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Auteur : Grafiati
Publié le 7 septembre 2023

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1

Bennett, Jeffrey A., Bradley A. Davis, Kirill Efimenko, Jan Genzer et Milad Abolhasani. « Network-supported, metal-mediated catalysis : progress and perspective ». Reaction Chemistry & ; Engineering 5, no 10 (2020) : 1892–902. http://dx.doi.org/10.1039/d0re00229a.

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Martín, Cristina del Mar García, José Ignacio Hernández García, Sebastián Bonardd et David Díaz Díaz. « Lignin-Based Catalysts for C–C Bond-Forming Reactions ». Molecules 28, no 8 (16 avril 2023) : 3513. http://dx.doi.org/10.3390/molecules28083513.

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Carbon–carbon (C–C) bond formation is the key reaction in organic synthesis to construct the carbon framework of organic molecules. The continuous shift of science and technology toward eco-friendly and sustainable resources and processes has stimulated the development of catalytic processes for C–C bond formation based on the use of renewable resources. In this context, and among other biopolymer-based materials, lignin has attracted scientific attention in the field of catalysis during the last decade, either through its acid form or as a support for metal ions and metal nanoparticles that drive the catalytic activity. Its heterogeneous nature, as well as its facile preparation and low cost, provide competitive advantages over other homogeneous catalysts. In this review, we have summarized a variety of C–C formation reactions, such as condensations, Michael additions of indoles, and Pd-mediated cross-coupling reactions that were successfully carried out in the presence of lignin-based catalysts. These examples also involve the successful recovery and reuse of the catalyst after the reaction.
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Liu, Xin, Xin Zhang et Changgong Meng. « Coadsorption Interfered CO Oxidation over Atomically Dispersed Au on h-BN ». Molecules 27, no 11 (5 juin 2022) : 3627. http://dx.doi.org/10.3390/molecules27113627.

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Similar to the metal centers in biocatalysis and homogeneous catalysis, the metal species in single atom catalysts (SACs) are charged, atomically dispersed and stabilized by support and substrate. The reaction condition dependent catalytic performance of SACs has long been realized, but seldom investigated before. We investigated CO oxidation pathways over SACs in reaction conditions using atomically dispersed Au on h-BN (AuBN) as a model with extensive first-principles-based calculations. We demonstrated that the adsorption of reactants, namely CO, O2 and CO2, and their coadsorption with reaction species on AuBN would be condition dependent, leading to various reaction species with different reactivity and impact the CO conversion. Specifically, the revised Langmuir–Hinshelwood pathway with the CO-mediated activation of O2 and dissociation of cyclic peroxide intermediate followed by the Eley–Rideal type reduction is dominant at high temperatures, while the coadsorbed CO-mediated dissociation of peroxide intermediate becomes plausible at low temperatures and high CO partial pressures. Carbonate species would also form in existence of CO2, react with coadsorbed CO and benefit the conversion. The findings highlight the origin of the condition-dependent CO oxidation performance of SACs in detailed conditions and may help to rationalize the current understanding of the superior catalytic performance of SACs.
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Campisi, Sebastiano, Carine Chan-Thaw et Alberto Villa. « Understanding Heteroatom-Mediated Metal–Support Interactions in Functionalized Carbons : A Perspective Review ». Applied Sciences 8, no 7 (17 juillet 2018) : 1159. http://dx.doi.org/10.3390/app8071159.

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Carbon-based materials show unique chemicophysical properties, and they have been successfully used in many catalytic processes, including the production of chemicals and energy. The introduction of heteroatoms (N, B, P, S) alters the electronic properties, often increasing the reactivity of the surface of nanocarbons. The functional groups on the carbons have been reported to be effective for anchoring metal nanoparticles. Although the interaction between functional groups and metal has been studied by various characterization techniques, theoretical models, and catalytic results, the role and nature of heteroatoms is still an object of discussion. The aim of this review is to elucidate the metal–heteroatoms interaction, providing an overview of the main experimental and theoretical outcomes about heteroatom-mediated metal–support interactions. Selected studies showing the effect of heteroatom–metal interaction in the liquid-phase alcohol oxidation will be also presented.
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Wieghold, S., L. Nienhaus, F. L. Knoller, F. F. Schweinberger, J. J. Shepherd, J. W. Lyding, U. Heiz, M. Gruebele et F. Esch. « Plasmonic support-mediated activation of 1 nm platinum clusters for catalysis ». Physical Chemistry Chemical Physics 19, no 45 (2017) : 30570–77. http://dx.doi.org/10.1039/c7cp04882c.

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Nanometer-sized metal clusters are prime candidates for photoactivated catalysis, based on their unique tunable properties. Under visible light illumination, these non-plasmonic particles can get catalytically activated by coupling to a plasmonic substrate.
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Zhao, Haiyan, Theodore Christensen, Zihan Lin, Annie Lynn et Liang Tang. « An unusual metal ion configuration in a viral DNA-packaging nuclease active site ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C489. http://dx.doi.org/10.1107/s2053273314095102.

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Nucleic acid metabolism is fundamental to many biological processes. A large class of enzymes such as RNase H, reverse transcriptase, retroviral integrase, topoisomerase, DNA and RNA polymerase, transposase, Holliday-junction resolvase, RNAi slicer Argonaute, and viral DNA-packaging terminase, utilize a common two-metal-ion catalytic mechanism for cleavage or synthesis of nucleic acid chains. Here we report an unusual metal-ion cluster in the active site of the nuclease domain of a viral DNA-packaging terminase unveiled by X-ray structures up to 1.38 Angstrom resolution. Two Mg2+ ions are situated in a coupled octahedral coordination system with liganding oxygen atoms from aspartic acid residues as well as water molecules. The two Mg2+ ions are located within a strikingly short distance of ~2.5 Å, which is unusual given the 1.6 Å atomic radius of Mg2+ and is shorter than previously observed metal-metal distances in metallocluster-containing enzymes or other biological systems. This provides the structural basis for distinguishing Mg2+ from other metal ions such as Ca2+ which are well known to support binding of the nucleic acid substrate but not support catalysis. Such an ultra-short distance between two metal-ions may be essential for generation of a highly positive niche, leading to nucleophilic attack at the phosphodiester bond of DNA. These results have defined the precise chemical configuration of the active site in nucleases using two-metal-ion catalytic mechanism. Moreover, assembly of this two-metal-ion cluster in the viral DNA-packaging terminase is mediated by an adjacent Lys residue, likely serving as a regulatory mechanism for activation of the nuclease activity of the terminase during packaging of viral genome.
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Jiang, Haihui, Ligang Gai et Yan Tian. « Altervalent cation-doped MCM-41 supported palladium catalysts and their catalytic properties ». Journal of the Serbian Chemical Society 76, no 6 (2011) : 923–32. http://dx.doi.org/10.2298/jsc100227073j.

