JOURNAL OF MEMBRANE SCIENCE
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2016
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IF 5.557
Dong Zou,Minghui Qiu,Xianfu Chen,Yiqun Fan
Compared to the traditional separation technology, membrane separation is particular beneficial for the treatment of contaminated fresh water such as agricultural runoff, and hydraulic fracturing wastewater. However, the development of cost-effective membranes with both high permeability and high rejection performance is still a challenge. In this study, we design one-step preparation of high-performance bi-layer α-alumina ultrafiltration (UF) membranes supported on coarse tubular substrates via co-sintering process. In this approach, boehmite sol and alumina nanoparticles were mixed in different ratios for the fabrication of microfiltration (MF) layer and UF layer, respectively. The effects of dip-coating dispersion formulation, coating time and thermal treatment process on the membrane microstructure and performance were comprehensively investigated. It was found that the presence of boehmite sol in the MF layer could accelerate its sintering process, while the addition of alumina nanoparticles into UF layer could promote the phase transition from γ phase to α phase at low temperature and retard the shrinkage. The optimized doping content of boehmite and alumina nanoparticles were 2 wt% and 4 wt% to achieve a good match of thermal expansion properties between the two co-sintering layers. For MF layer and UF layer, the membrane thickness were controlled to be 40–50 µm and about 1 µm, respectively. After co-sintering at 1000 °C for 2 h with a heating rate and cooling rate of 0.5 °C/min, tubular α-alumina UF membranes were found to display a high pure water permeability of 70 L m -2 h -1 bar -1 and a small pore size of ~5 nm, which also exhibited good dye removal capabilities in the process of treating dye waste water.
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MATERIALS RESEARCH BULLETIN
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2017
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IF 2.446
Kun He,Zewen Ruan,Xiangguo Teng,Yongming Zhu
Spherical nickel rich layer cathode materials (LiNi 0.85− x Co 0.15 Al x O 2 ( x = 0.02, 0.05 and 0.10), NCA) with excellent electrochemical performance for high energy densities lithium-ion batteries are successfully synthesized by a continuous co-precipitation method. An elaborate design of Al solution with sodium aluminate is successfully adopted, which can efficiently prevent rapid precipitation of Al(OH) 3 and obtain the precipitated precursors. The thermodynamic model is established in the Ni—Co—Al—NH 3 —H 2 O system and investigation of precipitation mechanism is carried out systematically, and the results demonstrate that the spherical LiNi 0.85− x Co 0.15 Al x O 2 can be obtained through this route. Charge and discharge tests show that LiNi 0.85− x Co 0.15 Al x O 2 synthesized has a high initial discharge specific capacity of 208 mAh/g at 0.1 C and a good capacity retention of 90.2% after 200 cycles at 0.5 C between 2.5 and 4.3 V. It is expected that performance of NCA electrodes for advancing lithium-ion batteries could be improved with the new process proposed in this study.
