Metal Oxide Nanofibers As Filters Catalyst And Catalyst Support Structures
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Metal Oxide Nanofibers As Filters Catalyst And Catalyst Support Structures
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Author : Sneha Swaminathan
language : en
Publisher:
Release Date : 2010
Metal Oxide Nanofibers As Filters Catalyst And Catalyst Support Structures written by Sneha Swaminathan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Automobiles categories.
For environmental protection, the suppression of automotive exhausts such as nitrogen oxides (NOx) and carbon monoxide (CO) is very important. These gases are potential health hazards and green house gases. Burning of hydrocarbon (HC) ideally leads to the formation of water and carbon dioxide; however, due to incomplete combustion and temperatures fluctuations reached in the combustion chamber, the exhaust contains significant amounts of pollutants which need to be transformed into harmless compounds. Hence this concern triggered the need for stringent environmental regulations which resulted in the introduction of catalytic devices in automobiles. Traditionally, the catalyst is impregnated onto a porous substrate. The limitation of this method is the difficulty involved in controlling the catalyst particle size during the sintering or reduction steps that result in high temperature agglomeration effects. In the present work, a novel approach has been developed wherein the noble metal nanocatalysts have been incorporated on ceramic nanofibers by the electrospinning process. The catalysts on ceramic nanofibers increase the overall exposed catalyst area and simultaneously immobilize the catalyst to minimize catalyst loss. A small amount of the catalyst incorporated into ceramic nanofibers was mixed with microfibers to fabricate a filter disk by vacuum molding technique. This filter disk termed as 'catalytic filter' is a combination of catalytic elements and filter. The catalyzed ceramic nanofiber augmented microfiber filter media can be used for two applications: reduction of NOx and oxidation of CO and for enhanced particulate removal. This filter would include advantages such as light weight structure, optimization of precious metals, high capture efficiency, high surface area, highly interconnected network of pores and high permeability. The key aspects in this dissertation can be divided into six parts: fabrication of catalytic filters and their optimization, fabrication of three-way catalysts and oxygen storage catalysts, crosslinking of nanofibers as an intermediate step to ceramic nanofiber manufacture, comparison of catalytic filter with the traditional methods and conventional catalytic converter, particle size reduction and studying the deactivation using water and H2S. All the types of catalytic filter which were fabricated were successful in reducing NO and oxidizing CO completely. The degradation temperature of NO and CO depended on the type, amount and loading of the catalyst nanoparticles on the alumina nanofiber.
Metal Oxide Based Nanofibers And Their Applications
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Author : Vincenzo Esposito
language : en
Publisher: Elsevier
Release Date : 2021-10-25
Metal Oxide Based Nanofibers And Their Applications written by Vincenzo Esposito and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-10-25 with Technology & Engineering categories.
Metal Oxide-based Nanofibers and their Applications provides an in-depth overview on developments surrounding the synthesis, characterization properties, and applications achieved by scientific leaders in the area. Sections deal with the theoretical and experimental aspects of the synthesis and methodologies to control microstructure, composition and shape of the nanofibrous metal oxides, review the applications of metal oxide nanofibers in diverse technologies, with special focus on the relation between the structural, morphological and compositional features of the nanofibers, cover applications of metal oxide nanofibers in the fields of sensing (biosensing, gas sensing), and consider biomedical and cleaning technologies. Lastly, a final section covers their application in energy generation and storage technologies (e. g. piezoelectric, solar cells, solid oxide fuel cells, lithium-ion batteries, supercapacitors, and hydrogen storage are reviewed. Reviews electrospinning methods for the synthesis and design of nanocomposites and hybrid metal oxide nanofibers Discusses applications of metal oxide nanofibers in sensing, biomedical fields, cleaning technologies, and energy Emphasizes the structural, morphological and compositional properties of nanofibers and their effect on device performance
Functional Nanofibers And Their Applications
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Author : Q Wei
language : en
Publisher: Elsevier
Release Date : 2012-05-24
Functional Nanofibers And Their Applications written by Q Wei and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-05-24 with Technology & Engineering categories.
