Academic literature on the topic 'CNF catalyst'
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Journal articles on the topic "CNF catalyst"
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Liu, Sichen, Víctor Frutos, María Ariadna Álvarez-Montero, Luisa María Gómez-Sainero, Juan José Rodriguez, and Maria Martin-Martinez. "Influence of Surface Chemistry of Carbon Nanofibers on the Hydrodechlorination of Chloroform to Olefins." Catalysts 12, no. 10 (September 21, 2022): 1084. http://dx.doi.org/10.3390/catal12101084.
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Functionalized carbon nanofibers (CNF) are fascinating materials to be used as supports in Pd-based catalysts for the treatment of waste chloroform (TCM) to produce light olefins through the catalytic hydrodechlorination (HDC). The CNF were functionalized by HNO3, HCl, and urea. Compared to the Pd supported on un-treated CNF, all the catalysts using functionalized CNF as support showed lower turnover frequency values with higher stability, owing to their smaller Pd nanoparticles (NPs). These smaller Pd NPs are formed due to the stronger metal–support interactions promoted by the higher concentration of surface groups on the functionalized catalysts. Since the smaller Pd NPs could hinder the hydrogenation of olefins to paraffins, the selectivity to olefins increased on the functionalized catalysts. Moreover, the N-doped CNF was successfully formed on the catalyst functionalized by urea. Since the nitrogen functional groups (pyridinic N and pyrrolic N) could provide much stronger metal–support interactions compared to the oxygen functional groups on the other catalysts, the catalyst functionalized by urea showed the smallest Pd NPs among the four catalysts, leading to the highest selectivity to light olefins.
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Din, Israf Ud, Maizatul Shima Shaharun, Duvvuri Subbarao, and A. Naeem. "Synthesis, Characterization and Activity Pattern of Carbon Nanofibres Based Cu-ZrO2 Catalyst in the Hydrogenation of Carbon Dioxide to Methanol." Advanced Materials Research 925 (April 2014): 349–53. http://dx.doi.org/10.4028/www.scientific.net/amr.925.349.
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Carbon nanofibers based Cu-ZrO2 catalysts (Cu-ZrO2/CNF) were synthesized by deposition precipitation method. Carbon nanofibers of herringbone type were used as a catalyst support. Before using as catalyst support, carbon nanofibers were oxidized to (CNF-O) with 10 % (v/v) nitric acid solution. A series of catalyst with various copper loadings of 10, 15 and 20 wt% were synthesized. X-ray diffraction (XRD) study revealed that degree of crystallization of catalyst increase with increasing the concentration of copper content in the catalyst. BET studies showed higher surface area for low loading of copper. Temperature-Programmed Reduction (TPR) analyses concluded good interaction of catalyst particles with higher loading of copper. The performance of Cu-ZrO2/CNF catalysts in hydrogenation of CO2 reaction was studied in slurry-typed reactor at 443 K, 30 bar and H2: CO2 ratio of 3:1. The highest yield of methanol was achieved using the 20 wt% copper loading.
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Hesterberg Butzlaff, Ashley, Sattar Alsaedi, Jacob Fields, David Cwiertny, and Syed Mubeen Jawahar Hussaini. "Implementing Catalysts into Electrospun Composite Carbon Nanofiber (CNF) Electrodes for Ammonia Production from Photoelectrocatalytic Nitrate Reduction." ECS Meeting Abstracts MA2022-01, no. 40 (July 7, 2022): 1805. http://dx.doi.org/10.1149/ma2022-01401805mtgabs.
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While novel carbon nanomaterials can serve as electrodes with exceptional electrical properties, carbon nanofibers (CNFs) merit further investigation for applications as electrodes in environmentally-relevant photoelectrocatalysis. Tunable, durable CNF structures can be easily synthesized as a convenient framework for catalyst implementation. Herein we investigate how catalysts can be integrated into carbon nanofiber mats to enhance the photoelectrocatalysis of nitrate reduction. As a frequent contaminant in agriculturally-intensive regions, the negative value of nitrate containing streams may be used to produce ammonia as a value-added product and to improve water quality in the resulting output stream. Catalysts were implemented using different methods (in situ sol gel, chemical reduction, electrochemical) on two different CNF composites (with and without titanium dioxide). We focus on copper as a catalyst due to its promising performance and economic advantage over traditional platinum group metals. After thorough characterization of the catalyst-CNF frameworks via XPS, XRD, Raman, the catalyst performance was measured by nitrate reduction product selectivity, catalyst lifetime, and Faradaic efficiency. The flexibility of CNF synthesis and catalyst implementation will provide photoelectrodes with properties desirable for the electrochemical reduction of nitrate in environmental conditions to generate valuable products. This work will help identify the types and properties of next-generation carbon composite electrode materials that are most promising for resource recovery and for improving photoelectrochemical catalytic cells purposed for drinking water treatment.
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Souza Macedo, Luana, Victor Teixeira da Silva, and Johannes Bitter. "Activated Carbon, Carbon Nanofibers and Carbon-Covered Alumina as Support for W2C in Stearic Acid Hydrodeoxygenation." ChemEngineering 3, no. 1 (March 5, 2019): 24. http://dx.doi.org/10.3390/chemengineering3010024.
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Carbon materials play a crucial role in sorbents and heterogeneous catalysis and are widely used as catalyst support for several reactions. This paper reports on an investigation of tungsten carbide (W2C) catalyst on three types of carbon support, namely activated carbon (AC), carbon nanofibers (CNF) and carbon-covered alumina (CCA). We evaluated their activity and selectivity in stearic acid hydrodeoxygenation at 350 °C and 30 bar H2. Although all three W2C catalysts displayed similar intrinsic catalytic activities, the support did influence product distribution. At low conversions (<5%), W2C/AC yielded the highest amount of oxygenates relative to W2C/CNF and W2C/CCA. This suggests that the conversion of oxygenates into hydrocarbons is more difficult over W2C/AC than over W2C/CNF and W2C/CCA, which we relate to the lower acidity and smaller pore size of W2C/AC. The support also had an influence on the C18-unsaturated/C18-saturated ratio. At conversions below 30%, W2C/CNF presented the highest C18-unsaturated/C18-saturated ratio in product distribution, which we attribute to the higher mesopore volume of CNF. However, at higher conversions (>50%), W2C/CCA presented the highest C18-unsaturated/C18-saturated ratio in product distribution, which appears to be linked to W2C/CCA having the highest ratio of acid/metallic sites.
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Parveen, Nazish, Thi Hiep Han, Sajid Ali Ansari, and Moonyong Lee. "Sustainable Bio-Energy Production in Microbial Fuel Cell Using MnO2 Nanoparticle-Decorated Hollow Carbon Nanofibers as Active Cathode Materials." Journal of Nanoelectronics and Optoelectronics 16, no. 2 (February 1, 2021): 127–35. http://dx.doi.org/10.1166/jno.2021.2926.