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Metal cation-doped MCM-41 (M-MCM-41, M=Al, Ce, Co, V, or Zr) supported Pd catalysts (Pd/M-MCM-41) were prepared by a solution-based reduction method. The catalysts were characterized by Xray diffraction (XRD) analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and further evaluated by selective hydrogenation of parachloronitrobenzene (p-CNB) in anhydrous ethanol. The metal cationcontaining Pd catalysts can efficiently enhance the selectivity for parachloroaniline (p-CAN). The highest selectivity of 96.5 % in the molar distribution for p-CNB to p-CAN was acquired over Pd (1.8 wt. %)/VMCM- 41 (Si/V=30, molar ratio) catalyst, and the corresponding turnover frequency (TOF) was 1.24?10-2 mol p-CNB mol-1 Pd s-1. Water molecules adsorbed by the support have important effects on both the catalytic activity of the sample and the selectivity for p-CAN. A water molecule-mediated catalytic hydrogenation is discussed.
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8

Wan, Yujia, Yanyan Feng, Decheng Wan et Ming Jin. « Polyamino amphiphile mediated support of platinum nanoparticles on polyHIPE as an over 1500-time recyclable catalyst ». RSC Advances 6, no 110 (2016) : 109253–58. http://dx.doi.org/10.1039/c6ra19013h.

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9

Seth, Jhumur, Prashant Dubey, Vijay R. Chaudhari et Bhagavatula L. V. Prasad. « Preparation of metal oxide supported catalysts and their utilization for understanding the effect of a support on the catalytic activity ». New Journal of Chemistry 42, no 1 (2018) : 402–10. http://dx.doi.org/10.1039/c7nj03753h.

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Bo, Guyue, Peng Li, Yameng Fan, Qiang Zhu, Linlin Xia, Yi Du, Shi Xue Dou et Xun Xu. « Liquid-Metal-Mediated Electrocatalyst Support Engineering toward Enhanced Water Oxidation Reaction ». Nanomaterials 12, no 13 (23 juin 2022) : 2153. http://dx.doi.org/10.3390/nano12132153.

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Functional and robust catalyst supports are vital in the catalysis field, and the development of universal and efficient catalyst support is essential but challenging. Traditional catalyst fabrication methods include the carbonization of ordered templates and high−temperature dehydration. All these methods involve complicated meso−structural disordering and allow little control over morphology. To this end, a eutectic GaInSn alloy (EGaInSn) was proposed and employed as an intermediate to fabricate low−dimensional ordered catalyst support materials. Owing to the lower Gibbs free energy of Ga2O3 compared to certain types of metals (e.g., Al, Mn, Ce, etc.), we found that a skinny layer of metal oxides could be formed and exfoliated into a two−dimensional nanosheet at the interface of liquid metal (LM) and water. As such, EGaInSn was herein employed as a reaction matrix to synthesize a range of two−dimensional catalyst supports with large specific surface areas and structural stability. As a proof−of-concept, Al2O3 and MnO were fabricated with the assistance of LM and were used as catalyst supports for loading Ru, demonstrating enhanced structural stability and overall electrocatalytic performance in the oxygen evolution reaction. This work opens an avenue for the development of functional support materials mediated by LM, which would play a substantial role in electrocatalytic reactions and beyond.
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Yentekakis, Ioannis V., Philippe Vernoux, Grammatiki Goula et Angel Caravaca. « Electropositive Promotion by Alkalis or Alkaline Earths of Pt-Group Metals in Emissions Control Catalysis : A Status Report ». Catalysts 9, no 2 (5 février 2019) : 157. http://dx.doi.org/10.3390/catal9020157.

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Recent studies have shown that the catalytic performance (activity and/or selectivity) of Pt-group metal (PGM) catalysts for the CO and hydrocarbons oxidation as well as for the (CO, HCs or H2)-SCR of NOx or N2O can be remarkably affected through surface-induced promotion by successful application of electropositive promoters, such as alkalis or alkaline earths. Two promotion methodologies were implemented for these studies: the Electrochemical Promotion of Catalysis (EPOC) and the Conventional Catalysts Promotion (CCP). Both methodologies were in general found to achieve similar results. Turnover rate enhancements by up to two orders of magnitude were typically achievable for the reduction of NOx by hydrocarbons or CO, in the presence or absence of oxygen. Subsequent improvements (ca. 30–60 additional percentage units) in selectivity towards N2 were also observed. Electropositively promoted PGMs were also found to be significantly more active for CO and hydrocarbons oxidations, either when these reactions occur simultaneously with deNOx reactions or not. The aforementioned direct (via surface) promotion was also found to act synergistically with support-mediated promotion (structural promotion); the latter is typically implemented in TWCs through the complex (Ce–La–Zr)-modified γ-Al2O3 washcoats used. These attractive findings prompt to the development of novel catalyst formulations for a more efficient and cost-effective control of the emissions of automotives and stationary combustion processes. In this report the literature findings in the relevant area are summarized, classified and discussed. The mechanism and the mode of action of the electropositive promoters are consistently interpreted with all the observed promoting phenomena, by means of indirect (kinetics) and direct (spectroscopic) evidences.
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Weber, Daniel, Tina He, Matthew Wong, Christian Moon, Axel Zhang, Nicole Foley, Nicholas J. Ramer et Cheng Zhang. « Recent Advances in the Mitigation of the Catalyst Deactivation of CO2 Hydrogenation to Light Olefins ». Catalysts 11, no 12 (28 novembre 2021) : 1447. http://dx.doi.org/10.3390/catal11121447.

