Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Enhanced Activity Of Nanocrystalline Zeolites For Selective Catalytic Reduction Of Nox
Download Enhanced Activity Of Nanocrystalline Zeolites For Selective Catalytic Reduction Of Nox full books in PDF, epub, and Kindle. Read online Enhanced Activity Of Nanocrystalline Zeolites For Selective Catalytic Reduction Of Nox ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Enhanced Activity of Nanocrystalline Zeolites for Selective Catalytic Reduction of NOx by : Vicki H. Grassian
Download or read book Enhanced Activity of Nanocrystalline Zeolites for Selective Catalytic Reduction of NOx written by Vicki H. Grassian and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanocrystalline zeolites with discrete crystal sizes of less than 100 nm have different properties relative to zeolites with larger crystal sizes. Nanocrystalline zeolites have improved mass transfer properties and very large internal and external surface areas that can be exploited for many different applications. The additional external surface active sites and the improved mass transfer properties of nanocrystalline zeolites offer significant advantages for selective catalytic reduction (SCR) catalysis with ammonia as a reductant in coal-fired power plants relative to current zeolite based SCR catalysts. Nanocrystalline NaY was synthesized with a crystal size of 15-20 nm and was thoroughly characterized using x-ray diffraction, electron paramagnetic resonance spectroscopy, nitrogen adsorption isotherms and Fourier Transform Infrared (FT-IR) spectroscopy. Copper ions were exchanged into nanocrystalline NaY to increase the catalytic activity. The reactions of nitrogen dioxides (NO{sub x}) and ammonia (NH{sub 3}) on nanocrystalline NaY and CuY were investigated using FT-IR spectroscopy. Significant conversion of NO{sub 2} was observed at room temperature in the presence of NH{sub 3} as monitored by FT-IR spectroscopy. Copper-exchanged nanocrystalline NaY was more active for NO{sub 2} reduction with NH{sub 3} relative to nanocrystalline NaY.
Book Synopsis Selective Catalytic Reduction of NOx by : Oliver Kröcher
Download or read book Selective Catalytic Reduction of NOx written by Oliver Kröcher and published by MDPI. This book was released on 2018-12-14 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Selective Catalytic Reduction of NOx" that was published in Catalysts
Book Synopsis Nano Catalysts for Diesel Engine Emission Remediation by :
Download or read book Nano Catalysts for Diesel Engine Emission Remediation written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this project was to develop durable zeolite nanocatalysts with broader operating temperature windows to treat diesel engine emissions to enable diesel engine based equipment and vehicles to meet future regulatory requirements. A second objective was to improve hydrothermal durability of zeolite catalysts to at least 675 C. The results presented in this report show that we have successfully achieved both objectives. Since it is accepted that the first step in NOx conversion under SCR (selective catalytic reduction) conditions involves NO oxidation to NO2, we reasoned that catalyst modification that can enhance NO oxidation at low-temperatures should facilitate NOx reduction at low temperatures. Considering that Cu-ZSM-5 is a more efficient catalyst than Fe-ZSM-5 at low-temperature, we chose to modify Cu-ZSM-5. It is important to point out that the poor low-temperature efficiency of Fe-ZSM-5 has been shown to be due to selective absorption of NH3 at low-temperatures rather than poor NO oxidation activity. In view of this, we also reasoned that an increased electron density on copper in Cu-ZSM-5 would inhibit any bonding with NH3 at low-temperatures. In addition to modified Cu-ZSM-5, we synthesized a series of new heterobimetallic zeolites, by incorporating a secondary metal cation M (Sc{sup 3+}, Fe{sup 3+}, In{sup 3+}, and La{sup 3+}) in Cu exchanged ZSM-5, zeolite-beta, and SSZ-13 zeolites under carefully controlled experimental conditions. Characterization by diffuse-reflectance ultra-violet-visible spectroscopy (UV-Vis), X-ray powder diffraction (XRD), extended X-ray absorption fine structure spectroscopy (EXAFS) and electron paramagnetic resonance spectroscopy (EPR) does not permit conclusive structural determination but supports the proposal that M{sup 3+} has been incorporated in the vicinity of Cu(II). The protocols for degreening catalysts, testing under various operating conditions, and accelerated aging conditions were provided by our collaborators at John Deere Power Systems. Among various zeolites reported here, CuFe-SSZ-13 offers the best NOx conversion activity in 150-650 C range and is hydrothermally stable when tested under accelerated aging conditions. It is important to note that Cu-SSZ-13 is now a commercial catalyst for NOx treatment on diesel passenger vehicles. Thus, our catalyst performs better than the commercial catalyst under fast SCR conditions. We initially focused on fast SCR tests to enable us to screen catalysts rapidly. Only the catalysts that exhibit high NOx conversion at low temperatures are selected for screening under varying NO2:NOx ratio. The detailed tests of CuFe-SSZ-13 show that CuFe-SSZ-13 is more effective than commercial Cu-SSZ-13 even at NO2:NOx ratio of 0.1. The mechanistic studies, employing stop-flow diffuse reflectance FTIR spectroscopy (DRIFTS), suggest that high concentration of NO, generated by heterobimetallic zeolites, is probably responsible for their superior low temperature NOx activity. The results described in this report clearly show that we have successfully completed the first step in a new emission treatment catalyst which is synthesis and laboratory testing employing simulated exhaust. The next step in the catalyst development is engine testing. Efforts are in progress to obtain follow-on funding to carry out scale-up and engine testing to facilitate commercialization of this technology.