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The widespread use of renewable energy remains a challenging and complex multidisciplinary problem. Developing alternatives using new technology such as nanotechnology is necessary to increase renewable energy’s scalability. Microbial fuel cells (MFCs) combined with nanotechnology can improve bioelectricity generation during wastewater treatment. In this study, hollow carbon nanofibers (H-CNF) were decorated with manganese oxide (MnO2) via a simple chemical reduction method. MnO2-decorated H-CNF prepared with varying concentrations of manganese precursor (MnO2@H-CNF) were characterized via different spectroscopic and microscopic techniques. The cathode catalyst performance of the MnO2@H-CNF was investigated in an //-type constructed MFC system using Shewanella Oneidensis MR1. The MnO2@H-CNF-1 in the assembled MFC displayed excellent power density of 25.7 mW/m2, which is higher than pure H-CNF (8.66 mW/m2), carbon cloth (5.10 mW/m2), and MnO2@H-CNF-3 (16 mW/m2). The maximum power generated in the MFC coupled with MnO2@H-CNF as a cathode catalyst may have been due to the synergistic effect of the MnO2@H-CNF, which increased the electric conductivity and catalytic activity in the MFC’s cathode chamber. These results demonstrate that the developed MnO2@H-CNF cathode catalyst could improve the MFC’s performance and reduce the operational costs of practical applications.
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Alcázar, Hermann E., Emilio Chire, María M. Vargas, Bryan L. Villagarcía, John Neira, Andre Contin, and Leopoldo O. Alcázar. "Production and characterization of carbon nanotubes by methane decomposition over Ni–Fe/Al2O3 catalyst and its application as nanofillers in polypropylene matrix." Materials Research Express 8, no. 11 (November 1, 2021): 115001. http://dx.doi.org/10.1088/2053-1591/ac327b.
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Abstract This paper studies the influence of metal precursors in the CVD´s catalyst synthesis of carbon nanotubes (CNTs) used as fillers in a polypropylene (PP) matrix (∼0.3 wt%). Two catalytic schemes, Fe/Al2O3 (50:50) and Ni–Fe/Al2O3 (40:10:50), were prepared to determine the influence of the reduction temperature over the characteristics and mechanical properties of CNT as PP fillers. The conversion temperature was varied to see the dependance of the CNT structure to this variable (700 °C–750 °C–800 °C). CNTs products were characterized by SEM and Raman spectroscopy. The SEM micrographs showed a sharper fiber type CNTs for the bimetallic catalyst and the Raman confirmed that better crystallites are obtain over the Fe catalyst. The Fe–PP composite presented enhanced mechanical properties when compare with Fe–Ni–PP, with tensile strength, hardness, and impact properties are higher in 16%, 9%, and 9% respectively. Other carbonaceous materials, as CNF, with less crystallinity presented poorer mechanical properties. Finally, can be stated that for the use of CNF as fillers in PP composites a Fe/Al2O3 catalyst, and a reaction temperature 700 °C–750 °C will produce a CNF with 60 nm mean diameter, is better than the use of Fe-Ni based catalysts.
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Luo, Mingsheng, Shuo Li, Zuoxing Di, He Li, Qinglong Liu, Baozhong Lü, Aimei Wang, Buchang Shi, and Iltaf Khan. "Fischer–Tropsch Synthesis: Study of Different Carbon Materials as Cobalt Catalyst Support." Reactions 2, no. 1 (March 10, 2021): 43–61. http://dx.doi.org/10.3390/reactions2010005.
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In this work, cobalt Fischer–Tropsch synthesis (FTS) catalyst supported on various carbon materials, i.e., carbon nanotube (CNT), activated carbon (AC), graphene oxide (GO), reduced graphene oxide (rGO), and carbon nanofiber (CNF), were prepared via impregnation method. Based on TGA, nitrogen physisorption, XRD, Raman spectroscopy, H2-TPR, NH3-TPD, ICP, SEM, and TEM characterization, it is confirmed that Co3O4 particles are dispersed uniformly on the supports of carbon nanotube, activated carbon and carbon nanofiber. Furthermore, the FT catalyst performance for as-prepared catalysts was evaluated in a fixed-bed reactor under the condition of H2:CO = 2:1, 5 SL·h−1·g−1, 2.5 MPa, and 210 °C. Interestingly, the defined three types of carbon materials exhibit superior performance and dispersion compared with graphene oxide and reduced graphene oxide. The thermal stability and pore structure of the five carbon materials vary markedly, and H2-TPR result shows that the metal–support interaction is in the order of Co/GO > Co/CNT > Co/AC > Co/CNF > Co/rGO. In brief, the carbon nanofiber-supported cobalt catalyst showed the best dispersion, the highest CO conversion, and the lowest gas product but the highest heavy hydrocarbons (C5+) selectivity, which can be attributed to the intrinsic property of CNF material that can affect the catalytic performance in a complicated way. This work will open up a new gateway for cobalt support catalysts on various carbon-based materials for Fischer–Tropsch Synthesis.
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Ozerova, Anna M., Arina R. Potylitsyna, Yury I. Bauman, Elena S. Tayban, Inna L. Lipatnikova, Anna V. Nartova, Aleksey A. Vedyagin, Ilya V. Mishakov, Yury V. Shubin, and Olga V. Netskina. "Synthesis of Chlorine- and Nitrogen-Containing Carbon Nanofibers for Water Purification from Chloroaromatic Compounds." Materials 15, no. 23 (November 25, 2022): 8414. http://dx.doi.org/10.3390/ma15238414.
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Chlorine- and nitrogen-containing carbon nanofibers (CNFs) were obtained by combined catalytic pyrolysis of trichloroethylene (C2HCl3) and acetonitrile (CH3CN). Their efficiency in the adsorption of 1,2-dichlorobenzene (1,2-DCB) from water has been studied. The synthesis of CNFs was carried out over self-dispersing nickel catalyst at 600 °C. The produced CNFs possess a well-defined segmented structure, high specific surface area (~300 m2/g) and high porosity (0.5–0.7 cm3/g). The addition of CH3CN into the reaction mixture allows the introduction of nitrogen into the CNF structure and increases the volume of mesopores. As a result, the capacity of CNF towards adsorption of 1,2-DCB from its aqueous solution increased from 0.41 to 0.57 cm3/g. Regardless of the presence of N, the CNF samples exhibited a degree of 1,2-DCB adsorption from water–organic emulsion exceeding 90%. The adsorption process was shown to be well described by the Dubinin–Astakhov equation. The regeneration of the used CNF adsorbent through liquid-phase hydrodechlorination was also investigated. For this purpose, Pd nanoparticles (1.5 wt%) were deposited on the CNF surface to form the adsorbent with catalytic function. The presence of palladium was found to have a slight effect on the adsorption capacity of CNF. Further regeneration of the adsorbent-catalyst via hydrodechlorination of adsorbed 1,2-DCB was completed within 1 h with 100% conversion. The repeated use of regenerated adsorbent-catalysts for purification of solutions after the first cycle of adsorption ensures almost complete removal of 1,2-DCB.
