Дисертації з теми "Light alkane"
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Schmidt, Iver. "Design of nanoporous materials for light alkane transformation." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369114.
Повний текст джерелаWaku, Toshio. "Light alkane conversion to useful chemicals on modified ZSM5 catalysts." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136343.
Повний текст джерелаNguyen, Luong Huu. "Development of a kinetic model for light alkane aromatisation over zeolite catalysts." Thesis, University of Bath, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419346.
Повний текст джерелаDerk, Alan Richard. "Understanding and Controlling Light Alkane Reactivity on Metal Oxides| Optimization Through Doping." Thesis, University of California, Santa Barbara, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3724768.
Повний текст джерелаMetal oxide catalysts have numerous industrial applications and have garnered research attention. Although oxides catalyze many important reactions, their yields to products are too low to be of economic value due to low conversion and/or low selectivity. For example, some oxides can catalyze the conversion of methane to intermediates or products that are liquefiable at yields no higher than 30%. With improved yield, such a process could help reduce the trillions of cubic feet of natural gas flared every year, saving billions of dollars and millions of tonnes of greenhouse gases. To this end, one goal of this work is to understand and improve the catalytic activity of oxides by substituting a small fraction of the cations of a "host oxide" with a different cation, a "dopant." This substitution disrupts chemical bonding at the surface of the host oxide, which can improve reactant and lattice oxygen activation where the reaction takes place. Another goal of this work is to combine catalysts with metal oxides reactants to improve thermodynamic limitations. Outstanding challenges for the study of doped metal oxide catalysts include (1) selection of dopants to ix synthesize within a host oxide and (2) understanding the nature of the surface of the doped oxide during reaction.
Herein, strongly coupled theoretical calculations and experimental techniques are employed to design, synthesize, characterize, and catalytically analyze doped oxide catalysts for the optimization of light alkane conversion processes. Density Functional Theory calculations are used to predict different energies believed to be involved in the reaction mechanism. These parameters offer valuable suggestions on which dopants may perform with highest yield and activity and why. Synthesis is accomplished using a combination of wet chemical techniques, suited specifically for the preparation of doped (rather than supported or mixed) metal oxide catalysts of high surface area and high reactivity. Characterization is paramount in any doped-oxide investigation to determine if the catalyst under reaction conditions is truly doped or merely small clusters of supported catalyst. With that goal, diffraction, X-ray, electron microscopies, infrared spectroscopy, and chemical probes are used to determine the nanoscopic nature of the catalysts. Additional novel measurement techniques, such as transient oxidation reaction spectroscopy, determined the nature of the active site's oxidation state.
Al-Sayari, Saleh Abdullah. "Synthesis of active supported gold catalysts for CO oxidation and light alkane activation." Thesis, Cardiff University, 2006. http://orca.cf.ac.uk/56051/.
Повний текст джерелаLøften, Thomas. "Catalytic isomerization of light alkanes." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1909.
Повний текст джерелаIn recent years the levels of sulfur and benzene in the gasoline pool have been reduced, and in the future there may also be new regulations on vapor pressure and the level of aromatics and olefins as well. The limitations on vapor pressure and aromatics will lead to reduced use of C4 and reformate respectively. The branched isomers of C5 and C6 alkanes have high octane numbers compared to the straight chain isomers, and are consequently valuable additives to the gasoline pool. To maintain the octane rating, it is predicted that an increased share of isomerate will be added to the gasoline pool.
Today there is a well established isomerization technology with platinum on chlorided alumina as the commercial catalyst for both isomerization of n-butane and of the C5/C6 fraction. This catalyst is very sensitive to catalyst poisons like water and sulfur, and strict feed pretreatment is required. Zeolites promoted by platinum are alternatives as isomerization catalysts, and has replaced Pt/alumina catalysts to some extent. The Pt/zeolite catalyst is more resistant to water and sulfur compounds in the feed, but it is less active than platinum on chlorided alumina. It does therefore require a higher reaction temperature, which is unfortunate since the formation of the branched isomers of the alkanes is thermodynamically favored by a low temperature.
