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Relevant bibliographies by topics / Metal catalyst nanoparticles

Academic literature on the topic 'Metal catalyst nanoparticles'

Author: Grafiati

Published: 10 December 2022

Last updated: 28 January 2023

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Journal articles on the topic "Metal catalyst nanoparticles"

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Sasaki, Teruyoshi, Yusuke Horino, Tadashi Ohtake, Kazufumi Ogawa, and Yoshifumi Suzaki. "A Highly Efficient Monolayer Pt Nanoparticle Catalyst Prepared on a Glass Fiber Surface." Catalysts 10, no. 5 (April 25, 2020): 472. http://dx.doi.org/10.3390/catal10050472.

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Over the past few years, various nanoparticle-supported precious metal-based catalysts have been investigated to reduce the emission of harmful substances from automobiles. Generally, precious metal nanoparticle-based exhaust gas catalysts are prepared using the impregnation method. However, these catalysts suffer from the low catalytic activity of the precious metal nanoparticles involved. Therefore, in this study, we developed a novel method for preparing highly efficient glass fiber-supported Pt nanoparticle catalysts. We uniformly deposited a single layer of platinum particles on the support surface using a chemically adsorbed monomolecular film. The octane combustion performance of the resulting catalyst was compared with that of a commercial catalyst. The precious metal loading ratio of the proposed catalyst was approximately seven times that of the commercial catalyst. Approximately one-twelfth of the mass of the proposed catalyst exhibited a performance comparable to that of the commercial catalyst. Thus, the synthesis method used herein can be used to reduce the weight, size, and manufacturing cost of exhaust gas purification devices used in cars.

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Lindenthal, Lorenz, Raffael Rameshan, Harald Summerer, Thomas Ruh, Janko Popovic, Andreas Nenning, Stefan Löffler, Alexander Karl Opitz, Peter Blaha, and Christoph Rameshan. "Modifying the Surface Structure of Perovskite-Based Catalysts by Nanoparticle Exsolution." Catalysts 10, no. 3 (March 1, 2020): 268. http://dx.doi.org/10.3390/catal10030268.

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In heterogeneous catalysis, surfaces decorated with uniformly dispersed, catalytically-active (nano)particles are a key requirement for excellent performance. Beside standard catalyst preparation routines—with limitations in controlling catalyst surface structure (i.e., particle size distribution or dispersion)—we present here a novel time efficient route to precisely tailor catalyst surface morphology and composition of perovskites. Perovskite-type oxides of nominal composition ABO3 with transition metal cations on the B-site can exsolve the B-site transition metal upon controlled reduction. In this exsolution process, the transition metal emerges from the oxide lattice and migrates to the surface where it forms catalytically active nanoparticles. Doping the B-site with reducible and catalytically highly active elements, offers the opportunity of tailoring properties of exsolution catalysts. Here, we present the synthesis of two novel perovskite catalysts Nd0.6Ca0.4FeO3-δ and Nd0.6Ca0.4Fe0.9Co0.1O3-δ with characterisation by (in situ) XRD, SEM/TEM and XPS, supported by theory (DFT+U). Fe nanoparticle formation was observed for Nd0.6Ca0.4FeO3-δ. In comparison, B site cobalt doping leads, already at lower reduction temperatures, to formation of finely dispersed Co nanoparticles on the surface. These novel perovskite-type catalysts are highly promising for applications in chemical energy conversion. First measurements revealed that exsolved Co nanoparticles significantly improve the catalytic activity for CO2 activation via reverse water gas shift reaction.

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Zhang, Xiaolong, Shilei Jin, Yuhan Zhang, Liyuan Wang, Yang Liu, and Qian Duan. "One-Pot Facile Synthesis of Noble Metal Nanoparticles Supported on rGO with Enhanced Catalytic Performance for 4-Nitrophenol Reduction." Molecules 26, no. 23 (November 30, 2021): 7261. http://dx.doi.org/10.3390/molecules26237261.

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In this study, reduced graphene oxide (rGO)-supported noble metal (gold, silver, and platinum) nanoparticle catalysts were prepared via the one-pot facile co-reduction technique. Various measurement techniques were used to investigate the structures and properties of the catalysts. The relative intensity ratios of ID/IG in rGO/Au, rGO/Ag, rGO/Pt, and GO were 1.106, 1.078, 1.047, and 0.863, respectively. The results showed the formation of rGO and that noble metal nanoparticles were decorated on rGO. Furthermore, the catalytic activities of the designed nanocomposites were investigated via 4-nitrophenol. The catalysts were used in 4-nitrophenol reduction. The catalytic performance of the catalysts was evaluated using the apparent rate constant k values. The k value of rGO/Au was 0.618 min−1, which was higher than those of rGO/Ag (0.55 min−1) and rGO/Pt (0.038 min−1). The result proved that the rGO/Au catalyst exhibited a higher catalytic performance than the rGO/Ag catalyst and the rGO/Pt catalyst. The results provide a facile method for the synthesis of rGO-supported nanomaterials in catalysis.

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José-Yacamán, M., M. Marín-Almazo, and J. A. Ascencio. "High Resolution TEM Studies On Palladium, Rhodium Nanoparticles." Microscopy and Microanalysis 7, S2 (August 2001): 1100–1101. http://dx.doi.org/10.1017/s1431927600031573.

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The field of catalysis is one of the most important areas of the nano-sciences for many years. in deed the goal of having a catalyst, with the maximum active area exposed to a chemical reaction, has produced enormous amount of research in nanoparticles. Particularly, the metal nanoparticles study is a very important field in catalysis. Electron Microscopy is one of the techniques that have played a mayor role on studding nanoparticles. Since bright field images, dark field techniques, to the high-resolution atomic images of nanoparticles and more recently the High Angle Annular dark field images or Z-contrast. However this technique provides only indirect evidence of the atomic arrangements on the particles. High Resolution Electron Microscopy (HREM) still appears as a very powerful technique to study nanoparticles and their internal structure. Among the most interesting metals to study is the palladium, which acts for instance as excellent catalyst for hydrogenation of unsaturated hydrocarbons and has many other applications such as environmental catalysts.

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Biehler, Erik, Qui Quach, Clay Huff, and Tarek M. Abdel-Fattah. "Organo-Nanocups Assist the Formation of Ultra-Small Palladium Nanoparticle Catalysts for Hydrogen Evolution Reaction." Materials 15, no. 7 (April 6, 2022): 2692. http://dx.doi.org/10.3390/ma15072692.