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The catalytic conversion of CO2 to value-added chemicals and fuels has been long regarded as a promising approach to the mitigation of CO2 emissions if green hydrogen is used. Light olefins, particularly ethylene and propylene, as building blocks for polymers and plastics, are currently produced primarily from CO2-generating fossil resources. The identification of highly efficient catalysts with selective pathways for light olefin production from CO2 is a high-reward goal, but it has serious technical challenges, such as low selectivity and catalyst deactivation. In this review, we first provide a brief summary of the two dominant reaction pathways (CO2-Fischer-Tropsch and MeOH-mediated pathways), mechanistic insights, and catalytic materials for CO2 hydrogenation to light olefins. Then, we list the main deactivation mechanisms caused by carbon deposition, water formation, phase transformation and metal sintering/agglomeration. Finally, we detail the recent progress on catalyst development for enhanced olefin yields and catalyst stability by the following catalyst functionalities: (1) the promoter effect, (2) the support effect, (3) the bifunctional composite catalyst effect, and (4) the structure effect. The main focus of this review is to provide a useful resource for researchers to correlate catalyst deactivation and the recent research effort on catalyst development for enhanced olefin yields and catalyst stability.
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Makertihartha, I. G. B. N., Noerma Juli Azhari et Grandprix T. M. Kadja. « A Review on Zeolite Application for Aromatic Production from Non-Petroleum Carbon-Based Resources ». Journal of Engineering and Technological Sciences 55, no 2 (23 mai 2023) : 131–42. http://dx.doi.org/10.5614/j.eng.technol.sci.2023.55.2.3.

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The application of zeolite catalyst has been expanded to support on-purpose sustainable technology. This review focused on zeolite application to produce aromatic compounds from non-petroleum carbon-based resources, including methanol, CO2, CO, and biomass. For COx resources, the two main routes for producing aromatics products are discussed, i.e., the olefinic and the oxygenates-mediated route. Moreover, several improvement strategies for enhancing catalytic performance are also discussed, i.e., the addition of metal components, tuning the metal and zeolite structure, and modifying the reaction process. Finally, prospects for future development are formulated.
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Geonmonond, Rafael S., Jhon Quiroz, Guilherme F. S. R. Rocha, Freddy E. Oropeza, Clara J. Rangel, Thenner S. Rodrigues, Jan P. Hofmann, Emiel J. M. Hensen, Rômulo A. Ando et Pedro H. C. Camargo. « Marrying SPR excitation and metal–support interactions : unravelling the contribution of active surface species in plasmonic catalysis ». Nanoscale 10, no 18 (2018) : 8560–68. http://dx.doi.org/10.1039/c8nr00934a.

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Xie, Bingqiao, Priyank Kumar, Tze Hao Tan, Ali Asghar Esmailpour, Kondo-Francois Aguey-Zinsou, Jason Scott et Rose Amal. « Doping-Mediated Metal–Support Interaction Promotion toward Light-Assisted Methanol Production over Cu/ZnO/Al2O3 ». ACS Catalysis 11, no 9 (27 avril 2021) : 5818–28. http://dx.doi.org/10.1021/acscatal.1c00332.

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Chiang, Yu-Chun, Zhi-Hui Pu et Ziyi Wang. « Study on Oxygen Evolution Reaction of Ir Nanodendrites Supported on Antimony Tin Oxide ». Nanomaterials 13, no 15 (7 août 2023) : 2264. http://dx.doi.org/10.3390/nano13152264.

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In this study, the iridium nanodendrites (Ir NDs) and antimony tin oxide (ATO)-supported Ir NDs (Ir ND/ATO) were prepared by a surfactant-mediated method to investigate the effect of ATO support and evaluate the electrocatalytic activity for the oxygen evolution reaction (OER). The nano-branched Ir ND structures were successfully prepared alone or supported on ATO. The Ir NDs exhibited major diffraction peaks of the fcc Ir metal, though the Ir NDs consisted of metallic Ir as well as Ir oxides. Among the Ir ND samples, Ir ND2 showed the highest mass-based OER catalytic activity (116 mA/mg at 1.8 V), while it suffered from high degradation in activity after a long-term test. On the other hand, Ir ND2/ATO had OER activity of 798 mA/mg, and this activity remained >99% after 100 cycles of LSV and the charge transfer resistance increased by less than 3 ohm. The enhanced durability of the OER mass activities of Ir ND2/ATO catalysts over Ir NDs and Ir black could be attributed to the small crystallite size of Ir and the increase in the ratio of Ir (III) to Ir (IV), improving the interactions between the Ir NDs and the ATO support.
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Dunn, James A., Hari K. Gupta, Alex D. Bain et Michael J. McGlinchey. « The metal-mediated conversion of octachlorocycloheptatriene into dodecachloroheptafulvalene : a synthetic, structural, and EHMO study ». Canadian Journal of Chemistry 74, no 11 (1 novembre 1996) : 2258–67. http://dx.doi.org/10.1139/v96-254.

