JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2019
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IF 2.298
Rui-Zhi Cui,Wu Li,Ya-Ping Dong
The phase equilibria relationship between the quaternary system LiCl–KCl–Li2SO4–K2SO4–H2O and its subsystems LiCl–KCl–H2O and LiCl–Li2SO4–H2O was studied by the isothermal dissolution equilibrium method at 288.15 K, and the corresponding phase diagrams were drawn. At 288.15 K, ternary systems LiCl–KCl–H2O and LiCl–Li2SO4–H2O all belong to the simple type. In the phase diagram of the quaternary system LiCl–KCl–Li2SO4–K2SO4–H2O, there are five equilibrium solid phase crystallization fields: LiCl·2H2O, KCl, Li2SO4·H2O, K2SO4, and Li2SO4·K2SO4. Compared with the multitemperature phase diagrams of this system at 288.15–348.15 K, it was found that the basic configuration of the phase diagrams is the same. As the temperature increased, the phase region of double salt Li2SO4·K2SO4 clearly increased, whereas the phase region of single salt KCl and K2SO4 clearly decreased. On the basis of the experiment, the extended Harvie–Weare model of the Pitzer model was used to predict the solubility data of the quaternary system. The simulated and measured values were basically in good agreement.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
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2018
·Vol. 125
·期 1
·1-9
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IF 1.604
He Junfeng,Hu Jiamin,Mo Xi,Hao Qing,Fan Zhili,He Guannan,Wang Yinzhen,Li Wei,He Qinyu
As photocatalysts exhibit selectivity toward various pollutants, it is necessary to develop different and novel photocatalysts. In this work, a novel photocatalyst-nitrogen-doped simonkolleite Zn 5 (OH) 8 Cl 2 ·H 2 O (DSM) is prepared through a new facile method: calcinating the mixture of zinc hydroxide, urea, and guanidine hydrochloride at 575 °C for 1 h in a furnace with an air atmosphere. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra, UV–visble near-infrared diffuse reflection spectra (UV–Vis–NIR DRS), Brunauer–Emmett–Teller (BET) method, Ramen spectra and Zeta potential measurement, photocatalytic properties, as well as active species trapping experiments. XRD and XPS show the as-prepared powder is nitrogen-doped simonkolleite Zn 5 (OH) 8 Cl 2 H 2 O (DSM) with a small ZnCl 2 fraction. SEM investigation indicates that the as-prepared powder possesses a flower-like layered shape. The UV–Vis–NIR exhibits that after doping, the DSM possesses strong light absorption in the ranges of 300–500 and 1400–2500 nm, a direct electronic transition with a band gap energy of 2.469 eV. PL measurement reveals a strong photoluminescence and an up-conversion from lower to higher-energy visible light in as-prepared samples. Zeta potential investigations show that during photocatalysis, the charges on as-prepared photocatalyst are positive. The photocatalytic experiments show a good dark adsorption, a high photodegradation (99.4% at 60 min), a high pseudo-first-order constant ( k ) of 0.0261 min −1 . Meanwhile, the active species trapping experiments suggest that hole (h + ) is the dominant active species during photocatalysis. It is concluded that the doping favors in enhancing vis-light-photocatalysis. This work makes a significant contribution to the literature.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Peipei Zhao,Mingyu Guo,Qingling Liu,Lijun Fan,Jinfeng Han,Caixia Liu,Na Ji,Chunfeng Song,Degang Ma,Zhenguo Li
A series of Mn a Zr b Cr c O x catalysts with different Cr/Mn molar ratios were synthesized via co-precipitation for the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). It was found that a Mn 5 Zr 2 Cr 2.5 O x catalyst with a Mn:Zr:Cr ratio of 5:2:2.5 exhibited excellent low-temperature activity and the best levels of H 2 O resistance at a high weight hourly space velocity (WHSV) of 54,000 ml/(h·g). NO conversion levels were measured as greater than 87% within a temperature range of 150–250 °C, and catalytic performance levels reached 90% even 50 h after reactions occurred in the presence of 15% H 2 O at 230 °C. The characterization results show that strong interactions occurring between Mn, Zr and Cr oxides and higher quantities of Mn 4+ and Lewis acid sites improved the redox properties and facilitated H 2 O resistance. In situ diffuse reflectance infrared Fourier transform spectra ( in situ DRIFTS) show that coordinated NH 3 on Lewis acid sites and bidentate nitrates play important roles in SCR reactions and that such reactions follow both Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms. The competitive adsorption of H 2 O and NO may be the main cause of the adverse effects of H 2 O on catalytic performance.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2018
·
IF 3.779
Yining Ma,Huaijuan Zhou,Rong Li,Aibin Huang,Xun Cao,Heliang Yao,Shanhu Bao,Shidong Ji,Ping Jin
Square block-like σ-Mg 0.25 V 2 O 5 ·H 2 O with an open layered framework has been successfully synthesized via a facile hydrothermal method . The entire synthetic process is efficient and economically beneficial. As a cathode material for lithium-ion batteries, the hydrated magnesium vanadium bronze exhibits a high reversible capacity and excellent cycling stability at high current rates. High discharge capacities of 294.2 and 221 mA h g −1 can be obtained at the current densities of 20 and 100 mA g −1 , respectively. Meanwhile, the electrode achieves a capacity retention of 87.12% after 100 cycles at 100 mA g −1 and has an excellent long-term cyclic stability with an average decay of 0.053% per cycle over 400 cycles at 800 mA g −1 . The structural stability and impedance variation of the σ-Mg 0.25 V 2 O 5 ·H 2 O electrodes upon cycling have also been investigated. The excellent electrochemical performance suggests that the layered Mg 0.25 V 2 O 5 ·H 2 O could be a promising candidate for the cathode material of lithium-ion batteries.