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Ultra-small palladium nanoparticles were synthesized and applied as catalysts for a hydrogen evolution reaction. The palladium metal precursor was produced via beta-cyclodextrin as organo-nanocup (ONC) capping agent to produce ultra-small nanoparticles used in this study. The produced ~3 nm nanoparticle catalyst was then characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and Fourier transform infrared spectroscopy (FTIR) to confirm the successful synthesis of ~3 nm palladium nanoparticles. The nanoparticles’ catalytic ability was explored via the hydrolysis reaction of sodium borohydride. The palladium nanoparticle catalyst performed best at 303 K at a pH of 7 with 925 μmol of sodium borohydride having an H2 generation rate of 1.431 mL min−1 mLcat−1. The activation energy of the palladium catalyst was calculated to be 58.9 kJ/mol.

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Patil, Siddappa A., Shivaputra A. Patil, and Renukadevi Patil. "Magnetic Nanoparticles Supported Carbene and Amine Based Metal Complexes in Catalysis." Journal of Nano Research 42 (July 2016): 112–35. http://dx.doi.org/10.4028/www.scientific.net/jnanor.42.112.

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Catalysis is one of the hottest research topics in chemistry. In recent years, metal complexes attracted great interest as catalysts towards various types of organic reactions. However, these catalysts, in most cases, suffer from the deficits during their recovery, recycling and the difficulty in separation of catalysts from the products. Therefore, the design and synthesis of recoverable and recyclable catalyst is very important aspect in catalysis. The aim of this review article is to highlight the speedy growth in the synthesis and catalytic applications of magnetic nanoparticles (Fe3O4, MNPs) supported N-heterocyclic carbene (NHC) and amine based metal complexes in various organic reactions. Furthermore, these catalysts can be easily separated from the reaction media with the external magnet and reused various times without a substantial loss of catalytic activity.

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Pisarek, Marcin, Piotr Kędzierzawski, Mariusz Andrzejczuk, Marcin Hołdyński, Anna Mikołajczuk-Zychora, Andrzej Borodziński, and Maria Janik-Czachor. "TiO2 Nanotubes with Pt and Pd Nanoparticles as Catalysts for Electro-Oxidation of Formic Acid." Materials 13, no. 5 (March 6, 2020): 1195. http://dx.doi.org/10.3390/ma13051195.

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In the present work, the magnetron sputtering technique was used to prepare new catalysts of formic acid electrooxidation based on TiO2 nanotubes decorated with Pt (platinum), Pd (palladium) or Pd + Pt nanoparticles. TiO2 nanotubes (TiO2 NTs) with strictly defined geometry were produced by anodization of Ti foil and Ti mesh in a mixture of glycerol and water with ammonium fluoride electrolyte. The above mentioned catalytically active metal nanoparticles (NPs) were located mainly on the top of the TiO2 NTs, forming ‘rings’ and agglomerates. A part of metal nanoparticles decorated also TiO2 NTs walls, thus providing sufficient electronic conductivity for electron transportation between the metal nanoparticle rings and Ti current collector. The electrocatalytic activity of the TiO2 NTs/Ti foil, decorated by Pt, Pd and/or Pd + Pt NPs was investigated by cyclic voltammetry (CV) and new Pd/TiO2 NTs/Ti mesh catalyst was additionally tested in a direct formic acid fuel cell (DFAFC). The results so obtained were compared with commercial catalyst—Pd/Vulcan. CV tests have shown for carbon supported catalysts, that the activity of TiO2 NTs decorated with Pd was considerably higher than that one decorated with Pt. Moreover, for TiO2 NTs supported Pd catalyst specific activity (per mg of metal) was higher than that for well dispersed carbon supported commercial catalyst. The tests at DFAFC have revealed also that the maximum of specific power for 0.2 Pd/TiO2 catalyst was 70% higher than that of the commercial one, Pd/Vulcan. Morphological features, and/or peculiarities, as well as surface composition of the resulting catalysts have been studied by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and chemical surface analytical methods (X-ray photoelectron spectroscopy—XPS; Auger electron spectroscopy—AES).

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Ahmad, Mohamad M., Shehla Mushtaq, Hassan S. Al Qahtani, A. Sedky, and Mir Waqas Alam. "Investigation of TiO2 Nanoparticles Synthesized by Sol-Gel Method for Effectual Photodegradation, Oxidation and Reduction Reaction." Crystals 11, no. 12 (November 25, 2021): 1456. http://dx.doi.org/10.3390/cryst11121456.

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Metal oxide titanium dioxide (TiO2) nanoparticles were synthesized by using a simple and economical sol-gel method. The prepared nanoparticles were used to evaluate methylene blue dye degradation and as catalysts in the oxidation of benzaldehyde. The crystallite size of the titanium dioxide nanoparticle was 18.3 nm, which was confirmed by X-ray diffraction analysis. The spherical morphology was confirmed by scanning electron microscopy (SEM), and the elemental composition of the nanoparticle was found by energy dispersive X-ray (EDAX) analysis. The anatase form of the nanoparticle was confirmed by the bandgap 3.2 eV, which was measured using UV–DRS analysis. The bond between metal and oxygen was confirmed by the peaks at 485 and 606 cm–1 analyzed by Fourier transform infrared analysis (FTIR). The efficiency of the catalyst in dye degradation was 60.08, 68.38, and 80.89% with respect to 50, 75, and 100 mg catalyst weight. The yield % of benzoic acid was 94%, and the reduction efficiency against 4-nitrophenol was 98.44%.

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Gutiérrez, Yael, Dolores Ortiz, Rodrigo Alcaraz de la Osa, José M. Saiz, Francisco González, and Fernando Moreno. "Electromagnetic Effective Medium Modelling of Composites with Metal-Semiconductor Core-Shell Type Inclusions." Catalysts 9, no. 7 (July 22, 2019): 626. http://dx.doi.org/10.3390/catal9070626.

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The possibility of using light to drive chemical reactions has highlighted the role of photocatalysis as a key tool to address the environmental and energy issues faced by today’s society. Plasmonic photocatalysis, proposed to circumvent some of the problems of conventional semiconductor catalysis, uses hetero-nanostructures composed by plasmonic metals and semiconductors as catalysts. Metal-semiconductor core-shell nanoparticles present advantages (i.e., protecting the metal and enlarging the active sites) with respect to other hetero-nanostructures proposed for plasmonic photocatalysis applications. In order to maximize light absorption in the catalyst, it is critical to accurately model the reflectance/absorptance/transmittance of composites and colloids with metal-semiconductor core-shell nanoparticle inclusions. Here, we present a new method for calculating the effective dielectric function of metal-semiconductor core-shell nanoparticles and its comparison with existing theories showing clear advantages. Particularly, this new method has shown the best performance in the prediction of the spectral position of the localized plasmonic resonances, a key parameter in the design of efficient photocatalysts. This new approach can be considered as a useful tool for designing coated particles with desired plasmonic properties and engineering the effective permittivity of composites with core-shell type inclusions which are used in photocatalysis and solar energy harvesting applications.