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Octachlorocycloheptatriene, C7Cl8, 3, reacts with a variety of organometallic precursors, e.g., Fe2(CO)9, Co2(CO)8, [(C5H5)Fe(CO)2]−, to give dodecachloroheptafulvalene, C14C12,12, in yields ranging from 54 to 68%. There is no evidence to support the intermediacy of carbene complexes of the type C7Cl6=MLn, and it is suggested that the reaction proceeds by the dechlorination of C7Cl8 to give hexachlorotropylidene, which dimerizes to the observed product. Extended Hückel molecular orbital calculations are used to show that the chlorinated carbene, C7Cl6, should be more stable than the corresponding parent system, C7Cl6. The EHMO calculations also reveal that planar heptafulvalenes are electronically disfavored and should exist preferentially in the S-anti conformation, as is the case for C14H12. The molecule C14Cl12,12, is shown by X-ray crystallography to be formed only as the syn conformer, which isomerizes to the anti structure only at high temperature. The conformations of the two seven-membered rings in 12 closely resemble that found in octachlorocycloheptatriene itself. C7Cl8, 3, crystallizes in the orthorhombic space group Pnma with a = 7.140(1) Å, b = 13.329(3) Å, c = 12.595(3) Å, and V = 1198.7(4) Å3 for Z = 4.3 adopts a severely bent boat structure in which the planes C(1)-C(7)-C(6) and C(2)-C(3)-C(4)-C(5) make angles of 51.8° and 32.4°, respectively, with the C(1)-C(2)-C(5)-C(6) plane. Key words: octachlorocycloheptatriene, heptafulvalenes, metal-mediated dimerization.
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Malik, Radhika, et Ronald E. Viola. « Structural characterization of tartrate dehydrogenase : a versatile enzyme catalyzing multiple reactions ». Acta Crystallographica Section D Biological Crystallography 66, no 6 (15 mai 2010) : 673–84. http://dx.doi.org/10.1107/s0907444910008851.

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The first structure of an NAD-dependent tartrate dehydrogenase (TDH) has been solved to 2 Å resolution by single anomalous diffraction (SAD) phasing as a complex with the intermediate analog oxalate, Mg2+and NADH. This TDH structure fromPseudomonas putidahas a similar overall fold and domain organization to other structurally characterized members of the hydroxy-acid dehydrogenase family. However, there are considerable differences between TDH and these functionally related enzymes in the regions connecting the core secondary structure and in the relative positioning of important loops and helices. The active site in these complexes is highly ordered, allowing the identification of the substrate-binding and cofactor-binding groups and the ligands to the metal ions. Residues from the adjacent subunit are involved in both the substrate and divalent metal ion binding sites, establishing a dimer as the functional unit and providing structural support for an alternating-site reaction mechanism. The divalent metal ion plays a prominent role in substrate binding and orientation, together with several active-site arginines. Functional groups from both subunits form the cofactor-binding site and the ammonium ion aids in the orientation of the nicotinamide ring of the cofactor. A lysyl amino group (Lys192) is the base responsible for the water-mediated proton abstraction from the C2 hydroxyl group of the substrate that begins the catalytic reaction, followed by hydride transfer to NAD. A tyrosyl hydroxyl group (Tyr141) functions as a general acid to protonate the enolate intermediate. Each substrate undergoes the initial hydride transfer, but differences in substrate orientation are proposed to account for the different reactions catalyzed by TDH.
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Hu, Hongyin, Shuanglong Lu, Ting Li, Yue Zhang, Chenxi Guo, Han Zhu, Yinghua Jin, Mingliang Du et Wei Zhang. « Controlled growth of ultrafine metal nanoparticles mediated by solid supports ». Nanoscale Advances 3, no 7 (2021) : 1865–86. http://dx.doi.org/10.1039/d1na00025j.

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This article reviews the controlled growth of UMNPs mediated by different types of solid supports and their catalytic properties. The importance of certain structural features of the supports is also discussed.
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Maridevaru, Madappa C., Andrea Sorrentino, Belqasem Aljafari et Sambandam Anandan. « Composites for Aqueous-Mediated Heterogeneously Catalyzed Degradation and Mineralization of Water Pollutants on TiO2—A Review ». Journal of Composites Science 6, no 11 (13 novembre 2022) : 350. http://dx.doi.org/10.3390/jcs6110350.

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Wastewater incorporates a wide range of organic toxins, which have an adverse impact on the health of humans and other living things. In recent years, nanotechnology has promoted effective strategies for the photodegradation of industrial organic toxins and tenacious medical contaminants present in wastewater. Advanced composites based on photocatalysts can provide promising solutions for environmental cleanup without generating hazardous byproducts, because they promote the complete oxidation of contaminants. This survey article recaps the essentials of heterogeneous catalysis. Among the major players in heterogeneous catalysis, the metal oxide catalyst (e.g., TiO2) groups cover photocatalysis of water toxins such as dyes, harmful organic molecules, and pharmaceutical contamination. The reasons for the proposal of TiO2 as an active filler for heterogeneous photocatalysts include its superior surface area, significant activity for distinct oxidation and reduction reactions at low temperatures and pressures, effective interaction with metal supports, and chemical stability. Because of the aforementioned features, heterogeneous TiO2 catalysts have a lot of potential in photocatalyst applications, and they can be improved even further by doping them with anionic or cationic dopants.
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Tolliver, Larry M., Natalie J. Holl, Fang Yao Stephen Hou, Han-Jung Lee, Melissa H. Cambre et Yue-Wern Huang. « Differential Cytotoxicity Induced by Transition Metal Oxide Nanoparticles is a Function of Cell Killing and Suppression of Cell Proliferation ». International Journal of Molecular Sciences 21, no 5 (3 mars 2020) : 1731. http://dx.doi.org/10.3390/ijms21051731.

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The application of nanoparticles (NPs) in industry is on the rise, along with the potential for human exposure. While the toxicity of microscale equivalents has been studied, nanoscale materials exhibit different properties and bodily uptake, which limits the prediction ability of microscale models. Here, we examine the cytotoxicity of seven transition metal oxide NPs in the fourth period of the periodic table of the chemical elements. We hypothesized that NP-mediated cytotoxicity is a function of cell killing and suppression of cell proliferation. To test our hypothesis, transition metal oxide NPs were tested in a human lung cancer cell model (A549). Cells were exposed to a series of concentrations of TiO2, Cr2O3, Mn2O3, Fe2O3, NiO, CuO, or ZnO for either 24 or 48 h. All NPs aside from Cr2O3 and Fe2O3 showed a time- and dose-dependent decrease in viability. All NPs significantly inhibited cellular proliferation. The trend of cytotoxicity was in parallel with that of proliferative inhibition. Toxicity was ranked according to severity of cellular responses, revealing a strong correlation between viability, proliferation, and apoptosis. Cell cycle alteration was observed in the most toxic NPs, which may have contributed to promoting apoptosis and suppressing cell division rate. Collectively, our data support the hypothesis that cell killing and cell proliferative inhibition are essential independent variables in NP-mediated cytotoxicity.
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Ronchin, Lucio, Claudio Tortato, Alessio Pavanetto, Mattia Miolo, Evgeny Demenev et Andrea Vavasori. « Formates for green catalytic reductions via CO2 hydrogenation, mediated by magnetically recoverable catalysts ». Pure and Applied Chemistry 90, no 2 (23 février 2018) : 337–51. http://dx.doi.org/10.1515/pac-2017-0704.