Because of the limitations of the two types of isomerization catalysts, there is a search for a new catalyst that is resistant to sulfur and water in the feed and is highly active so it can be operated at low temperature. A new type of catalyst that seems to be promising in that respect is sulfated zirconia.
The first part of this study focuses on a series of iron and manganese promoted SZ catalysts. The catalysts were characterized by various techniques such as XRD, TGA, N2 adsorption and IR spectroscopy of adsorbed pyridine. The catalytic activity in n-butane isomerization at 250°C and atmospheric pressure was compared to the physical and chemical properties of the samples. No promoting effect of iron and manganese was found when n-butane was diluted in nitrogen. When nitrogen was replaced by hydrogen as the diluting gas the activity of the unpromoted SZ sample was dramatically lowered, while the activity of the promoted catalyst was not significantly changed.
If we only consider the promoted samples, the catalytic activity increases with increasing iron/manganese ratio. We also observe that the activity of the samples is clearly correlated with the number of strong Brønsted acid sites. The total number of strong acid sites (i.e. the sum of Brønsted and Lewis sites) does not change significantly when the promoter content is changing, hence no correlation between catalytic activity and the total number of acid sites is found. This underlines the importance of discrimination between Lewis and Brønsted acidity when characterizing the acidity of the samples.
The second part of this study is focused on a series of noble metal promoted sulfated zirconia. Their catalytic activity in n-hexane isomerization at high pressures was compared to a commercial Pt/zeolite catalyst. Among the noble metal promoted samples the catalyst promoted with platinum was the most active. The samples promoted with rhodium, ruthenium and iridium showed equal activity.
Common for all the noble metal promoted catalysts is the large increase in activity when catalysts are reduced with hydrogen compared to when they are pretreated in helium. The increase in activity is most likely connected to the reduction of the metal oxides of the promoters to ensure that the promoters are in the metallic state. Reduction at too high temperatures does however give lower activity. This is probably due to the reduction of surface sulfate groups leading to a loss in acid sites.
The commercial sample was considerably less active than the sample of platinum promoted sulfated zirconia. The commercial catalyst was however more stable than the PtSZ catalyst. All the sulfated zirconia catalysts deactivated, but the initial activity could be regenerated by reoxidation at 450°C followed by reduction at 300°C. The promotion with noble metals appears to inhibit coke formation on the catalyst. But, the main cause of deactivation of the platinum promoted sample is most likely the reduction of sulfate species leading to a loss of acid sites.
The kinetic study of the catalysts indicates that the n-hexane isomerization proceeds via a classical bifunctional mechanism where the role of the promoting metal is to produce alkenes, which are subsequently protonated on the acid sites. The reaction orders of hydrogen, n-hexane and total pressure are all in accordance with this mechanism. The activation energies of the catalysts are within the typical range of bifunctional catalysts.
All catalysts, except the unpromoted SZ sample, showed close to 100% selectivity to branched hexane isomers and a similar distribution of these isomers. The isomer distribution being the same for both the noble metal promoted catalyst and the Pt/zeolite is another indication that the isomerization proceeds via the bifunctional mechanism over the promoted samples. The different selectivity of the unpromoted SZ catalyst indicates that the isomerization proceeds via a different pathway over this catalyst; this is probably a pure acidic mechanism
The acidity characterization can not explain the differences in isomerization activity. It is however likely that the activity of the promoting metals in the dehydrogenation of alkanes is important since the classical bifunctional mechanism is prevailing.
Pithan, Linus. "On the role of external stimuli to tailor growth of organic thin films." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17749.