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Kreitz, Bjarne, Aurina Martínez Arias, Jan Martin, Alfred Weber, and Thomas Turek. "Spray-Dried Ni Catalysts with Tailored Properties for CO2 Methanation." Catalysts 10, no. 12 (December 2, 2020): 1410. http://dx.doi.org/10.3390/catal10121410.

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A catalyst production method that enables the independent tailoring of the structural properties of the catalyst, such as pore size, metal particle size, metal loading or surface area, allows to increase the efficiency of a catalytic process. Such tailoring can help to make the valorization of CO2 into synthetic fuels on Ni catalysts competitive to conventional fossil fuel production. In this work, a new spray-drying method was used to produce Ni catalysts supported on SiO2 and Al2O3 nanoparticles with tunable properties. The influence of the primary particle size of the support, different metal loadings, and heat treatments were applied to investigate the potential to tailor the properties of catalysts. The catalysts were examined with physical and chemical characterization methods, including X-ray diffraction, temperature-programmed reduction, and chemisorption. A temperature-scanning technique was applied to screen the catalysts for CO2 methanation. With the spray-drying method presented here, well-organized porous spherical nanoparticles of highly dispersed NiO nanoparticles supported on silica with tunable properties were produced and characterized. Moreover, the pore size, metal particle size, and metal loading can be controlled independently, which allows to produce catalyst particles with the desired properties. Ni/SiO2 catalysts with surface areas of up to 40 m2 g−1 with Ni crystals in the range of 4 nm were produced, which exhibited a high activity for the CO2 methanation.

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Dissertations / Theses on the topic "Metal catalyst nanoparticles"

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Ogiwara, Naoki. "Integration of Metal Nanoparticles and Metal-Organic Frameworks for Control of Water Reactivity." Kyoto University, 2019. http://hdl.handle.net/2433/242627.

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Iwase, Yukari. "Application of Metal Nanoparticles and Polyoxometalates for Efficient Photocatalysis and Catalysis." Kyoto University, 2018. http://hdl.handle.net/2433/232051.

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Xu, Chunbao. "Continuous and batch hydrothermal synthesis of metal oxide nanoparticles and metal oxide-activated carbon nanocomposites." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-07302006-231517/.

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Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2007.
Teja, Amyn, Committee Chair ; Kohl, Paul, Committee Member ; Liu, Meilin, Committee Member ; Nair,Sankar, Committee Member ; Rousseau, Ronald, Committee Member.

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Zahmakiran, Mehmet. "Synthesis And Characterization Of Ruthenium(0) Metal Nanoparticles As Catalyst In The Hydrolysis Of Sodium Borohydride." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12605966/index.pdf.

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Sodium borohydride is stable in alkaline solution, however, it hydrolyses and generates hydrogen gas in the presence of suitable catalyst. By this way hydrogen can be generated safely for the fuel cells. All of the catalyst having been used in the hydrolysis of sodium borohydride, with one exception, are heterogeneous. The limited surface area of the heterogeneous and therefore, have limited activity because of the surface area. Thus, the use of metal nanoclusters as catalyst with large surface area is expected to provide a potential route to increase the catalytic activity. In this dissertation we report for the first time the use of ruthenium(0) nanoparticles as catalyst in the hydrolysis of sodium borohydride. The water dispersible ruthenium(0) nanoparticles were prepared by the reduction of RuCl3.xH2O with sodium borohydride and were stabilized by three different ligands dodecanethiol, ethylenediamine and acetate. Among these three colloidal materials the acetate stabilized ruthenium(0) nanoparticles were found to have the highest catalytic activity in catalyzing the hydrolysis of sodium borohydride. The acetate stabilized ruthenium(0) nanoparticles were characterized by tranmission electron microscopy (TEM), X-ray photoelectron spectroscopy and FT-IR spectroscopy. The particle size of the acetate stabilized ruthenium(0) nanoparticles was determined to be 2.62±
1.18 nm from the TEM analysis. The kinetic of the ruthenium(0) nanoparticles catalyzed hydrolysis of sodium borohydride was studied depending on the catalyst concentration, substrate concentration and temperature. The activation parameters of this reaction were also determined from the evaluation of the kinetic data. This catalyst provides the lowest activation energy ever found for the hydrolysis of sodium borohydride.

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Marina, Nancy. "The Use of Metal Nanoparticles as an Antimicrobial Agent and as a Catalyst for Organic Synthesis." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38427.

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Nanomaterial’s applications have expanded greatly in the last few decades due to their interesting properties. Example of nanomaterials are metal nanoparticles NP. NP have interesting physical and optical properties that make them different and more useful than their bulk counterpart. Some of these properties are the large surface area to mass ratio and their ability to absorb light. NP have been applied in the health, environment, and catalysis fields The main focus of this thesis will be on the applications of nanomaterials in medicine and catalysis. In the first part of the thesis, coated polydispersed and polymorphic silver nanostructures AgNS were synthesized using seed mediated method. The synthesized AgNS were characterized using SEM, TEM, and UV-VIS. The stability of these AgNS were determined by measuring the shift in the plasmon band over time and by measuring their zeta potential. Moreover, the bactericidal properties of coated AgNS were tested on gram negative bacteria such as Escherichia coli and Pseudomonas aeruginosa and gram positive bacteria such as Methicillin- Resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus. The second part of the thesis discusses the field of nanocatalysis where different supported metal nanoparticles on TiO2 were synthesized and characterized by TEM, diffuse reflectance DR, XPS and ICP. The activity of the synthesized catalysts was tested for Ullmann C-C cross coupling reaction. The use of the photoresponisve Pd@TiO2 under the combination of UVA 368 and visible light 465nm irradiation offered the highest selectivity toward the cross coupling product.

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Binti, Wan Ramli Wan Khairunnisa. "Exsolved base metal catalyst systems with anchored nanoparticles for carbon monoxide (CO) and nitric oxides (NOx) oxidation." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3875.