Book Synopsis Characterization and Design of Zeolite Catalysts by : Miki Niwa
Download or read book Characterization and Design of Zeolite Catalysts written by Miki Niwa and published by Springer Science & Business Media. This book was released on 2010-08-17 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalysis and catalyst is a key technology to solve the problems in energy and environment issues to sustain our human society. We believe that comprehensive understanding of the catalysis and catalyst provides us a chance to develop a new catalyst and contributes greatly to our society. However, the ?eld of heterogeneous catalyst is dif?cultto study andstill stays behindmoredeveloped?elds ofchemistry such as organic and physical chemistries. This is a dilemma to the chemists who study the catalysis and catalyst. While we can accomplish the progress in the - dustrial application, the scienti?c understandingis not complete yet. A gap between the useful application and incomplete scienti?c understanding, however, becomes smaller and smaller in recent years. Because zeolites are ?ne crystals, and the structure is clearly known, the study on the catalysis using the zeolites is easier than those encountered in other catalysts such as metals and metal oxides. Very fortunately, zeolites provide us the strong acidity with the ?ne distribution which enables various useful catalytic reactions. When some metals and cations are loaded in close to the acid sites, these loadede- ments show extraordinarycharacters, and many catalytic reactions proceed thereon.
Book Synopsis New and Future Developments in Catalysis by : Zdenek Sobalik
Download or read book New and Future Developments in Catalysis written by Zdenek Sobalik and published by Elsevier Inc. Chapters. This book was released on 2013-07-17 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Zeolites in Sustainable Chemistry by : Feng-Shou Xiao
Download or read book Zeolites in Sustainable Chemistry written by Feng-Shou Xiao and published by Springer. This book was released on 2015-09-28 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is devoted to the new development of zeolitic catalysts with an emphasis on new strategies for the preparation of zeolites, novel techniques for their characterization and emerging applications of zeolites as catalysts for sustainable chemistry, especially in the fields of energy, biomass conversion and environmental protection. Over the years, energy and the environment have become the most important global issues, while zeolitic catalysts play important roles in addressing them. With individual chapters written by leading experts, this book offers an essential reference work for researchers and professionals in both academia and industry. Feng-Shou Xiao is a Professor at the Department of Chemistry, Zhejiang University, China. Xiangju Meng is an Associate Professor at the Department of Chemistry, Zhejiang University, China.
Book Synopsis The Selective Catalytic Reduction of Nitrogen Oxides with Methane Using Nanocrystalline Metal Oxides by : Mark Douglas Fokema
Download or read book The Selective Catalytic Reduction of Nitrogen Oxides with Methane Using Nanocrystalline Metal Oxides written by Mark Douglas Fokema and published by . This book was released on 2000 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Zeolite Catalysts by : Subhash Bhatia
Download or read book Zeolite Catalysts written by Subhash Bhatia and published by CRC Press. This book was released on 1989-12-21 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented in an easy-to-read form, this book on zeolite catalysis cover all aspects of the subject. It focuses on synthesis, structure, diffusion, deactivation, and industrial applications. This book is an ideal text for courses on catalysis or as a supplementary text for those studying applied or industrial chemistry. It is also a useful resource for anyone who works with zeolites as catalysts in the laboratory, pilot plants, or commercial installations.