Повний текст джерелаThe research performed in the framework of this thesis focuses on new strategies to effectively control the growth of crystalline thin films of functional organic molecules and attributes the quest for additional growth control parameters in organic molecular beam deposition (OMBD). First the influence of light on the growth process of the sexithiophene (6T) is studied. We find that 6T thin films deposited as conventional in dark environments on KCl exhibit a bimodal growth with phase coexistence of two crystal polymorphs. In contrast, films grown under illumination with 532 nm light show increased phase purity. Further, we establish light-directed molecular self-assembly (LDSA) to generate permanently aligned thin films of tetracene (C18H12) and demonstrate direct patterning with light. Polarized light illumination leads to azimuthally photoaligned films on isotropic, amorphous substrates. Thus, LDSA can be regarded as a new degree of freedom in the quest for control-parameters in organic thin film growth. Next the impact of dynamic temperature oscillations on the time scales of molecular monolayer growth during organic molecular beam deposition is discussed. We strongly increase the island density during nucleation and selectively increase interlayer diffusion at later stages of monolayer growth. We analyse the interplay between molecular interlayer transport and island sizes to understand kinetic processes during growth. In a fourth experiment we show how thermal annealing can be used to improve smoothness and to increase the lateral size of crystalline islands of n-alkane (TTC, C44H90) films. We employ real-time optical phase contrast microscopy to track the diffusion across monomolecular step edges which causes the unusual smoothing during annealing. We rationalise the smoothing behaviour with the highly anisotropic attachment energies and low surface energies of TTC.
Ramakrishnan, Ayyappan. "Visible light induced catalytic sulfoxidation of alkanes." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981136915.
Повний текст джерелаSu, Yee San 1977. "The heterogeneous partial oxidation of light alkanes." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28306.
Повний текст джерелаIncludes bibliographical references.
(cont.) With this approach, an upper bound on the yield for OCM was computed. Results showed that even with optimal surface chemistry, strict limits existed on the attainable yield. Surface energetics necessary for superior OCM performance were identified and the origins of these requirements elucidated. The resulting upper bound on OCM yield under conventional, packed-bed, continuous-feed operation was found to be 28%. The catalytic properties of LiCl/sulfated ZrO₂-based catalysts were explored for ODHE. LiCl was shown to strongly interact with the acid sites on sulfated ZrO₂ (SZ), influencing its catalytic behavior. Two approaches were taken to modify the nature/strength of the LiCl-support interaction. Firstly, LiCl/Nd₂O₃-impregnated MoO/ZrO₂ and WOx/ZrO₂ were examined. Unlike SZ, these supports allowed for the tailoring of MoO[sub]x and WO[sub]x surface densities, which in turn drastically altered their ODHE performance. The poor stability of these supports, however, rendered them inferior to SZ. Secondly, the effects of dopant incorporation on the catalytic behavior of LiCI/MO,/SZ were studied. Si-doped ZrO₂-based catalysts synthesized via the sol-gel method were found to exhibit superior activity, selectivity and stability for ODHE. Sulfate decomposition experiments related the ODHE activity of these materials to the influence of the Si dopant on the sulfate binding strength. The sol-gel synthesis conditions were optimized with respect to sol pH, water:alkoxide ratio and silicon precursor, achieving improved catalyst homogeneity and enhanced ODHE performance ...
Within the petrochemical industry, a sizeable economic incentive exists for the upgrading of low-value, light alkanes. For instance, the dehydrogenation of ethane to ethene is of considerable interest due to ethene's use as a polymeric and chemical precursor. Partial oxidation provides an attractive alternative to standard pyrolysis methods for alkane-to-alkene conversion. Unlike pyrolysis, partial oxidative routes are largely unaffected by coke formation and have the added benefit of exothermicity. With the inclusion of oxygen as a reactant, however, numerous additional reaction pathways result. Among these, the presence of parallel and consecutive reaction channels to CO[sub]x products is of major concern. For this reason, previous efforts to create selective partial oxidation catalysts with high activity have typically fallen below economic feasibility requirements. This thesis focuses on the following alkane-to-alkene transformation reactions: Oxidative Coupling of Methane (OCM): 2CH₄ + O₂ <--> C₂H₄ + 2 H₂O Oxidative Dehydrogenation of Ethane (ODHE): C₂H₆ + 1/2 O₂ <--> C₂H₄ + H₂O Oxidative Dehydrogenation of Propane (ODHP): C₃H₈ + 1/2 O₂ <--> C₃H₆ + H₂O. Regarding OCM, an approach was presented for determining an upper bound on the yield of a catalytic process, which allowed for variations in the catalytic chemistry. Scaling and thermodynamic arguments were used to set parameters of an elementary step surface mechanism at values resulting in optimal yields, subjected only to physical constraints. Remaining unknowns were treated as independent variables and varied over a broad range. The result was a set of thermodynamically consistent mechanisms with optimal kinetics that could be incorporated into reactor-transport models.
by Yee San Su.