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Noble metals notably platinum (Pt), is a major element of heterogeneous catalysts, excel in catalysing an extensive number of important catalytic reactions in chemical and automotive industries. Since the increased use of these metals is severely limited because of their high cost and scarcity’s, there is therefore an urgent need for the search of alternative base metal catalysts that are cheaper and more widely available. This can only be practical if the main drawbacks of base metals such as the agglomeration of particles under high temperatures operational conditions and irreversible sulphur poisoning can be overcome, and their activity enhanced, such that they can directly replace Pt on a weight-to-weight basis. However, most previous studies have been restricted to low temperature reaction conditions and have not compared their activity directly to that of Pt, whether in terms of active sites or on a weight-to-weight basis. Moreover, most researchers have not investigated extensively the long-term stability of their base metal catalysts, since the longest was at most around 200 hours and at relatively low temperatures, for example at room temperature. It is proposed that long term stability can be achieved by producing uniformly distributed nano-sized socketed and strained base metal particles via the exsolution method. The main objective of this thesis is to produce exsolved base metals catalyst systems rivalling Pt on a weight-to-weight basis in two base reactions; CO and NO oxidation. NO oxidation was also chosen as our model reaction in this research since most Pt in the automotive industry are used in the lean NOx trap (LNT) or a combination of LNT and selective catalytic reduction (SCR), which demand the high conversion of NO to NO2 at low temperatures to work effectively. Initial screening experiments were performed to evaluate the potential CO oxidation activities and long-term stability at 520 °C of two different exsolved metal pellet systems namely lanthanum-doped ceria nickel titanates to exsolve nickel (Ni) metal (La0.8Ce0.1Ni0.4Ti0.6O3) and lanthanum-doped strontium iron nickel titanates to exsolve iron-nickel (FeNi) alloy (La0.5Sr0.4Fe0.1Ni0.1Ti0.6O3). Exsolved FeNi pellet system gives high and stable turnover frequencies (TOFs) of 103 s-1 at 520 °C for almost 170 hours, which confirms the potential of these stable exsolved metal systems for CO oxidation. Sixty exsolved metal powder systems with various metal formulations were produced to enable direct activity comparison to Pt on a weight-to-weight basis. Most exsolved metal systems displayed increasing CO2 production rates with increasing CO partial pressures (PCO) and reversible sulphur poisoning with exsolved CoNi powder system showing remarkable stability at 200 °C for 655 hours (one month). This exsolved CoNi system also showed enhanced activity for CO oxidation upon exposure to CO-rich environment, as a result of the restructuring of particles iv into metal oxide nanocubes anchored onto nanosockets within the support surface. The CO2 production rates of the activated exsolved CoNi powder system at 200 and 520 °C were 0.13 x 10-4 and 1.5 x 10-4 mol s-1 g-1 compared to its initial rate of around 0 (below the detected limit of 0.007 x10-4 mol s-1 g-1) and 0.8 x 10-4 mol s-1 g-1 prior to activation. These active spinel (CoNi)3O4 cubic structures were seen planted at an angle of ~55°, at the edge of an empty socket with mediocre features for CO oxidation, such as rich in Co2+ with exposed (100) planes that had only 44 cubes μm-2 compared to its initial 144 particles μm-2 particle population. Above 450 °C, the main active sites for CO oxidation were thought to be close to or at the metal-support interface of the exsolved CoNi systems. Comparable NO2 production rates to those of commercial Pt catalyst was achieved with only ± 5 % of difference at each measured point within the temperature range used (100-440 °C) over exsolved CoNi system by exploiting the effect of having two particle size ranges (10 and 30 nm). These results confirm the dual functionality of the activated exsolved CoNi system and its huge potential to be commercialised as an alternative catalyst to Pt in two oxidation reactions; CO and NO oxidation. In general, a simple procedure that induces high, long-lasting activity in a base metal catalyst, rivalling platinum for CO and NO oxidation on a weight-to-weight basis was demonstrated. The nature of this activation by tracking individual nanoparticles was successfully elucidated to link their microstructural evolution to their catalytic and kinetic behaviour. This research also illustrates new strategies for enhancing and tailoring the catalytic activity of base metal systems towards replacing platinum.

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Strossi, Pedrolo Débora Regina. "Synthesis of metal-zeolite composite materials for bifunctional catalytic reactions." Thesis, Université de Lille (2018-2021), 2021. https://pepite-depot.univ-lille.fr/LIBRE/EDSMRE/2021/2021LILUR065.pdf.

