Добірка наукової літератури з теми "Double Atom Catalysis"

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Статті в журналах з теми "Double Atom Catalysis"

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Chen, Wei, Binbin Wu, Yanyong Wang, Wang Zhou, Yingying Li, Tianyang Liu, Chao Xie, et al. "Deciphering the alternating synergy between interlayer Pt single-atom and NiFe layered double hydroxide for overall water splitting." Energy & Environmental Science 14, no. 12 (2021): 6428–40. http://dx.doi.org/10.1039/d1ee01395e.

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Shan, Hui, and Paul R. Sharp. "Double Oxygen Atom Centered Rhodium–Gold Clusters." Angewandte Chemie International Edition in English 35, no. 6 (April 1, 1996): 635–36. http://dx.doi.org/10.1002/anie.199606351.

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Mark, Brian L., and Michael NG James. "Anchimeric assistance in hexosaminidases." Canadian Journal of Chemistry 80, no. 8 (August 1, 2002): 1064–74. http://dx.doi.org/10.1139/v02-130.

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Анотація:
Configuration retaining glycosidases catalyse the hydrolysis of glycosidic bonds via a double displacement mechanism, typically involving two key active site carboxyl groups (Glu or Asp). One of the enzymic carboxyl groups functions as a general acid–base catalyst, the other acts as a nucleophile. Alternatively, configuration-retaining hexosaminidases from the sequence-related glycosidase families 18, 20, and 56 lack a suitably positioned enzymic nucleophile; instead, they use the carbonyl oxygen atom of the neighbouring C2-acetamido group of the substrate. The carbonyl oxygen atom of the 2-acetamido group provides anchimeric assistance to the enzyme catalyzed reaction by acting as an intramolecular nucleophile, attacking the anomeric center and forming a cyclized oxazolinium ion intermediate that is stereochemically equivalent to the glycosyl–enzyme intermediate formed in the "normal" double displacement mechanism. Although there is little sequence similarity between families 18, 20, and 56 hexosaminidases, X-ray crystallographic studies demonstrate that they have evolved similar catalytic domains and active site architectures that are designed to distort the bound substrate so that the C2-acetamido group can become appropriately positioned to participate in catalysis. The substrate distortion allows for a substrate-assisted catalytic reaction that displays all the general characteristics of the classic double-displacement mechanism including the formation of a covalent intermediate.Key words: glycoside hydrolase, hexosaminidase, glycosidase, substrate-assisted catalysis, anchimeric assistance.
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Cao, Rong, Jie-Zhen Xia, and Qi Wu. "Computational Insight into Defective Boron Nitride Supported Double-Atom Catalysts for Electrochemical Nitrogen Reduction." Catalysts 12, no. 11 (November 10, 2022): 1404. http://dx.doi.org/10.3390/catal12111404.

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Designing highly selective and efficient double-atom electrocatalysts (DACs) is essential for achieving a superior nitrogen-reduction reaction (NRR) performance. Herein, we explored the defective boron nitride–supported cage-like double-atom catalysts to rummage the qualified NRR catalysts. Based on a systematic evaluation of the stability, N2 adsorption, NRR selectivity and activity of 10 DACs of TM1-TM2@VB-BN, we predicted Ru-Ti@VB-BN to be the NRR candidate with a limiting potential of −0.40 V. Compared to the corresponding single-atom catalysts, the introduction of Ti/Mo modulates the d-band center of the active metal atom, which improves the NRR performance. Moreover, the magnetic Ru-Ti dimer can facilitate the transfer of charge to molecular N2, ensuring a significant activation of the inert N≡N bond. This research not only opens up new avenues for designing boron nitride–supported DACs for NRR, but also deepens the understanding of DACs in N2 activation.
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Cheng, Jian, Jin Xie, and Chengjian Zhu. "Relay photocatalytic cascade reactions: synthesis of indolo[2,1-a]isoquinoline derivatives via double C(sp3)–H bond functionalization." Chemical Communications 54, no. 13 (2018): 1655–58. http://dx.doi.org/10.1039/c7cc09820k.

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A relay photoredox catalysis strategy concomitant with [1,5] hydrogen atom transfer has been applied in the construction of a biologically important indolo[2,1-a]isoquinoline framework via a cascade reaction. This reaction enables double C(sp3)–H bond functionalization and formation of two carbon–carbon double bonds.
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Wang, Zelin, Si-Min Xu, Yanqi Xu, Ling Tan, Xian Wang, Yufei Zhao, Haohong Duan, and Yu-Fei Song. "Single Ru atoms with precise coordination on a monolayer layered double hydroxide for efficient electrooxidation catalysis." Chemical Science 10, no. 2 (2019): 378–84. http://dx.doi.org/10.1039/c8sc04480e.