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Abstract Precious metal catalyst has been prepared by conventional wet impregnation method followed by precipitation and reduction with hydrogen finally passivated with water in air. The magnetically recoverable catalyst has been prepared starting from a stoichiometric Fe3O4 and ZrO2–Fe3O4 as supports prepared following a sequential precipitation procedure. Precious metal catalysts supported on carbon, alumina, magnetite and zirconia-magnetite nanocomposite has been used in the reduction of nitrobenzenes and acetophenone by using sodium and potassium formate as reducing agent in the presence and in absence of an aqueous phase. In addition, the same catalysts has been tested in CO2 and NaHCO3 hydrogenation, for verifying their potentiality in the CO2 as hydrogen carrier for hydrogenation processes.
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Peters, Alyse N., Nakaja A. Weaver, Kathryn S. Monahan et Kyoungtae Kim. « Non-ROS-Mediated Cytotoxicity of ZnO and CuO in ML-1 and CA77 Thyroid Cancer Cell Lines ». International Journal of Molecular Sciences 24, no 4 (17 février 2023) : 4055. http://dx.doi.org/10.3390/ijms24044055.

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Metal oxide nanoparticles (MONPs) are widely used in agriculture and food development but there is little understanding of how MONPs, including ZnO, CuO, TiO2, and SnO2, impact human health and the environment. Our growth assay revealed that none of these (up to 100 µg/mL) negatively affect viability in the budding yeast, Saccharomyces cerevisiae. In contrast, both human thyroid cancer cells (ML-1) and rat medullary thyroid cancer cells (CA77) displayed a significant reduction in cell viability with the treatment of CuO and ZnO. The production of reactive oxygen species (ROS) in these cell lines, when treated with CuO and ZnO, was found to be not significantly altered. However, levels of apoptosis with ZnO and CuO were increased, which led us to conclude that the decreased cell viability is mainly caused by non-ROS-mediated cell death. Consistently, data from our RNAseq studies identified differentially regulated pathways associated with inflammation, Wnt, and cadherin signaling across both cell lines, ML-1, and CA77, after ZnO or CuO MONP treatment. Results from gene studies further support non-ROS-mediated apoptosis being the main factor behind decreased cell viability. Together, these findings provide unique evidence that the apoptosis in response to treatment of CuO and ZnO in these thyroid cancer cells was not mainly due to oxidative stress, but to the alteration of a range of signal cascades that promotes cell death.
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Wang, Lo, Chi, Lai, Lin et Lin. « Affinity Immobilization of a Bacterial Prolidase onto Metal-Ion-Chelated Magnetic Nanoparticles for the Hydrolysis of Organophosphorus Compounds ». International Journal of Molecular Sciences 20, no 15 (24 juillet 2019) : 3625. http://dx.doi.org/10.3390/ijms20153625.

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In this study, silica-coated magnetic nanoparticles (SiMNPs) with isocyanatopropyltriethoxysilane as a metal-chelating ligand were prepared for the immobilization of His6-tagged Escherichia coli prolidase (His6-EcPepQ). Under one-hour coupling, the enzyme-loading capacity for the Ni2+-functionalized SiMNPs (NiNTASiMNPs) was 1.5 mg/mg support, corresponding to about 58.6% recovery of the initial activity. Native and enzyme-bound NiNTASiMNPs were subsequently characterized by transmission electron microscopy (TEM), superparamagnetic analysis, X-ray diffraction, and Fourier transform infrared (FTIR) spectroscopy. As compared to free enzyme, His6-EcPepQ@NiNTASiMNPs had significantly higher activity at 70 °C and pH ranges of 5.5 to 10, and exhibited a greater stability during a storage period of 60 days and could be recycled 20 times with approximately 80% retention of the initial activity. The immobilized enzyme was further applied in the hydrolysis of two different organophosphorus compounds, dimethyl p-nitrophenyl phosphate (methyl paraoxon) and diethyl p-nitrophenyl phosphate (ethyl paraoxon). The experimental results showed that methyl paraoxon was a preferred substrate for His6-EcPepQ and the kinetic behavior of free and immobilized enzymes towards this substance was obviously different. Taken together, the immobilization strategy surely provides an efficient means to deposit active enzymes onto NiNTASiMNPs for His6-EcPepQ-mediated biocatalysis.
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Wu, Yi Y., Neema A. Mashayekhi et Harold H. Kung. « Au–metal oxide support interface as catalytic active sites ». Catalysis Science & ; Technology 3, no 11 (2013) : 2881. http://dx.doi.org/10.1039/c3cy00243h.

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Wang, Baoxiang, Dan Cheng, Ziyan Chen, Manman Zhang, Guoqiang Zhang, Mingyi Jiang et Mingpu Tan. « Bioinformatic Exploration of the Targets of Xylem Sap miRNAs in Maize under Cadmium Stress ». International Journal of Molecular Sciences 20, no 6 (23 mars 2019) : 1474. http://dx.doi.org/10.3390/ijms20061474.