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Ud Din, Israf, Maizatul S. Shaharun, Duvvuri Subbarao, and A. Naeem. "Homogeneous Deposition Precipitation Method for Synthesis of Carbon Nanofibre Based Cu-ZrO2 Catalyst for Hydrogenation of CO2 to Methanol." Applied Mechanics and Materials 446-447 (November 2013): 83–87. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.83.
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Deposition precipitation method was employed to synthesize carbon nanofiber based Cu-ZrO2catalyst (Cu-ZrO2/CNF). Carbon nanofibre of herringbone type was used as a catalyst support. Prior deposition of catalyst particles, carbon nanofibre was oxidized to (CNF-O) with nitric acid solution. Catalyst was characterized by X-ray diffraction (XRD), Fourier Transmission Infrared (FTIR), Transmission Electron Microscopy (TEM) and Temperature-Programmed Reduction (TPR). Highly loaded, well-dispersed and thermally stable catalyst particles with average size of 4 nm were obtained by deposition precipitation method. Reaction studies confirmed the activity of the catalyst towards methanol formation.
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Woo, Seongwon, Jooyoung Lee, Dong Sub Lee, Jung Kyu Kim, and Byungkwon Lim. "Electrospun Carbon Nanofibers with Embedded Co-Ceria Nanoparticles for Efficient Hydrogen Evolution and Overall Water Splitting." Materials 13, no. 4 (February 13, 2020): 856. http://dx.doi.org/10.3390/ma13040856.
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In this study, simple electrospinning combined with pyrolysis were used to fabricate transition-metal-based-nanoparticle-incorporated carbon nanofiber (CNF) electrocatalysts for a high-efficiency hydrogen evolution reaction (HER) and overall water splitting. Co-CeO2 nanoparticle-incorporated carbon nanofibers (Co-CeO2@CNF) exhibit an outstanding electrocatalytic HER performance with an overpotential and Tafel slope of 92 mV and 54 mV/dec, respectively. For the counterpart, electrolysis, we incorporate the widely used Ni2Fe catalyst with a high oxygen evolution reaction (OER) activity into the carbon nanofiber (Ni2Fe@CNF). To evaluate their electrochemical properties for the overall water splitting, Co-CeO2@CNF and Ni2Fe@CNF were used as the HER and OER electrocatalysts in an alkaline electrolyzer. With the paired Co-CeO2@CNF and Ni2Fe@CNF electrodes, an overall water splitting current density of 10 mA/cm2 was achieved by applying 1.587 V across the electrodes with a remarkably lower overpotential of 257 mV compared to that of an electrolyzer comprised of Pt/C and IrO2 electrodes (400 mV). Owing to the conformal incorporation of nanoparticles into the CNF, the electrocatalysts exhibit significant long-term durability over 70 h of overall water splitting. This study provides rational designs of catalysts with high electrochemical catalytic activity and durability to achieve overall water splitting.
Dissertations / Theses on the topic "CNF catalyst"
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Hou, Guangfeng. "Substrate Patterning by Nanomachining for Controlled Carbon Nanotube Growth." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1407410214.
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Hermann, Sascha. "Growth of carbon nanotubes on different support/catalyst systems for advanced interconnects in integrated circuits." Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-78189.
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Since there is a continuous shrinking of feature sizes in ultra-large scale integrated (ULSI) circuits, requirements on materials and technology are going to rise dramatically in the near future. In particular, at the interconnect system this calls for new concepts and materials. Therefore, carbon nanotubes (CNTs) are considered as a promising material to replace partly or entirely metal interconnects in such devices. The present thesis aims to make a contribution to the CNT growth control with the thermal chemical vapor deposition (CVD) method and the integration of CNTs as vertical interconnects (vias) in ULSI circuits. Different support/catalyst systems are examined in processes for catalyst pretreatment and CNT growth. The investigations focus on the catalyst formation and the interactions at the interfaces. Those effects are related to the CNT growth. To get an insight into interactions at interfaces, film structure, composition, and CNT growth characteristics, samples are extensively characterized by techniques like AFM, SEM, TEM, XRD, XPS, and Raman spectroscopy. Screening studies on nanoparticle formation and CNT growth with the well known system SiO2/Ni are presented. This system is characterized by a weak support/catalyst interaction, which leads to undirected growth of multi-walled CNTs (MWCNTs). By contrast, at the Ta/Ni system a strong interaction causes a wetting of catalyst nanoparticles and vertically aligned MWCNT growth. At the system W/Ni a strong interaction at the interface is found as well, but there it induces Stranski-Krastanov catalyst film reformation upon pretreatment and complete CNT growth inhibition. Studies on the SiO2/Cr/Ni system reveal that Cr and Ni act as a bi-catalyst system, which leads to a novel nanostructure defined as interlayer CNT (ICNT) structure. The ICNT films are characterized by well crystallized vertically aligned MWCNTs, which grow out a Cr/Ni layer lifted off as a continuous and very smooth layer from the substrate with the growth. Besides, this nanostructure offers new possibilities for the integration of CNTs in different electronic applications. Based on the presented possibilities of manipulating CNT growth, an integration technology was derived to fabricate CNT vias. The technology uses a surface mediated site-selective CVD for the growth of MWCNTs in via structures. Developments are demonstrated with the fabrication of via test vehicles and the site-selective growth of MWCNTs in vias on 4 inch wafers. Furthermore, the known resistance problem of CNT vias, caused by too low CNT density, is addressed by a new approach. A CNT/metal heterostructure is considered, where the metal is implemented through atomic layer deposition (ALD). The first results of the coating of CNTs with readily reducible copper oxide nanoparticles are presented and discussedAufgrund der kontinuierlichen Verkleinerung von Strukturen in extrem hoch integrierten (engl. Ultra-Large Scale Integration − ULSI) Schaltkreisen werden die Anforderungen an die Materialien und die Technologie in naher Zukunft dramatisch ansteigen. Besonders im Leitbahnsystem sind neue Materialien und Konzepte gefragt. Kohlenstoffnanoröhren (engl. Carbon Nanotubes − CNT) stellen hierbei ein vielversprechendes Material dar, um teilweise oder sogar vollständig metallische Leitbahnen zu ersetzen. Die vorliegende Arbeit liefert einen Beitrag zur CNT-Wachstumskontrolle mit der thermischen Gasphasenabscheidung (engl. Chemical Vapor Deposition − CVD) sowie der Integration von CNTs als vertikale Leitungsverbindungen (Via) in ULSI-Schaltkreisen. Verschiedene Untergrund/Katalysator-Systeme werden in Prozessen zur Katalysatorvorbehandlung sowie zum CNT-Wachstum betrachtet. Die Untersuchungen richten sich insbesondere auf die Katalysatorformierung und die Wechselwirkungen an den Grenzflächen. Diese werden mit dem CNT-Wachstum in Verbindung gebracht. Für Untersuchungen von Grenzflächeninteraktionen, Schichtstruktur, Zusammensetzung sowie CNT-Wachstumscharakteristik werden Analysen mit AFM, REM, TEM, XRD, XPS und Raman-Spektroskopie genutzt. Zunächst werden Voruntersuchungen an dem gut bekannten System SiO2/Ni zur Nanopartikelformierung und CNTWachstum vorgestellt. Dieses System ist gekennzeichnet durch eine schwache Wechselwirkung zwischen Untergrund und Katalysator sowie ungerichtetem Wachstum von mehrwandigen CNTs (MWCNTs). Im Gegensatz dazu hat bei dem System Ta/Ni eine starke Interaktion an der Grenzfläche eine Katalysatornanopartikelbenetzung und vertikales MWCNT-Wachstum zur Folge. Für das W/Ni-System gelten ebenfalls starke Interaktionen an der Grenzfläche. Bei diesem System wird allerdings eine Stranski-Krastanov-Schichtformierung des Katalysators und eine vollständige Unterbindung von CNT-Wachstum erreicht. Bei dem System SiO2/Cr/Ni