Dissertations / Theses: 'Ethane'

1

Khan, Asad Ahmad. "Oxidative dehydrogenation (ODH) of ethane to ethene over supported vanadium containing oxide catalysts." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/91544/.

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In this thesis work oxidative dehydrogenation (ODH) of ethane to ethane over MoV oxide catalyst was investigated. The influence of the preparation techniques and different reaction conditions were studied thoroughly. It was found that the precipitation method for the catalyst preparation using variable pH produces a more active catalyst at pH values of 3 to 3.5. Slurry temperature and calcination temperature are also very important parameters which affect the selectivity pattern of the products. This selectivity pattern was found to be further influenced by reaction temperature, pressure, GHSV and ethane-oxygen ratio in the feed. The influence of the V: Mo ratio on the performance of the catalyst for the ODH was investigated by several characterisation techniques, such as BET, XRD, XPS, TEM, SEM, EDX coupled with catalytic performance tests in a fixed bed reactor. The optimum V: Mo ratio was found to be 0.25:1 (i.e., MoV0.40). At this ratio, the oxidation state of vanadium with respect to total vanadium concentration (V5+/Vtotal) is at an optimum in terms of the adsorption strength of the desired products. It was further fine-tuned by investigating the influence of reaction conditions. An improvement on the most active MoV oxide catalyst for the ODH reaction was developed with the addition of oxalic acid as the vanadium dissolution and pH adjustment agent. Addition of oxalic acid influenced the catalytic properties in a variety of ways as observed from characterisation and reaction results. Addition of either a smaller amount or an excess amount compared with the optimal amount has determental impact on the activity of the catalyst. Further catalytic activities were tested by the addition of different types of supports (e.g., ZrO2, TiO2, Nb2O5, SiO2, and AlO3) into the MoV oxide catalytic system. The alumina support was extensively tested with different amounts onto the base MoV oxide for the ethane ODH to ethane.

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patankar, sumant s. "Role of Confinement on the Properties of Ethane and Ethane-CO2 Mixtures in Mesoporous Silica." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471541134.

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3

Ducatel, Estelle. "Composting of ethane pyrolysis quench sludge." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/MQ48061.pdf.

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4

Haddleton, D. M. "Photochemistry of some metal-ethane complexes." Thesis, University of York, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374165.

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Rose, Jeffrey Lawrence. "Extraction of Peace River bitumen using supercritical ethane." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0024/NQ49534.pdf.

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6

Wells, Nigel P. "Oxidation of ethane over SnOâ†2 based catalysts." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238226.

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7

Hacoob, Saboonchian Vahe. "Bis(Dimethylphosphino)ethane and related complexes of transition metals." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46796.

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8

Karamullaoglu, Gulsun. "Dynamic And Steady-state Analysis Of Oxidative Dehydrogenation Of Ethane." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606269/index.pdf.

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In this research, oxidative dehydrogenation of ethane to ethylene was studied over Cr-O and Cr-V-O mixed oxide catalysts through steady-state and dynamic experiments. The catalysts were prepared by the complexation method. By XRD, presence of Cr2O3 phase in Cr-O
and the small Cr2O3 and V2O4 phases of Cr-V-O were revealed. In H2-TPR, both catalysts showed reduction behaviour. From XPS the likely presence of Cr+6 on fresh Cr-O was found. On Cr-V-O, the possible reduction of V+5 and Cr+6 forms of the fresh sample to V+4, V+3 and Cr+3 states by TPR was discovered through XPS. With an O2/C2H6 feed ratio of 0.17, Cr-O exhibited the highest total conversion value of about 0.20 at 447°
C with an ethylene selectivity of 0.82. Maximum ethylene selectivity with Cr-O was obtained as 0.91 at 250°
C. An ethylene selectivity of 0.93 was reached with the Cr-V-O at 400°
C. In the experiments performed by using CO2 as the mild oxidant, a yield value of 0.15 was achieved at 449°
C on Cr-O catalyst. In dynamic experiments performed over Cr-O, with C2H6 pulses injected into O2-He flow, the possible occurrence of two reaction sites for the formation of CO2 and H2O was detected. By Gaussian fits to H2O curves, the presence of at least three production ways was thought to be probable. Different from Cr-O, no CO2 formation was observed on Cr-V-O during pulsing C2H6 to O2-He flow. In the runs performed by O2 pulses into C2H6-He flow over Cr-V-O, formation of CO rather than C2H4 was favored.