Nanofibers are a flexible material with a huge range of potential applications in such areas as technical textiles. Functional nanofibers and their applications summarises key trends in the processing and applications of these exciting materials. Part one focuses on the types and processing of nanofibers. Beginning with an overview of the principles and techniques involved in their production, it goes on to review core-shell, aligned, porous and gradient nanofibers. The processing and application of composite functional nanofibers, carbon and polymer nanofiber reinforcements in polymer matrix composites, and inorganic functional nanofibers are then explored in detail, before part one concludes with a consideration of surface functionalization. A wide variety of functional nanofiber applications are then reviewed in part two. Following consideration of their use in filtration, drug delivery and tissue engineering applications, the role of functional nanofibers in lithium-ion batteries, sensor applications, protective clothing, food processing and water purification is explored. Discussion of their use in sound absorption, electromagnetic wave attenuation and biomedical and microelectronic applications follows, before a final discussion of future trends. With its distinguished editor and international team of expert contributors, Functional nanofibers and applications is a key text for all those working in the fields of technical textiles, as well as areas using nanofibers such as composites, biomaterials and microelectronics. Summarises key trends in the processing and applications of functional nanofibres in areas such as technical textiles Provides an overview of the principles and techniques involved in the production of nanofibres and reviews core-shell, aligned, porous and gradient nanofibres Considers the use of nanofibres in filtration, drug delivery and tissue engineering applications and the role of functional nanofibres in lithium-ion batteries, sensor applications, protective clothing, food processing and water purification
Metal Oxide Nanostructures From Electrospun Carbon Templates
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Author : Dickson Andala
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2012-03
Metal Oxide Nanostructures From Electrospun Carbon Templates written by Dickson Andala and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-03 with categories.
The work covered herein discusses for the first time various techniques used in the fabrication of metal oxide nanofibers and nanotubes from eletrospun carbon fibers as templates. The nanofibers were prepared by electrospinning metal oxide precursor inside a polymer matrix. The metal oxide tubes were by tubes by fiber templating. This was followed by calcination to yield the nanofibers and nanotubes. Their morphological, structural, optoelectronic and catalytic properties are also discussed. Among key applications they have found utilization as catalyst supports. Palladium nanoparticles have been supported on Titanium dioxide nanofibers and applied in Heck-coupling reactions. Similarly, included is the effect of impurities on the metal oxide tubes properties done by doping with metal ions. In addition, photocatalytic behavior of metal oxides nanofibers have also been discussed.
Metal Oxide Nanofiber Catalysis
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Author : Daniel Patrick Noon
language : en
Publisher:
Release Date : 2015
Metal Oxide Nanofiber Catalysis written by Daniel Patrick Noon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The synthesis of solids with finely turned nanostructures that offer superior catalytic performance is a major challenge in heterogeneous catalysis for gas phase reactions. Industrial catalysts are almost universally composed of quasi-spherical nanoparticles, or powders plagued with particle agglomeration, migration and sintering problems that lead to deactivation. In this work, quasi-cylindrical nanofibers are electrospun and extensively utilized for the oxidative coupling of methane (OCM), as well as for propylene epoxidation and the catalytic partial oxidation (CPO) of methane. Electrospun nanofibers of metal oxides may be tuned to have high surface areas but typically possess no internal porosity, reducing diffusion limitations that would lengthen the exposure of target intermediate oxidation products to unselective catalysis. Additionally, experiments and density functional theory (DFT) studies have previously shown that pentagonal Ag nanowires exhibit higher selectivity than conventional particles in ethylene epoxidation since their surfaces are terminated mainly by the (100) surface facet rather than the lowest energy (111) facet that dominates particles. Hence, nanofibers may