Book Synopsis SELECTIVE REDUCTION OF NOX IN OXYGEN RICH ENVIRONMENTS WITH PLASMA-ASSISTED CATALYSIS by :
Download or read book SELECTIVE REDUCTION OF NOX IN OXYGEN RICH ENVIRONMENTS WITH PLASMA-ASSISTED CATALYSIS written by and published by . This book was released on 2003 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The control of NOx (NO and NO2) emissions from so-called ''lean-burn'' vehicle engines remains a challenge. In recent years, there have been a number of reports that show that a plasma device combined with a catalyst can reduce as high as 90% or more of NOx in simulated diesel and other ''lean-burn'' exhaust. In the case of propylene containing simulated diesel exhaust, the beneficial role of a plasma treatment is now thought to be due to oxidation of NO to NO2, and the formation of partially oxidized hydrocarbons that are more active for the catalytic reduction of NO2 than propylene. Thus, the overall system can be most usefully described as hydrocarbon selective catalytic reduction (SCR) enhanced by 'reforming' the exhaust with a non-thermal plasma (NTP) device. For plasma-enhanced catalysis, both zeolite- and alumina-based materials have shown high activity, albeit in somewhat different temperature ranges, when preceded by an NTP reactor. This paper will briefly describe our research efforts aimed at optimizing the catalyst materials for NTP-catalysis devices based, in part, on our continuing studies of the NTP- and catalytic-reaction mechanisms. Various alkali- and alkaline earth-cation-exchanged Y zeolites have been prepared, their material properties characterized, and they have been tested as catalytic materials for NOx reduction in laboratory NTP-catalysis reactors. Interestingly, NO2 formed in the plasma and not subsequently removed over these catalysts, will back-convert to NO, albeit to varying extents depending upon the nature of the cation. Besides this comparative reactivity, we will also discuss selected synthesis strategies for enhancing the performance of these zeolite-based catalyst materials. A particularly important result from our mechanistic studies is the observation that aldehydes, formed during the plasma treatment of simulated diesel exhaust, are the important species for the reduction of NOx to N2. Indeed, acetaldehyde has been found to be especially effective in the thermal reduction of both NO and NO2 over Ba- and Na-Y zeolite catalysts.
Book Synopsis Oxford Handbook of Nanoscience and Technology by : A. V. Narlikar
Download or read book Oxford Handbook of Nanoscience and Technology written by A. V. Narlikar and published by OUP Oxford. This book was released on 2010-02-11 with total page 960 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an agenda-setting and high-profile book that presents an authoritative and cutting-edge analysis of nanoscience and technology. The Oxford Handbook of Nanoscience and Technology provides a comprehensive and accessible overview of the major achievements in different aspects of this field. The Handbook comprises 3 volumes, structured thematically, with 25 chapters each. Volume I presents fundamental issues of basic physics, chemistry, biochemistry, tribology etc. of nanomaterials. Volume II focuses on the progress made with host of nanomaterials including DNA and protein based nanostructures. Volume III highlights engineering and related developments, with a focus on frontal application areas. All chapters are written by noted international experts in the field. The book should be useful for final year undergraduates specializing in the field. It should prove indispensable to graduate students, and serious researchers from academic and industrial sectors working in the field of Nanoscience and Technology from different disciplines including Physics, Chemistry, Biochemistry, Biotechnology, Medicine, Materials Science, Metallurgy, Ceramics, Information Technology as well as Electrical, Electronic and Computational Engineering.
Book Synopsis Mesoporous Zeolites by : Javier García-Martínez
Download or read book Mesoporous Zeolites written by Javier García-Martínez and published by John Wiley & Sons. This book was released on 2015-05-26 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: Authored by a top-level team of both academic and industrial researchers in the field, this is an up-to-date review of mesoporous zeolites. The leading experts cover novel preparation methods that allow for a purpose-oriented fine-tuning of zeolite properties, as well as the related materials, discussing the specific characterization methods and the applications in close relation to each individual preparation approach. The result is a self-contained treatment of the different classes of mesoporous zeolites. With its academic insights and practical relevance this is a comprehensive handbook for researchers in the field and related areas, as well as for developers from the chemical industry.
