Download or read book Carbon Nanotube Supported Metal Catalysts for NOx Reduction Using Hydrocarbon Reductants written by Eduardo Santillan-Jimenez and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NOx Reduction with Hydrocarbons Under Oxidizing Conditions Over Alumina Supported Metal Catalysts written by Erol Seker and published by . This book was released on 2000 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fullerenes Advances in Research and Application 2012 Edition written by and published by ScholarlyEditions. This book was released on 2012-12-26 with total page 1855 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fullerenes—Advances in Research and Application: 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Fullerenes. The editors have built Fullerenes—Advances in Research and Application: 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Fullerenes in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Fullerenes—Advances in Research and Application: 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Nanocarbon and Its Composites written by Anish Khan and published by Woodhead Publishing. This book was released on 2018-11-30 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanocarbon and Its Composites: Preparation, Properties and Applications provides a detailed and comprehensive review of all major innovations in the field of nanocarbons and their composites, including preparation, properties and applications. Coverage is broad and quite extensive, encouraging future research in carbon-based materials, which are in high demand due to the need to develop more sustainable, recyclable and eco-friendly methods for materials. Chapters are written by eminent scholars and leading experts from around the globe who discuss the properties and applications of carbon-based materials, such as nanotubes (buckytubes), fullerenes, cones, horns, rods, foams, nanodiamonds and carbon black, and much more. Chapters provide cutting-edge, up-to-date research findings on the use of carbon-based materials in different application fields and illustrate how to achieve significant enhancements in physical, chemical, mechanical and thermal properties. Demonstrates systematic approaches and investigations from design, synthesis, characterization and applications of nanocarbon based composites Aims to compile information on the various aspects of synthesis, properties and applications of nano-carbon based materials Presents a useful reference and technical guide for university academics and postgraduate students (Masters and Ph.D.)

Download or read book CRC Concise Encyclopedia of Nanotechnology written by Boris Ildusovich Kharisov and published by CRC Press. This book was released on 2016-01-06 with total page 1203 pages. Available in PDF, EPUB and Kindle. Book excerpt: The CRC Concise Encyclopedia of Nanotechnology sets the standard against which all other references of this nature are measured. As such, it is a major resource for both skilled professionals and novices to nanotechnology.The book examines the design, application, and utilization of devices, techniques, and technologies critical to research at the

Download or read book Scalable Carbon Nanotube Growth and Design of Efficient Catalysts for Fischer Tropsch Synthesis written by Haider H. Almkhelfe and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The continued depletion of fossil fuels and concomitant increase in greenhouse gases have encouraged worldwide research on alternative processes to produce clean fuel. Fischer-Tropsch synthesis (FTS) is a heterogeneous catalytic reaction that converts syngas (CO and H2) to liquid hydrocarbons. FTS is a well-established route for producing clean liquid fuels. However, the broad product distribution and limited catalytic activity are restricting the development of FTS. The strong interactions between the active metal catalyst (Fe or Co) and support (Al2O3, SiO2 and TiO2) during post-synthesis treatments of the catalyst (such as calcination at ~500°C and reduction ~550°C) lead to formation of inactive and unreducible inert material like Fe2SiO4, CoAl2O4, Co2SiO4. The activity of FTS catalyst is negatively impacted by the presence of these inactive compounds. In our study, we demonstrate the use of a modified photo-Fenton process for the preparation of carbon nanotube (CNT)-supported Co and Fe catalysts that are characterized by small and well-dispersed catalyst particles on CNTs that require no further treatments. The process is facile, highly scalable, and involves the use of green catalyst precursors and an oxidant. The reaction kinetic results show high CO conversion (85%), selectivity for liquid hydrocarbons and stability. Further, a gaseous product mixture from FTS (C1-C4) was utilized as an efficient feedstock for the growth of high-quality, well-aligned single-wall carbon nanotube (SWCNT) carpets of millimeter-scale heights on Fe and (sub) millimeter-scale heights on Co catalysts via chemical vapor deposition (CVD). Although SWCNT carpets were grown over a wide temperature range (between 650 and 850°C), growth conducted at optimal temperatures for Co (850°C) and Fe (750°C) yielded predominantly SWCNTs that are straight, clean, and with sidewalls that are largely free of amorphous carbon. Also, low-temperature CVD growth of CNT carpets from Fe and Fe-Cu catalysts using a gaseous product mixture from FTS as a superior carbon feedstock is demonstrated. The efficiency of the growth process is evidenced by the highly dense, vertically aligned CNT structures from both Fe and Fe-Cu catalysts even at temperatures as low as 400°C-a record low growth temperature for CNT carpets obtained via conventional thermal CVD. The use of FTS-GP facilitates low-temperature growth of CNT carpets on traditional (alumina film) and nontraditional substrates (aluminum foil) and has the potential of enhancing CNT quality, catalyst lifetime, and scalability. We demonstrate growth of SWCNT carpets with diameter distributions that are smaller than SWCNTs in conventional carpets using a CVD process that utilizes the product gaseous mixture from Fischer-Tropsch synthesis (FTS-GP). The high-resolution transmission electron microscopic (HR-TEM) and Raman spectroscopic results reveal that the use of a high melting point metal as a catalyst promoter in combination with either Co (1.5 nm ± 0.7) at 850oC or Fe (1.9 nm ± 0.8) at 750oC yields smaller-diameter SWCNT arrays with narrow diameter distributions. Scalable synthesis of carbon nanotubes (CNTs), carbon nanofibers (CNFs), and onion like carbon (OLC) in a batch reactor using supercritical fluids as a reaction media is demonstrated. The process utilizes toluene, ethanol, or butanol as a carbon precursor in combination with ferrocene that serves as a catalyst precursor and a secondary carbon source. The use of supercritical fluids for growth does not only provide a route for selective growth of a variety of carbon nanomaterials, but also provides a unique one-step approach that is free of aggressive acid treatment for synthesis of CNT-supported metallic nanoparticle composites for catalysis and energy storage applications.