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9

Fröhlich, Thomas. "Novel, sequence-defined oligo (ethane amino) amides for siRNA delivery." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-143311.

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10

Ricklund, Niklas. "Environmental occurrence and behaviour of the flame retardant decabromodiphenyl ethane." Doctoral thesis, Stockholms universitet, Institutionen för tillämpad miljövetenskap (ITM), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-34060.

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The environmental occurrence and behaviour of the brominated flame retardant (BFR) decabromodiphenyl ethane (dbdpe) has only been studied to a limited extent. It is structurally similar to decabromodiphenyl ether (decaBDE), which makes it conceivable that dbdpe may also become an environmental contaminant of concern. A method for environmental analysis and comparative assessments of dbdpe and decaBDE was developed. Both BFRs were studied in: a mass balance of the Henriksdal WWTP in Stockholm (Paper I); an international survey of sewage sludge (Paper II); sediment along a transect from Henriksdal WWTP to the outer archipelago of Stockholm and from isolated Swedish lakes (Paper III); and a benthic food web from the Scheldt estuary (Paper IV). Dbdpe was found in sludge from every country surveyed, indicating that it may be a worldwide concern. The WWTP mass balance showed that virtually all of the BFRs were transferred from wastewater to sludge. A small fraction was emitted via the effluent, confirming emissions to the aquatic environment. In the marine sediment, the BFR levels close to the WWTP outfall were high. They decreased along the transect to low levels in the outer archipelago. The study of lake sediment showed a widespread presence of dbdpe in the Swedish environment and provided evidence that it originates from long range atmospheric transport. In the food web, dbdpe did bioaccumulate to a small extent which was similar to decaBDE. The transfer of the BFRs from sediment to benthic invertebrates was low, while transfer from prey to predator was higher. Biodilution was observed rather than biomagnification. This work suggests that the persistence, the susceptibility to long range atmospheric transport, and the potential for bioaccumulation are similar for dbdpe and the regulated decaBDE that it is replacing. Thus, there is a risk that a problematic environmental pollutant is being replaced with a chemical that is equally problematic.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.

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11

Rungta, Meha. "Carbon molecular sieve dense film membranes for ethylene/ethane separations." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/50121.

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The current work focused on defining the material science options to fabricate novel, high performing ethylene/ethane (C₂H₄/C₂H₆) separation carbon molecular sieve (CMS) dense film membranes. Three polymer precursors: Matrimid®, 6FDA-DAM and 6FDA:BPDA-DAM were used as precursors to the CMS membranes. CMS performances were tailored by way of tuning pyrolysis conditions such as the pyrolysis temperature, heating rate, pyrolysis atmosphere etc. The CMS dense film membranes showed attractive C₂H₄/C₂H₆ separation performance far exceeding the polymeric membrane performances. Semi-quantitative diffusion size pore distributions were constructed by studying the transport performance of a range of different penetrant gases as molecular sized probes of the CMS pore structure. This, in conjunction with separation performance data, provided critical insights into the structure-performance relationships of the CMS materials. The effects of testing conditions, i.e. the testing temperature, pressure and feed composition on C₂H₄/C₂H₆ separation performance of CMS dense films were also analyzed. These studies were useful not just in predicting the membrane behavior from a practical stand-point, but also in a fundamental understanding of the nature of CMS membrane separation. The study helped clarify why CMS membranes outperform polymeric membrane performance, as well as allowed comparison between CMS derived from different precursors and processing conditions. The effects on C₂H₄/C₂H₆ separation in the presence of binary gas mixture were also assessed to get a more realistic measure of the CMS performance resulting from competition and bulk flow effects. The current work thus establishes a framework for guiding research ultimately aimed at providing a convenient, potentially scalable hollow fiber membrane formation technology for C₂H₄/C₂H₆ separation

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12

Sonntag, Olivier. "The development of catalysts for the partial oxidation of ethane." Thesis, Nottingham Trent University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442097.

