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71.
Kinetics of Lifetime Changes in Bimetallic Nanocatalysts Revealed by Quick X‐ray Absorption Spectroscopy 下载免费PDF全文
Dr. Matthias Filez Dr. Hilde Poelman Dr. Evgeniy A. Redekop Dr. Vladimir V. Galvita Dr. Konstantinos Alexopoulos Dr. Maria Meledina Dr. Ranjith K. Ramachandran Dr. Jolien Dendooven Prof. Christophe Detavernier Prof. Gustaaf Van Tendeloo Dr. Olga V. Safonova Dr. Maarten Nachtegaal Prof. Bert M. Weckhuysen Prof. Guy B. Marin 《Angewandte Chemie (International ed. in English)》2018,57(38):12430-12434
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S. V. Demishev N. E. Sluchanko L. Weckhuysen V. V. Moshchalkov H. Ohta S. Okubo Y. Oshima N. G. Spitsina 《Physics of the Solid State》2002,44(3):441-443
Magnetization study of the C60 · TMTSF · 2CS2 molecular complex in magnetic fields up to 47 T for the temperature range 1.8–300 K and ESR spectroscopy of the molecular complex (ET)2C60 at T=1.8 K for the frequency range 60–90 GHz in magnetic fields up to 32 T provide experimental evidence that paramagnetic centers with reduced g-factor values g<1 control the magnetic properties of these solids. A model is suggested in which the renormalization of the g factor is due to the dynamic Jahn-Teller effect involving negative C60 ions that appear as defects in the crystalline structure with a weak charge transfer. 相似文献
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Bergwerff JA Lysova AA Espinosa-Alonso L Koptyug IV Weckhuysen BM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(8):2363-2374
An indirect magnetic resonance imaging (MRI) method has been developed to determine in a noninvasive manner the distribution of paramagnetic Co2+ complexes inside Co/Al2O3 catalyst extrudates after impregnation with Co2+/citrate solutions of different pH and citrate concentrations. UV/Vis/NIR microspectroscopic measurements were carried out simultaneously to obtain complementary information on the nature of the Co2+ complexes. In this way, it could be confirmed that the actual distribution of Co2+ inside the extrudates could be derived from the MRI images. By combining these space- and time-resolved techniques, information was obtained on both the strength and the mode of interaction between [Co(H2O)6]2+ and different Co2+ citrate complexes with the Al2O(3) support. Complexation of Co2+ by citrate was found to lead to a stronger interaction of Co with the support surface and formation of an eggshell distribution of Co2+ complexes after impregnation. By addition of free citrate and by changing the pH of the impregnation solution, it was possible to obtain the rather uncommon egg-yolk and egg-white distributions of Co2+ inside the extrudates after impregnation. In other words, by carefully altering the chemical composition and pH of the impregnation solution, the macrodistribution of Co2+ complexes inside catalyst extrudates could be fine-tuned from eggshell over egg white and egg yolk to uniform. 相似文献
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Cover Picture: Separation of Time‐Resolved Phenomena in Surface‐Enhanced Raman Scattering of the Photocatalytic Reduction of p‐Nitrothiophenol (ChemPhysChem 3/2015) 下载免费PDF全文
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Dr. Donglong Fu Alessandra Lucini Paioni Dr. Cheng Lian Onno van der Heijden Prof. Marc Baldus Prof. Bert M. Weckhuysen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):20199-20205
The chemical industry has exploited zeolite shape selectivity for more than 50 years, yet our fundamental understanding remains incomplete. Herein, the zeolite channel geometry–reactive intermediate relationships are studied in detail using anisotropic zeolite ZSM-5 crystals for the methanol-to-hydrocarbon (MTH) process, and advanced magic-angle spinning solid-state NMR (ssNMR) spectroscopy. The utilization of anisotropic ZSM-5 crystals enabled the preferential formation of reaction intermediates in single-orientation zeolite channels, as revealed by molecular dynamics simulations and in situ UV/Vis diffuse-reflectance spectroscopy. The ssNMR results show that the slightly more constrained sinusoidal zeolite channels favor the olefin cycle by promoting the homologation of alkanes, whereas the more extended straight zeolite channels facilitate the aromatic cycle with a higher degree of alkylation of aromatics. Dynamic nuclear polarization experiments further indicate the preferential formation of heavy aromatics at the zeolite surface dominated by the sinusoidal channels, providing further insight into catalyst deactivation. 相似文献
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