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Wang, Yun, and Lihua Kang. "Selective Hydrogenation of Acetylene Catalysed by a B12N12 Cluster Doped with a Single Nickel Atom: A DFT Study." Catalysts 10, no. 1 (January 13, 2020): 115. http://dx.doi.org/10.3390/catal10010115.

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To obtain a catalyst based on a non-precious metal that can replace traditional palladium-based selective catalysts of acetylene hydrogenation, the catalytic performances of two different configurations of a B12N12 cluster doped with a single nickel atom were studied by a density functional theory computational approach. After analysing the effect that the adsorption of reactants onto the clusters has on the reaction path, we determined the lowest energy path for the acetylene double hydrogenation. Comparing the acetylene hydrogenation activities and ethylene product selectivities of the B11N12Ni and B12N11Ni clusters, which have different doping sites, we determined the activities of these two catalysts to be similar to each other; however, the B11N12Ni cluster was calculated to have higher selectivity for ethylene as a product. This difference may be related to the moderate adsorption of hydrogen and acetylene on the B11N12Ni cluster. As a new type of nickel-based single-atom catalyst, B11N12Ni clusters may have research value in the selective hydrogenation of acetylene.
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Poulos, Thomas L. "Intermediates in P450 catalysis." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1829 (April 15, 2005): 793–806. http://dx.doi.org/10.1098/rsta.2004.1537.

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Анотація:
Cytochromes P450 catalyse the insertion of one O 2 -derived oxygen atom in unactivated C–H bonds, and as such, are potent oxidants. A significant amount is known about the P450 catalytic cycle owing partly to the single heme group at the active site that provides spectroscopic handles in tracking various intermediates. A sophisticated array of electron paramagnetic, electron double nuclear resonance, and more traditional absorption spectroscopies have been able to identify key intermediates, while crystallography has defined the structure of the substrate-free, -bound, and oxy-complexes. What has remained elusive is the Fe(IV)=O intermediate, thought to be the active hydroxylating agent. Here, theory and especially density functional calculations have provided valuable insights.
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Zhang, Xi-Sha, Kang Chen, and Zhang-Jie Shi. "Transition metal-catalyzed direct nucleophilic addition of C–H bonds to carbon–heteroatom double bonds." Chem. Sci. 5, no. 6 (2014): 2146–59. http://dx.doi.org/10.1039/c3sc53115e.

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Анотація:
Compared with the traditional Grignard reaction, direct insertion of polar double bonds to C–H bonds via transition-metal catalysis is ideal from the viewpoint of atom-, step- and cost-economy and the avoidance of the waste emission, as well as of the complex manipulation of sensitive reagents.
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Rasool, Anjumun, Insha Anis, Mudit Dixit, Ashakiran Maibam, Afshana Hassan, Sailaja Krishnamurty, and Manzoor Ahmad Dar. "Tantalum based single, double, and triple atom catalysts supported on g-C2N monolayer for effective nitrogen reduction reaction: a comparative DFT investigation." Catalysis Science & Technology 12, no. 1 (2022): 310–19. http://dx.doi.org/10.1039/d1cy01292d.

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Density functional theory simulations demonstrate that single and triple Ta-atom catalysts anchored to C2N monolayer act as superior catalysts for the nitrogen reduction reaction via alternating and distal pathways.
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Дисертації з теми "Double Atom Catalysis"

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Richard, Mélissandre. "Application de la technique d'échange isotopique à l'étude de systèmes catalytiques innovants : activation et mobilité d'O2 sur YSZ au sein d’un double-lit et réactivité de l’azote dans les matériaux nitrures pour la catalyse hétérogène." Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2293/document.