Download or read book Nitrogen doped Carbon Materials as Oxygen Reduction Reaction Catalysts for Metal air Fuel Cells and Batteries written by Zhu Chen and published by . This book was released on 2012 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal air battery has captured the spotlight recently as a promising class of sustainable energy storage for the future energy systems. Metal air batteries offer many attractive features such as high energy density, environmental benignity, as well as ease of fuel storage and handling. In addition, wide range of selection towards different metals exists where different energy capacity can be achieved via careful selection of different metals. The most energy dense systems of metal-air battery include lithium-air, aluminum-air and zinc-air. Despite the choice of metal electrode, oxygen reduction (ORR) occurs on the air electrode and oxidation occurs on the metal electrode. The oxidation of metal electrode is a relatively facile reaction compared to the ORR on the air electrode, making latter the limiting factor of the battery system. The sluggish ORR kinetics greatly affects the power output, efficiency, and lifetime of the metal air battery. One solution to this problem is the use of active, affordable and stable catalyst to promote the rate of ORR. Currently, platinum nanoparticles supported on conductive carbon (Pt/C) are the best catalyst for ORR. However, the prohibitively high cost and scarcity of platinum raise critical issues regarding the economic feasibility and sustainability of platinum-based catalysts. Cost reduction via the use of novel technologies can be achieved by two approaches. The first approach is to reduce platinum loading in the catalyst formulation. Alternatively platinum can be completely eliminated from the catalyst composition. The aim of this work is to identify and synthesize alternative catalysts for ORR toward metal air battery applications without the use of platinum or other precious metals (i.e., palladium, silver and gold). Non-precious metal catalysts (NPMC) have received immense international attentions owing to the enormous efforts in pursuit of novel battery and fuel cell technologies. Different types of NPMC such as transition metal alloys, transition metal or mixed metal oxides, chalcogenides have been investigated as potential contenders to precious metal catalysts. However, the performance and stability of these catalysts are still inferior in comparison. Nitrogen-doped carbon materials (NCM) are an emerging class of catalyst exhibiting great potential towards ORR catalysis. In comparison to the metal oxides, MCM show improved electrical conductivity. Furthermore, NCM exhibit higher activity compared to chalcogenides and transition metal alloys. Additional benefits of NCM include the abundance of carbon source and environmental benignity. Typical NCM catalyst is composed of pyrolyzed transition metal macrocycles supported by high surface area carbon. These materials have demonstrated excellent activity and stability. However, the degradation of these catalysts often involves the destruction of active sites containing the transition metal centre. To further improve the durability and mass transport of NCM catalyst, a novel class of ORR catalyst based on nitrogen-doped carbon nanotubes (NCNT) is investigated in a series of studies. The initial investigation focuses on the synthesis of highly active NCNT using different carbon-nitrogen precursors. This study investigated the effect of using cyclic hydrocarbon (pyridine) and aliphatic hydrocarbon (ethylenediamine) towards the formation and activity of NCNT. The innate structure of the cyclic hydrocarbon promotes the formation of NCNT to provide higher product yield; however, the aliphatic hydrocarbon promotes the formation of surface defects where the nitrogen atoms can be incorporated to form active sites for ORR. As a result, a significant increase in the ORR activity of 180 mV in half-wave potential is achieved when EDA was used as carbon-nitrogen precursor. In addition, three times higher limiting current density was observed for the NCNT synthesized from ethylenediamine. Based on the conclusion where highly active NCNT was produced from aliphatic hydrocarbon, similar carbon-nitrogen precursors with varying carbon to nitrogen ratio in the molecular structure (ethylenediamine, 1, 3-diaminopropane, 1, 4-diaminobutane) were adapted for the synthesis of NCNT. The investigation led to the conclusion that higher nitrogen to carbon ratio in the molecular structure of the precursors benefits the formation of active NCNT for ORR catalysis. The origin of such phenomena can be correlated with the higher relative nitrogen content of the resultant NCNT synthesized from aliphatic carbon precursor that provided greater nitrogen to carbon ratio. As the final nitrogen content increased in the molecular structure, the half-wave potential of the resultant NCNT towards ORR catalysis was increased by 120 mV. The significant improvement hints the critical role of nitrogen content towards ORR catalysis.