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Les catalyseurs à base de zéolite ont été largement utilisés dans la conversion de la biomasse. Les rendements catalytiques des produits recherchés sont fortement limités en raison de la taille relativement petite des pores dans les zéolithes et la préparation du catalyseur par imprégnation conduit généralement à des nanoparticules métalliques relativement grosses et à un faible contact entre les sites métalliques et acides. Le but de ce travail est la conception de catalyseurs nanocomposites métal-zéolithe contenant des nanoparticules de ruthénium uniformément réparties dans les zéolithes hiérarchiques BEA et ZSM-5. L'utilisation de ruthénium évite la formation de silicates et d'aluminates métalliques inertes difficilement réductibles, tandis que les nanotubes de carbone avec des nanoparticules d'oxyde métallique supportées jouent un rôle de gabarit sacrificiel, ce qui permet de créer une mésoporosité et d'apporter une fonctionnalité métallique à l'intérieur de la matrice zéolithique. Par rapport aux catalyseurs métalliques supportés par des zéolites classiques, les zéolites ruthénium hiérarchiques synthétisées présentaient une activité beaucoup plus élevée et une sélectivité en méthane plus faible dans la synthèse Fischer-Tropsch. La caractérisation des catalyseurs préparés a indiqué l'initiation de la cristallisation des zéolites sur des nanoparticules métalliques. Cet effet a en outre été utilisé pour augmenter la dispersion de nanoparticules métalliques par cristallisation secondaire de Ru supporté sur ZSM-5. Nos résultats montrent une redispersion significative des nanoparticules d'oxyde métallique incorporées et une augmentation de l'activité des réactions modèles. De plus, une stratégie de synthèse a été développée pour la préparation de catalyseurs nanocomposites métalliques et zéolithiques hiérarchiques pour la synthèse directe d'iso-paraffines à partir de gaz de synthèse. Les nanocomposites sont synthétisés en trois étapes. Dans la première étape, la zéolite mère (noyau) est gravée avec une solution de fluorure d'ammonium. La gravure crée de petits mésopores à l'intérieur des cristaux de zéolite. Dans la deuxième étape, les nanoparticules de Ru préparées à l'aide de microémulsion eau-dans-huile sont déposées dans les mésopores de la zéolithe. Dans la troisième étape, une enveloppe de zéolite de zéolites de type MFI (silicalite-1 ou ZSM-5) est cultivée sur les cristaux de zéolite parent recouvrant à la fois la surface gravée et les nanoparticules métalliques. Ainsi, les nanoparticules métalliques deviennent entièrement encapsulées à l'intérieur de la matrice zéolithique. Les paramètres les plus importants tels que la teneur en ruthénium, la mésoporosité de la zéolite, et plus particulièrement, l'acidité de l'enveloppe du catalyseur, qui affectent les performances catalytiques des matériaux nanocomposites synthétisés dans la synthèse Fischer-Tropsch à basse température ont été identifiés dans ce travail. La quantité relative plus élevée d'iso-paraffines a été observée sur les catalyseurs contenant une enveloppe de ZSM-5. La proximité entre les sites métalliques et acides dans l'enveloppe zéolithique des catalyseurs nanocomposites est un paramètre crucial pour la conception de catalyseurs bifonctionnels zéolithiques métalliques efficaces pour la synthèse sélective de carburants de type essence via la synthèse Fischer-Tropsch, tandis que l'acidité du cœur du catalyseur a qu'un impact limité sur les performances catalytiques
Zeolite-based catalysts have been widely used in the conversion of biomass. The catalytic yields of the desired products are strongly limited due to the relatively small size of the pores in zeolites and the catalyst preparation by impregnation usually leads to relatively large metal nanoparticles and low contact between metal and acid sites. The purpose of this work is the design of metal-zeolite nanocomposite catalysts containing ruthenium nanoparticles uniformly distributed in the hierarchical BEA and ZSM-5 zeolites. Use of ruthenium avoids formation of inert hardly reducible inert metal silicates and metal aluminates, while carbon nanotubes with supported metal oxide nanoparticles play a role of sacrificial template, which allows creating mesoporosity and bringing metallic functionality inside the zeolite matrix. Compared to the conventional zeolite supported metal catalysts the synthesized hierarchical ruthenium-zeolites exhibited much higher activity and lower methane selectivity in Fischer-Tropsch synthesis. Characterization of the prepared catalysts has indicated initiation of crystallization of zeolites over metal nanoparticles. This effect has been further used to increase the dispersion of metal nanoparticles by secondary crystallization of Ru supported over ZSM-5. Our results show significant re-dispersion of embedded metal oxide nanoparticles and increase in the activity of model reactions. In addition, a synthetic strategy was developed for the preparation of hierarchical metal and zeolite nanocomposite catalysts for direct synthesis of iso-paraffins from syngas. The nanocomposites are synthesized in three steps. In the first step, the parent (core) zeolite is etched with an ammonium fluoride solution. The etching creates small mesopores inside the zeolite crystals. In the second step, the Ru nanoparticles prepared using water-in-oil microemulsion are deposited in the mesopores of the zeolite. In the third step, a zeolite shell of MFI-type zeolites (silicalite-1 or ZSM-5) is grown on the parent zeolite crystals coating both the etched surface and metallic nanoparticles. Thus, the metal nanoparticles become entirely encapsulated inside the zeolite matrix. Most important parameters such as ruthenium content, zeolite mesoporosity, and more particularly, the acidity of the catalyst shell, which affect the catalytic performance of the synthesized nanocomposite materials in low-temperature Fischer−Tropsch synthesis were identified in this work. The higher relative amount of iso-paraffins was observed on the catalysts containing a shell of ZSM-5. The proximity between metal and acid sites in the zeolite shell of the nanocomposite catalysts is a crucial parameter for the design of efficient metal zeolite bifunctional catalysts for selective synthesis of gasoline-type fuels via Fischer−Tropsch synthesis, while the acidity of the catalyst core has only a limited impact on the catalytic performance

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Vijwani, Hema. "Hierarchical Porous Structures with Aligned Carbon Nanotubes as Efficient Adsorbents and Metal-Catalyst Supports." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1433350549.

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VU, YEN THI. "SYNTHESIS AND CHARACTERIZATION OF ELASTOMER-BASED COMPOSITES AND POLYMER-IMMOBILIZED COLLOIDAL TRANSITION METAL NANOPARTICLES: CATALYTIC SELECTIVITY AND MORPHOLOGY." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1004541836.

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Fu, Fangyu. "Synthèses et applications catalytiques de nanoparticules d’élements de transition." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0195/document.

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La catalyse constitue un élément clé en synthèse chimique et la recherche actuelle tend à rendre les procédés catalytiques plus propres dans le contexte de la chimie verte. Dans cet esprit, cette thèse a impliqué la recherche de catalyseurs nanoparticulaires utilisés en milieu aqueux, sans ligand toxique et en très faible quantité. La synthèse des nanoparticules (NPs) catalytiques a utilisé des ions des éléments de transition de la droite du tableau périodique et des réducteurs capables de réduire rapidement ces cations en atomes de degré d’oxydation nul s’agrégeant en petites NPs métalliques très actives en catalyse. Les réducteurs choisis ont été des composés réservoirs d’électron organique (naphthyl sodium) ou organométalliques (complexes sandwichs à 19 électrons de valence du fer tel que [Fe(I)Cp*(ŋ6-C6Me6)] ou du cobalt tel que [Co(II)Cp*2], (Cp* = ŋ5-C5Me5)). Les supports limitant l’agrégation des NPs métalliques ont été le solvant (polyéthylène glycol, 1ère partie de la thèse), les cations des réservoirs d’électron organométalliques (2ème partie de la thèse) ou un réseau zéolitique imidazolate (MOF de type ZIF-8, 3ème partie de la thèse). Au lieu d’un cation métallique, il a aussi été possible d’utiliser un cluster tel que [Au25(SR)18] (R = CH2CH2Ph) comme précurseur, auquel cas la réduction peut se limiter à un simple transfer d’électron produisant un cluster anionique stabilisé par le contre-cation sandwich encombré du réservoir d’électron. Les petites NPs ainsi stabilisées se sont avérées d’excellents catalyseurs “verts” de plusieurs réactions de couplage C-C ou C-N et de production d’hydrogène par hydrolyse d’hydrures métalliques en milieu aqueux dans des conditions très douces. Cette dernière réaction a été efficacement catalysée par des NPs bimétalliques Ni2Pt NP@ZIF-8 avec une synergie spectaculaire entre les deux métaux
Catalysis is a key element in chemical synthesis, and current research is focusing on making catalytic processes cleaner in the context of green chemistry. In this spirit, this thesis involves the research of nanoparticle (NP) catalysts used in aqueous medium, without toxic ligand and in very small quantities toward a variety of useful processes. The synthesis of the catalytic NPs used cations of the transition elements of the right of the periodic table and of reducing agents capable of rapidly reducing these cations to atoms of zero oxidation state aggregating into small catalytically active metal NPs. The chosen reducing agents were organic (naphthyl sodium) or organometallic (19-electron) sandwich complexes of iron such as [Fe(I)Cp*(ŋ6-C6Me6)] or cobalt such as [Co(II)Cp*2], (Cp* = ŋ5-C5Me5)) used as electron reservoirs. The supports limiting the aggregation of the metal NPs were the solvent (polyethylene glycol, first part of the thesis), the cations of the organometallic electron reservoirs (2nd part of the thesis) or a zeolitic imidazolate framework (MOF of ZIF-8 type, 3rd part of the thesis). Instead of a metal cation, it has also been possible to use a cluster such as [Au25(SR) 18] (R = CH2CH2Ph) as a precursor, in which case the reduction was limited to a simple electron transfer producing an anionic cluster stabilized by the congested sandwich counter cation of the electron reservoir. The small NPs thus stabilized proved to be excellent "green" catalysts for several C-C or C-N reactions and hydrogen production by hydrolysis of metal hydrides in an aqueous medium under very mild conditions. This latter reaction was efficiently catalyzed by Ni2Pt@ZIF-8 bimetallic NPs with a spectacular synergy between the two metals

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Books on the topic "Metal catalyst nanoparticles"

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Tao, Franklin, ed. Metal Nanoparticles for Catalysis. Cambridge: Royal Society of Chemistry, 2014. http://dx.doi.org/10.1039/9781782621034.