Ph.D.
Du, Xian. "Catalysis for CO2 activation reactions with light alkanes." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:924c17f7-5b71-4e70-b304-e0686d0413ea.
Повний текст джерелаDeRose, Kenneth J. "Observation of Slow Light, Stored Light, and Dicke Narrowing in Warm Alkali Vapor." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1565312435917479.
Повний текст джерелаFodor, William Lester. "Molecular analysis of human myosin alkali light chain genes /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487588939087998.
Повний текст джерелаGiraud, Carrier Matthieu C. "Perforated Hollow Core Waveguides for Alkali Vapor-cells and Slow Light Devices." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/5692.
Повний текст джерелаLi, Jianqiao. "Robust Storage of Topologically Protected Light in Warm Alkali Vapor." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1626991644038.
Повний текст джерелаWada, Kenji. "Studies on Selective Partial Oxidation of Methane and Light Alkanes on Solid Metal Oxide Catalysts." Kyoto University, 1992. http://hdl.handle.net/2433/74592.
Повний текст джерелаGoyal, Gaurav. "Light Olefin Production by Cracking Nannochloris oculata Microalgae using Aluminosilicate Catalysts." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6619.
Повний текст джерелаSkoulakis, Efthimios Makis Charalambous. "Analysis of the regulation of alternative splicing of myosin alkali light chain transcipts in Drosophila melanogaster /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487686243820744.
Повний текст джерелаPacheco, Alexander Bonifacio. "First principles dynamics of transient light absorption and emission of alkali atoms interacting with rare gas atoms." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013825.
Повний текст джерелаFergusson, Stanley MacArthur, and mac fergusson@rmit edu au. "The Effect of Laundry Detergents and Residual Alkali on the Light Fastness of Reactive Dyes on 100% Cotton." RMIT University. Fashion and Textiles, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081128.162252.
Повний текст джерелаHulbert, John Frederick. "ARROW-Based On-Chip Alkali Vapor-Cell Development." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3594.
Повний текст джерелаSchreiber, Moritz Wilhelm [Verfasser], Johannes A. [Akademischer Betreuer] Lercher, Thomas [Gutachter] Brück, and Johannes A. [Gutachter] Lercher. "Bifunctional catalysis of metal and Brønsted acid sites for hydrodeoxygenation of triglycerides and dehydrogenation of light alkanes / Moritz Wilhelm Schreiber ; Gutachter: Thomas Brück, Johannes A. Lercher ; Betreuer: Johannes A. Lercher." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1173898875/34.
Повний текст джерелаJankovský, Jiří. "Nové možnosti využití lehčených kameniv z druhotných surovin." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225654.
Повний текст джерелаFalahati, Hamid. "The Characterization of Bimodal Droplet Size Distributions in the Ultrafiltration of Highly Concentrated Emulsions Applied to the Production of Biodiesel." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/19585.
Повний текст джерелаNatural Sciences and Engineering Research Council of Canada (NSERC)
西, 宏二, and Koji Nishi. "Structure and catalytic properties of gallium promoted zeolites in light alkane conversion." Thesis, 1998. http://hdl.handle.net/2237/15731.
Повний текст джерела(7022285), Laryssa Goncalves Cesar. "Light Alkanes to Higher Molecular Weight Olefins: Catalysits for Propane Dehydrogenation and Ethylene Oligomerization." Thesis, 2020.