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JOURNAL OF CATALYSIS
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2018
·
IF 6.759
Yujie Song,Hao Wang,Shijing Liang,Yan Yu,Liuyi Li,Ling Wu
The photoalkylation of nitroarenes with benzyl alcohols in one pot at room temperature and 1 atm N 2 was achieved over the Pd/H 1.07 Ti 1.73 O 4 ·H 2 O nanosheets. The sample shows efficient photocatalytic activity with high conversion of nitrobenzene (99%) and selectivity of secondary amine (85%). This flexible photocatalytic system is also applicable to other nitroarenes with high efficiency. Results of in situ FTIR, DRS, and in situ ESR revealed that the benzyl alcohol and nitrobenzene molecules can bind with the surface Lewis and Brønsted acid sites in the catalyst via the H O⋯Ti and NO 2 ⋯H O Ti species. The formation of surface coordination species results in not only the activation of reactant molecules via surface electron transfer, but also the expanded visible light absorption of the catalyst. Moreover, in situ ESR suggested that the surface coordination can also facilitate the formation of oxygen vacancies in catalysts, which can greatly promote the exposure of Lewis sites and enhance the activation of reactant molecules. Finally, a possible hydrogen transfer strategy over the sample is proposed on a molecular level.
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CATALYSIS TODAY
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2018
·
IF 4.667
Shuohan Yu,Yiyang Lu,Yuan Cao,Jiaming Wang,Bowen Sun,Fei Gao,Changjin Tang,Lin Dong
Mn-based catalysts were believed to be promoting low temperature NH 3 -SCR catalysts for their satisfactory catalytic activity, whereas their poor SO 2 and H 2 O tolerance inhibited their applications. In this work, utilizing poor SO 2 tolerance of Mn oxides, composite catalytic systems containing Mn oxides as deSO x catalyst was designed and synthesized, which exhibited excellent low temperature NH 3 -SCR performance in the presence of SO 2 and H 2 O. The deSO x mechanism of Mn oxides was systematically investigated. In results, SO 2 was catalytic oxidized on the surface of Mn oxides. Oxidized sulfur species could flow away from Mn oxides surface through feed gas flow or form MnSO 4 . When NH 3 and H 2 O were introduced into the feed gas, the oxidized sulfur species were completely deposited as NH 4 HSO 4 instead of forming MnSO 4 . Thus, SO 2 was removed from feed gas entirely resulting in the superb low temperature NH 3 -SCR performances. This work provided a general strategy to enhance SO 2 and H 2 O tolerance of NH 3 -SCR catalysts at low temperature by removing SO 2 using NH 3 and H 2 O who existed in the exhaust gas from stationary sources.
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JOURNAL OF CHEMICAL THERMODYNAMICS
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2016
·
IF 2.196
Yunxue Gao,Shuni Li,Quanguo Zhai,Yucheng Jiang,Mancheng Hu
The (solid + liquid) phase equilibrium of the ternary system (NaCl + RbCl + H 2 O) at T = (288.15, 298.15 and 308.15) K was studied by the method of isothermal solution saturation. Moreover, the density and refractive index of the solution was also determined. The solid phase was studied by the Schreinemaker’s wet residue method and verified by X-ray diffraction. The results show that each of the phase diagrams contains one invariant point, two univariant curves, and three crystallization regions. The crystallization region of NaCl increased obviously with the temperature increasing, while the crystallization regions of RbCl and the mixed crystallization region of (NaCl + RbCl) decreased a little. Furthermore, there are break points at the invariant points for density and refractive index curves.