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Mariscal, Marcelo Mario. Metal Clusters and Nanoalloys: From Modeling to Applications. New York, NY: Springer New York, 2013.

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Metal Nanoparticles for Catalysis: Advances and Applications. Royal Society of Chemistry, The, 2014.

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Tao, Franklin, James Spivey, James Hoefelmeyer, and Agnes Ostafin. Metal Nanoparticles for Catalysis: Advances and Applications. Royal Society of Chemistry, The, 2014.

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Signoretto, Michela, and Federica Menegazzo, eds. Metal Nanoparticles as Catalysts for Green Applications. MDPI, 2022. http://dx.doi.org/10.3390/books978-3-0365-4473-1.

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Jolivet, Jean-Pierre. Metal Oxide Nanostructures Chemistry. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190928117.001.0001.

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This much-anticipated new edition of Jolivet's work builds on the edition published in 2000. It is entirely updated, restructured and increased in content. The book focuses on the formation by techniques of green chemistry of oxide nanoparticles having a technological interest. Jolivet introduces the most recent concepts and modelings such as dynamics of particle growth, ordered aggregation, ionic and electronic interfacial transfers. A general view of the metal hydroxides, oxy-hydroxides and oxides through the periodic table is given, highlighting the influence of the synthesis conditions on crystalline structure, size and morphology of nanoparticles. The formation of aluminum, iron, titanium, manganese and zirconium oxides are specifically studied. These nanomaterials have a special interest in many technological fields such as ceramic powders, catalysis and photocatalysis, colored pigments, polymers, cosmetics and also in some biological or environmental phenomena.

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Ozkar, Saim. Transition Metal Nanoparticle Catalysts in H2 Release from Hydrogen Storage Materials. Elsevier, 2021.

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Creation of New Metal Nanoparticles and Their Hydrogen-Storage and Catalytic Properties. Springer, 2014.

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Kusada, Kohei. Creation of New Metal Nanoparticles and Their Hydrogen-Storage and Catalytic Properties. Springer Japan, 2014.

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Kusada, Kohei. Creation of New Metal Nanoparticles and Their Hydrogen-Storage and Catalytic Properties. Springer Japan, 2016.

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Book chapters on the topic "Metal catalyst nanoparticles"

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Kapil, Nidhi. "Controlled Engineering of Supported Metal Nanoparticles Using Electrospraying: Robust Removal of Stabilising Ligands." In Stable Supported Gold Nanoparticle Catalyst for Environmentally Responsible Propylene Epoxidation, 157–81. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-15066-1_7.

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Akbayrak, Serdar, and Saim Özkar. "Hydrogen Generation from the Hydrolysis of Ammonia Borane Using Transition Metal Nanoparticles as Catalyst." In Hydrogen Production Technologies, 207–30. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2017. http://dx.doi.org/10.1002/9781119283676.ch5.

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Jitsukawa, Koichiro, and Takato Mitsudome. "Metal Nanoparticles for Redox Reactions." In Nanoparticles in Catalysis, 49–75. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/3418_2020_40.

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Vinod, C. P., A. B. Vysakh, and S. Sreedhala. "Model Nanoparticles in Catalysis." In Metal Nanoparticles and Clusters, 165–99. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-68053-8_5.

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Yasukawa, Tomohiro, and Shū Kobayashi. "Chiral Metal Nanoparticles for Asymmetric Catalysis." In Nanoparticles in Catalysis, 279–314. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/3418_2020_39.

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Cortes-Clerget, Margery, Nnamdi Akporji, Balaram S. Takale, Alex Wood, Evan Landstrom, and Bruce H. Lipshutz. "Earth-Abundant and Precious Metal Nanoparticle Catalysis." In Nanoparticles in Catalysis, 77–129. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/3418_2020_36.

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Lanterna, Anabel Estela. "Supported Metal Nanoparticles in Catalysis." In Nanostructured Multifunctional Materials Synthesis, Characterization, Applications and Computational Simulation, 118–36. First edition. | Boca Raton : CRC Press, Taylor & Francis: CRC Press, 2021. http://dx.doi.org/10.1201/9780367822194-6.

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Dhakshinamoorthy, Amarajothi, and Hermenegildo Garcia. "Catalysis by Metal Nanoparticles Encapsulated Within Metal–Organic Frameworks." In Recent Advances in Nanoparticle Catalysis, 221–47. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45823-2_7.

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Devi, Laxmi, Komal, Sunita Kanwar, Kamal Nayan Sharma, Anirban Das, and Jyotirmoy Maity. "Noble Metal Nanoparticles in Organic Catalysis." In Heterogeneous Catalysis in Organic Transformations, 51–78. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003126270-3.

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Palazzolo, A., J. M. Asensio, D. Bouzouita, G. Pieters, S. Tricard, and B. Chaudret. "Metal Nanoparticles for Hydrogen Isotope Exchange." In Recent Advances in Nanoparticle Catalysis, 281–302. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45823-2_9.

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Conference papers on the topic "Metal catalyst nanoparticles"

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Ito, Kyohei, Shuhei Inoue, and Yukihiko Matsumura. "Synthesis of Single-Walled Carbon Nanotube Containing Platinum Group Element." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44257.

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To prepare homogeneous nanoparticles is a key issue for catalytic reaction because it directly connects to the control of the reaction. Using the sidewall of SWCNT as a catalyst supporter, the size of nanoparticle can be controlled, because the particle size should be affected by the interaction between SWCNT and metal species and its curvature. In this study, we focused on the direct synthesis of SWCNT with highly dispersed platinum group metal species. As a result, adding an adequate amount of platinum group metals into catalysts never disturbs the synthesis of SWCNT. Referring to TGA measurement, the presence of metal attached and/or metal involved SWCNT is suggested. Furthermore, SEM images show many nanoparticles are on SWCNT. When ruthenium catalyst is used, ruthenium nanoparticles are observed on the surface of nano carbon materials, which looks like SWCNT. These results indicate the possibility of direct synthesis of metal-containing SWCNT in CVD technique.