Знайти повний текст джерелаThe increase in shale gas exploitation has motivated the studies towards new processes for converting light alkanes into higher valuable chemicals, including fuels. The works in this dissertation focuses on two processes: propane dehydrogenation and ethylene oligomerization. The former involves the conversion of propane into propylene and hydrogen, while the latter converts light alkenes into higher molecular weight products, such as butylene and hexene.
The thesis project focuses on understanding the effect of geometric effects of Pt alloy catalysts for propane dehydrogenation and the methodologies for their characterization. Pt-Co bimetallic catalysts were synthesized with increasing Co loadings, characterized and evaluated for its propane dehydrogenation performance. In-situ synchrotron X-Ray Powder Diffraction (XRD) and X-Ray Absorption (XAS) were used to identify and differentiate between the intermetallic compound phases in the nanoparticle surface and core. Difference spectra between oxidized and reduced catalysts suggested that, despite the increase in Co loading, the catalytic surface remained the same, Pt3Co in a Au3Cu structure, while the core became richer in Co, changing from a monometallic Pt fcc core at the lowest Co loading to a PtCo phase in a AuCu structure at the highest loading. CoII single sites were also observed on the surface, due to non-reduced Co species. The catalytic performance towards propane dehydrogenation reinforced this structure, as propylene selectivity was around 96% for all catalysts, albeit the difference in composition. The Turnover Rate (TOR) of these catalysts was also similar to that of monometallic Pt catalysts, around 0.9 s-1, suggesting Pt was the active site, while Co atoms behaved as non-active, despite both atoms being active in their monometallic counterparts.
In the second project, a single site CoII catalyst supported on SiO2 was evaluated for ethylene oligomerization activity. The catalyst was synthesized, evaluated for propane dehydrogenation, propylene hydrogenation and ethylene oligomerization activities and characterized in-situ by XAS and EXAFS and H2/D2 exchange experiments. The catalysts have shown negligible conversion at 250oC for ethylene oligomerization, while a benchmark Ni/SiO2 catalyst had about 20% conversion and TOR of 2.3x10-1 s-1. However, as the temperature increased to above 300oC, ethylene conversion increased significantly, reaching about 98% above 425oC. In-situ XANES and EXAFS characterization suggested that H2 uptake under pure H2 increased in about two-fold from 200oC to 500oC, due to the loss of coordination of Co-O bonds and formation of Co-H bonds. This was further confirmed by H2/D2 experiments with a two-fold increase in HD formation per mole of Co. In-situ XAS characterization was also performed with pure C2H4 at 200oC showed a similar trend in Co-O bond loss, suggesting the formation of Co-alkyl, similarly to that of Co-H. The in-situ XANES spectra showed that the oxidation state remained stable as a Co2+ despite the change in the coordination environment, suggesting that the reactions occurs through a non-redox mechanism. These combined results allowed the proposition of a reaction pathway for dehydrogenation and oligomerization reactions, which undergo a similar reaction intermediate, a Metal-alkyl or Metal-Hydride intermediates, activating C-H bonds at high temperatures.
Twesme, Troy Matthew. "Oxidation of light alkanes using photocatalytic thin films." 2006. http://www.library.wisc.edu/databases/connect/dissertations.html.
Повний текст джерелаRamakrishnan, Ayyappan [Verfasser]. "Visible light induced catalytic sulfoxidation of alkanes / vorgelegt von Ayyappan Ramakrishnan." 2006. http://d-nb.info/981136915/34.
Повний текст джерелаNgobeni, Maropeng Walter. "The nonoxidative conversion of light alkanes over metal-loaded H-ZSM-5 zeolite catalysts." Thesis, 2008. http://hdl.handle.net/10539/4971.
Повний текст джерелаPham, Thong Minh Le, and Thong Minh Le Pham. "Density-Functional Theory Studies on Activation and Reactions of Light Alkanes over IrO2 (110) Surface." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/44601457250067622558.