agieren Cr und Ni als Bi- Katalysatorsystem. Dies führt zu einer neuartigen Nanostruktur, die als Zwischenschicht-CNT (engl. Interlayer Carbon Nanotubes − ICNTs) Struktur definiert wird. Die Schichten sind durch eine gute Qualität von gerichteten MWCNTs charakterisiert, die aus einer geschlossenen, sehr glatten und von den CNTs getragenen Cr/Ni-Schicht herauswachsen. Darüber hinaus bietet die Struktur neue Möglichkeiten für die Integration von CNTs in verschiedene elektronische Anwendungen. Auf der Grundlage der vorgestellten Manipulationsmöglichkeiten von CNT-Wachstum wurde eine Integrationstechnologie für CNTs in Vias abgeleitet. Der Ansatz ist eine oberflächeninduzierte selektive CVD von vertikal gerichteten MWCNTs in Via-Strukturen. Diese Technologie wird mit der Herstellung von einem Via-Testvehikel und dem selektiven CNT-Wachstum in Vias auf 4 Zoll Wafern demonstriert. Um das Widerstandsproblem von CNT-Vias, verursacht durch eine zu niedrige CNT-Dichte, zu reduzieren, wird eine Technologieerweiterung vorgeschlagen. Der Ansatz geht von einer CNT/Metall-Heterostruktur aus, bei der das Metall mit Hilfe der Atomlagenabscheidung (engl. Atomic Layer Deposition − ALD) implementiert wird. Es werden erste Ergebnisse zur CNT-Beschichtung mit reduzierbaren Kupferoxidnanopartikeln vorgestellt und diskutiert
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Zhang, Qiang. "Probing the Active Site of CNx Catalysts for the Oxygen Reduction Reaction in Acidic Media: A First-Principles Study." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531312924087566.
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Acosta, Roberto I. "Ostwald Ripening of Iron (Fe) Catalyst Nanoparticles on Aluminum Oxide Surfaces (Al2O3) for the Growth of Carbon Nanotubes." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1263485314.
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Biddinger, Elizabeth Joyce. "Nitrogen-Containing Carbon Nanofibers as Non-Noble Metal Cathode Catalysts in PEM and Direct Methanol Fuel Cells." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274389015.
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Linck, Nicholas W. "PRECISE CONTROL OF CARBON NANOTUBE MEMBRANE STRUCTURE FOR ENZYME MIMETIC CATALYSIS." UKnowledge, 2014. http://uknowledge.uky.edu/cme_etds/35.
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The ability to fabricate a charge-driven water pump is a crucial step toward mimicking the catalytic ability of natural enzyme systems. The first step towards making this water pump a reality is the ability to make a carbon nanotube (CNT) membrane with uniform, 0.8 nm pore diameter. Proposed in this work is a method for synthesizing these carbon nanotubes via VPI-5 zeolite templated, transition metal catalyzed pyrolysis. Using a membrane composed of these CNTs, it is possible to get water molecules to flow single file at a high flow rate, and to orient them in such a way that would maximize their ability to be catalyzed. Additionally, using the ability to plate a monolayer of precious metal catalyst molecules around the exit to the membrane, catalyst efficiency can be maximized by making every catalyst atom come into contact with a substrate molecule. In this work, we also demonstrate the ability to plate a monolayer of precious metal catalyst atoms onto an insulating, mesoporous, support material. By combining these two chemical processes, it is possible to mimic the catalytic efficiency of natural enzyme systems.
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Rautio, A. R. (Anne-Riikka). "On the stability of carbon nanotube and titania nanowire based catalyst materials:from synthesis to applications." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526211060.
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Abstract Degradation of the support and sintering of catalyst nanoparticles inherently leads to a loss of functionality of catalyst materials in converters and sensors. Malfunction in such devices may lead to serious economic and environmental damage. The quest for novel and sustainable catalyst materials with better durability is thus ongoing. In this thesis, one-dimensional nanomaterials such as carbon nanotubes and titanium dioxide nanowires are studied and compared to their conventional zero-dimensional counterparts in regard to their structural and functional stability. With the combination of several catalyst nanomaterials and supporting surfaces, aging properties of more than 70 different materials are assessed by the means of X-ray diffraction, transmission electron microscopy and energy-dispersive X-ray analyses. Although CNTs were shown to be thermally the most stable carbonaceous supports for metal nanoparticles, they are, similar to other carbon supports, more sensitive to high temperatures than metal oxide supports and can suffer deactivation by catalytic oxidation and gasification even at moderate temperatures. In addition, the irradiation of the samples with e-beams caused the most dramatic changes in CNT based materials, where nanosized deformities (voids, channels) were formed when either nanoparticles or defects were present. The prepared nanocompositions have been utilized successfully in three different applications including (i) synthesis of hydrogen from ethanol via a steam reforming reaction, (ii) hydrogenation of citral to form value added chemicals and (iii) the application of advanced electrode materials in electric double-layer capacitors. Both CNT and TiO₂ nanowire based nanomaterials were shown to outperform their conventional nano- and microparticle based counterparts in the studied catalytic reactions, i.e. in citral hydrogenation and steam reforming of ethanol, respectively. Furthermore, nanostructured CNTs obtained by catalytic partial oxidation of the material showed an increased specific surface area, which could be exploited in supercapacitor electrodes with enhanced specific capacitanceTiivistelmä Katalyyttitukimateriaalin pilaantuminen ja katalyyttinanopartikkelien sintrautuminen johtavat siihen, että muuntajissa ja sensoreissa käytettävät katalyyttiset materiaalit eivät enää toimi, mikä voi aiheuttaa sekä vakavia taloudellisia haittoja että ympäristöhaittoja. Tämän vuoksi kehitetään uusia kestävämpiä katalyyttimateriaaleja. Tässä väitöskirjassa tutkittiin yksiulotteisia nanomateriaaleja, kuten hiilinanoputkia sekä titaanidioksidinanojohtimia ja verrattiin niiden rakenteellista ja toiminnallista stabiiliutta perinteisiin nollaulotteisiin vastineisiin. Erilaisten katalyyttinanomateriaalien ja tukimateriaalien yhdistelmien ikääntymistä arvioitiin röntgendiffraktion, läpäisyelektronimikroskopian ja energiadispersiivisen röntgenanalyysin avulla yli 70 erilaisesta näytteestä. Vaikka hiilinanoputket osoittautuivat termisesti stabiileimmaksi hiilipohjaiseksi tukimateriaaliksi metallinanopartikkeleille, ne ovat kuten kaikki hiilimateriaalit, metallioksiditukimateriaaleja herkempiä korkeille lämpötiloille. Hiilinanoputkipohjaiset katalyytit voivat deaktivoitua katalyyttisen hapettumisen tai kaasuuntumisen vuoksi jo kohtalaisissa lämpötiloissa. Lisäksi elektronisäteellä säteilytetyt nanopartikkelit tai pintavirheitä sisältävät hiilinanoputkipohjaiset katalyytit olivat tutkituista nanomateriaaleista herkimpiä muodostamaan nanorakenteita (koloja, kanavia). Valmistettuja nanokomposiitteja käytettiin onnistuneesti kolmessa eri sovelluksessa: i) vedyn valmistuksessa etanolista höyryreformointireaktiolla, ii) hienokemikaalien valmistuksessa sitraalin hydrauksella sekä iii) elektrodimateriaalina EDLC-kondensaattorissa. Sekä hiilinanoputki- sekä TiO₂-nanojohdinpohjaiset nanomateriaalit toimivat testatuissa katalyyttisissa reaktioissa (etanolin reformointi sekä sitraalin hydraus) paremmin kuin niiden perinteiset vastineet. Lisäksi superkondensaattorin ominaiskapasitanssia onnistuttiin nostamaan lisäämällä hiilinanoputkipohjaisen elektrodin ominaispinta-alaa katalyyttisella hapetusreaktiolla
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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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Demir-kivrak, Hilal. "Synthesis And Characterization Of Ethanol Electro-oxidation Catalysis." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12613887/index.pdf.