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FUEL PROCESSING TECHNOLOGY
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2017
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IF 3.752
Xiang-Xue Liu,Zhi-Min Zong,Wei-Tu Li,Xiang Li,Zhan-Ku Li,Sheng-Kang Wang,Xian-Yong Wei
A novel and highly active magnetic solid superbase (MSSB) with extraordinary recovery and recycling properties was prepared by impregnating Mg 2 Si onto mesoporous silica coated magnetite via one-pot preparation and successfully applied in the catalytic hydroconversion (CHC) of sawdust at 220 °C. Detailed molecular compositions of the soluble portions from non-catalytic hydroconversion (SP NCHC ) and CHC (SP CHC ) were characterized with a Fourier transform infrared spectrometer and gas chromatograph/mass spectrometer (GC/MS). As a result, the yield of SP CHC is significantly higher than that of SP NCHC and most of the GC/MS-detectable compounds in SP CHC are guaiacols , while SP NCHC is rich in guaiacols and esters, indicating that MSSB effectively catalyzed the cleavage of C O bridged bonds in sawdust. The mechanism for catalytically hydrocracking C O bridged bonds over MSSB is proposed using benzyloxybenzene and oxybis(methylene)dibenzene as model compounds. MSSB can be easily separated by using an external magnetic field and the recovered MSSB proved to be still highly active for catalyzing the hydrocracking of C O bridged bonds in sawdust.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2016
·
IF 3.205
Zhiming Gao,Lin Cui,Hongwei Ma
Four methods were adopted to prepare samples 20%NiO/Al 2 O 3 with calcination fixed at 500 °C, which were then reduced into 20%Ni/Al 2 O 3 and used as catalysts for reaction of selective methanation of CO in H 2 -rich gas (CO-SMET). XRD and TPR measurements indicate that nickel aluminates were formed in the calcined samples and their formation was influenced by preparation methods. Higher temperatures were required to reduce the calcined samples more efficiently and to achieve a higher catalytic activity for CO-SMET. Among the four methods, the precipitation method using ammonium carbonate as precipitant produced the highest catalytic activity both for CO methanation and for CO 2 methanation after reduction at 800 °C for 2 h. The calcined sample 20%NiO/Al 2 O 3 prepared with the method was therefore used as support and impregnated with Ru 3+ solution. Ru addition promoted reduction of Ni 2+ ions in the calcined sample even at the low temperatures of 400 °C and 500 °C. The catalyst 1%Ru–20%Ni/Al 2 O 3 reduced at 500 °C thus had a superior performance, removing CO to ca. 30 ppm with a selectivity as high as 75% at reaction temperature of 220 °C.
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CHEMICAL ENGINEERING JOURNAL
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2016
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IF 5.31
Yan Chao Xu,Zhen Xing Wang,Xi Quan Cheng,You Chang Xiao,Lu Shao
Herein, a novel positively charged nanofiltration (NF) membrane has been facilely fabricated via a highly efficient one-step mussel-substance-simulated co-deposition of low-cost catechol and branched polyetheylenimine (PEI) onto substrates. The co-deposition behaviour, physicochemical properties and separation performances of resultant membranes can be readily tailored by varying PEI molecular weight. In particular, the catechol/PEI600 co-deposited NF membrane shows good removals toward dyes, common salts and heavy metal ions for textile wastewater treatment. Our membranes exhibit high removal efficiency toward cationic dye and metal ions due to the Donnon effect. In addition, EtOH activation process can greatly enhance the membrane permeance with a factor of 1.8–2.4 without compromising rejection. Especially, the novel membranes show stable long-term separation performance toward MgCl 2 removal, and the dye-fouled co-deposited membranes can be facilely regenerated and reused with a simple static immersion operation. The co-deposited membrane can perform well in alcohols solvents, indicating its excellent performance for practically environmentally-friendly usages. The facile strategy disclosed in our study can provide new opportunities to not only nanofiltration membrane modification but also the surface engineering of vast kinds of materials towards energy and environmental applications.
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Progress in Natural Science-Materials International
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2016
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IF 1.753
Yu Bai,Chunlei Wang,Xingyi Zhou,Junling Lu,Yujie Xiong
Pd typically exhibits relatively low catalytic activity in CO oxidation, as CO is apt to be adsorbed on Pd to poison the surface for O 2 activation. In this Letter, we report that this limitation can be overcome by integrating Pd with TiO 2 . The TiO 2 was coated on Pd nanocubes with a controllable thickness using atomic layer deposition (ALD) method. Given the different work functions of TiO 2 and Pd, the electrons in TiO 2 semiconductor will flow toward Pd. With the electron density increased on Pd, the adsorption of CO to Pd will be weakened while the oxygen activation can be facilitated. Meanwhile, the interface-confined sites at Pd-TiO 2 may further enhance the oxygen activation. As the species adsorption and activation are strongly correlated with electron density, the performance of Pd-TiO 2 in CO oxidation turns out to depend on the TiO 2 thickness, which determines the number of transferred electrons, within a certain range (<1.8 nm). This work provides a new strategy for enhancing catalytic performance through tailoring charge densities in hybrid catalysts.
