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141.
在反应温度下以1%O2对Mo/MCM-22催化剂的原位再生 总被引:1,自引:0,他引:1
In recent years, the catalytic dehydroaromatization of methane to yield aromatics has been a challenging and intriguing topic in heterogeneous catalysis. Until now, the two effective methane dehydroaromatization catalysts are Mo/HZSM-5[1] and Mo/MCM-22[2]. However, this reaction suffers from rapid catalyst deactivation due to coking[3]. 相似文献
142.
Several mesoporous silicas with different morphologies were controllably prepared by sol-gel method with adjustable ratio of dual template,and they were further impregnated with aqueous solution of nickel nitrate,followed by calcination in air.The synthesized silica supports and supported nickel samples were characterized using N2-adsorption/desorption,X-ray diffraction(XRD),H2 temperature-programmed reduction(H2-TPR),Scanning electron microscope(SEM),Transmission electron microscope(TEM) and thermo-gravimetric analysis(TGA-DTG) techniques.The Ni nanoparticles supported on shell-like silica are highly dispersed and yielded much narrower nickel particle-size than those on other mesoporous silica.The methane reforming with dioxide carbon reaction results showed that Ni nanoparticles supported on shell-like silica carrier exhibited the better catalytic performance and catalytic stability than those of nickel catalyst supported on other silica carrier.The thermo-gravimetric analysis on used nickel catalysts uncovered that catalyst deactivation depends on the type and nature of the coke deposited.The heterogeneous nature of the deposited coke was observed on nickel nanoparticles supported on spherical and peanut-like silica.Much narrower and lower TGA derivative peak was founded on Ni catalyst supported on the shell-like silica. 相似文献
143.
Rh基催化剂上CO加氢制C2含氧化物的原位红外光谱研究 总被引:5,自引:0,他引:5
用原位红外光谱考察了Rh-Mn-Li-Fe/SiO2和Rh/SiO2催化剂表面上CO的吸附态及CO加氢反应过程中吸附物种的变化. 结果表明,CO在Rh/SiO2催化剂上仅有线式吸附态存在,而CO在Rh-Mn-Li-Fe/SiO2催化剂上既有线式吸附态存在,又有孪生吸附态存在. 这说明Rh-Mn-Li-Fe/SiO2催化剂中Rh的分散度较高. 经CO加氢反应(3.0 MPa,593 K)后,在Rh-Mn-Li-Fe/SiO2催化剂上可观测到C2含氧化物前驱物种的吸收谱带,而在Rh/SiO2催化剂上未观测到相应的谱带; CO在这两种催化剂上主要以线式吸附态存在,孪生吸附态基本消失. 结合催化剂对CO加氢的催化性能,可以认为线式吸附的CO对生成C2含氧化物有贡献. Rh-Mn-Li-Fe/SiO2催化剂的高活性是由于助剂的存在削弱了其表面吸附CO的 C-O键,促进了CO的活化,从而有利于C2含氧化物前驱物的生成. 相似文献
144.
Copolymerization of fluorene‐based main‐chain benzoxazine and their high performance thermosets 下载免费PDF全文
Tiantian Feng Jun Wang Hui Wang Noureddine Ramdani Liwu Zu Wenbin Liu Xiaodong Xu 《先进技术聚合物》2015,26(6):581-588
A series of fluorene‐based benzoxazine copolymers were synthesized from the mixture of 9,9‐bis(4‐hydroxyphenyl)fluorene and bisphenol A, and 4,4′‐diaminodiphenyloxide and paraformaldehyde. And the cured polybenzoxazine films derived from these copolymers were also obtained. Fourier transform infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonances confirmed the structure of these benzoxazines. Their molecular weight was estimated by gel permeation chromatography. The curing behavior of the precursors was monitored by FTIR and differential scanning calorimetry. Dynamic mechanical analysis and thermogravimetric analysis were performed to study the thermal properties of the cured polymers. The cured polybenzoxazines exhibit excellent heat resistance with glass transition temperatures (Tg) of 286–317°C, good thermal stability along with the values of 5% weight loss temperatures (T5) over 340°C, and high char yield over 50% at 800°C. The mechanical properties of the cured polymers were also measured by bending tests. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
145.
146.
CHEN LiQiao LIU WeiPing CHEN JiaLin YANG XianFeng LIU Jia FU XiongHui & WU MingMei Key Laboratory of Bioinorganic Synthetic Chemistry Ministry of Education State Key Laboratory of Optoelectronic Materials Technologies School of Chemistry Chemical Engineering Sun Yat-Sen University Guangzhou China State Key Lab of Advanced Technology for Comprehensive Utilization of Platinum Metals Kunming Institute of Precious Metals Kunming China 《中国科学B辑(英文版)》2011,(6)
Monodispersed magnetite Fe3O4 and hematite α-Fe2O3 nanocrystals have been grown in co-solvents of alcohol and water. Either the shape or the size of the nanocrystals could be easily controlled. Both the phases and nanostructures have been characterized by powder X-ray diffraction patterns and electron microscopy. The magnetic and catalytic properties of these products were investigated and compared with each other. The obtained results clearly demonstrate that these iron oxide nanocrystals are soft ferromag... 相似文献
147.
In recent years there has been ever-increasing interest in space propellants that are more environmentally benign,less toxic and easier and safer to handle than conventional ones 相似文献
148.
Electrochemical impedance spectra of CdSe quantume dots sensitized nanocrystalline TiO_2 solar cells
XU XueQing & XU Gang Guangzhou Institute of Energy Conversion Renewable Energy Gas Hydrate Key Laboratory of Chinese Academy of Sciences Guangzhou China 《中国科学B辑(英文版)》2011,(1)
Quantum dots sensitized nanocrystalline TiO2 solar cells (QDSSCs) are promising third-generation photovoltaic devices.In comparison with conventional dye-sensitized solar cells (DSSCs),the efficiency of QDSSCs is still very low (about 3%).In this paper,the electrochemical impedance spectroscopy technology has been adopted to investigate the quasi-Fermi level and the carrier dynamics of the colloidal CdSe QDs sensitized TiO2 eletrode with S2-/Sxredox electrolytes and the series resistance of the QDSSCs.In co... 相似文献
149.
WANG Cheng MA TianBao & LU Jie State Key Laboratory of Explosion Science Technology Beijing Institute of Technology Beijing China Taiyuan Gas Company Taiyuan 《中国科学:物理学 力学 天文学(英文版)》2010,(2)
In combination with experimental research,numerical simulation is performed to investigate the influence law of the obstacles in a duct on the explosion flame of premixed coal gas and air. The numerical method uses upwind WENO scheme and two-step chemical reaction model. The interaction mechanism is addressed between the compression wave from reflection on the right end of the duct and flame propagation. The reflected wave is found to result in the decrease of flame velocity. On this basis,we analyze the me... 相似文献
150.