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Crabb, Eleanor Mary. "An investigation of the oxidative dehydrogenation of ethane and propane." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304514.

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14

Wurtele, Matthew. "Ethane Conversion to Ethylene in a Direct Hydrocarbon Fuel Cell." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38818.

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Direct hydrocarbon fuel cells are fuel cells than use hydrocarbons directly as fuel instead of the most commonly used fuel in a fuel cell, hydrogen. Studies are being done on direct hydrocarbon fuel cells because they have the potential to be energetically more efficient than hydrogen fuel cells. There are many different hydrocarbons that are available to use as a feed stock and each one reacts at different reaction rates. As the current density of a fuel cell is linked to the reaction rate, it is important to know the energetics of an oxidation reaction that is occurring. Density Functional Theory (DFT) is a technique that can be used to predict the energy states of intermediate reaction steps in a given mechanism. The focus of this study is the using DFT to explore the energetics of the oxidation of ethane to ethylene in a nickel-anode catalyst fuel cell. DFT was used in adsorption runs to optimize the geometries beginning (adsorbed ethane) and end (adsorbed ethylene) of the oxidation reaction. DFT was then used to calculate the energy of transition states by varying bond lengths. It was determined the removal of the second hydrogen from the ethyl radical is the most energy intensive step and, thus, the rate limiting step. Hydrogen, ethane, and ethylene were all explored in this study. The heats of adsorption varied from largest to smallest in the order of ethylene, hydrogen, and ethane. It was determined that the heat of adsorption of hydrogen is sufficient to meet the energy requirements for the dissociation reaction. This may help explain why hydrogen reacts so readily in fuel cells. Conversely, the heats of adsorption for the hydrocarbons did not meet the energy requirements for the dissociation reactions. This may help explain why ethane and ethylene react more slowly in a fuel cell as compared to hydrogen. Also, the oxidation of ethane to ethylene requires two large activation energies. These two additional activation energies may help explain why ethylene reacts more readily than ethane in a fuel cell.

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15

Raggett, Charlotte. "The economics of extracting ethane in Alberta versus the United States." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ31304.pdf.

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16

Moradinia, Iraj. "The solubility of high molecular weight solid hydrocarbons in supercritical ethane." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/11786.

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17

Salt, J. E. "[1,2-bis(dimethylphosphino)ethane] complexes on the first row transition metals." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37844.

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18

Massey, Alan Robert. "The adsorption and oxidation of methane and ethane on Pd{100}." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610715.

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19

Walters, Kevin M. "A flow-reactor study of vitiated ethane oxidation at intermediate temperatures /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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20

Patterson, Claire Siobhan. "Portable spectroscopy system for ultra-sensitive, real-time measurement of breath ethane." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/538/.