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ELECTROCHIMICA ACTA
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2016
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IF 4.803
Hong Xiao,Wenjun Guo,Bin Sun,Meishan Pei,Guowei Zhou
A series of mesoporous TiO 2 nanotubes/reduced graphene oxide (TiO 2 NT/RGO) and Co-doped TiO 2 NT/RGO composites were synthesized via a hydrothermal method. In this method, graphene oxide (GO) was reduced to RGO, whereas TiO 2 NT and Co-doped TiO 2 NT were prepared using poly(ethylene-glycol)-block-poly(propy glycol)-block-poly(ethylene-glycol) as a structure-directing agent through a simple solvothermal route. Their morphology and properties were determined using X-ray diffraction, field emission scanning electron microscopy, UV–vis diffuse reflectance spectra, and Raman measurement. Results indicated that TiO 2 NT displayed mesoporous structures with lengths ranging from about 3 μm to 10 μm, tube diameters ranging from about 400 nm to 600 nm, wall thickness of about 250 nm, and mesoporous walls of about 6 nm. The electrochemical performance of the TiO 2 -based electrodes for supercapacitor was confirmed by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge in 0.5 mol L −1 Na 2 SO 4 aqueous electrolyte solution. The Co-doped TiO 2 NT/RGO composite electrode with 10.00 wt.% GO exhibited a specific capacitance of 27.5 F g −1 at a current density of 0.2 A g −1 in a symmetrical two-electrode cell, whereas the specific capacitance of TiO 2 was 0.7 F g −1 . The Co-doped TiO 2 NT/RGO composite electrode exhibited high rate capability and excellent long-term cycle stability. The outstanding performance of the Co-doped TiO 2 NT/RGO composite electrode was attributed to the synergistic effects on capacitive behavior of Co-doped TiO 2 NT combined with high electronic conductivity of the RGO sheets.
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JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
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2015
·Vol. 78
·期 2
·293-298
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IF 1.532
Cui Hongtao,Ma Wenle,Wang Li,Xue Junying
Abstract
In this work, α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ). The protonation and the following ring-opening reaction of epoxide promoted the hydrolysis of [Co(H 2 O) 6 ] 2+ , leading to the formation of α-Co(OH) 2 nanosheets. The obtained nanosheets were then exfoliated to monolayer nanosheets in formamide under ultrasonic vibration. A possible exfoliation mechanism is proposed for the exfoliating process of α-Co(OH) 2 nanosheets. The water molecules incorporated in the layered structure of α-Co(OH) 2 are considered to be the key medium for the layer exfoliation. It seems that the water molecules coordinated with the cobalt ions weakened the interlayer interaction. Therefore, the extraction of water molecules by formamide readily broke the interlayer connection in α-Co(OH) 2 , resulting in the exfoliation of nanosheets. Graphical Abstract α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ).
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2015
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IF 3.313
Xianpei Ren,Xiaodong Ren,Liuqing Pang,Yunxia Zhang,Qiang Ma,Haibo Fan,Shengzhong (Frank) Liu
Cost-effective materials for electrocatalytic water splitting are key to renewable energy research. In this work, MoS 2 /sulfur and nitrogen co-doped reduced graphene oxide (SNG) nanocomposite was produced via a two-step hydrothermal process. The formation of nanocomposite was confirmed by X-ray diffraction (XRD), Raman spectroscopy , scanning electron microscopy (SEM), transmission electron microscopy (TEM). It is found that the MoS 2 /SNG nanocomposite exhibits much higher catalytic activity for the hydrogen evolution reaction (HER) relative to MoS 2 and MoS 2 /RGO catalysts, as manifested by much larger cathodic current density with smaller overpotential of −120 mV and lower Tafel slope of 45 mV dec −1 . It is believed that the outstanding performance is attributed to the high electronic conductivity of SNG for fast charge transport. This study highlights the significance of the strong electronic coupling effect between the MoS 2 and SNG in the enhancement of HER electrocatalytic activity .