Book Synopsis Investigating the High-temperature Chemistry of Zeolites by : Dustin W. Fickel
Download or read book Investigating the High-temperature Chemistry of Zeolites written by Dustin W. Fickel and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we show using mass-spectrometry temperature-programmed-desorption (MS-TPD) that the product of heating high-silica H-zeolites is predominantly hydrogen. Using electronicstructure calculations we also show a plausible path for the formation of hydrogen from zeolite Brønsted acid sites and propose that the reaction should lead to the formation of [AlO 4/ h] 0 sites in the zeolite. These [AlO 4/ h] 0 sites can act as nonacidic one-electron acceptors of adsorbed molecules and could react further to form a more stable species. As such these sites could play an important role in the catalytic chemistry of hydrocarbons at high temperatures. It is proposed that the disappearance of hydrogen from the hydroxyl nests is accompanied by the formation of bisperoxysilyl groups (Si-O-O-Si). Electronic structure calculations are also employed to support the energetic feasibility of this reaction mechanism. Silicalite-1 samples made with tetraethyl-orthosilicate show a number of differences in their IR and UV-Vis spectra compared to samples made with other silica sources, and it appears that the source of silica plays an important role in the structure of the internal defects. Nitrogen oxides (NOx) are a major atmospheric pollutant produced through the combustion of fossil fuels in internal combustion engines. Copper-exchanged zeolites are promising as selective catalytic reduction (SCR) catalysts for the conversion of NO into N 2 and O 2 . Previously, it has been shown that when fresh, Cu-ZSM-5 has high NH 3 -SCR activity, however, ZSM-5 zeolites are highly susceptible to dealumination during steaming, which results in a lost of SCR activity. Whereas, recent reports have shown the enhanced performance of Cu-CHA catalysts over other zeolite frameworks in the NO decomposition of exhaust gas streams. In the present study, Rietveld refinement of variable-temperature XRD synchrotron data obtained for Cu-SSZ-13 and Cu-SSZ-16 is used to investigate the location of copper cations in the zeolite pores and the effect of temperature on these sites and on framework stability. The XRD patterns show that the thermal stability of the zeolite SSZ-13 is increased significantly when copper is exchanged into the framework compared with the acid form of the zeolite, H-SSZ-13. Cu-SSZ-13 is also more thermally stable than Cu-SSZ-16. From the refined diffraction patterns, the atomic positions of framework atoms, copper locations and occupancies, and thermal displacement parameters were determined as a function of temperature for both zeolites. Copper is found in the cages coordinated to three oxygen atoms of the six-membered rings. These results lead us to investigate the NH 3 -SCR activity of the small-pore zeolites, Cu-SSZ-13, Cu-SSZ-16, and Cu-SAPO-34. These copper exchanged smallpore zeolites have high SCR activity between 150-500°C and are shown to be much more hydrothermally stable than the medium-pore zeolite, Cu-ZSM-5. The degree of copper exchange, the dimensionality of the framework, and heteroatom framework substitution all impact the SCR activity and hydrothermal stability of the materials. Of the small-pore zeolites tested, Cu-SSZ-13 and Cu-SAPO-34 display superior SCR performance, both before and after high-temperature hydrothermal treatment. Overall, the results of this thesis bring about new ideas as to what happens to zeolite systems at high-temperatures. The decomposition of Brønsted acid sites and hydroxyl nests within zeolite frameworks are startling finds that reevaluate previously held decomposition mechanisms within zeolites. By exchanging copper into small-pore zeolites, we showed that there is a resulting increase in the thermal stability of the material. The findings here also provide evidence that the pore size of the zeolite framework plays a crucial role in the stability of the material. Lastly, future recommendations are given for ways in which to utilize the properties of these unique materials. (Abstract shortened by UMI.).