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This thesis describes the development, characterisation and application of a portable spectroscopy system for ultra-sensitive, real-time detection of breath ethane. In healthcare, breath ethane is a widely accepted marker of free radical-induced cell damage and may be used to indicate changes in oxidative stress. The aim was to deliver a compact instrument capable of long-term, on-site use in a clinical environment, while also retaining the high performance previously achieved by lab-based systems at the University of Glasgow. The newly developed instrument has a sensitivity of 70 parts per trillion with a 1 Hz sampling rate. The system incorporates a cryogenicallycooled lead-salt laser and uses a second derivative wavelength modulation detection scheme. A thermally-managed closed-loop refrigeration system has eliminated the need for liquid coolants. The instrument has been field-tested to ensure target performance is sustained in a range of environments, both indoor and outdoor. It has since been used in a number of pilot clinical studies, both off-site and on-site, in which breath ethane was monitored as a marker of oxidative stress. The three main clinical areas investigated were dialysis, radiotherapy and intensive care. In the intensive care study, the instrument was modified to enable automatic breath sampling of inspired and expired gases of ventilated patients. This technique proved highly successful and the instrument then remained at the Southern General hospital, where it continued to be used as part of a wider study into breath ethane in intensive care patients. The use of the new spectroscopy system has enabled ultra-sensitive, rapid analysis of a large number of breath samples. The use of the new instrument, in particular for continual breath monitoring, has enabled the detection of short-lived fluctuations in breath ethane, yielding some interesting findings in a number of pilot clinical studies. Our results suggest that breath ethane may be used as an indicator of dynamic changes in oxidative stress. Further studies will be required to determine if such monitoring is of clinical benefit. Chapter 1 gives a general introduction to spectroscopy and some background to our project. A number of spectroscopic techniques and laser sources are discussed, along with a review of previous work in ethane detection. In chapter 2 some background theory of molecular spectroscopy is given, with a more detailed discussion of the wavelength modulation technique. Chapter 3 describes in detail the development of the portable spectroscopy system. The achieved performance and factors contributing to this performance are discussed in chapter 4. The field test of the instrument is reported on in chapter 5. In chapter 6 the application of the technology to breath analysis and the current challenges in this field are discussed. Example breath ethane measurements for healthy controls are provided. The clinical pilot studies conducted using the new system in areas of dialysis, intensive care and radiotherapy are discussed in chapters 7, 8, and 9 respectively. Chapter 10 contains the thesis summary and conclusions, with suggestions for future work.

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21

Velaga, Srinath Chowdary. "Stability of Methane-Ethane-Propane Mixed Gas Hydrates under Deep Water Conditions." Thesis, West Virginia University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3618152.

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Methane hydrates are globally distributed in sediments along the continental margins and potentially contain more energy than all fossil fuel reserves. However, methane is also a potential greenhouse gas which could play a major role in global climate change. Understanding the stability of gas hydrates can help us to understand their role in the climate change. Three main factors affect the stability of hydrates: Temperature (T), Pressure (P) and composition. Hydrates become unstable when they are exposed to pressures and temperatures outside the hydrate stability zone (HSZ) in a process commonly called dissociation. However, hydrates can also become unstable even when the pressure and temperature are within the HSZ but the concentrations of the hydrate forming gases are below their fully-saturated levels in the surrounding water phase. This process can be described as dissolution. In situ observations of marine outcrops of gas hydrates indicate that these hydrates exposed to surrounding seawater are more stable than predicted using diffusion-controlled models based on the surrounding methane saturations.

Naturally-occurring hydrates may not be simple structure I (sI) methane hydrates and may contain higher hydrocarbons like ethane, propane etc., which forms structure II (sII) hydrates. Therefore, these mixed hydrates may act to stabilize the hydrates. In this work, the dissolution of sII hydrates in the presence of water has been studied using molecular dynamics (MD) simulations to understand if and how the presence of ethane and propane may stabilize the hydrate. Lattice constants for sII hydrates were calculated and compared to experimental values to validate the OPLS potentials used for the hydrocarbon guest molecules. The effect of higher hydrocarbons, such as ethane and propane, on the stability of gas hydrate was studied by changing the composition in the hydrate phase keeping the methane composition constant in the large cage and small cages. Also, the effect of methane composition was also studied by changing the methane occupancy in large and small cages. MD simulations reveal that the fully occupied hydrate is more stable than the presence of empty cages. The number of methane molecules moved into the liquid phase from the hydrate phase has been increased with the decrease in the large cage occupancy. No effect was found on the dissolution of sII hydrate by changing the small cage occupancy from 100% to 81.5%. The dissolution of sII hydrate was linear in the first few nanometers of the simulations and then observed an oscillatory behavior; this oscillatory behavior is due to the hydrate formation and dissociation at the hydrate-water layer interface.