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Small
·
2016
·Vol. 13
·期 3
·1602507
·
IF 8.315
Feng Hu,Hongchao Yang,Changhong Wang,Yejun Zhang,Huan Lu,Qiangbin Wang
Rational design of cost-effective, nonprecious metal-based catalysts with desirable oxygen reduction reaction (ORR) performance is extremely important for future fuel cell commercialization, etc. Herein, a new type of ORR catalyst of Co-N-doped mesoporous carbon hollow sphere (Co-N-mC) was developed by pyrolysis from elaborately fabricated polystyrene@polydopamine-Co precursors. The obtained catalysts with active Co sites distributed in highly graphitized mesoporous N-doped carbon hollow spheres exhibited outstanding ORR activity with an onset potential of 0.940 V, a half-wave potential of 0.851 V, and a small Tafel slope of 45 mV decade −1 in 0.1 m KOH solution, which was comparable to that of the Pt/C catalyst (20%, Alfa). More importantly, they showed superior durability with little current decline (less than 4%) in the chronoamperometric evaluation over 60 000 s. These features make the Co-N-mC one of the best nonprecious-metal catalysts to date for ORR in alkaline condition.
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PubMed
高影响因子
WASTE MANAGEMENT
·
2017
·
IF 4.03
Yunpu Wang,Leilei Dai,Liangliang Fan,Leipeng Cao,Yue Zhou,Yunfeng Zhao,Yuhuan Liu,Roger Ruan
In this study, a ZrO 2 -based polycrystalline ceramic foam catalyst was prepared and used in catalytic co-pyrolysis of waste vegetable oil and high density polyethylene (HDPE) for hydrocarbon fuel production. The effects of pyrolysis temperature, catalyst dosage, and HDPE to waste vegetable oil ratio on the product distribution and hydrocarbon fuel composition were examined. Experimental results indicate that the maximum hydrocarbon fuel yield of 63.1 wt. % was obtained at 430 °C, and the oxygenates were rarely detected in the hydrocarbon fuel. The hydrocarbon fuel yield increased when the catalyst was used. At the catalyst dosage of 15 wt.%, the proportion of alkanes in the hydrocarbon fuel reached 97.85 wt.%, which greatly simplified the fuel composition and improved the fuel quality. With the augment of HDPE to waste vegetable oil ratio, the hydrocarbon fuel yield monotonously increased. At the HDPE to waste vegetable oil ratio of 1:1, the maximum proportion (97.85 wt.%) of alkanes was obtained. Moreover, the properties of hydrocarbon fuel were superior to biodiesel and 0 # diesel due to higher calorific value, better low-temperature low fluidity, and lower density and viscosity.
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CERAMICS INTERNATIONAL
·
2017
·
IF 2.986
Li Fang,Leixin Hou,Yuhao Zhang,Yongkang Wang,Guanghong Yan
Highly hydrophobic rutile titania-silica nanocomposites were synthesized by an improved hydrolysis co-precipitation method using low-cost sodium metasilicate and titanium oxysulfate (TiOSO 4 ) as precursors, followed sequentially by calcination at 800 °C and modification with trimethylchlorosilane (TMCS). It was found that the resulting TiO 2 -SiO 2 nanocomposites had a Ti/Si molar ratio of 5:1 and exhibited single-phase rutile with a specific surface area of 269 m 2 g −1 . The addition of acetylacetone (AcAc) during the hydrolysis co-precipitation process played a key role in the growth of well-ordered TiO 2 -SiO 2 crystallites since the hydrolysis rate of TiOSO 4 might be retarded due to the complexation of AcAc to the Ti atoms in TiOSO 4 . The TMCS-modified TiO 2 -SiO 2 nanocomposites exhibited a high root-mean-square (RMS) roughness of 22 nm and good hydrophobicity with a static contact angle of 143.7°, highlighting its potential application as a filler in exterior wall coatings.
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危险品化学品经营许可证（带存储）