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Cadmium (Cd) has the potential to be chronically toxic to humans through contaminated crop products. MicroRNAs (miRNAs) can move systemically in plants. To investigate the roles of long-distance moving xylem miRNAs in regulating maize response to Cd stress, three xylem sap small RNA (sRNA) libraries were constructed for high-throughput sequencing to identify potential mobile miRNAs in Cd-stressed maize seedlings and their putative targets in maize transcriptomes. In total, about 199 miRNAs (20–22 nucleotides) were identified in xylem sap from maize seedlings, including 97 newly discovered miRNAs and 102 known miRNAs. Among them, 10 miRNAs showed differential expression in xylem sap after 1 h of Cd treatment. Two miRNAs target prediction tools, psRNAtarget (reporting the inhibition pattern of cleavage) and DPMIND (discovering Plant MiRNA-Target Interaction with degradome evidence), were used in combination to identify, via bioinformatics, the targets of 199 significantly expressed miRNAs in maize xylem sap. The integrative results of these two bioinformatic tools suggested that 27 xylem sap miRNAs inhibit 34 genes through cleavage with degradome evidence. Moreover, nearly 300 other genes were also the potential miRNAs cleavable targets without available degradome data support, and the majority of them were enriched in abiotic stress response, cell signaling, transcription regulation, as well as metal handling. These approaches and results not only enhanced our understanding of the Cd-responsive long-distance transported miRNAs from the view of xylem sap, but also provided novel insights for predicting the molecular genetic mechanisms mediated by miRNAs.
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Adhikari, Aniruddha, Susmita Mondal, Soumendra Darbar et Samir Kumar Pal. « Role of Nanomedicine in Redox Mediated Healing at Molecular Level ». Biomolecular Concepts 10, no 1 (29 octobre 2019) : 160–74. http://dx.doi.org/10.1515/bmc-2019-0019.

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AbstractNanomedicine, the offspring born from the marriage of nanotechnology and medicine, has already brought momentous advances in the fight against a plethora of unmet diseases from cardiovascular and neurodegenerative to diabetes and cancer. Here, we review a conceptual framework that will provide a basic understanding about the molecular mechanism of action of a therapeutic nanomaterial inside biological milieu. In this review, we highlight how the catalytic nature of a transition metal oxide nanomaterial influences the cellular redox homeostasis, supports the cellular antioxidant defence system and reactivates the reactive oxygen species (ROS) mediated signalling to perform normal cell functions like cell cycle, differentiation, apoptosis, inflammation, toxicity, and protein interactions. With numerous examples, we describe the redox modulatory nature of d-block metal oxide nanomaterials and their biomimetic nanozyme activities to protect the mitochondria, the cellular redox mediator which prevents an organism from various diseases. This knowledge will be useful to design new nanomaterials capable of intracellular redox modulation, which in turn can be effective therapeutic agents for treatment of various unmet diseases that are beyond the ability of modern synthetic medicine.
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Yang, Bo, Kamal Sharkas, Laura Gagliardi et Donald G. Truhlar. « The effects of active site and support on hydrogen elimination over transition-metal-functionalized yttria-decorated metal–organic frameworks ». Catalysis Science & ; Technology 9, no 24 (2019) : 7003–15. http://dx.doi.org/10.1039/c9cy01069f.

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Transition-metal catalysts supported on a metal–organic framework have been screened computationally to reveal the best catalytic candidates for hydrogen elimination reactions, which are critical in many catalytic cycles.
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Kirsebom, L. A. « RNase P RNA-mediated catalysis ». Biochemical Society Transactions 30, no 6 (1 novembre 2002) : 1153–58. http://dx.doi.org/10.1042/bst0301153.

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The endoribonuclease RNase P is involved in the processing of tRNA precursors to generate mature 5′ termini. The catalytic activity of RNase P is associated with an RNA, RNase P RNA. A specific interaction between the 3′ end of the substrate and RNase P RNA, to form an RNase P RNA-substrate complex, is referred to as the ‘73–294-interaction’. This interaction has an important role for efficient and correct cleavage to occur. Here our understanding of the contribution of the 73–294-interaction and metal ions, with respect to efficient and correct cleavage in RNase P RNA-mediated catalysis, will be discussed.
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30

Fatimah, Is. « Metal Oxide and Metal Complex Immobilization Modified Smectite Clay For Green Catalysis and Photo-Catalysis Applications : A Mini Review ». Chemical 3, no 1 (6 janvier 2018) : 54–59. http://dx.doi.org/10.20885/ijcr.vol2.iss1.art7.

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Clay minerals are promising modifiable material for catalysis application. Fit to green chemistry issue, green catalysis based on clay minerals modification has been designed in our research group. Metal oxide and metal complexes modification onto natural and synthetic smectite clay via pillarization and intercalation processes and its application as green catalyst have been investigated. This paper presents the study on preparation of Ni, Zr and Pt insertion on smectite clay structure for green conversion of citronellal to menthol via catalytic hydrogen transfer mechanism and Ru-complex modified smectite clay as novel photocatalysis application. Effect of clay structure modification was also studied in order to investigate the relationship between physicochemical characteristic change of material modifications and its catalytic/photo-catalytic activity. Some interesting phenomena related to the interaction of metal-clay support for their performance toward reaction kinetics and mechanism are reviewed, with emphasis on the evolution of surface properties and some factors affecting catalytic/photo-catalytic activity
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Kurup, Sudheer S., et Stanislav Groysman. « Catalytic synthesis of azoarenes via metal-mediated nitrene coupling ». Dalton Transactions 51, no 12 (2022) : 4577–89. http://dx.doi.org/10.1039/d2dt00228k.

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This article summarizes recent findings in the field of transition metal-mediated nitrene coupling catalysis through the lens of mechanistic and structure–activity studies, and highlights unsolved challenges in the field.
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Sheldon, Roger A., et Isabel W. C. E. Arends. « Catalytic oxidations mediated by metal ions and nitroxyl radicals ». Journal of Molecular Catalysis A : Chemical 251, no 1-2 (mai 2006) : 200–214. http://dx.doi.org/10.1016/j.molcata.2006.02.016.

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Tilly, David, Gandrath Dayaker et Prabhakar Bachu. « Cobalt mediated C–H bond functionalization : emerging tools for organic synthesis ». Catal. Sci. Technol. 4, no 9 (2014) : 2756–77. http://dx.doi.org/10.1039/c4cy00053f.

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This review provides a perspective on C–H bond functionalization mediated by cobalt complexes used in either stoichiometric or catalytic amounts, without the contribution of any other transition metal, for organic synthesis applications.
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Wang, Fei, Jianzhun Jiang et Bin Wang. « Recent In Situ/Operando Spectroscopy Studies of Heterogeneous Catalysis with Reducible Metal Oxides as Supports ». Catalysts 9, no 5 (23 mai 2019) : 477. http://dx.doi.org/10.3390/catal9050477.

