly composed of Fe2O3, CoO, and CeO2. The COD removal efficiency of methyl orange aqueous solution for NH3·H2O reached 92.9% in the catalytic wet air oxidation. Such a catalytic property was maintained for six runs.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）