The probable phase in the marine sediments can be a two phase hydrate (H)-Liquid water (L_w) thermodynamic equilibrium in the absence of vapor phase. Understanding the fate and transport of hydrocarbons and hydrocarbon mixtures in the deepsea and underlying sediments requires accurate determination of this two phase H-L_w thermodynamic equilibrium in the absence of a free gas phase. In addition to controlling hydrate formation directly from the aqueous phase, the H-L_w equilibrium also provides the aqueous solubility of dissolving hydrate. The two phase H-L_w thermodynamic model is based on the van der Waals and Platteeuw model and the Holder model. The Langmuir constants, an important term, in the van der Waals Platteeuw model were calculated from cell potential parameters obtained from ab initio intermolecular potentials and the experimental data, i.e. it does not rely on empirical fitting parameters. Variable reference parameters were used for each guest molecule instead of using single value for all the guests. The Pitzer model was used to calculate the activity of seawater. The solubilities of pure methane, ethane, and propane in water at H-L_w equilibrium are compared to the available experimental data and shown to be as accurate as the experimental data. The model predictions show that the ratio of large to small cage occupancy decreasing with increase in temperature or pressure. The prediction of the model shows that at the two phase H-L_w equilibrium in the presence of electrolytes forms the hydrate at lower pressures compares to the pure water at a given temperature and dissolved hydrocarbon solubility. Thus the presence of electrolyte promotes the hydrate formation rather than acting as an inhibitor. This is in reverse to that in the three phase vapor-liquidwater-hydrate (VL_wH) region where it is well known that salts act as an inhibitor to hydrate formation. Finally, the methane-ethane-propane ratio from the Macondo oil spill had been used as a typical thermogenic hydrocarbon mixture and hydrocarbon solubilities at H-L_w equilibrium under deepsea conditions have been presented for pure water and seawater.

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22

Wong, Kae Shin. "Benzene alkylation with ethane into ethylbenzene over Pt-containing zeolite bifunctional catalysts." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512307.

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Ethylbenzene (EB) is currently produced via acid catalyzed benzene alkylation with ethene, which is a product of highly endothermic and energy intensive processes. The new reaction, which uses ethane for benzene alkylation, instead of ethene, would eliminate the ethene production step, thus, leading to the commercial and environmental benefits in the EB manufacturing. Benzene alkylation with ethane into EB can be achieved using bifunctional zeolite catalysts, which combine ethane dehydrogenation into ethene over metal sites with benzene alkylation by ethene over BrÃ¸nsted acid sites. The benzene alkylation with ethane into EB over Pt-containing (1 wt.%) ZSM-5 bifunctional catalyst was investigated at six different temperatures (290, 330, 370, 410, 450 and 490oC). The optimum reaction temperature as well as the effect of temperature on the catalyst performance and reaction pathways were established. Excellent catalyst performance was obtained at 370oC, at which very stable catalyst operation (46 h on stream) is observed and the EB selectivity above 90 mol.% is achieved at benzene conversion of 12.5%, which is very close to the maximum equilibrium conversion of benzene into EB at this temperature (13.6%). The obtained results have shown that the temperature has different effects on the rates of the different reaction steps, leading to the different product distributions at different temperatures.

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23

Laffir, Fathima Riyaza. "Adsorption dynamics and reactivity of water and ethane on Pt{110}-(1x2)." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613092.

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24

Armstrong, Robert. "Partial oxidative upgrading of ethane with Fe- and Cu-ZSM-5 catalysts." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/59701/.

