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991.
Haojie Gao Yuezhao Zhu Feng Fu Hao Wu Yang DU Haijun Chen Chuanhua Liao Hongtu Fan 《Journal of Thermal Analysis and Calorimetry》2014,117(2):973-978
An in situ pyrolysis process of high moisture content lignite in an autogenerated steam agent was proposed. The aim is to utilize steam autogenerated from lignite moisture as a reactant to produce fuel gas and additional hydrogen. Thermogravimetric analysis revealed that mass loss and maximum mass loss rate increased with the rise of heating rates. The in situ pyrolysis process was performed in a screw kiln reactor to investigate the effects of moisture content and reactor temperature on product yields, gas compositions, and pyrolysis performance. The results demonstrated that inherent moisture in lignite had a significant influence on the product yield. The pyrolysis of L R (raw lignite with a moisture content of 36.9 %, wet basis) at 900 °C exhibited higher dry yield of 33.67 mL g?1 and H2 content of 50.3 vol% than those from the pyrolysis of the predried lignite. It was also shown that increasing reaction temperature led to a rising dry gas yield and H2 yield. The pyrolysis of L R showed the maximum dry yield of 33.7 mL g?1 and H2 content of 53.2 vol% at 1,000 °C. The LHV of fuel gas ranged from 18.45 to 14.38 MJ Nm?3 when the reactor temperature increased from 600 to 1,000 °C. 相似文献
992.
Shuhua Liu Lu Wang Yuxin Gao Baoying Yu Yun Bai 《Journal of Thermal Analysis and Calorimetry》2014,118(3):1483-1492
The hydration properties of slag sulfate cement (SSC), slag Portland cement (PSC), and ordinary Portland cement (POC) were compared in this study by determining the compressive strength of pastes, the hydration heat of binders within 72 h, the pore structure, the hydration products, and the hydration degree. The results indicated that main hydration products of PSC paste and POC paste are calcium hydroxide and C–S–H gel, while those of SSC paste are ettringite and C–S–H gel from the analyses of XRD, TG–DTA, and SEM. At the early curing age, the compressive strength depends on the clinker content in the cementitious system, while at the late curing age, which is related to the potential reactivity of slag. From hydration heat analysis, the cumulative hydration heat of PSC is lower than that of POC, but higher than that of SSC. Slag can limit chemical reaction and the delayed coagulation of gypsum, which also plays a role in the early hydration. So SSC shows the lowest heat release and slag can’t be simulated without a suitable alkaline solution. Based on MIP analysis, the porosity of POC paste is the smallest while the average pore size is the biggest. At the age of 90 days, the compressive strength of SSC can get higher development because of its relative smaller pore size than that of PSC and POC paste. 相似文献
993.
Zhaolei Li Xiaoming Jiang Huanhuan Gao Dongshan Zhou Wenbing Hu 《Journal of Thermal Analysis and Calorimetry》2014,118(3):1531-1536
We employed fast-scan chip-calorimeter (FSC) measurement (Flash DSC1) to study the melting of syndiotactic polystyrene after melt-crystallized at various cooling rates as well as after isothermally crystallized at various high temperatures. We attributed the observed double melting peak to a melting-recrystallization process of beta-form crystals upon heating, as evidenced by their variations with different cooling and heating rates. Our experiments demonstrated the advantages of FSC techniques in the investigation of crystallization and melting behaviors of polymer materials. 相似文献
994.
Yilong Gao Jianxiang Wu Wei Zhang Yueyue Tan Jing Gao Jiachang Zhao Bohejin Tang 《Journal of Solid State Electrochemistry》2014,18(11):3203-3207
Zeolitic imidazolate framework-8 (ZIF-8) is synthesized by typical solvothermal method and subsequently calcined under air and nitrogen atmosphere, respectively. The carbon in the calcined ZIF-8 under nitrogen atmosphere was from the carbonization of the guest molecules, without adding any other carbon sources. The samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and electrochemical analyzer system. When the ZIF-8 is used as electrode materials for a supercapacitor in 6 M KOH electrolyte, it displays a pseudocapacitive behavior. The untreated ZIF-8 and calcined ZIF-8 under air and nitrogen atmosphere electrodes exhibit a specific capacitance of 96, 156, and 185 F g?1, respectively, at a scan rate of 5 mV s?1 and good stability over 1,500 cycles. These results indicate that the ZIF-8 is a promising material for supercapacitors. 相似文献
995.