Download or read book New Heterogeneous Catalysts for the Selective Reduction of NOx Under Lean Conditions Final Report written by and published by . This book was released on 2004 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The original goal of this program was the identification and design of new noble-metal-based catalysts for the selective catalytic reduction of nitric oxide by hydrocarbons under excess oxygen (i.e., ''lean'') conditions (HC-SCR). Work conducted in the first funding cycle of this award (i.e., 1997-2000) was successful in allowing us to develop an understanding of the fundamental surface chemistry taking place during the adsorption and reaction of nitrogen oxides and propylene on the surface of supported noble metal catalysts. Both experimental results collected in our own group as well as molecular simulation results published by Professor Neurock suggested that in order to improve the performance of the Pt catalysts--in terms of the nitrogen selectivity and the temperature window of operation-- it was necessary to introduce a second metal. However, synthesizing such catalysts with the metals of interest (i.e., Pt-Au, Pt-Ru, Pt-Rh, etc.) with some degree of control of the structure and composition of the resulting supported metal particles is in itself a research challenge. Consequently, the bulk of our efforts during the second funding cycle of this award (covered by this report) was shifted to the use of organometallic cluster precursors for the synthesis on novel bimetallic catalysts. During this time we have also continued to maintain an interest in NOx abatement, but have redirected our efforts from the HC-SCR process to the more promising from a commercial standpoint NOx Storage Reduction (NSR) approach.

Download or read book Catalysts for Alcohol fuelled Direct Oxidation Fuel Cells written by Zhen-Xing Liang and published by Royal Society of Chemistry. This book was released on 2012 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a state-of-the-art review on recent advances in nanocatalysts and electrocatalysis in DOFCs.