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ABSTRACT
SYNTHESIS AND CHARACTERIZATION OF ETHANOL ELECTRO-OXIDATION CATALYSIS
Demir-Kivrak, Hilal
Ph.D., Department of Chemical Engineering
Supervisor : Prof. Dr. Deniz Üner Co-supervisor : Dr. Sadig Kuliyev October 2010, 196 pages In this study, the role of defects, the role of Sn in relation to defects, and the role of oxide phase of tin in ethanol electro-oxidation reaction were investigated. Firstly, adsorption calorimetry measurements were conducted on monometallic (1%Pt, 2%Pt, and 5%Pt) and bi-metallic (5% Pt-Sn) &gamma
-Al2O3 supported Pt catalysts. It was observed that while saturation coverage values decreased, intermediate heats remained same for Pt-Sn catalysts by the increasing amount of tin. The effect of particle size was investigated on Pt/C (pH=5), Pt/C (pH=11) catalysts at different scan rates. At high scan rates (quite above diffusion limitations), current per site activities were nearly the same for 20% Pt/C (E-Tek), Pt/C (pH=11), and Pt/C (pH=5) catalysts, which explained as electro-oxidation reaction takes place at the defects sites. Furthermore, the effect of support on ethanol electro-oxidation was investigated on CNT supported Pt catalyst. Results indicate that only the metal v dispersions improved ethanol electro-oxidation reaction and support did not have any effect on ethanol electro-oxidation reaction. Results on the 20% Pt-Sn/C (15:1 to 1:1 Pt: Sn atomic ratios) and 20% Pt-SnO2/C (6:1 and 1:1) catalysts indicated that ethanol electro-oxidation activity increased by increasing tin amount. For 20% Pt-Sn/C catalysts, Pt-Sn (6:1)/C indicated best activity. On the other hand, 20% Pt-SnO2 (6:1)/C catalyst was better than Pt-Sn (6:1)/C in terms of ethanol electro-oxidation activity due to the fact that there was low contact between Pt and tin oxide particles.
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Pap, A. E. (Andrea Edit). "Investigation of pristine and oxidized porous silicon." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:9514277759.
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Abstract
While numerous publications deal with the properties and applications of porous silicon (PS), some of the related topics are not complete or could be investigated from different aspects. Therefore, the main objective of this thesis is to provide novel information associated with the optical and chemical properties of PS.
For the investigations, various PS samples are manufactured by electrochemical dark etching of boron-doped p+-type Si wafers. Amongst others, (i) the wavelength-dependent refractive indices of freestanding PS monolayers having different porosities were obtained from optical transmission and reflection spectra in the 700–1700 nm wavelength range, and compared to those calculated from Bruggeman's effective medium approximation (EMA). The refractive indices of the PS samples are shown to be described well with the EMA. In addition, optical scattering at the air-PS interface was demonstrated. (ii) Multilayer stacks are created by alternating the porosities of PS layers within the same sample to form Bragg filters. The Bragg conditions of the filters are calculated and compared to optical transmission measurements. (iii) The oxidation of PS membranes in dry air is investigated with emphases on the reaction kinetics and on the structural changes of the porous matter. As revealed, oxidation proceeds faster in PS than in Si bulk. The formed SiO2 is amorphous and causes stress in the lattice of the residual Si skeleton. (iv) The effect of oxidation extent of PS layers on the growth mechanism of multi-walled carbon nanotubes (CNTs) is investigated. The density of the CNT network is found proportional to the oxidation extent of the substrates. (v) Finally, the chemically-reductive nature of PS is studied and exploited via the immersion plating method to deposit palladium and silver nanoparticles in the nanopores and on the surface of PS samples.
The presented novel results have potential in silicon-based technologies, including integrated active and passive optical components (waveguides, filters, antireflection coatings, optical gas/liquid sensors), electronic devices (electrochemical gas/liquid sensors, diodes, field effect devices) and selective chemical catalysis (substrates, growth templates).
Books on the topic "CNF catalyst"
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M, Schaefer Ronald, and United States. Environmental Protection Agency. Office of Mobile Sources., eds. Evaluation of three catalysts formulated for methane oxidation on a CNG-fueled pickup truck. Ann Arbor, MI: U.S. Environmental Protection Agency, Office of Mobile Sources, 1993.
Find full textBook chapters on the topic "CNF catalyst"
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Xie, Tianchi, Hongqi Liu, Haipeng Deng, Yupeng Wang, and Ying Gao. "Research on Diagnostics Methods of CNG Engine After Treatment Catalyst." In Lecture Notes in Electrical Engineering, 1896–903. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-3648-5_243.
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El Beji, Rabii, Marwa Saidi, Houcemeddine Hermassi, and Rhouma Rhouma. "An Improved CNN Steganalysis Architecture Based on “Catalyst Kernels” and Transfer Learning." In Lecture Notes in Business Information Processing, 119–28. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-97749-2_9.
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Karthikeyan, S., A. Raj, A. L. Suresh, and S. Krishnan. "Three-Way Catalyst System Design and Emission Characteristics Study with Precious Group Metal Loadings for CNG Vehicles." In Recent Advances in Energy Technologies, 571–86. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-3467-4_36.
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Haeger, Heather, and Natasha Oehlman. "Chapter 12. “You’re Invited to the Rejection Party” and Other Strategies for Normalizing Rejection and Failure as Part of the Research Process." In Confronting Failure: Building Confidence and Resilience in Undergraduate Researchers, 148–60. Council on Undergraduate Research, 2022. http://dx.doi.org/10.18833/cf/16.