Mechanistic Insights into the Interface‐Directed Transformation of Thiols into Disulfides and Molecular Hydrogen by Visible‐Light Irradiation of Quantum Dots 下载免费PDF全文
Xu‐Bing Li Zhi‐Jun Li Yu‐Ji Gao Qing‐Yuan Meng Shan Yu Prof. Dr. Richard G. Weiss Prof. Dr. Chen‐Ho Tung Prof. Dr. Li‐Zhu Wu 《Angewandte Chemie (International ed. in English)》2014,53(8):2085-2089
Quantum dots (QDs) offer new and versatile ways to harvest light energy. However, there are few examples involving the utilization of QDs in organic synthesis. Visible‐light irradiation of CdSe QDs was found to result in virtually quantitative coupling of a variety of thiols to give disulfides and H2 without the need for sacrificial reagents or external oxidants. The addition of small amounts of nickel(II) salts dramatically improved the efficiency and conversion through facilitating the formation of hydrogen atoms, thereby leading to faster regeneration of the ground‐state QDs. Mechanistic studies reveal that the coupling reaction occurs on the QD surfaces rather than in solution and offer a blueprint for how these QDs may be used in other photocatalytic applications. Because no sacrificial agent or oxidant is necessary and the catalyst is reusable, this method may be useful for the formation of disulfide bonds in proteins as well as in other systems sensitive to the presence of oxidants. 相似文献
996.
Clickable Periodic Mesoporous Organosilicas: Synthesis,Click Reactions,and Adsorption of Antibiotics 下载免费PDF全文
Dr. Jinsuo Gao Xueying Zhang Dr. Shutao Xu Prof. Feng Tan Prof. Xinyong Li Prof. Yaobin Zhang Prof. Zhenping Qu Prof. Xie Quan Dr. Jian Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):1957-1963
Pharmaceutical antibiotics are not easily removed from water by conventional water‐treatment technologies and have been recognized as new emerging pollutants. Herein, we report the synthesis of clickable azido periodic mesoporous organosilicas (PMOs) and their use as adsorbents for the adsorption of antibiotics. Ethane‐bridged PMOs, functionalized with azido groups at different densities, were synthesized by the co‐condensation of 1,2‐bis(trimethoxysilyl)ethane (BTME) and 3‐azidopropyltrimethoxysilane (AzPTMS), in the presence of nonionic‐surfactant triblock‐copolymer P123, in an acidic medium. Four different alkynes were conjugated to azide‐terminated PMOs by means of an efficient click reaction. The clicked PMOs showed improved adsorption capacity (241 μg g?1) for antibiotics (ciprofloxacin hydrochloride) compared with azido‐functionalized PMOs because of the enhanced π–π stacking interactions. These results indicate that click reactions can introduce multifunctional groups onto PMOs, thus demonstrating the great potential of PMOs for environmental applications. 相似文献
997.
Shujun Cai Zheming Xiao Yingbo Shi Prof. Dr. Shuanhu Gao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8677-8681
The reaction conditions and scope of the photo‐Nazarov reaction of aryl vinyl ketones were investigated. In contrast to the conventional acid‐catalyzed methods, this photolytic electrocyclization proceeds in the neutral or basic conditions. Irradiating substrates bearing various aromatic rings, acid‐sensitive groups, cyclohexenyl, cycloheptenyl, and unsaturated pyran with UV‐light (254 nm) smoothly yielded hexahydrofluorenones and related structures. This photo‐Nazarov reaction could also be applicable to the substrates carrying β‐alkyl groups on the enone, which gave corresponding polycyclic rings containing quaternary centers. These photo‐electrocyclized products may prove useful for synthesizing a variety of natural products and their derivatives. Further application of this mild photo‐Nazarov reaction in the synthesis of taiwaniaquinol B was achieved. 相似文献
998.
Back Cover: Two‐Dimensional Tetrathiafulvalene Covalent Organic Frameworks: Towards Latticed Conductive Organic Salts (Chem. Eur. J. 45/2014) 下载免费PDF全文
999.
Frontispiece: New Insight into the Hydrocarbon‐Pool Chemistry of the Methanol‐to‐Olefins Conversion over Zeolite H‐ZSM‐5 from GC‐MS,Solid‐State NMR Spectroscopy,and DFT Calculations 下载免费PDF全文
1000.
Phenylene‐Coated Magnetic Nanoparticles that Boost Aqueous Asymmetric Transfer Hydrogenation Reactions 下载免费PDF全文
Dr. Xiaoshuang Gao Rui Liu Dacheng Zhang Meng Wu Tanyu Cheng Prof. Guohua Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1515-1519
Phenylene‐coated organorhodium‐functionalized magnetic nanoparticles are developed through co‐condensation of chiral 4‐(trimethoxysilyl)ethyl)phenylsulfonyl‐1,2‐diphenylethylene‐diamine and 1,4‐bis(triethyoxysilyl)benzene onto Fe3O4 followed complexation with [{Cp*RhCl2}2]. This magnetic catalyst exhibits excellent catalytic activity and high enantioselectivity in asymmetric transfer hydrogenation in aqueous medium. Such activity is attributed to the high hydrophobicity and the confined nature of the chiral organorhodium catalyst. The magnetic catalyst can be easily recovered by using a small external magnet and it can be reused for at least 10 times without loss of its catalytic activity. This characteristic makes it an attractive catalyst for environmentally friendly organic syntheses. 相似文献