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51.
52.
Zizwe A. Chase Stanislav Kasakov Dr. Hui Shi Dr. Aleksei Vjunov Dr. John L. Fulton Dr. Donald M. Camaioni Dr. Mahalingam Balasubramanian Dr. Chen Zhao Dr. Yong Wang Prof. Dr. Johannes A. Lercher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16541-16546
The state of Ni supported on HZSM‐5 zeolite, silica, and sulfonated carbon was studied during aqueous‐phase catalysis of phenol hydrodeoxygenation using in situ extended X‐ray absorption fine structure spectroscopy. On sulfonated carbon and HZSM‐5 supports, NiO and Ni(OH)2 were readily reduced to Ni0 under reaction conditions (≈35 bar H2 in aqueous phenol solutions containing up to 0.5 wt. % phosphoric acid at 473 K). In contrast, Ni supported on SiO2 was not stable in a fully reduced Ni0 state. Water enables the formation of NiII phyllosilicate, which is more stable, that is, difficult to reduce, than either α‐Ni(OH)2 or NiO. Leaching of Ni from the supports was not observed over a broad range of reaction conditions. Ni0 particles on HZSM‐5 were stable even in presence of 15 wt. % acetic acid at 473 K and 35 bar H2. 相似文献
53.
CH. Sedlmair K. Seshan A. Jentys J. A. Lercher 《Research on Chemical Intermediates》2003,29(3):257-269
The influence of SO2 exposure under lean (oxidizing) and rich (reducing) reaction conditions on the storage and oxidation/reduction function of a commercial NOx storage-reduction catalyst was investigated by temperature-programmed uptake experiments and high temperature XRD. Both the storage capacity and the oxidation/reduction function of the catalyst were deactivated by SO2 exposure under lean and rich reaction conditions. The deactivation of the storage component, i.e. the loss of the NOx storage capacity, resulted mainly from the formation of Ba-sulfates accumulating in the bulk phase, which have a high thermal stability (>800°C) and, therefore, cannot be removed under the typical operation conditions of a NSR catalyst. For the oxidation function only a temporarily deactivation during lean reaction conditions was observed. Besides the formation of SO2-
4 species on the storage component at the beginning of the SO2 exposure under rich conditions, an adsorption of SO2 on the noble metal component was observed resulting in the formation of sulfur deposits. The oxidation of these sulfur species with a subsequent spillover of SO2-
4 species to the storage component during lean conditions could accelerate the deactivation of the storage capacity. 相似文献
54.
Navneet K. Gupta Dr. Anastasia Pashigreva Dr. Evgeny A. Pidko Prof. Emiel J. M. Hensen Prof. Leslaw Mleczko Dr. Stefan Roggan Dr. Erika E. Ember Prof. Johannes A. Lercher 《Angewandte Chemie (International ed. in English)》2016,55(5):1728-1732
Active sites in carbon‐catalyzed phosgene synthesis from gaseous CO and Cl2 have been identified using C60 fullerene as a model catalyst. The carbon atoms distorted from sp2 coordination in non‐planar carbon units are concluded to generate active Cl2. Experiments and density functional theory calculations indicate the formation of a surface‐bound [C60???Cl2] chlorine species with radical character as key intermediate during phosgene formation. It reacts rapidly with physisorbed CO in a two‐step Eley–Rideal‐type mechanism. 相似文献
55.
Daniel Melzer Pinghong Xu Daniela Hartmann Yuanyuan Zhu Nigel D. Browning Maricruz Sanchez‐Sanchez Johannes A. Lercher 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(31):9019-9023
Aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) has been used to image the basal {001} plane of the catalytically relevant M1 phase in MoVTeNb complex oxides. Facets {010}, {120}, and {210} are identified as the most frequent lateral termination planes of the crystals. Combination of STEM with He ion microscopy (HIM) images, Rietveld analysis, and kinetic tests reveals that the activation of ethane is correlated to the availability of facets {001}, {120}, and {210} at the surface of M1 crystals. The lateral facets {120} and {210} expose crystalline positions related to the typical active centers described for propane oxidation. Conversely, the low activity of the facet {010} is attributed to its configuration, consisting of only stable M6O21 units connected by a single octahedron. Thus, we quantitatively demonstrated that differences in catalytic activity among M1 samples of equal chemical composition depend primarily on the morphology of the particles, which determines the predominant terminating facets. 相似文献
56.
电感耦合等离子体原子发射光谱法测定钛酸钡纳米粉体中7种杂质元素 总被引:3,自引:0,他引:3
钛酸钡纳米粉体样品用盐酸溶解,在所得样品溶液中用电感耦合等离子体原子发射光谱法测定了以氧化物存在于样品中的7种杂质元素(包括镁、锶、钾、钠、铝、硅及铁),对测定的光谱条件进行了试验并优化达到上述各元素的测定上限为0.1%(质量分数).测得方法的检出限(3S/b)为(单位μg·L-1):2.0(铝),1.0(铁),20.0(钾),0.2(镁),4.0(钠),3.0(硅)及0.5(锶).应用此方法分析了两件实样,所得结果的相对标准偏差(n=6)小于等于2.0%,对其中4种杂质元素(镁、钾、钠和锶)同时用HG/T 3587-1999标准中的方法作分析校核,所得结果与此方法结果一致. 相似文献
57.
A fuzzy rule based framework for noise annoyance modeling 总被引:2,自引:0,他引:2
Botteldooren D Verkeyn A Lercher P 《The Journal of the Acoustical Society of America》2003,114(3):1487-1498
Predicting the effect of noise on individual people and small groups is an extremely difficult task due to the influence of a multitude of factors that vary from person to person and from context to context. Moreover, noise annoyance is inherently a vague concept. That is why, in this paper, it is argued that noise annoyance models should identify a fuzzy set of possible effects rather than seek a very accurate crisp prediction. Fuzzy rule based models seem ideal candidates for this task. This paper provides the theoretical background for building these models. Existing empirical knowledge is used to extract a few typical rules that allow making the model more specific for small groups of individuals. The resulting model is tested on two large-scale social surveys augmented with exposure simulations. The testing demonstrates how this new way of thinking about noise effect modeling can be used in practice both in management support as a "noise annoyance adviser" and in social science for testing hypotheses such as the effect of noise sensitivity or the degree of urbanization. 相似文献
58.
The direct addition of NH across a CC multiple bond (hydroamination) was efficiently catalysed in a liquid-liquid two-phase system. The latter comprised a polar catalyst phase of Zn(CF3SO3)2 in the ionic liquid 1-ethyl-3-methylimidazolium trifuoromethanesulfonate and a substrate mixture in heptane. The possibility of catalysing different hydroamination reactions continuously was demonstrated. 相似文献
59.
Jentys A Mukti RR Lercher JA 《The journal of physical chemistry. B》2006,110(35):17691-3; discussion 17694-5
60.