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Undergraduate research can facilitate remarkable achievements and successes, but experiences of failure in research can be just as transformative. Experiencing failure can communicate to students that they do not belong in their field or in research, but reframing those experiences can help students persist and catalyze their learning and development. This case study presents interventions developed at California State University, Monterey Bay aimed at normalizing failure in the research process, recognizing failure and rejection as part of academic success, and utilizing failure as a catalyst for growth. The authors use interviews and written reflections from a diverse group of undergraduate researchers to understand how students make meaning out of experiences of failure and rejection, as well as the factors that shape how students respond to these challenges.
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Bi, Shuai. "Photoredox Catalysis by Covalent Organic Frameworks." In Covalent Organic Frameworks [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107485.
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In recent years, photocatalysis that uses solar energy for either fuel production, such as hydrogen evolution and hydrocarbon production, or directed organic transformations, has shown great potential to achieve the goal of finding clean and renewable energy sources. Covalent organic frameworks (COFs) are crystalline organic porous materials formed by the covalent bonding of organic building blocks, which features superior structural regularity, robust framework, inherent porosity, and diverse functionality. The introduction of organic monomers with adjustable light absorption ability into COFs can make them show strong potential in photocatalysis. This chapter presents the recent progress of COF-based photocatalysts. The use of COF photocatalysts in a myriad of photoredox catalysts with a range of applications, including photocatalytic water splitting, photocatalytic CO2 reduction, photocatalytic organic transformations, and photocatalytic environmental pollutant degradation will be highlighted. Furthermore, various linkers between COF building blocks such as nitrogen-containing connections and all sp2-carbon connections will be summarized and compared. Finally, a perspective on the opportunities and challenges for the future development of COF and COF-based photocatalysts will be given.
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Zhang, Denghua. "The UNDP as a Catalyst for China’s Development Cooperation: The Case of the China–UNDP–Cambodia Trilateral Cassava Project." In A Cautious New Approach: China's Growing Trilateral Aid Cooperation, 107–45. ANU Press, 2020. http://dx.doi.org/10.22459/cna.2020.04.
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Muhammad Raini, Kamal, Syuhaida Ismail, Mohamad Syazli Fathi, and Halim Syah Hamzah. "Causative Failure Factors of Delay in Heavy Equipment Procurement Management During the COVID-19 Pandemic." In Handbook of Research on Promoting Logistics and Supply Chain Resilience Through Digital Transformation, 22–33. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-5882-2.ch002.
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Since COVID-19 outbreak from Wuhan, China, rapid transformations worldwide demonstrate commitments in many countries towards new norms of social distancing and mask-compulsory trends of life. As the economic downturn affects public sector in terms of supply, services, and development projects, new challenges should be viewed as an opportunity for fundamental change, and public procurement reform as a catalyst for improving public policy and engaging civil society. Thus, this paper aims to examine the causative failure factors (CFF) of delay of mechanical asset procurement during pandemic from the Malaysian perspective. The literature reviews consider recent journal articles involving project management to understand the CFF of delay in overall project management and its relativity to mechanical asset procurement. Then, the paper suggests implementation of project management tools: Ishikawa diagram and PESTLE relatively to heavy equipment. Finally, this paper discusses the CFF to enable a comprehensive project scheduling to eliminate or avoid nuisance during project execution and completion.
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Le Gars, Manon, Loreleï Douard, Naceur Belgacem, and Julien Bras. "Cellulose Nanocrystals: From Classical Hydrolysis to the Use of Deep Eutectic Solvents." In Smart Nanosystems for Biomedicine, Optoelectronics and Catalysis. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.89878.
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During the last two decades, interest in cellulosic nanomaterials has greatly increased. Among these nanocelluloses, cellulose nanocrystals (CNC) exhibit outstanding properties. Indeed, besides their high crystallinity, cellulose nanocrystals are interesting in terms of morphology with high aspect ratio (length 100–1000 nm, width 2–15 nm), high specific area, and high mechanical properties. Moreover, they can be used as rheological modifier, emulsifier, or for barrier properties, and their surface chemistry opens the door to numerous feasible chemical modifications, leading to a large panel of applications in medical, electronic, composites, or packaging, for example. Traditionally, their extraction is performed via monitored sulfuric acid hydrolysis, leading to well-dispersed aqueous CNC suspensions; these last bearing negative charges (half-sulfate ester groups) at their surface. More recently, natural chemicals called deep eutectic solvents (DESs) have been used for the production of CNC in a way of green chemistry, and characterization of recovered CNC is encouraging.
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Lambert, Tristan H. "Reactions of Alkenes." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0031.
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Paul J. Chirik at Princeton University reported (Science 2012, 335, 567) an iron catalyst that hydrosilylates alkenes with anti-Markovnikov selectivity, as in the conversion of 1 to 2. A regioselective hydrocarbamoylation of terminal alkenes was developed (Chem. Lett. 2012, 41, 298) by Yoshiaki Nakao at Kyoto University and Tamejiro Hiyama at Chuo University, which allowed for the chemoselective conversion of diene 3 to amide 4. Gojko Lalic at the University of Washington reported (J. Am. Chem. Soc. 2012, 134, 6571) the conversion of terminal alkenes to tertiary amines, such as 5 to 6, with anti-Markovnikov selectivity by a sequence of hydroboration and copper-catalyzed amination. Related products such as 8 were prepared (Org. Lett. 2012, 14, 102) by Wenjun Wu at Northwest A&F University and Xumu Zhang at Rutgers via an isomerization-hydroaminomethylation of internal olefin 7. Seunghoon Shin at Hanyang University (experimental work) and Zhi-Xiang Yu at Peking University (computational work) reported (J. Am. Chem. Soc. 2012, 134, 208) that 9 could be directly converted to bicyclic lactone 11 with propiolic acid 10 using gold catalysis. A nickel/Lewis acid multicatalytic system was found (Angew. Chem. Int. Ed. 2012, 51, 5679) by the team of Professors Nakao and Hiyama to effect the addition of pyridones to alkenes, such as in the conversion of 12 to 13. Radical-based functionalization of alkenes using photoredox catalysis was developed (J. Am. Chem. Soc. 2012, 134, 8875) by Corey R.J. Stephenson at Boston University, an example of which was the addition of bromodiethyl malonate across alkene 14 to furnish 15. Samir Z. Zard at Ecole Polytechnique reported (Org. Lett. 2012, 14, 1020) that the reaction of xanthate 17 with terminal alkene 16 led to the product 18. The radical-based addition of nucleophiles including azide to alkenes with Markovnikov selectivity (cf. 19 to 20) was reported (Org. Lett. 2012, 14, 1428) by Dale L. Boger at Scripps La Jolla using an Fe(III)/NaBH4-based system. A remarkably efficient and selective catalyst 22 was found (J. Am. Chem. Soc. 2012, 134, 10357) by Douglas B. Grotjahn at San Diego State University for the single position isomerization of alkenes, which effected the transformation of 21 to 23 in only half an hour.