elevate catalytic performance in broad range of partial oxidation reaction schemes. Research into the oxidative coupling of methane, or, the catalytic conversion of methane to ethane and ethylene by molecular oxygen, almost exclusively utilized powders and failed to result in viable catalyst despite four decades of intense, global efforts. Accordingly, the use of catalytic nanofibers provides a potentially fruitful path towards a solution. Here, nanofiber fabrics of La2O3-CeO2 were electrospun and used in fixed bed OCM reactors to achieve 70% selectivity and 16% yield for C2+ hydrocarbons at a CH4/O2 feed ratio of 7 and remarkably low feed temperature of 470 ?C. Powders of La2O3-CeO2 documented in the literature exhibit similar selectivity and yield, but with the feed at 715 ?C. The electrospun fabrics used in this research were found to have dense nanofibers of diameters typically within the 20 - 200 nm range and, accordingly, surface areas of 10 - 20 m2/g as well as thinner fibers tending towards both higher C2+ selectivity and CH4 conversion. While performing reaction engineering studies using the aforementioned fabrics, it was found that designing reactors comprising dual catalytic La2O3-CeO2 fabric beds with inter-stage O2 injection and cooling pushes yields to 21%. Moreover, a novel in-situ microprobe sampling technique for acquiring spatial temperature and concentration profiles within these OCM reactors was developed, providing a means to formulate and validate detailed chemical kinetic mechanisms. This has led to the discovery of prompt H2 formation in OCM, a feature previously unidentified that may break ground in mechanism refinement. Additionally, spatial concentration and temperature profiles were acquired in fixed bed reactors comprising La2O3-CeO2 fabrics doped with varying levels of Ir and fed CH4/O2 mixtures to gain insight into the transition from OCM to the catalytic partial oxidation of methane. It was found that, in general, OCM and CPO appear to occur both in parallel and sequentially in a fixed bed, evidenced by the temporary rise and subsequent destruction of C2+ hydrocarbons when the catalyst is doped with 0.05 wt% Ir. Clearly, this sampling technique has broad applicability in catalysis research over a limitless number of reactions for the acquisition of comprehensive data sets potentially useful for formulating and refining detailed chemical kinetic mechanisms (DCKM), thus furthering a fundamental understanding of the catalysis and advancing faster towards the development of higher performing materials.
Catalytic Nanofiber Media For Air And Hot Gas Filtration
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Author : Sneha Swaminathan
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2013
Catalytic Nanofiber Media For Air And Hot Gas Filtration written by Sneha Swaminathan and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
For environmental protection, the suppression of automotive exhausts such as nitrogen oxides and carbon monoxide is very important. These gases are potential health hazards and green house gases. Hence this concern triggered the need for stringent environmental regulations which resulted in the introduction of catalytic devices in automobiles. In this book, a novel approach has been developed wherein the noble metal nanocatalysts have been incorporated on ceramic nanofibers by the electrospinning process. The catalysts on ceramic nanofibers increase the overall exposed catalyst area and simultaneously immobilize the catalyst to minimize catalyst loss. A small amount of the catalyst incorporated into ceramic nanofibers was mixed with microfibers to fabricate a filter disk by vacuum molding. This filter disk termed as 'catalytic filter'is a combination of catalytic elements and filter. The catalyzed ceramic nanofiber augmented microfiber filter media can be used for two applications: reduction of NOx and oxidation of CO and for enhanced particulate removal.
Novel Catalytic Applications Of Carbon Nanofibers On Sintered Metal Fibers Filters As Structured Supports
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Author : Marina Ruta
language : en
Publisher:
Release Date : 2008
Novel Catalytic Applications Of Carbon Nanofibers On Sintered Metal Fibers Filters As Structured Supports written by Marina Ruta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
Metal Metal Oxide Nanoparticles Supported On Nanostructured Carbons For Electrochemical Applications
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Author : 杨纯臻
language : en
Publisher:
Release Date : 2017-01-26
Metal Metal Oxide Nanoparticles Supported On Nanostructured Carbons For Electrochemical Applications written by 杨纯臻 and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-26 with categories.
