共查询到20条相似文献,搜索用时 15 毫秒
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(44):13858-13862
Ethylene and propylene are the key building blocks of the chemical industry, but current processes are unable to close the growing gap between demand and manufacture. Reported herein is an exceptional europium oxychloride (EuOCl) catalyst for the selective (≥95 %) production of light olefins from ethane and propane by oxychlorination chemistry, thus achieving yields of ethylene (90 %) and propylene (40 %) unparalleled by any existing olefin production technology. Moreover, EuOCl is able to process mixtures of methane, ethane, and propane to produce the olefins, thereby reducing separation costs of the alkanes in natural gas. Finally, the EuOCl catalyst was supported on suitable carriers and evaluated in extrudate form, and preserves performance for >150 h under realistic process conditions. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(42):13258-13262
A dynamic structural behavior of Pt nanoparticles on the ceria surface under reducing/oxidizing conditions was found at moderate temperatures (<500 °C) and exploited to enhance the catalytic activity of Pt/CeO2‐based exhaust gas catalysts. Redispersion of platinum in an oxidizing atmosphere already occurred at 400 °C. A protocol with reducing pulses at 250–400 °C was applied in a subsequent step for controlled Pt‐particle formation. Operando X‐ray absorption spectroscopy unraveled the different extent of reduction and sintering of Pt particles: The choice of the reductant allowed the tuning of the reduction degree/particle size and thus the catalytic activity (CO>H2>C3H6). This dynamic nature of Pt on ceria at such low temperatures (250–500 °C) was additionally confirmed by in situ environmental transmission electron microscopy. A general concept is proposed to adjust the noble metal dispersion (size, structure), for example, during operation of an exhaust gas catalyst. 相似文献
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NHC-Stabilized Iridium Nanoparticles as Catalysts in Hydrogen Isotope Exchange Reactions of Anilines
Mégane Valero Dr. Donia Bouzouita Dr. Alberto Palazzolo Dr. Jens Atzrodt Dr. Christophe Dugave Dr. Simon Tricard Dr. Sophie Feuillastre Dr. Grégory Pieters Dr. Bruno Chaudret Dr. Volker Derdau 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(9):3545-3550
The preparation of N-heterocyclic carbene-stabilized iridium nanoparticles and their application in hydrogen isotope exchange reactions is reported. These air-stable and easy-to-handle iridium nanoparticles showed a unique catalytic activity, allowing selective and efficient hydrogen isotope incorporation on anilines using D2 or T2 as isotopic source. The usefulness of this transformation has been demonstrated by the deuterium and tritium labeling of diverse complex pharmaceuticals. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(30):8935-8938
Fe‐N‐C catalysts with high O2 reduction performance are crucial for displacing Pt in low‐temperature fuel cells. However, insufficient understanding of which reaction steps are catalyzed by what sites limits their progress. The nature of sites were investigated that are active toward H2O2 reduction, a key intermediate during indirect O2 reduction and a source of deactivation in fuel cells. Catalysts comprising different relative contents of FeNx Cy moieties and Fe particles encapsulated in N‐doped carbon layers (0–100 %) show that both types of sites are active, although moderately, toward H2O2 reduction. In contrast, N‐doped carbons free of Fe and Fe particles exposed to the electrolyte are inactive. When catalyzing the ORR, FeNx Cy moieties are more selective than Fe particles encapsulated in N‐doped carbon. These novel insights offer rational approaches for more selective and therefore more durable Fe‐N‐C catalysts. 相似文献
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Huimei Duan Rui You Shutao Xu Zhaorui Li Kun Qian Tian Cao Weixin Huang Xinhe Bao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(35):12171-12176
Supported Pd catalysts are active in catalyzing the highly exothermic methane combustion reaction but tend to be deactivated owing to local hyperthermal environments. Herein we report an effective approach to stabilize Pd/SiO2 catalysts with porous Al2O3 overlayers coated by atomic layer deposition (ALD). 27Al magic angle spinning NMR analysis showed that Al2O3 overlayers on Pd particles coated by the ALD method are rich in pentacoordinated Al3+ sites capable of strongly interacting with adjacent surface PdOx phases on supported Pd particles. Consequently, Al2O3‐decorated Pd/SiO2 catalysts exhibit active and stable PdOx and Pd–PdOx structures to efficiently catalyze methane combustion between 200 and 850 °C. These results reveal the unique structural characteristics of Al2O3 overlayers on metal surfaces coated by the ALD method and provide a practical strategy to explore stable and efficient supported Pd catalysts for methane combustion. 相似文献