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Brando, Carlos Andrés. "From Sub-Regional Industrial Financier to Latin America’s Main Development Bank." In Regional Development Banks in the World Economy, 131–67. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198861089.003.0007.
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This chapter traces the historical evolution of the Andean Financial Corporation (CAF), according to its changing mandates, from its initial role as financial catalyst of economic integration to the expanding range of tasks it has assumed over time. The chapter analyses the most salient trends and changes in the CAF’s nearly fifty years of operations; specifically, by looking at patterns of loan allocations and the evolving origins of funding sources through the distinctive operational phases that have come to characterize concrete periods of its existence. The analysis shows, that by fulfilling the original mandate of treating less-developed countries within the group of founding members in preferential terms, the CAF conformed to one of the major political goals set by the Andean-region agreements which created the Corporation. Despite profound political change in all of the CAF’s founding countries, this regional development bank has managed to continue to operate according to its constitutive principles.
Conference papers on the topic "CNF catalyst"
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Arana, Claudya P., Ishwar K. Puri, and Swarnendu Sen. "How Do the Local Conditions Influence the Flame Synthesis of Carbon Nanostructures?" In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-60382.
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Since prepared substrates offer an appropriate method for the selective production of uniform arrays of aligned CNTs and CNFs, it is important to illustrate the influence of different catalysts on the resulting nanostructures. This investigation characterizes the activity of three catalysts — iron in alloyed form as stainless steel, nickel, and platinum — on carbon nanostructure formation under identical conditions in an ethylene/air nonpremixed flame. We have synthesized well-aligned multi-walled CNTs (on Ni) and CNFs (on stainless steel). The third transition metal Pt produces CNF structures of a different kind and its activity has not been previously characterized in flames. The catalyst and gas-phase conditions leading to the formation of these different structures are discussed.
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Hossain, Muhammad E., Mohammad K. Hossain, Mahesh V. Hosur, and Shaik Jeelani. "Investigation of Carbon Nanofibers (CNFs) Effects on the Flexural and Thermal Behavior of E-Glass/Polyester Composites." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-39336.
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Properties of polymeric composites can be enhanced tailoring with nanomaterials such as CNFs, CNTs, nanoclay etc. A high intensity ultrasonic liquid processor was used to infuse CNFs into the polyester matrix which was then mixed with catalyst using a high speed mechanical agitator. Both conventional and nanophased GRPC were fabricated by VARTM. Flexure tests were performed on the conventional, 0.1%, 0.2%, 0.3%, and 0.4 wt.% CNF-filled GRPC. The results showed 49% and 31% increase in the flexural strength and modulus, respectively, with increasing loading percentage of CNFs up to 0.2%. DMA showed 92% increase in the storage modulus, and slight increase in the Tg in the nanophased GRPC, respectively, as compared to the conventional GRPC. TGA exhibited insignificant effect of CNFs in the decomposition temperature. TMA showed less CTE in the nanophased GRPC. SEM evaluations revealed relatively less damage in fractured surfaces of the nanophased GRPC.
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Huitink, David R., Debjyoti Banerjee, and Saion K. Sinha. "Precise Control of Carbon Nanotube Synthesis of a Single Chirality." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42588.
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This work demonstrates precise control over the synthesis conditions and location during CNT formation, such that single chirality tubes are obtainable. This technique obviates two significant hurdles that prevent the exploitation of CNTs in micro- and nano-devices. Microelectronic applications require precise location and chirality of synthesized CNTs. Conventional CVD synthesis techniques typically yield mixtures of CNTs (semi-conducting and metallic types) that grow at random locations. Dip Pen Nanolithography (DPN) techniques were used to deposit the catalysts at precisely defined locations and to pattern the catalysts on a substrate with specific sizes as well as to control the catalyst composition. After deposition of catalysts, a low temperature Chemical Vapor Deposition (CVD) process was used to synthesize CNT. Various known catalysts were deposited. Characterization studies before and after CVD synthesis of CNT showed that the CNT were of a single chirality as well as uniform diameter (with a very narrow range of variability). The results indicate that the chirality of the synthesized CNT can be controlled by changing the synthesis conditions (e.g., size of the catalyst patterns, composition of the catalysts, temperature of CVD, gas flow rates, etc.).
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Abbo, Hanna S., Ivan R. Green, and Salam J. J. Titinchi. "Synthesis of Highly Dispersed Carbon Supported Platinum Nanocatalyst for Fuel Cells." 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/fuelcell2011-54669.
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Pt/C and Pt/CNT catalysts were prepared by colloidal method using sodium citrate as a stabilizer, and ethylene glycol as the reducing agent and solvent. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results showed that the Pt particles were highly dispersed on the support and had a very narrow particle distribution with particle size range of 1.5–2.4 nm for both catalysts. Based on the electrochemical properties characterized by cyclic voltammetry, it was found that the as-synthesized electrocatalysts possessed a significantly higher catalytic activity than those of commercial Pt/C Johnson Matthey catalyst.
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Kumar, Anand, and Anchu Ashok. "Catalytic Decomposition of Ethanol over Bimetallic Nico Catalysts for Carbon Nanotube Synthesis." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0039.
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In this work we investigate the use of NiCo bimetal/oxide as catalyst for hydrogen production from ethanol, with a focus on the deactivation pattern and the nature of the observed carbon deposition. It is well known that sintering and coke deposition during decomposition reaction significantly reduces the activity of the catalysts at higher temperature, by blocking the active sites of the catalysts. During ethanol decomposition reaction, the cleavage of C-C bond produces adsorbed *CH4 and *CO species that further decompose to form carbonaceous compounds. FTIR in-situ analysis was conducted between 50 to 400°C for all the catalysts to understand the reaction mechanism and product selectivity. Cobalt was found to be selective for aldehyde and acetate, whereas bimetallic Ni-Co was selective for the formation of CO at 400°C along with aldehyde. Complete conversion of ethanol was observed at 350°C and 420°C for NiCo and Cobalt respectively indicating an improvement in the rate of conversion when Ni was added to cobalt. The crystallinity, morphology and particle analysis of the used catalyst after reaction were studied using XRD, SEM and TEM respectively. The XRD shows the complete phase change of porous NiCoO2 to NiCo alloy and SEM indicates the presence of fibrous structure on the surface with 91.7 % of carbon while keeping 1:1 ratio of Ni and Co after the reaction. The detailed analysis of carbon structure using HRTEM-STEM shows the simultaneous growth of carbon nano fibers (CNFs) and multiwalled carbon nanotubes (MWCNTs) that were favored on larger and smaller crystallites respectively. Analysis of carbon formation on individual Co catalyst and bimetallic NiCo catalyst shows a clear difference in the initiation pattern of carbon deposition. Metallic Co nanoparticles were found to be more mobile where Co disperses along the catalysts surface, whereas NiCo nanoparticles were relatively less mobile, and maintained their structure.
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Hajilounezhad, Taher, and Matthew R. Maschmann. "Numerical Investigation of Internal Forces During Carbon Nanotube Forest Self-Assembly." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-86567.