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Ce travail porte sur l’étude de systèmes catalytiques innovants par la technique d’échange isotopique (EI) permettant d’apprécier des propriétés fondamentales (activation des molécules en surface, mobilité et réactivité des atomes de réseau) pour comprendre les mécanismes de réaction mis en jeu en catalyse hétérogène et développer des systèmes plus performants. Aussi, l’identification d’espèces adsorbées intermédiaires est possible en couplant la spectrométrie de masse (analyse de la phase gaz) à l’observation de la surface catalytique par spectroscopie DRIFT.L’EI 16O/18O montre des effets de dispersion ou de synergie de LaMnO3 (LM) supportée sur YSZ ou TiO2 expliquant les performances de cette structure pérovskite pour l’oxydation catalytique de C7H8 via un mécanisme suprafacial. L’activité en EI C16O2/C18O2 démontre la mobilité exceptionnelle des atomes O de réseau de YSZ dès 150 °C via la formation d’espèces (hydrogéno)carbonates en surface. En catalyse d’oxydation, à T < 800 °C, cette mobilité est pourtant limitée par l’activation d’O2 à la surface de YSZ. La solution proposée ici est la génération préalable d’une espèce oxygène réactive sur un lit de matériau réductible type LM. Le double-lit LM-YSZ montre d’excellentes performances pour abaisser la température d’oxydation de CH4 à 425 °C via un mécanisme Mars van Krevelen (MvK) où les atomes O de YSZ participent à la réaction par l’intermédiaire d’espèces formiates.L’EI 14N/15N est également utilisé dans ce travail pour analyser la réactivité des atomes N de réseau dans les nitrures métalliques. En particulier, Co3Mo3N et Ni2Mo3N montrent des propriétés remarquables, dépendant de la méthode de préparation ou du prétraitement appliqué. Leur comportement suggère la participation des atomes N dans la réaction de synthèse de NH3 sur le principe d’un mécanisme MvK
This work concerns the study of new catalytic systems by isotopic exchange (IE) technique allowing to appreciate basic properties (molecules surface activation, mobility and reactivity of lattice atoms) to better understand catalytic mechanisms and to develop efficient catalysts. The identification of intermediate adsorbed species is possible by coupling mass spectrometry (gas-phase analysis) with the catalytic surface analysis by DRIFT spectroscopy.IE 16O/18O shows dispersal and synergetic effect of supported LaMnO3 perovskite (LM) on YSZ or TiO2 which explain catalytic performances of this perovskite structure for toluene oxidation via a suprafacial mechanism. IE C16O2/C18O2 activity demonstrates the remarkable lattice O atoms mobility of YSZ from 150 °C via adsorbed (hydrogeno)carbonates. To the contrary, in oxidation catalysis, under 800 °C, this mobility is very limited by O2 activation on YSZ surface. The solution proposed in this work is the previous generation of reactive oxygen species on a first catalytic bed of reducible material as LM. LM+YSZ dual-bed shows very efficient activity to reduce methane oxidation temperature at 425 °C via a Mars-van Krevelen (MvK) mechanism in which lattice O atoms of YSZ take part in the reaction by intermediate formate species.IE 14N/15N is thereafter used to analyse lattice N atoms reactivity of metal nitrides materials. In particular, Co3Mo3N and Ni2Mo3N show interesting properties depending on preparation or pre-treatement routes. This behaviour supposes that ammonia synthesis reaction could be procced via MvK type mechanism with the participation of lattice N of this nitrides
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Частини книг з теми "Double Atom Catalysis"

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Cheng, Z., M. Li, and Z. Lu. "2.2 Cobalt- and Iron-Catalyzed Hydrosilylation." In Base-Metal Catalysis 2. Stuttgart: Georg Thieme Verlag KG, 2023. http://dx.doi.org/10.1055/sos-sd-239-00077.

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AbstractThe hydrosilylation of readily available alkenes and alkynes represents an atom-economic and straightforward method for the preparation of value-added organosilicon compounds. Among various catalysts, those based on earth-abundant metals such as cobalt and iron demonstrate great potential due to their low cost and toxicity, as well as good catalytic performance. This review discusses recent progress in the cobalt- and iron-catalyzed hydrosilylation of alkenes and alkynes, as well as the sequential double hydrosilylation of alkynes, with an emphasis on the synthetic utility of the methods. The reactivity, regioselectivity, and enantioselectivity can be well-controlled by applying suitable ligands.
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Nawaz Shariff, Shakeel, Supriya Saravu, and Dileep Ramakrishna. "Schiff Base Complexes for Catalytic Application." In Schiff Base in Organic, Inorganic and Physical Chemistry [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107904.

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Primary amines are combined with an aldehyde group to generate Schiff base compounds, which are called condensation imine products. This class of compounds has a general structure, R-C=NR\', where R and R\' represent alkyl/aryl/cyclohexyl/heterocyclic group. These compounds contain an azomethine group that is basic in nature due to, (i) the presence of lone pair of electrons on the nitrogen and (ii) electron-donating nature of the double bond. Hence, these compounds, as ligands, participate in the formation of metal complexes. The presence of lone pair of electrons on the nitrogen atom and the hybridization involved explains the physical, chemical, and spectral properties of nitrogen-containing moieties. In the case of (sp2) hybridization (trigonal structure), the lone pair of electrons occupies either a symmetrical unhybridized 2p orbital that is perpendicular to the plane of trigonal hybrids or a symmetrical hybrid orbital, whose axis is in the plane, leaving behind only the π-electrons in the unhybridized 2p orbital. A very similar type of hybridization is experienced by the nitrogen atom in the azomethine group. Traditional phosphine complexes of nickel, palladium, and platinum, particularly those of palladium, have played an extremely important role in the development of homogeneous catalysis. Schiff base complexes as catalysts have been studied for various organic transformations such as oxidation, epoxidation, reduction, coupling reactions, polymerization reactions, hydroformylations, and many more.
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R., Deeksha, and Deepak Kumar. "Design of Supported Catalysts for Nitrogen Reduction Reaction: A Continuous Challenge." In Advanced Materials and Nano Systems: Theory and Experiment (Part-1), 66–91. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050745122010007.