Повний текст джерела國立臺灣科技大學
化學工程系
103
The capability to activate light alkanes at mild temperature and selectively control the oxidation reactions are defined the characteristic of an efficient catalyst for the direct oxidation of light alkanes to value-added products. IrO2 (110) surface, which possesses coordinativedly unsaturated iridium and oxygen atoms, is expected to be a potential catalyst to activate light alkanes at mild temperature. In this thesis, density functional theory (DFT) calculations were employed to explore the activation of methane and ethane on the IrO2 (110) surface. The possible reaction pathways of methane and ethane on the IrO2 (110) surface were also investigated. Furthermore, the adsorption characeristics of CHx (x=1-4) and C2H6 on the IrO2 (110) surface were studied using the analyses of density of states (DOS) and electron density difference (EDD) contours. The calculated results indicate that CH4 and C2H6 adsorb on the IrO2 (110) surface by the agostic interaction between C-H bonds and coordinativedly unsaturated Ir atoms of surface. In addition to the agostic interaction, dispersion interaction also plays an important role in the interaction of CH4 and C2H6 with IrO2 (110) surface. Both of the agostic and dispersion interaction facilitate molecular-mediated mechanism for the first C–H bond cleavage of these alkanes with a low kinetic barriers of 0.25 eV and 0.50 eV which are likely to occur at mild temperature condition. The dehydrogenation reactions of methane and ethane on the IrO2 (110) surface are occurred by the transfer of hydrogen atoms to Obr and Otop sites. Among the dehydrogenation reactions of methane, CH2 dissociation into CH has highest activation energy, making CH2 the most significant monomeric building block on the IrO2 (110) surface. Based on our DFT calculations, the direct conversion of methane to formaldehyde is a possible route on the IrO2 (110) surface via selective CH4 dehydrogenation reactions to CH2 and then the coupling reaction of CH2 with the Otop atom. The energetics for ethane dehydrogenation to ethylene are accessible. However, since the adsorption energy of ethylene is rather high on the IrO2 (110) surface, ethylene prefers undergoing further reactions than desorption from the surface. Therefore, the production of ethylene is infeasible on the IrO2 (110) surface. Instead, the coupling reaction ethylene with Otop to form oxametallacycle is favorable on the IrO2 (110) surface. DFT calculations predict that 1, 2-H shift reaction of oxametallacycle intermediate towards the formation of acetaldehyde is more favorable than ring closure of oxametallacycle to the formation of ethylene oxide. The density functional theory calculations from this work provide an initial basis for understanding and designing efficient catalyst for the direct conversion of light alkanes to the value-added chemicals under mild temperature.
Lin, Jyun-Han, and 林君翰. "Study on Light-induced Synthesis of Alkali Soluble Metal / Photosensitive Polymer Nanocomposites and its Properties." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/03808606687018204858.
Повний текст джерела國立中興大學
化學工程學系所
103
Nanotechnology has become a trend in the 21st century, leading the development of science and technology. Nanocomposite material is formed by two kinds or more types of materials in nanoscale. It is a potential material for application in the fields of electronics, magnetics, optical components and structural materials, such as capacitor of integrated circuit and thermal conducting material of semi-conductor packing. How nanotechnology can be well combined with photo-lithography in high-tech manufacturing process is a significant subject nowadays. This research aids to study alkali soluble metal and photosensitive polymer nanocomposites by utilizing cresol epoxy acrylate resin as oligomer, acetonitrile as solvent, trimethylolpropane triacrylate (TMPTA) as monomer, 50% of 1-hydroxycyclohexyl phenyl ketone and 50% of benzophenone as photoinitiator to combine with AgNO3. This material can generate free-radical through photoinitiator being irradiated by ultraviolet visible light, cross-linking TMPTA and cresol epoxy acrylate resin as well as reducing silver ions into silver nanoparticles simultaneously. Taguchi Method is employed to optimize formula and process. Silver nanoparticle absorption value of ultraviolet visible spectrophotometer (UV-vis) is designed as an indicator based on “Larger the Better” of Taguchi Method. In experiment, UV-Vis, field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), insulation resistance meter, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), are respectively used to character properties of as-prepared composite material, including morphology, crystal phase, particle size and distribution, electric resistance, chemical structure and thermal resistance. In addition, photo-lithographic process is used to examine the patterning of as-fabricated Ag/photosensitive polymer composite. As shown from the results, this study summarizes some significant remarks as follows: (1)The use of acetonitrile as solvent can evenly mix cresol epoxy acrylate resin with 20wt% of AgNO3 because acetonitrile is aprotic solvent with high level of molecular polarity. (2)As the concentration of AgNO3 increases from 5.8wt% to 20wt%, under equivalent level of resin, monomer, photoinitiator, and exposure dosage, electrical resistance decreases from 4.18×1011Ω to 9.64×108Ω; silver nanoparticle absorption value of UV-vis increases from 2.4 to 2.7; through FESEM, the range of silver nanoparticle average diameter enlarges from 20nm±8nm to 37nm±20nm; and by AFM, the material surface roughness changes from 0.20 nm to 14nm. (3)Taguchi method and analysis of variance are applied to analyze effects of amounts of AgNO3, monomer and photoinitiator, as well as exposure dosage, on UV-Vis absorption value of photosensitive polymer material. As shown from the result, three by factors of monomer, AgNO3, and exposure dosage are found, which contributions are 5.8%, 20.53%, and 49% respectively; and through response graph of S/N ratio, the optimal condition is 1 g of AgNO3, 0.1 g of monomer, 0.2 g of photoinitiator, 6 J/cm2 of exposure dosage, which error value is less than 20%. (4)For Ag/ cresol epoxy acrylate polymer nanocomposites with 20wt% of AgNO3, after exposing of 8 J/cm2, the temperature of thermal weight loss by 5wt% is 146℃ and the temperature of thermal decomposition reaches 296℃. (5)With 3wt% of AgNO3, film thickness of 6.57μm, and exposure dosage of 3 J/cm2 and 0.5 J/cm2, the photolithographic resolutions of Ag/ cresol epoxy acrylate polymer nanocomposite are 11μm and 10μm, respectively, after developing by 5wt% of NaOH in de-ionic water for 60 seconds at temperature of 25℃.
Tu, Kuan-Ju, and 杜冠儒. "Photodegradation of Dye by TiO2 Modified with Hydrogen Peroxide in Alkaline Solution under Visible Light." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/91773958574246605439.
Повний текст джерела國立清華大學
生醫工程與環境科學系
100
TiO2 is widely used in the field of environment and energy, such as dye-sensitized solar cells and photocatalysts for the degradation of organic pollutants. This study is to enhance of the photodegradation of dye (Sulforhodamine B as a model compound) under visible light by TiO2 pretreated with alkaline hydrogen peroxide. Modified TiO2 nanoparticles were characterized by dynamic laser light scattering (DLS), fourier transform infrared (FT-IR), thermogravimetry analysis (TGA), surface area analysis (BET), high-resolution transmission electron microscopy (HRTEM) and X-ray powder diffraction (XRPD). In addition, electron paramagnetic resonance spectrometer (EPR) was utilized to observe the formation of hydroxyl radicals in the system. TiO2 could not only increase the density of surface hydroxyl groups on the TiO2 surface (13.89 OH/nm2), but also lead to smaller particle size (4 nm). The dispersion and photocatalytic activity of the modified TiO2 were greatly enhanced. On the other hand, TiO2 pretreated with UVC light could increase the surface hydroxyl groups on the TiO2 surface though, the degradation rate was not unexpectedly enhanced. The effect of metal ion (Fe3+, Cu2+, Zn2+ and Al3+) on the photocatalytic activity of the modified TiO2 was investigated under visible light. The results show that Fe3+ accelerated the photodegradation of dyes in aqueous modified TiO2 dispersions with one order of magnitude larger than commercial P-25. This may be ascribed to the complexation of the hydroxyl groups bound to TiO2 surface with Fe3+ to form Fe(OH)2+.
Liao, Yu-Fen, and 廖玉芬. "The Study of Suspension Stability of Titania Nanoparticles Dispersed in Alkaline Solution by Dynamic Light Scattering." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/45540642382981081453.