Download or read book Reformate Assisted Hydrocarbon Selective Catalytic NOx Reduction Over Silver Supported on Alumina Catalysts written by William L. Johnson and published by . This book was released on 2006 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Chemistry of Metal Catalyst Under Carbon Nanotube Growth Conditions written by Tyson Cody Back and published by . This book was released on 2010 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: The catalyst nanoparticle is critical to the yield, type, and diameter in the growth and nucleation of carbon nanotubes. The objective of this study is focused on determining what changes take place with the catalyst chemistry under growth conditions typically seen in chemical vapor deposition, CVD, experiments. It is well known that catalyst poisoning can occur and in turn effects the catalytic activity of the nanoparticle. A complete description of this mechanism is as of yet undetermined. In order to elucidate this process iron films were deposited onto Si substrates that contained a support layer of Al2O3 or SiO2. These samples were investigated with various surface chemistry techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and electron energy loss spectroscopy (EELS). In addition, structural characteristics were investigated with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface techniques were used in-situ in order to observe chemistries that might not be observable outside a CVD reactor. Two sets of experiments were performed on the silica and alumina supports. The first consisted of carbon nanotube growth at near atmospheric pressure, while the second was performed under vacuum. The oxide support was shown to have an affect on the type of nanotubes grown under identical conditions. The silica support films produced more MWNT, while the alumina support films produced more SWNT. This difference was due to the amount of ripening that takes place on the oxide supports. Also in-situ XPS revealed differences in the chemistry of iron catalyst during growth and these differences were attributed to substrate interactions between alumina and iron. Finally, in-situ XPS analysis showed no evidence of carbides or oxides acting as a catalyst during the nucleation process.

Download or read book Aligned Carbon Nanotube with Electro catalytic Activity for Oxygen Reduction Reaction written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A catalyst for an electro-chemical oxygen reduction reaction (ORR) of a bundle of longitudinally aligned carbon nanotubes having a catalytically active transition metal incorporated longitudinally in said nanotubes. A method of making an electro-chemical catalyst for an oxygen reduction reaction (ORR) having a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, where a substrate is in a first reaction zone, and a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into the first reaction zone which is maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is then introduced to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes over the substrate with a catalytically active transition metal incorporated throughout the nanotubes.

Download or read book Two stage Catalytic Reduction of NOx with Hydrocarbons written by Umit S. Ozkan and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A two-stage system for the catalytic reduction of NO from lean-burn natural gas reciprocating engine exhaust is investigated. Each of the two stages uses a distinct catalyst. The first stage is oxidation of NO to NO{sub 2} and the second stage is reduction of NO{sub 2} to N{sub 2} with a hydrocarbon. The central idea is that since NO{sub 2} is a more easily reduced species than NO, it should be better able to compete with oxygen for the combustion reaction of hydrocarbon, which is a challenge in lean conditions. Early work focused on demonstrating that the N{sub 2} yield obtained when NO{sub 2} was reduced was greater than when NO was reduced. NO{sub 2} reduction catalysts were designed and silver supported on alumina (Ag/Al{sub 2}O{sub 3}) was found to be quite active, able to achieve 95% N{sub 2} yield in 10% O{sub 2} using propane as the reducing agent. The design of a catalyst for NO oxidation was also investigated, and a Co/TiO{sub 2} catalyst prepared by sol-gel was shown to have high activity for the reaction, able to reach equilibrium conversion of 80% at 300 C at GHSV of 50,000h{sup -1}. After it was shown that NO{sub 2} could be more easily reduced to N{sub 2} than NO, the focus shifted on developing a catalyst that could use methane as the reducing agent. The Ag/Al{sub 2}O{sub 3} catalyst was tested and found to be inactive for NOx reduction with methane. Through iterative catalyst design, a palladium-based catalyst on a sulfated-zirconia support (Pd/SZ) was synthesized and shown to be able to selectively reduce NO{sub 2} in lean conditions using methane. Development of catalysts for the oxidation reaction also continued and higher activity, as well as stability in 10% water, was observed on a Co/ZrO{sub 2} catalyst, which reached equilibrium conversion of 94% at 250 C at the same GHSV. The Co/ZrO{sub 2} catalyst was also found to be extremely active for oxidation of CO, ethane, and propane, which could potential eliminate the need for any separate oxidation catalyst. At every stage, catalyst synthesis was guided by the insights gained through detailed characterization of the catalysts using many surface and bulk analysis techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, Temperature-programmed Reduction, Temperature programmed Desorption, and Diffuse Reflectance InfraRed Fourier Transform Spectroscopy as well as steady state reaction experiments. Once active catalysts for each stage had been developed, a physical mixture of the two catalysts was tested for the reduction of NO with methane in lean conditions. These experiments using a mixture of the catalysts produced N2 yields as high as 90%. In the presence of 10% water, the catalyst mixture produced 75% N{sub 2} yield, without any optimization. The dual catalyst system developed has the potential to be implemented in lean-burn natural gas engines for reducing NOx in lean exhaust as well as eliminating CO and unburned hydrocarbons without any fuel penalty or any system modifications. If funding continues, future work will focus on improving the hydrothermal stability of the system to bring the technology closer to application.