Book Synopsis Developing Synthesis and Characterization Methods for Enhancing Material Performance by : Aamena Parulkar
Download or read book Developing Synthesis and Characterization Methods for Enhancing Material Performance written by Aamena Parulkar and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Design and development of functional nano materials especially, heterogeneous catalysts can directly impact the sustainability of industrial processes. This dissertation focuses on developing novel synthetic strategies and utilizing advanced characterization techniques to synthesize functional nanomaterials with focus on designing well-defined catalysts. The primary focus is on synthesizing and catalytic testing of Lewis acidic nano-zeolites. Lewis acidic zeolites, especially, tin containing zeolites like Sn-Beta and Sn-MFI, have been shown to catalyze a large array of chemical reactions. However, micropores of these zeolites can reduce the catalytic performance because of diffusion limitations. To overcome these limitations, strategies including development of hierarchical structures and reduction in particle size have been investigated. Nonetheless, synthesizing Lewis acidic nano-zeolites still remains a challenge. In this work, the synthesis conditions are modified to achieve a five-fold reduction in particle size for Sn-MFI (nSnMFI) as compared to conventional synthesis (cSnMFI). To demonstrate the benefit of nano-zeolites for catalytic application, epoxide ring opening (ERO) with alcohol is used as a probe reaction. Enhanced diffusion within the nSnMFI improves catalytic performance for bulky reactants, while retaining the inherent activity of the catalytic sites. The advantage of nSnMFI is however limited by the small pore size of MFI structure. To expand the scope, nano-Sn-Beta, a large pore zeolite is also synthesized. The improvement in performance over nSnMFI and conventional Sn-Beta zeolite is demonstrated using ring opening of 1,2-epoxyoctane with ethanol.
Book Synopsis Preparation of Nanocrystalline Zeolite Beta and Its Catalytic Activity by : Lu Gao
Download or read book Preparation of Nanocrystalline Zeolite Beta and Its Catalytic Activity written by Lu Gao and published by . This book was released on 2002 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Cu-ZSM-5 Zeolite Catalysts for the Selective Catalytic Reduction of NOx by : Jan Connerton
Download or read book Cu-ZSM-5 Zeolite Catalysts for the Selective Catalytic Reduction of NOx written by Jan Connerton and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis, Modification, Characterization and Catalytic Studies of Zeolite Based Bifunctional Catalysts for Hydroisomerization Reactions by :
Download or read book Synthesis, Modification, Characterization and Catalytic Studies of Zeolite Based Bifunctional Catalysts for Hydroisomerization Reactions written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Zeolite ZSM-12 was identified as a promising candidate for hydroisomerization of n-alkanes and a large part of the work was focused on the preparation of ZSM-12 and studying its catalytic performance. Reliable and efficient methods for synthesis of ZSM-12 with high levels of acidity were not available in the literature. Through systematic studies, the synthesis was greatly simplified and ZSM-12 was successfully crystallized at a relatively low Si/Al ratio of 30 using tetraethylammonium cations as the template. In the hydroisomerization of n-heptane as well as mixtures of n-alkanes, ZSM-12 catalysts provided a significantly higher selectivity to both monobranched and dibranched isomers, compared to other large pore zeolites. Kinetic studies carried out using individual octane isomers showed that the formation of certain dibranched and tribranched isomers was mildly hindered by the shape selective effect of the ZSM-12 pore, which resulted in the higher isomer yield. It was found that the cracking activity of ZSM-12 could be increased by three to four times by carrying out the calcination to remove the template at temperatures higher than what is normally used. The variation of the cracking activity with respect to the calcination temperature was very unusual, only the samples calcined in two separate narrow temperature ranges showed substantially enhanced activity. Extensive FTIR characterizations, with pyridine adsorbed on the acidic zeolite, indicated that the enhancement in the cracking activity was due to a synergistic interaction between the framework Brn̲sted acid sites and a Lewis acidic extra framework aluminum (possibly cationic) species present in the zeolite. Hydroisomerization of n-heptane was studied over large pore zeolites with different acidity properties and wide range of Si/Al ratios. The performance of zeolite catalysts with enhanced activity were very sensitive to the platinum precursor used and the pretreatment conditions. The results suggested that zeolite acidity characteristics do not affect the isomer yield, provided the catalyst is carefully prepared to ensure good metal/acidity balance. Therefore, it appears that the only way to obtain isomer yields higher than that of Y zeolite is by employing shape selective zeolites.
Book Synopsis Selective Catalytic Reduction of NOx by NH3 Over a Fe Zeolite Monolith Catalyst by : Nelson Salazar
Download or read book Selective Catalytic Reduction of NOx by NH3 Over a Fe Zeolite Monolith Catalyst written by Nelson Salazar and published by . This book was released on 2009 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