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Tomoda, Masahiro, Teppei Kawahara, Yohei Tasaki, Yasuyuki Takata, Makoto Hirasawa, Takafumi Seto, and Masamichi Kohno. "Carbon Nanotube Synthesis From Metal Nanoparticles Size-Classified by a Differential Mobility Analyzer." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44414.

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In this study, carbon nanotubes (CNTs) were synthesized from size-classified catalyst metal nanoparticles to observe the effect of the nanoparticles’ diameter on the diameter of the CNTs. The nanoparticles were generated by laser vaporization and classified by a differential mobility analyzer, which sorts them by diameter according to differences in electrical mobility. After classification, the nanoparticles were collected on a Si substrate. CNTs were synthesized from these catalyst metal nanoparticles by using chemical vapor deposition. This experiment synthesized mainly multi-walled carbon nanotubes (MWNTs), with a small amount of single-walled carbon nanotubes (SWNTs). The reason is thought to be that the particles’ diameters were appropriate for MWNT synthesis.

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Cody, Jonathan W., and Sungwon S. Kim. "Effects of Annealing Parameters on Nickel Catalyst Nanoparticle Size for Carbon Nanotube Synthesis Applications." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65514.

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The properties of carbon nanotubes are dependent, in part, on the size of the catalyst metal nanoparticles from which the carbon nanotubes are grown. Annealing is a common technique for forming the catalyst nanoparticles from deposited films. While there is ample work connecting catalyst film properties or catalyst nanoparticle properties to carbon nanotube growth outcomes, the control of catalyst nanoparticle size by means other than the variation of initial film thickness is less explored. This work develops an empirical correlation for the control of nickel nanoparticle equivalent diameter by modification of anneal plateau temperature and anneal plateau time, thereby providing an additional avenue of control for catalyst properties. It has been hypothesized that the size of catalyst nanoparticles can be predetermined by appropriate selection of the initial catalyst film thickness, plateau temperature, and plateau time of the annealing process. To this end, buffer layers of 50 nm titanium, followed by 20 nm aluminum, were deposited onto silicon substrates via electron beam evaporation. Nickel catalyst layers were then deposited with thicknesses of either 5, 10, or 20 nm. Samples of each of the three nickel layer thicknesses were annealed in an ambient air environment at different combinations of 500, 600, 700, 800, and 900 °C plateau temperature and 5, 10, and 15 minute plateau time. Representative time-temperature curves corresponding to each plateau temperature were also acquired. The end result was a set of 45 samples, each with a unique combination of initial nickel film thickness, anneal plateau temperature, and anneal plateau time. Resulting nanoparticles were characterized by atomic force microscopy, and distributions of nanoparticle equivalent diameter were collected via a watershed algorithm implemented by the Gwyddion software package. Comparison of the 45 parameter combinations revealed a wide range of nanoparticle sizes. In most cases, comparable equivalent diameters were obtained from a variety of parameter combinations. Thus, results provide multiple options for achieving the same nanoparticle diameter, for use in cases where additional restraints are present. To facilitate such decisions, a correlation was developed that connected catalyst nanoparticle diameter to the three process parameters of initial catalyst film thickness, anneal plateau temperature, and anneal plateau time. For example, a given initial Ni film thickness can be annealed to a specified nanoparticle size by selecting anneal plateau temperature and plateau time per the correlation, provided that comparable buffer layers were chosen. This correlation provides a more robust array of options for specification of catalyst nanoparticle size and final carbon nanotube properties for a specific application.

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Riyaz, Najam US Sahar, Karthik Kannan, Aboubakr M. Abdullah, and Kishor Kumar Sadasivuni. "Facile Synthesis of Mesoporous Silica Nanoparticles and its Electrochemical Conversion of CO2 to Fuels." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0094.

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The increasing amount of CO2 emissions from the industries is proving to have disastrous consequences on the environment. It would be highly beneficial if this CO2 is to be recycled and converted into useful fuel. The aim of this project involves synthesizing a suitable catalyst which can be used for the electrochemical (EC) conversion of CO2 to fuel. The developed catalyst should be mesoporous silica nanoparticles and loaded on to a metal oxide surface. The synthesis involved a relatively simple procedure of forming a homogenous mixture for the nanoparticles, drying the mixture for 2 days then loading on to the metal nitrate. Finally, multiple scans and tests were run on the synthesized sample to characterize its qualities. The results show that the synthesized mesoporous silica nanoparticles have suitable catalytic properties for electrochemical reduction of CO2 to fuel.

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Avramenko, Valentin, Vitaly Mayorov, Dmitry Marinin, Alexander Mironenko, Marina Palamarchuk, and Valentin Sergienko. "Macroporous Catalysts for Hydrothermal Oxidation of Metallorganic Complexes at Liquid Radioactive Waste Treatment." In ASME 2010 13th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2010. http://dx.doi.org/10.1115/icem2010-40186.

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One of the main problems of liquid radioactive waste (LRW) management is concerned with treatment of decontamination waters containing organic ligands. The organic ligands like oxalic, citric and ethylenediaminetetraacetic acids form stable complexes with radionuclides which puts restrictions on application of many technologies of LRW management. One of the ways of destruction of metallorganic complexes consists in using the catalytic oxidation. However, the heterophase catalytic oxidation is rather problematic due to formation of metal oxides on the catalyst surface and calmatation of meso- and micropores. A possible solution of the above problem can be found in synthesis of macroporous catalysts for oxidation having a regular macroporous structure. The present paper describes the template synthesis of macroporous metalloxide catalysts performed with using siloxane-acrylate microemulsions as templates. The method for impregnation of precious metals (PM) particles into the template, which enables one to produce PM nanoparticles of a specific size and immobilize them in the porous structure of the synthesized metalloxide catalysts, is presented. A possible mechanism of the synthesis of macroporous catalysts is suggested and the comparison of the electronic and photon-correlation spectroscopy results obtained at different stages of catalysts synthesis was conducted.

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Riupassa, Helen, Nevada JM Nanulaitta, Herman Tj Taba, Basri Katjo, Jusuf Haurissa, Trismawati, and Hendry Y. Nanlohy. "The effect of graphene oxide nanoparticles as a metal based catalyst on the ignition characteristics of waste plastic oil." In THE 4TH INTERNATIONAL CONFERENCE ON MATERIALS ENGINEERING AND NANOTECHNOLOGY (ICMEN 2021). AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0075009.