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For heterogeneous catalysis, the metal catalysts supported on reducible metal oxides, especially CeO2 and TiO2, have long been a research focus because of their excellent catalytic performance in a variety of catalytic reactions. Detailed understanding of the promotion effect of reducible metal oxides on catalytic reactions is beneficial to the rational design of new catalysts. The important catalytic roles of reducible metal oxides are attributed to their intimate interactions with the supported metals (e.g., strong metal-support interaction, electronic metal-support interaction) and unique support structures (e.g., oxygen vacancy, reversible valence change, surface hydroxyl). However, the structures of the catalysts and reaction mechanisms are strongly affected by environmental conditions. For this reason, in situ/operando spectroscopy studies under working conditions are necessary to obtain accurate information about the structure-activity relationship. In this review, the recent applications of the in situ/operando spectroscopy methodology on metal catalysts with reducible metal oxides as supports are summarized.
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35

Nuthanakanti, Ashok. « Cytidine and ribothymidine nucleolipids synthesis, organogelation, and selective anion and metal ion responsiveness ». New Journal of Chemistry 43, no 34 (2019) : 13447–56. http://dx.doi.org/10.1039/c9nj03276b.

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Nucleolipids of 2′,3′-O-diacylatedribothymidine supports the organogelation by utilizing inherent self-base pairing and solvent mediated bifurcated H-bonding and hydrophobic effect. These organogels exhibits unusual Hg2+ mediated base pairing.
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36

Cheng, Hui-cheng, Peng-hu Guo, Jiao-li Ma et Xiao-Qiang Hu. « Directing group strategies in catalytic sp2 C–H cyanations : scope, mechanism and limitations ». Catalysis Science & ; Technology 11, no 10 (2021) : 3308–25. http://dx.doi.org/10.1039/d1cy00241d.

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Directing group strategy in transition metal catalyzed sp2 C–H bond cyanation has contributed to the direct conversion of hydrocarbons to cyano-containing compounds. Recent developments in transition metal-mediated sp2 C–H bond cyanation using this strategy are reviewed.
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Gancarczyk, Anna, Katarzyna Sindera, Marzena Iwaniszyn, Marcin Piątek, Wojciech Macek, Przemysław J. Jodłowski, Sebastian Wroński, Maciej Sitarz, Joanna Łojewska et Andrzej Kołodziej. « Metal Foams as Novel Catalyst Support in Environmental Processes ». Catalysts 9, no 7 (5 juillet 2019) : 587. http://dx.doi.org/10.3390/catal9070587.

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Metal foams are considered as promising catalyst carriers due to their high porosity, large specific surface area, and satisfactory thermal and mechanical stability. The study presents heat transfer and pressure drop experiments performed for seven foams of different pore densities made from diverse metals. Mass transfer characteristics are derived using the Chilton–Colburn analogy. It was found that the foams display much more intense heat/mass transfer than a monolith, comparable to packed bed. Next, the foams’ efficiencies have been compared, using 1D reactor modeling, in catalytic reactions displaying either slower (selective catalytic reduction of NOx) or faster kinetics (catalytic methane combustion). For the slow kinetics, the influence of carrier specific surface area at which catalyst can be deposited (i.e., catalyst amount) was decisive to achieve high process conversion and short reactor. For this case, monolith appears as the best choice assuming it’s the lowest pressure drop. For the fast reaction, the mass transfer becomes the limiting parameter, thus solid foams are the best solution.
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38

Mummadi, Suresh, et Clemens Krempner. « Triphenylborane in Metal-Free Catalysis ». Molecules 28, no 3 (31 janvier 2023) : 1340. http://dx.doi.org/10.3390/molecules28031340.

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The development and application of new organoboron reagents as Lewis acids in synthesis and metal-free catalysis have dramatically expanded over the past 20 years. In this context, we will show the recent uses of the simple and relatively weak Lewis acid BPh3—discovered 100 years ago—as a metal-free catalyst for various organic transformations. The first part will highlight catalytic applications in polymer synthesis such as the copolymerization of epoxides with CO2, isocyanate, and organic anhydrides to various polycarbonate copolymers and controlled diblock copolymers as well as alternating polyurethanes. This is followed by a discussion of BPh3 as a Lewis acid component in the frustrated Lewis pair (FLP) mediated cleavage of hydrogen and hydrogenation catalysis. In addition, BPh3-catalyzed reductive N-methylations and C-methylations with CO2 and silane to value-added organic products will be covered as well along with BPh3-catalyzed cycloadditions and insertion reactions. Collectively, this mini-review showcases the underexplored potential of commercially available BPh3 in metal-free catalysis.
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Polo-Garzon, Felipe, Thomas F. Blum, Zhenghong Bao, Kristen Wang, Victor Fung, Zhennan Huang, Elizabeth E. Bickel, De-en Jiang, Miaofang Chi et Zili Wu. « In Situ Strong Metal–Support Interaction (SMSI) Affects Catalytic Alcohol Conversion ». ACS Catalysis 11, no 4 (28 janvier 2021) : 1938–45. http://dx.doi.org/10.1021/acscatal.0c05324.

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Su, Tian-Yue, Guo-Ping Lu, Kang-Kang Sun, Min Zhang et Chun Cai. « ZIF-derived metal/N-doped porous carbon nanocomposites : efficient catalysts for organic transformations ». Catalysis Science & ; Technology 12, no 7 (2022) : 2106–21. http://dx.doi.org/10.1039/d1cy02211c.

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ZIF-derived metal/N-doped porous carbon have emerged as efficient heterogeneous catalysts in organic reactions, due to controllable 3D structure, uniformly dispersed metal sites, tunable metal–support interactions and superior catalytic performance.
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41

Mueller, Vesna Havran, Milorad P. Duduković et Cynthia S. Lo. « The role of metal–support interaction on catalytic methane activation ». Applied Catalysis A : General 488 (novembre 2014) : 138–47. http://dx.doi.org/10.1016/j.apcata.2014.09.021.