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Анотація:
The production of ammonia is facilitated by the nitrogen reduction reaction (NRR), where the inert di-nitrogen molecule is converted to ammonia. Along with being a major carrier of hydrogen, ammonia holds authority in the fertilizer realm. Therefore, it is inevitable to develop a viable and eco-friendly method of production that is cost-effective and resource-efficient. The primary challenge of nitrogen reduction is the cleavage of the particularly stable nitrogen bond. The most popular Haber-Bosch process for ammonia production, although efficient, is highly energy-intensive, and the need for maintaining exceptionally high temperature and pressure conditions is an environmental concern. As an alternative, the direct conversion of nitrogen has been carried out by photocatalysis and electrocatalysis. However, this strategy falls short of achieving superior conversion efficiencies. Consequently, it is conceivable that a fitting catalyst can be the solution for the difficulties associated with NRR. Over the years, several attempts have been made at formulating the best catalyst, including chromium oxynitride nanoparticles, niobium dioxide, various metal (Ru, Al, Rh, Ga) clusters, single-atom catalysts supported on different surfaces, and double atom catalysts. Recently, perovskites have emerged into the spotlight as excellent catalysts for NRR. In this chapter, we discuss the challenges faced by researchers to formulate righteous catalysts for the sustainable reduction of nitrogen by studying each of these types with a few examples. We also review the recent advancements in the experimental domain of NRR using different electrochemical cells.
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Тези доповідей конференцій з теми "Double Atom Catalysis"

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Sekachev, Mikhail, Cheng-Xian Lin, Zhiyu Hu, and Don Dareing. "A Computational Study of Catalytic Platinum Nanoparticles With and Without OH Chemisorption During Reactions." In ASME 2008 3rd Energy Nanotechnology International Conference collocated with the Heat Transfer, Fluids Engineering, and Energy Sustainability Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/enic2008-53029.

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In this paper, various energies and geometries of pure platinum nanoparticles and those of platinum nanoparticles with adsorbed OH were investigated. Ten different platinum clusters of up to 28 atoms were studied using spin-unrestricted density functional theory (DFT) with a double numerical plus polarization basis set. Three different shapes were presented, and the effect of cluster size on binding energy, total energy, and HOMO-LUMO energy gap was investigated. The same set of calculations was performed for selected clusters with OH adsorbate on the Pt(111) surface. The results show that the stability of both the pure clusters and the clusters with adsorbed OH molecule increases with an increase of cluster size. This fact indicates that direct influence of the size of Pt cluster on the reaction rate is possible, and the understanding of how cluster size would affect binding energy is important. The effect of cluster size on total energy of molecule was shown to be a linear function independent of cluster type, as expected. We also found that optimized (stable) Pt clusters were bigger in size than that of the initial clusters, or clusters with bulk geometry.
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Kodama, Tatsuya, Nobuyuki Gokon, Shin-ichi Inuta, Shin-go Yamashita, Tsuyoshi Hatamachi, and Taebeom Seo. "Molten-Salt Tubular Absorber/Reformer (MoSTAR) Project: Metal-Plate-Bridged Double Tube Reactor." In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90230.

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The Molten-Salt Tubular Absorber/Reformer (MoSTAR) Project, which is jointly conducted by Niigata University, Japan, and Inha University, Korea, aims to develop a novel-type of “double-walled” tubular absorbers/reformers with molten-salt thermal storage at high temperature for use in solar natural-gas reforming and solar air receiver, and to demonstrate their performances on sun with a 5-kWt dish-type solar concentrator. The new concept of “double-walled” reactor tubes was proposed for use in a solar reformer by Niigata University, Japan, and involves packing a molten salt in the annular region between the internal catalyst tube and the exterior solar absorber tube of the double reactor tube. In this work, “metal-plate-bridged” double reactor tubes are newly proposed for use in a solar reformer. Two different sized reactor tubes are constructed, and tested on chemical reaction performance for dry reforming of methane during cooling or heat-discharge mode of the reactor tube using an electric furnace. The experimental results obtained under feed gas mixture of CH4/CO2 = 1:3 at a residence time of 0.36 s and at 1 atm showed that the double reactor tube with the heat storage medium Na2CO3 in the annular region successfully sustained a high methane conversion above 90% with about 0.7-kW output power of the reformed gas based on HHV for 40 min of the heat-discharge mode. The application of the new reactor tubes to solar tubular reformers is expected to help realize stable operation of the solar reforming process under fluctuating insolation during a cloud passage.
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