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JOURNAL OF MOLECULAR LIQUIDS
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2017
·
IF 3.648
Yucui Hou,Jiahe Yan,Lixia Feng,Fan Xie,Weize Wu
Rice straw is a renewable, cheap, and abundant resource in agriculture. Due to its controllable and recoverable properties, H 2 O-SO 2 system was studied as a reaction medium to hydrolyze rice straw to produce chemicals by a two-step treatment. The first-step treatment converted hemicellulose to xylose (17.1%), glucose (3.1%) and arabinose (3.5%) at 140 °C. The second-step treatment converted cellulose to glucose (10.9%) at 190 °C. The total yield of products by the two-step treatment of rice straw was 41.1%, which is more than that in the one-step treatment (21.0% at 190 °C). The apparent activation energies for hemicellulose conversion and xylose dehydration were 76.7 and 66.9 kJ/mol, respectively. The degradation products obtained from the two-step treatment are less than that from the one-step treatment.
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CHINESE CHEMICAL LETTERS
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2016
·
IF 1.947
Ting-Ting Zhang,Jing-Yang Jiang,Yan-Hua Wang
Various supported Pt-Pb bimetallic catalysts were prepared and applied for the catalytic conversion of nitrobenzene to p -aminophenol in the environmentally benign pressurized CO 2 /H 2 O system. Among the bimetallic catalysts prepared, Pt-Pb/SiO 2 is the best and nitrobenzene could be converted to p -aminophenol with a selectivity as high as 82% when the reaction was carried out using this catalyst at 110 °C under 5 MPa CO 2 and 0.2 MPa H 2 .
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COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
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2016
·
IF 3.719
Peng Fei,Xing Chen,Hanguo Xiong,Zia-ud-Din,Lei Chen,Jie Cai
H 2 Ti 2 O 3 ·H 2 O nanotubes (TNTs) were prepared through hydrothermal synthesis and dispersed in bamboo fiber/HDPE (BH) composites to improve the flame retardancy of the composites. TEM observation showed that TiO 2 particles were transformed into TNTs through hydrothermal treatment at 120 °C for 12 h in 8 M NaOH solution. Then, a cone calorimeter and a limiting oxygen index chamber were used to evaluate the effects of the TNTs on the flame retardancy of the BH composites. Results demonstrated that TNTs definitely improved the flame retardancy of BH composites by absorbing decomposition products from combustion due to its large specific area and tubular structure. Additionally, the TNTs reduced the free volume in the microzone, strengthened the molecular chain rigidity, and then contributed to the thermostability and flame retardancy of the BH composites.
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CATALYSIS COMMUNICATIONS
·
2015
·
IF 3.699
Yangang Wang,Yangling Xu,Yunzhu Wang,Hengfei Qin,Xi Li,Yuanhui Zuo,Shifei Kang,Lifeng Cui
Molybdenum doped graphitic carbon nitride (g-C 3 N 4 ) catalysts were prepared by a simple pyrolysis method using melamine and ammonium molybdate as precursors. The characterization results indicated that the obtained Mo-doped g-C 3 N 4 catalysts had worm-like mesostructures with higher surface area. Introduction of Mo species can effectively extend the spectral response property and reduce the recombination rate of photogenerated electrons and holes. CO 2 photocatalytic reduction tests showed that the Mo-doped g-C 3 N 4 catalysts exhibited considerably higher activity (the highest CO and CH 4 yields of 887 and 123 μmol g − 1 -cat., respectively, after 8 h of UV irradiation.) compared with pure g-C 3 N 4 from melamine.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2017
·
IF 2.323
Yunxue Gao,Shuni Li,Quanguo Zhai,Yucheng Jiang,Mancheng Hu
Complete phase diagrams and physico-chemical properties for the ternary system (CsCl + NaCl + H2O) were determined at T = (298.15, 308.15, and 318.15) K, respectively. The X-ray diffraction method and Schreinemaker’s wet residue method were used to verify the solid phase. The phase diagrams show this ternary system is a complex type. Three crystallization regions were found corresponding to the single salt NaCl, a compound CsCl·2NaCl·2H2O, and a solid solution series [Cs1–x(Na·H2O)x]Cl (x in [Cs1–x(Na·H2O)x]Cl changed from 0 to 0.43 (298.15 K), 0.39 (308.15 K), and 0.36 (318.15 K) at each temperature. With rising temperature, the crystallization area of NaCl increased, but CsCl·2NaCl·2H2O and [Cs1–x(Na·H2O)x]Cl decreased simultaneously. However, density and refractive index increased with increasing CsCl concentration.
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