Download or read book Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity written by and published by . This book was released on 2007 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon SWNTs are attractive materials for supporting electrocatalysts. The properties of SWNTs are highly tunable and controlled by the nanotube's circumferential periodicity and their surface chemistry. These unique characteristics suggest that architectures constructed from these types of carbon support materials would exhibit interesting and useful properties. Here, we expect that the structure of the carbon nanotube support will play a major role in stabilizing metal electrocatalysts under extreme operating conditions and suppress both catalyst and support degradation. Furthermore, the chemical modification of the carbon nanotube surfaces can be expected to alter the interface between the catalyst and support, thus, enhancing the activity and utilization of the electrocatalysts. We plan to incorporate discrete reaction sites into the carbon nanotube lattice to create intimate electrical contacts with the catalyst particles to increase the metal catalyst activity and utilization. The work involves materials synthesis, design of electrode architectures on the nanoscale, control of the electronic, ionic, and mass fluxes, and use of advanced optical spectroscopy techniques.

Download or read book Synthesis of Carbon Nanotube supported Catalytic Nanoparticles and Their Applications in Catalysis written by Horng-Bin Pan and published by . This book was released on 2011 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fine Rh nanoparticles can be deposited uniformly on surfaces of carboxylate functionalized MWNTs using the one-pot sonochemical method. The CNT-supported Rh nanoparticles show remarkably high catalytic active and are reusable for hydrogenation of arenes at room temperature. Complete ring saturation of polycyclic aromatic hydrocarbons (PAHs) can be achieved under mild hydrogenation conditions using the MWNTs catalyst that can not be done by commercially available Rh nanocatalysts (Rh- Escat 3401 ). This technique also provides a simple and rapid way of making Rh nanoparticles of different size, which allows us to study particle size effects on catalysis. Furthermore, we extended the sonochemical method to synthesize well-dispersed Pt-Rh alloy bimetallic nanoparticles on sidewalls of CNTs and studied the potentially improved activity (synergistic effect) for room temperature catalytic hydrogenation of neat benzene, neat alkylbenzenes, and PAHs.

Download or read book Modification of supported metal catalysts written by Adrianus J. den Hartog and published by . This book was released on 1990 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book MECHANISTIC STUDIES AND DESIGN OF HIGHLY ACTIVE CUPRATE CATALYSTS FOR THE DIRECT DECOMPOSITION AND SELECTIVE REDUCTION OF NITRIC OXIDE AND HYDROCARBONS TO NITROGEN FOR ABATEMENT OF STACK EMISSIONS written by and published by . This book was released on 1998 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: A flow trough type catalytic reactor system was adequately modified for NO related catalytic and adsorption measurements, including the on-line connection of a digital chemiluminescent NO-NO(subscript x) analyzer to the reactor outlet system. Moreover, we have largely completed the installation of an FTIR coupled catalytic system containing a HTEC cell for high temperature DRIFT studies. Three different barium cuprate samples, Ba2CuO3, BaCuO2, and Ba2Cu3O5 were synthesized and characterized by powder XRD for catalytic tests. Prior to catalytic studies over these cuprates, a new, liquid indium based supported molten metal catalyst (In-SMMC) was tested in the reduction of NO by various reductants. In the presence of excess O2 and H2O, the In-SMMC proved to be more active for the selective catalytic reduction (SCR) of NO to N2 by ethanol than most other catalysts. Using C1-C3 alcohols as reductants, self sustained periodic oscillations observed in the NO(subscript x) concentrations of reactor effluents indicated the first time that radical intermediates can be involved in the SCR of NO by alcohols. Further, In-SMMC is the only effective and water tolerant SCR catalyst reported thus far which contains SiO2 support. Thus, this novel catalyst opens up a promising new alternative for developing an effective and durable catalyst for NO(subscript x) abatement in stack emission.