This dissertation, "Metal/metal oxide nanoparticles supported on nanostructured carbons for electrochemical applications" by 杨纯臻, Chunzhen, Yang, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Among various electrochemical devices that have been developed for energy storage and conversion, electric double layer capacitors (EDLCs) and direct methanol fuel cells (DMFC) have received much research attention. Nanostructured carbon materials have been playing an important role in the development of these devices, due to such characteristics as good electrical conductivity, high chemical stability, high surface area and large pore volumes and etc. In an EDLC, nanostructured carbon electrodes, possessing pores of varied length scales, can deliver electric energy at high current loadings. This kind of pore structure also benefits the deposition of metal catalysts and the transport of reactants and products in the methanol oxidation reaction. In order to systematically study the structural effects on the electrochemical capacitance and ionic transport, a series of three-dimensional hierarchical carbons with hollow core-mesoporous shell (HCMS) structure were template-synthesized. Periodically ordered macroscopic hollow cores of 330 nm in diameter were surrounded by a mesoporous shell containing uniform pores of 3.9 nm. The shell thickness was stepwise increased from 0, 25, 50 to 100 nm. The HCMS structure was modeled by a 5-level transmission line model to study the capacitance contribution from the pores at different length scale. Results revealed that the HCMS carbon with thicker mesoporous shells can provide high capacitance, while thinner shells could deliver high power output. A series of HCMS carbon sphere supported Pt nanoparticles were synthesized via the "Carbonization over Protected and Dispersed Metal" (CPDM) method. Contrary to the conventional "polyol" synthetic method, whereas most of Pt nanoparticles were deposited on the external surface of carbon spheres; the Pt nanoparticles synthesized via the CPDM method were found encapsulated in the mesoporous carbon shells and highly dispersed throughout the carbon texture. "Accelerated stress tests‟ (ASTs) were conducted to investigate the nanopores confinement effect toward the electrochemical stability of these Pt catalysts. Results revealed that (1) the nanopores confined Pt nanoparticles on HCMS carbon spheres exhibited a stable electrochemical active surface area (ECSA) and catalytic activity; and (2) thick mesoporous carbon shells could provide better protection over the Pt nanoparticles. This "CPDM" method was further extended to synthesize highly alloyed PtRu nanoparticles supported electrocatalysts. It is expected that this CPDM method can also be applied to synthesize other metal/metal oxide supported catalysts with stable electrochemical performance. WO3 has been demonstrated as a promsing co-catalyst for Pt in the methanol oxidation reaction (MOR). The synthesis of Pt-WO3/C catalyst with well-controlled nanoparticle size (2.5 nm) and composition was achieved via a microwave-assisted water-oil microemulsion reaction. Hydrogen adsorption, CO-stripping and Cu- stripping methods were used to estimate the ECSA of Pt in the Pt-WO3/C catalysts. Among these, Cu-stripping method was relatively more reliable due to the overlapping involvement of the WO3 component in the other methods. The methanol oxidation measurement shows that a 1:1 Pt: W ratio catalyst exhibits the highest Pt-mass current density of 271 mA mg-1-Pt, 1.4 times higher than that of commercial E-TEK catalyst.