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A time-resolved two-dimensional finite element simulation is developed to model the forces generated during the self-assembly of actively growing CNT populations with distributed properties and growth characteristics. CNTs are simulated as interconnected frame elements that undergo the base growth mechanism. Mechanical equilibrium at each computational node is determined at each time step using the Updated Lagrangian method. Emphasis is placed on the transmission of force to the growth substrate, where catalyst particles reside. The simulated CNT forest structural morphology is similar to that of physical CNT forests, and results indicate that stresses on the order of GPa are transmitted to catalyst particles. The force transmitted to a given catalyst particle is correlated to the rate at which the CNT grows relative to the population averaged growth rate. The effect of diameter-dependent CNT growth rates and the persistence of vdW bonds are also examined relative to the forces generated during forest self-assembly. Results from this study may be applied to the study of CNT forest self-assembly, resultant ensemble forest properties, and force-modulated CNT growth kinetics.
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Kallinen, Kauko, Matti Härkönen, and Mikko Pitkänen. "ADVANCED CATALYSTS FOR CNG-ENGINES." In SIAT 2004. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2004. http://dx.doi.org/10.4271/2004-28-0028.
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Watcharasing, Sunisa, Chularat Wattanakit, Anawat Thivasasith, and Prapoj Kiattikomol. "Hierarchical Zeolites from Production Sand Waste as Catalysts for CO2 to Carbon Nanotubes CNTs: Exploration and Production Sustainability." In IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition. SPE, 2022. http://dx.doi.org/10.2118/209923-ms.
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Abstract This project targets to convert sand waste from oil & gas production, which is typically disposed as landfill, to be the higher-value products, called "Hierarchical Zeolites". This project also explores opportunities to lower amount of sand waste to landfill and try to convert CO2 to CNTs, as part of Sustainable Development Goals. Hierarchical Zeolites is developed with nanosheets morphology to overcome limitation of conventional zeolites in terms of, 1) microporous structure improvement to enhance the mass transport through active sites, 2) longer catalyst lifetime, and 3) higher surface area. With these superior characteristics, it is popularly used in wide range of applications ranging from adsorption, separation, and ion-exchange to catalysis. In this work, the Hierarchical Zeolites are utilized as catalysts for CO2 conversion to CNTs, which is the futuristic materials. Methods, The procedure to produce hierarchical zeolites with nanosheet morphology for ZSM-5, and Faujasite (FAU) topologies have been developed. Production sand waste is used as a silica source; after it is passed sand pretreatment and silica extraction steps, for hierarchical zeolites synthesis, to reduce their production cost. Physicochemical properties of the synthesized hierarchical zeolites are analyzed, such as surface area, porosity, topology, and textural properties. These physicochemical properties will be compared with the one obtained using the commercial silica sources. Then, the developed Hierarchical zeolites are applied as catalyst for CNTs production from CO2. The fixed bed Chemical Vapor Deposition (CVD) technique is introduced for CNTs synthesis, as its low energy cost consumption, high quality of CNTs synthesis. The physical properties of CNTs, including tube diameter, graphitic structure (ID/IG). To prove of concept for extracting silica source as a substance for hierarchical zeolite synthesis and use as catalyst for CNTs production from CO2. Two types of hierarchical zeolites nanosheet (ZSM-5, and FAU) have been successfully synthesized from nano silica obtained froms and waste, with high yield more than 75%. The hierarchical-FAU, and hierarchical -FAU-5's performance on CNTs production from CO2 are compared together. It was found that the hierarchical-FAU provide the best catalyst for CNT production with the CNTs yield of 28.9%, the average diameter of 22.8 nm and ID/IGof 0.68. The optimal condition for hierarchical zeolites synthesis will be further applied in the prototype phase, in the 50X up-scaling. This technology is expected to lower an amount of production sand waste disposal to landfill. Moreover, the synthesized hierarchical zeolites will be further explored in other advanced reactions apart from CNTs synthesis, such as catalytic cracking. Hierarchical zeolites from production sand waste are firstly initiated and successfully achieved in PTTEP. From these findings, information will be applied to the process design of Hierarchical zeolites synthesis in prototype, and scale-up phase.
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Davis, Benjamin, Nitin Muralidharan, Cary Pint, and Matthew R. Maschmann. "Electrically Addressable Hierarchical Carbon Nanotube Forests." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67226.
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Hierarchical, branched carbon nanotube (CNT) forest assemblies were created by synthesizing a second generation of CNTs directly from the alumina-coated surface of a parent CNT forest. First, a parent CNT forest generation was synthesized using floating catalyst chemical vapor deposition (CVD) in which gaseous argon and hydrogen are flowed into a tube furnace, along with a controlled flow rate of ferrocene nanoparticles suspended in xylene solvent. Next, a thin alumina coating was applied to the parent CNT forest using atomic layer deposition (ALD). The ALD process pulses alternating gases of water vapor and trimethylaluminum (TMA) and is repeated for 100 cycles, yielding a 10nm coating. This coating adheres to the outer walls of the larger CNTs and serves as a supportive surface to enable the growth of a second CNT generation. Finally, a second CNT generation was synthesized from the parent CNT forest using a floating-catalyst CVD method similar to that used for the parent generation. The relatively low areal density of the parent CNT generation allows for gas-phase additive processing (i.e. ALD and floating catalyst CVD) to occur deep within the volume of the original parent CNT forest. Transmission electron microscopy analysis of the hierarchical CNT forests shows that second-generation CNTs nucleate and grow from the alumina-coated walls of the parent generation rather than nucleating from the original growth substrate, as has been previously reported. Further, physical confinement of the second-generation catalyst particle on the external surface of the parent generation CNTs (28 nm average diameter) leads to small-diameter CNTs (8 nm average) for the second generation. Further, radial breathing modes are detected by Raman spectroscopy, indicating single-walled or few-walled CNTs are synthesized in the second generation. The hierarchical forests exhibit many desirable properties compared to single generation forests. Because the second generation CNTs within the interstitial regions of the parent CNT forest, they increase the structural rigidity of the cellular CNT forest morphology, increasing in mechanical stiffness by ten-fold, relative to the parent CNT forest. Further, we demonstrate that electrical continuity between the CNT generations is retained. Because a thin alumina buffer layer exists between CNT generations, electrical continuity is not guaranteed. Cyclic voltammetry and electrochemical impedance spectroscopy are used to characterize the electrical resistance elements within the hierarchical forest. This hierarchical structure offers a new avenue to tailor the performance of CNT forests and offers performance enhancements for applications in thermal interfaces, electrical interconnects, dry adhesives and energy generation and storage.
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Ayala, Alberto, Michael E. Gebel, Robert A. Okamoto, Paul L. Rieger, Norman Y. Kado, Cherie Cotter, and Namita Verma. "Oxidation Catalyst Effect on CNG Transit Bus Emissions." In 2003 JSAE/SAE International Spring Fuels and Lubricants Meeting. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2003. http://dx.doi.org/10.4271/2003-01-1900.
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