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Titinchi, Salam J. J., Waheed Saban, Leslie Petrik, and Hanna S. Abbo. "Synthesis, Characterization and Physiochemical Properties of Platinum Supported on Mesoporous Carbon." In ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54670.

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Ordered mesoporous carbon (OMC) has been prepared by impregnating the pores of the silica template (SBA-15) with liquid petroleum gas (LPG) or sucrose. The desired support (OMC) was obtained after dissolution with NaOH. Platinum nanoparticles were dispersed on ordered mesoporous carbons using Chemical Vapour Deposition (CVD) method and Pt(acac)2 as metal source. The resulting ordered mesoporous carbon possess a large surface area with high microporosity, and a controlled pore size distribution, High-quality carbon replicas of SBA-15 show an X-ray diffraction peak at low angle, which indicates that the structural periodicity of the (111) planes has been maintained. Their pore volume and specific surface area are high and the pore volume is almost entirely microporous. The synthesized Pt/OMC was characterized by powder X-Ray diffraction, HR-TEM, HR-SEM, EDS, thermogravimetric analysis, and nitrogen adsorption. The performance of Pt catalyst supported OMC was evaluated by electrochemical studies, which shows almost similar activity to the commercial catalyst.

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Yadav, Anil Kumar, Malleboina Purushotham, Nikita Indrapalsingh Gour, Gaurav Gulab Gurnule, Vikas C. Choudhary, and Karm Raj Yadav. "Brief Review on Nanotechnology as an Effective Tool for Production of Biofuels." In International Conference on Recent Advancements in Biomedical Engineering. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/p-bdzjch.

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Bio-fuel is world's best substitutes to petroleum fuels, particularly in developing countries, especially in present situation, in which fossil fuels are rapidly decreasing. By emitting greenhouse gases when fossil-based fuels are burned, they pose a serious danger to the environment and human health. Bio-fuel production on a large scale requires longer time and activity due to many constraints in currently available technology and supplementary increased costs. Furthermore, depending on the techniques and materials used, the procedures used to convert diverse feed stocks to the intended output are varied. Nanoparticles (NPs) are one of the most versatile materials in terms of time management, energy efficiency, and selectivity. It is the best way to address the issues of biomass usage. Lots of technology has implemented based on nanoparticles includes metal oxide and magnetic oxides, are engaged to progress bio-fuel production. NPs are useful biofuel additives because of their stability, higher surface area, reusability and catalytic activity. Furthermore, nanomaterials include carbon nanofibers, nanosheets and carbon nanotubes have been discovered to be a stable catalyst for enzyme immobilisation, resulting in improved bio-fuel production. The current research provides a thorough examination of the utilisation of different nanocomposites for bio-fuel production, as well as the significant hurdles and potential prospects.

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Tsakalakos, Loucas, Lauraine Denault, Michael Larsen, Mohamed Rahmane, Yan Gao, Joleyn Balch, and Paul Wilson. "Mo2C Nanowires and Ribbons on Si via Two-Step Vapor Phase Growth." In ASME 2004 3rd Integrated Nanosystems Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/nano2004-46098.

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Transition metal carbides are an interesting class of electronic materials owing to their high electrical conductivity at room temperature, which is only slightly lower than that of their constituent transition metal elements. For example, the room temperature electrical resistivity of bulk Mo2C is ∼70 μΩ-cm compared to that of Mo (4.85 μΩ-cm), whereas that of NbC is ∼50 μΩ-cm as compared to 15.2 μΩ-cm for Nb. Indeed, the temperature dependent resistivity of many transition metal carbides suggests metallic-like conduction. Furthermore, certain transition metal carbides are known to become superconducting, with transition temperatures ranging from 1.15 °K for TiC1−x to 14 °K for NbC. [1] They are also able to withstand high temperatures and are chemically stable. Initial synthesis of metal carbide nanorods was demonstrated using the carbon nanotube (CNT) confined reaction mechanism by Lieber and co-workers [2] and subsequent superconducting behavior was shown by Fukunaga et al. [3]. Vapor-liquid-solid growth was employed by Johnson et al. [4] to synthesize micron-sized carbide whiskers. Here, we have successfully synthesized Mo2C nanorods and ribbons on Si substrates using a novel two-step catalytic approach, which allows for synthesis of such high temperature nanostructures at manufacturable temperatures (≤ 1000 °C) and time scales (≤ 60 min). In the first step we utilize a catalytic vapor phase process to grow Mo and/or molybdenum oxide nanostructures, which are subsequently carburized in situ to form the desired Mo2C nanostructures. Unlike true VLS growth of carbides, in which high temperature (≤ 1100–1200 °C) is required to adequately dissolve carbon into the catalyst particles, our strategy is to react the nanostructures along their entire length with a carbon vapor source after creating the oxide/metal nanostructures, which for Mo2C can be achieved at relatively low temperatures. (≤ 1000 °C). The nanorods and ribbons are polycrystalline, with a mean grain size of 20–50 nm and 50–150 nm, respectively. We hypothesize that the growth mechanism is a complex mixture of VLS, VSS, and auto-catalytic growth, in which molten catalyst nanoparticles enter a three phase region once the metal precursor is supplied. The growth then presumably continues via a vapor-solid-solid process and is possible assisted by the presence of various molybdenum oxide species on the surface. Initial single nanowire electrical measurements yield a higher resistivity than in the bulk, which is attributed to the fine grain sizes and/or the presence of an oxide layer. A discussion of the growth mechanism will be presented along with issues relating to single nanowire device fabrication and control of nanowire orientation.

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Rossi, Liane M., Tiago A. G. Silva, Erico Teixeira-Neto, and Núria Lopez. "Catalytic oxidations by metal nanoparticles: Pd, Au and AuPd core-shell nanoparticle catalysts." In 15th Brazilian Meeting on Organic Synthesis. São Paulo: Editora Edgard Blücher, 2013. http://dx.doi.org/10.5151/chempro-15bmos-speech8.

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Reports on the topic "Metal catalyst nanoparticles"

1

Musselwhite, Nathan. The Catalysis of Uniform Metal Nanoparticles Deposited onto Oxide Supports: The Components of a Catalyst that Control Activity and Selectivity. Office of Scientific and Technical Information (OSTI), May 2015. http://dx.doi.org/10.2172/1469158.

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Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova, and Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604286.bard.

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The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.

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Kliewer, Christopher J. In-situ Studies of the Reactions of Bifunctional and Heterocyclic Molecules over Noble Metal Single Crystal and Nanoparticle Catalysts Studied with Kinetics and Sum-Frequency Generation Vibrational Spectroscopy. Office of Scientific and Technical Information (OSTI), June 2009. http://dx.doi.org/10.2172/973607.

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