Повний текст джерела元智大學
化學工程與材料科學學系
96
The physical dispersion, suspension stability and resuspension after precipitation of aqueous suspensions of Degussa P25 powders in alkaline condition (pH7-12) was investigated by dynamic light scattering (DLS), apparent turbidity, and field emission scanning electron microscopy (FESEM). DLS was used to obtain time evolution of the histograms of particles at upper and lower layers of the suspensions. FESEM was used to confirm the size distribution of coverage. Experimental parameters include pH value, stirring conditions, surfactant and sodium salt addition, and pH adjustment. The results suggested that in alkaline condition, the stability of P25 suspension increased with increasing initial pH and reached its peak at pH11 but decreased further with increasing pH. Resuspension of precipitated suspensions cannot reverse the stability achieved with freshly prepared ones. Extended ultrasound treatment significantly improved the stability those pH8 ones but not so for the pH11. For suspensions of different pH value, the addition of sodium chloride to adjust to the same the sodium ion concentration leads to reduced electrical double layer thickness, thereby enhanced particle agglomeration and speed up particle settling. Initial pH value appeared to be critical to suspension stability, pH adjustment after suspensions were made may not help improve stability.
Nasrifar, K., and Nejat Rahmanian. "High-pressure solubility of light gases in heavy n-alkanes from apredictive equation of state: Incorporating Henry’s law constant intobinary interaction parameter." 2014. http://hdl.handle.net/10454/10316.
Повний текст джерелаUsing fugacity coefficient of a cubic equation of state, Henry’s law constant of a solute in a solvent isincorporated into binary interaction parameter of the classical attractive parameter mixing rule. Thedeveloped equation is a function of temperature. The binary interaction parameter is evaluated by purecomponent critical properties and acentric factors of the solute and the solvent and the Henry’s lawconstant of the solute in the solvent. The developed model accurately describes the solubility of gasesincluding methane, ethane, nitrogen, carbon dioxide and hydrogen sulphide in heavy n-alkanes from lowto high pressure for wide range of temperature. The solubility of methane and carbon dioxide in wateris also predicted adequately.
Klein, Tobias, Wenchang Wu, Manuel Kerscher, Michael H. Rausch, Cédric Giraudet, Thomas M. Koller, and Andreas P. Fröba. "Fick diffusion coefficients in binary liquid mixtures of n-alkanes or 1-alcohols with dissolved gases investigated by molecular dynamics simulations and dynamic light scattering." 2019. https://ul.qucosa.de/id/qucosa%3A72424.
Повний текст джерелаLu, Ting-Hsuan, and 呂庭萱. "The Synthesis and Characterization of Narrow-Band Eu2+-doped Alkali Metal Silicate Phosphors and Their Application in Back Light Source for LCDs." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/83b5mn.
Повний текст джерела國立交通大學
應用化學系碩博士班
108
In this study, narrow-band Eu2+-doped alkali metal silicate phosphors were prepared by solid state synthesis. This study investigate and describe two series of Mn (Li3SiO4)n:Eu2+ (n=2 and 4). The crystal structure belongs to the UCr4C4 type. The crystal structure and luminescence properties were characterized by using powder X-ray diffraction, fluorescence spectrometer, quantum efficiency measurement, thermal quenching experiment, and investigation scanning electron microscope. Finally, we evaluate the applications by fabrication of white light emitting diodes. In this thesis, Eu2+ is used as an activator in the alkali metal silicate phosphors. The excitation range is from 330 nm to 450 nm. Due to the rigidity of the main structure, the emission band was narrow, and the full width at half maximum ( FWHM ) is about 41.6 nm. In the thermal quenching experiments, the heat resistance is as high as 300 °C. Finally, in the results of LED packaging, we use the 450 nm blue LED chip the red phosphor K2SiF6:Mn4+ combinated with the title phosphors in this study. This white light-emitting diode devices was found to show with wide NTSC color gamut of about 111%.