Electrospun Nanofiber Metal Oxides For Reactive Sorption And Catalysis
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Author : Faisal Alshafei
language : en
Publisher:
Release Date : 2018
Electrospun Nanofiber Metal Oxides For Reactive Sorption And Catalysis written by Faisal Alshafei and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Electrospun metal oxides is a new class of materials that have demonstrated auspicious potential and have been used in a wide range of applications. In this work, various smooth, continuous, and defect-controlled metal-polymer nanofibers were synthesized via electrospinning with diameters ranging from approximately 50 to 600 nm, and subsequently thermally treated to decompose the polymer (PVP or PEO) and form highly porous, fibrous metal (Cu-, Ni-, Mg-, and Ca-) oxide nanostructures. In the first part of this thesis, parameters that influence the electrospinning process were systematically investigated for PVP-Cu(NO3)2 systems. Both solution properties (polymer/metal concentration, polymer molecular weight, and solvent identity) and processing conditions (applied voltage, tip-of-needle to collector distance, extrusion rate, and humidity) were varied to probe the effect of these electrospinning factors on fiber quality prior to thermal treatment. The data collected demonstrated that factors that do not directly and strongly influence viscosity, conductivity and solvent evaporation (e.g., applied voltage, extrusion rate, and tip-of-needle to collecting plate distance) do not have substantial effects on fiber diameter and morphology. Subsequent thermal treatment of the electrospun nanofibers and choice of metal, however, were found to markedly impact the morphology of the formed fiber oxides (e.g., string-like structures or segmented particles). In the second part of this thesis, electrospun fiber metal oxide materials were tested in two main applications (high temperature CO2 removal and low-temperature H2S removal) and their performance was compared to materials prepared via traditional synthesis routes (e.g., sol-gel, co-precipitation, hydrothermal treatment, etc.) In the first application, CaO-based materials were tested as potential sorbents in sorption enhanced steam methane reforming (SE-SMR) to capture CO2 and shift the reaction towards producing more hydrogen. The electrospun CaO-nanofibers, when reacted with CO2, achieved complete conversion to CaCO3 and had an initial CO2 sorption capacity of 0.79gCO2/gsorbent at 873 K and 923 K (highest of all materials tested), as the macro-porosity imparted by the electrospinning process improved the CO2 diffusion through the CaCO3 product layers. Furthermore, when these electrospun sorbents were added to a commercial catalyst and tested in SE-SMR conditions, they had three to four times longer breakthrough times than CaO sorbents derived from natural sources (e.g., CaO-marble). To further improve the stability of CaO-based sorbents, chemical doping of Ca-supports with Mg, Al, Y, La, Zn, Er, Ga, Li, Nd, In, and Co was combined with electrospinning to yield mixed oxide materials with high sorption capacities (~0.4-0.7 gCO2/gsorbent) and improved durability (up to 17 cycles). It was demonstrated that metals that have high Tammann temperatures were effective at reducing sintering and CaO particle agglomeration by acting as spacers, thus, retaining the sorbent's initial sorption capacity upon repeated cycling. In the second application, CuO nanofibers with varying diameters (~70-650 nm) were prepared from two polymers (PEO and PVP) and reacted with H2S at ambient conditions to form CuS. The results from this study demonstrated that the sulfur removal capacity of CuO materials, whether prepared via electrospinning, hydrothermal treatment, sol-gel or co-precipitation, was strongly dependent on crystallite size (a linear relationship was established between CuO removal capacity and crystallite size and held true for all CuO materials with crystallites between 5-26 nm) and CuO purity (i.e., presence of residual carbon on the surface of the oxide). Indeed, properties such as surface area, pore volume and morphology (e.g., flowerlike, fiber-like, belt-like, etc.) were found to have an insignificant impact on removal capacity. This work offers fundamental insights into the design of multifunctional and highly porous metal oxide nanofibers for sorptive and catalytic applications.
Carbon And Oxide Nanostructures
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Author : Noorhana Yahya
language : en
Publisher: Springer Science & Business Media
Release Date : 2011-01-12
Carbon And Oxide Nanostructures written by Noorhana Yahya and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-01-12 with Technology & Engineering categories.
This volume covers all aspects of carbon and oxide based nanostructured materials. The topics include synthesis, characterization and application of carbon-based namely carbon nanotubes, carbon nanofibres, fullerenes, carbon filled composites etc. In addition, metal oxides namely, ZnO, TiO2, Fe2O3, ferrites, garnets etc., for various applications like sensors, solar cells, transformers, antennas, catalysts, batteries, lubricants, are presented. The book also includes the modeling of oxide and carbon based nanomaterials. The book covers the topics: Synthesis, characterization and application of carbon nanotubes, carbon nanofibres, fullerenes Synthesis, characterization and application of oxide based nanomaterials. Nanostructured magnetic and electric materials and their applications. Nanostructured materials for petro-chemical industry. Oxide and carbon based thin films for electronics and sustainable energy. Theory, calculations and modeling of nanostructured materials.