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42

Zhou, Xuemei, Linxiao Chen, George E. Sterbinsky, Debangshu Mukherjee, Raymond R. Unocic et Steven L. Tait. « Pt-Ligand single-atom catalysts : tuning activity by oxide support defect density ». Catalysis Science & ; Technology 10, no 10 (2020) : 3353–65. http://dx.doi.org/10.1039/c9cy02594d.

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43

Huang, Tiefan, Guan Sheng, Priyanka Manchanda, Abdul H. Emwas, Zhiping Lai, Suzana Pereira Nunes et Klaus-Viktor Peinemann. « Cyclodextrin polymer networks decorated with subnanometer metal nanoparticles for high-performance low-temperature catalysis ». Science Advances 5, no 11 (novembre 2019) : eaax6976. http://dx.doi.org/10.1126/sciadv.aax6976.

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The synthesis of support materials with suitable coordination sites and confined structures for the controlled growth of ultrasmall metal nanoparticles is of great importance in heterogeneous catalysis. Here, by rational design of a cross-linked β-cyclodextrin polymer network (CPN), various metal nanoparticles (palladium, silver, platinum, gold, and rhodium) of subnanometer size (<1 nm) and narrow size distribution are formed via a mild and facile procedure. The presence of the metal coordination sites and the network structure are key to the successful synthesis and stabilization of the ultrasmall metal nanoparticles. The as-prepared CPN, loaded with palladium nanoparticles, is used as a heterogeneous catalyst and shows outstanding catalytic performance in the hydrogenation of nitro compounds and Suzuki-Miyaura coupling reaction under mild conditions. The CPN support works synergistically with the metal nanoparticles, achieving high catalytic activity and selectivity. In addition, the catalytic activity of the formed catalyst is controllable.
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44

Astruc, D. « Organometallic chemistry at the nanoscale. Dendrimers for redox processes and catalysis ». Pure and Applied Chemistry 75, no 4 (1 janvier 2003) : 461–81. http://dx.doi.org/10.1351/pac200375040461.

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An overview of the metal-mediated synthesis and use of nanosized metallodendrimers is given with emphasis on electron-transfer processes (molecular batteries consisting in dendrimers decorated with a large number of equivalent redox-active centers) and catalytic reactions (electron-transfer-chain catalytic synthesis of dendrimers decorated with ruthenium carbonyl clusters, redox catalysis of nitrate and nitrite electroreduction in water by star-shape hexanuclear catalysts).
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45

Tada, Mizuki. « Surface-Mediated Design and Catalytic Properties of Active Metal Complexes for Advanced Catalysis Creation ». Bulletin of the Chemical Society of Japan 83, no 8 (15 août 2010) : 855–76. http://dx.doi.org/10.1246/bcsj.20090336.

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46

Erdőhelyi, András. « Catalytic Reaction of Carbon Dioxide with Methane on Supported Noble Metal Catalysts ». Catalysts 11, no 2 (23 janvier 2021) : 159. http://dx.doi.org/10.3390/catal11020159.

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The conversion of CO2 and CH4, the main components of the greenhouse gases, into synthesis gas are in the focus of academic and industrial research. In this review, the activity and stability of different supported noble metal catalysts were compared in the CO2 + CH4 reaction on. It was found that the efficiency of the catalysts depends not only on the metal and on the support but on the particle size, the metal support interface, the carbon deposition and the reactivity of carbon also influences the activity and stability of the catalysts. The possibility of the activation and dissociation of CO2 and CH4 on clean and on supported noble metals were discussed separately. CO2 could dissociate on metal surfaces, this reaction could proceed via the formation of carbonate on the support, or on the metal–support interface but in the reaction the hydrogen assisted dissociation of CO2 was also suggested. The decrease in the activity of the catalysts was generally attributed to carbon deposition, which can be formed from CH4 while others suggest that the source of the surface carbon is CO2. Carbon can occur in different forms on the surface, which can be transformed into each other depending on the temperature and the time elapsed since their formation. Basically, two reaction mechanisms was proposed, according to the mono-functional mechanism the activation of both CO2 and CH4 occurs on the metal sites, but in the bi-functional mechanism the CO2 is activated on the support or on the metal–support interface and the CH4 on the metal.
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Chen, Yu-Zhen, Linfeng Liang, Qihao Yang, Maochun Hong, Qiang Xu, Shu-Hong Yu et Hai-Long Jiang. « A seed-mediated approach to the general and mild synthesis of non-noble metal nanoparticles stabilized by a metal–organic framework for highly efficient catalysis ». Materials Horizons 2, no 6 (2015) : 606–12. http://dx.doi.org/10.1039/c5mh00125k.

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Liu, Xue, Dawei Gao, Yue Chi, Hongli Wang, Zhili Wang et Zhankui Zhao. « Ultrafine AuPd nanoparticles supported on amine functionalized monochlorotriazinyl β-cyclodextrin as highly active catalysts for hydrogen evolution from formic acid dehydrogenation ». Catalysis Science & ; Technology 10, no 15 (2020) : 5281–87. http://dx.doi.org/10.1039/c9cy02464f.

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Zhu, Yun-Pei, Ya-Lu Liu, Tie-Zhen Ren et Zhong-Yong Yuan. « Mesoporous nickel phosphate/phosphonate hybrid microspheres with excellent performance for adsorption and catalysis ». RSC Adv. 4, no 31 (2014) : 16018–21. http://dx.doi.org/10.1039/c4ra01466a.

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Mesoporous nickel phosphate/phosphonate microspheres were synthesized through a template-free phosphate-mediated self-assembly procedure, exhibiting excellent performance for CO2 capture, heavy metal ion adsorption and catalytic hydrogenation of 4-nitrophenol to 4-aminophenol.
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50

Dauscher, A., W. M�ller et G. Maire. « Catalytic behaviour of polycrystalline Pt3Ti in relation to strong metal-support interaction phenomenon ». Catalysis Letters 2, no 3 (1989) : 139–44. http://dx.doi.org/10.1007/bf00775062.

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