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81.
Zhongxian Song Yun Xing Tingji Zhang Jinggang Zhao Junkai Wang Yanli Mao Baolin Zhao Xuejun Zhang Min Zhao Ziang Ma 《应用有机金属化学》2020,34(3):e5446
A series of Ce-Fe-Ox catalysts prepared by the different calcination temperatures (marked as CF-X, where X represented calcination temperature) were used to the selectivity catalytic reduction of NOx by NH3. The results explained the relationship between calcination temperature and the sulfate species over Ce-Fe-Ox, and then investigated the surface acidity and catalytic performance. The large amounts of sulfate species were formed over CF-450 and CF-550 while it was decomposed with further the increasing of calcination temperature, which resulted in the loss of surface acidity, causing a decrease in the catalytic activity over Ce-Fe-Ox. Thereby, the CF-450 catalyst showed the best catalytic activity and over 90% NOx conversion was obtained at 244–450 °C. Besides, the favored pore structure, more Fe3+ active species, higher Ce3+ concentration and the abundance of chemical adsorbed oxygen species, as well as the surface acid sites, would together contribute to the excellent catalytic activity of CF-450 catalyst. 相似文献
82.
在超临界水反应器中,硫酸钠是易造成堵塞的一种常见无机盐,研究其结晶动力学对于防盐沉积反应器的设计具有重要意义.本文采用LAMMPS分子动力学模拟软件研究硫酸钠在超临界水中的微观结晶过程,其中水分子采用SPC/E模型,离子-离子、离子-水分子相互作用采用Coulumb和Lennard-Jones联合势能函数.结果表明:水对离子的静电屏蔽作用随温度升高而增强、随密度减小而减弱;增大超临界水的温度和密度有利于离子扩散,进而促进离子相互碰撞、成核;在模拟的超临界水参数范围内,其成核速率的数量级为1029cm-3·s-1,生长速率为(19.8~25.8) m·s-1. 相似文献
83.
Slow evaporation of an aqueous solution containing l-threonine and magnesium sulphate heptahydrate, results in the fractional crystallization of the less soluble l-threonine crystal and not any novel optoelectronic ‘magnesium sulfate admixtured l-threonine’ crystal as reported by Puhal Raj et al. in Optik, 124 (2013) 6887–6891. 相似文献
84.
Abstract In this study, the molecular weights of the polymer from vinyl benzoate has been reported for different dose rates and different temperatures. The mol.wt. remains around 4000. With increasing dose, the molecular weight increases to about 14,000. The degrees of polymerization and the kinetic chain lengths calculated from the experimentally determined G R values have been compared which show that the kinetic chain length is larger than the D ? Pn. From a plot of the (D ? Pn)?1 vs. R p , an intercept is obtained which is equal to 3.25 × 10?2 which is higher than obtained in conventional polymerization. By examining the effect of temperature on mol.wt., the dependence of R p on dose rate and the absence of induction period it has been concluded that chain transfer occurs to impurities that are generated during radiolysis. 相似文献
85.
Majid M. Heravi Neda Zamani Ahari Hossein A. Oskooie Mitra Ghassemzadeh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1701-1712
Abstract Mild and efficient S-methylation of thiols and o-methylation of phenols and naphthols occurs with dimethyl sulfate (DMS) supported on basic alumina under microwave irradiation in solventless system. 相似文献
86.
Michèle Willson Jacques Navech Ramon Burgada 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):457-467
Abstract The PMR spectra of some spirophosphorans containing the P–C bond are analysed. The results allow us to determine the stereochemistry of these compounds (conformation, stereoisomerism). Le spectre de RMP de quelques spirophosphoranes à liaison P–C est analysé. Les résultats sont utilisés pour préciser la stéréochimie de ces composés (conformation, stéréoisomérie). 相似文献
87.
Ali Ramazani Ebrahim Ahmadi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):565-567
Magnesium hydrogen sulfate powder was found to catalyze stereoselective conversion of dialkyl 2-(imido-N-yl)-3-(triphenylphosphorany-lidene)butanedioates to electron-poor (Z)-N-vinylimides in solvent-free conditions at 95°C 1 h in high conversions. Microwave also was found to catalyze the same reactions in the presence of magnesium hydrogen sulfate powder in solvent-free conditions in 3 min. 相似文献
88.
Hamid Reza Shaterian Asghar Hosseinian Majid Ghashang Fahimeh Khorami Neda Karimpoor 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):2333-2338
An environmentally friendly procedure for the preparation of dihydropyrimidinone derivatives or their sulfur analogues under thermal solvent-free conditions in the presence of aluminium hydrogen sulfate [Al(HSO4)3] and alumina sulfuric acid (Al2O3-SO3H) as heterogeneous catalysts was developed. 相似文献
89.
Orazio Attanasi Paolo Battistoni Gabriele Fava 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):271-277
Abstract The rates of the base-catalyzed hydrogen-deuterium exchange at position 2, and the reverse, in some 5-and 6-substituted benzothiazoles are reported. The plots of log k sH, and log k sD against the [sgrave]m + [sgrave]p values of the substituents, according to the Hammett-Jaffé equations, are slightly curved. The primary hydrogen isotope effect k sH/k sD varies between 0.7 and 2.3 and the plot of log k sH/k sD against the [sgrave]m + [sgrave]p values of the substituents is a more pronounced curve, showing a maximum near to the [sgrave]m + [sgrave]p value of ?0.3. By these investigations the simple utilization of the primary hydrogen isotope effect in the prediction of reaction mechanisms seems extremely hazardous. 相似文献
90.
通过控制丝素蛋白自组装过程制备了溶液状态下的丝素纳米纤维(silk fibroin nanofibers,SFFs),与硫酸钙、万古霉素(vancomycin,VCM)复合,制备了VCM/CS/SFFs抗菌骨材料。通过SEM、XRD、紫外分光光度计、万能力学试验机、抑菌圈、MTT等手段分别研究了复合材料的微观形貌与结构、药物释放、力学、抑菌及细胞相容性等性能。结果显示,与水作为固化液相比,随着SFFs溶液(0.017 5~2.1 mg·mL-1)的加入,复合材料凝固时间可控,降解率逐渐降低,抗水性增强,韧性提高;同时随丝素纳米纤维含量的增加骨材料抗压强度表现为先增加后减小的趋势,一周内药物释放速率降低;材料同时具有抑菌作用;MTT实验结果显示,加入丝素纳米纤维后与纯的硫酸钙相比MC3T3细胞增殖明显。 相似文献