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The selective oxidation of lower alkane components of natural gas, such as ethane, to partial oxygenates remains a major challenge for both industry and academia. At present 60% of industry’s 7.8 Mt annual acetic acid demand is met through the carbonylation of methane, the operation of which is highly energy intensive, leads to formation of corrosive iodide by-products and requires high pressures of CO. Meanwhile ethene, a feedstock of great industrial importance, is produced via steam cracking of alkanes such as ethane, a process which is typically operated at > 800 oC and accounts for ca. 40% of the petrochemical industry’s annual energy consumption. The development of an atom efficient, low temperature, environmentally benign process for the direct conversion of ethane to either of these molecules would circumvent the need for current practices and thereby represent an important milestone in the valorisation of natural gas. The heterogeneous catalyst system explored in this thesis is based upon zeolite (ZSM-5) catalysts, which may be modified via post synthesis deposition of either or both of iron and copper and are shown to selectively transform ethane to a variety of higher value products including but not limited to ethanol, acetaldehyde, acetic acid and ethene under mild, environmentally benign conditions (H2O2 as oxidant, water as solvent, temperatures of < 90oC). C-C scission of C2 products led to formation of carbon centred radicals and yielded C1 products including methylhydroperoxide, methanol and formic acid, whilst deep oxidation yielded CO2, typically at selectivities of < 5%. The method by which catalysts were prepared was shown to impact significantly upon catalyst performance, with chemical vapour impregnation, a novel vapour deposition technique being shown to yield highly active catalysts. Investigations of reaction conditions such as ethane pressure, ethane partial pressure, temperature, oxidant concentration and catalyst mass [Chapter 1] III were conducted in a batch reaction system. All parameters were found to impact significantly upon both catalytic activity and product distributions allowing for directed selectivity to either ethanol or acetic acid as major product. Through extensive mechanistic studies, it was shown that a complex reaction scheme operates with these catalysts, which results in the primary C2 products ethanol, ethylhydroperoxide and ethene. Of these the former two were shown to undergo consecutive oxidation to acetaldehyde and acetic acid, whilst ethene was shown to react under test conditions to yield acetic acid. Additionally, upon deposition of Cu2+ onto ZSM-5 catalysts ethene was shown to become the major reaction product, with selectivities of 45.5% at 1.15% conversion. Following development under batch reaction conditions, the ZSM-5 catalysts were then applied under a continuous flow regime through co-feeding of an aqueous hydrogen peroxide solution and mixed ethane/ argon feed through a custom built fixed bed trickle bed reactor system. Through optimisation of reaction conditions 23% ethane conversion to acetic acid (73% selectivity) was observed. Through varying the catalyst bed makeup, turnover frequencies equal to those observed at comparable conditions under batch reaction conditions were observed, thereby showing the viability for translating this catalyst system to a more industrially viable continuous flow system. High ethene and acetic acid selectivities of 37.8% and 43.0% were observed, respectively at 3.3% ethane conversion upon testing of 1.25% Fe 1.25% Cu/ZSM-5 (30) within this regime at 50 oC. Subsequent studies focused upon elucidating the role played by aluminium sites within the zeolite framework in catalyst activity and determining product selectivities. This has led to the development of Cu/ZSM-5 and FeCu/ZSM-5 catalysts which are not only highly active for the activation of ethane, but also highly selective for the formation of ethene, with productivity to ethene alone shown to reach 25.6 mol (ethene) kg-1 (catalyst) [Chapter 1] IV h-1 (at 50% ethene selectivity). Through studies of ZSM-5 catalysts of varying support composition, headway has been made in decoupling the effects which increased exchange capacity (aluminium content) has upon catalyst performance, thereby paving the way for future development of more active, selective catalysts for the transformation of ethane to higher value products, specifically ethene. An interesting aspect of this work was the discovery that copper oxide particle size and size distribution may be controlled through varying of the ZSM-5 support’s SiO2/Al2O3 ratio due to a metal support interaction.

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25

Park, Justin Lane. "The Investigation of Nickel-Based Catalysts for the Oxidative Dehydrogenation of Ethane." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7393.

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The Investigation of Nickel-Based Catalysts for the Oxidative Dehydrogenation of Ethane Justin Lane ParkDepartment of Chemistry & Biochemistry, BYU Doctor of Philosophy Chemistry The advancement of creating ethylene from ethane via oxidative dehydrogenation (ODH) rather than the traditional direct dehydrogenation is right on the cusp of commercialization. The oxidative pathway provides a novel route that reduces the operating temperature of this reaction by 400-500°C. A variety of metals including Mo, V, and Ni that have redox properties suitable for the partial oxidation of small chain alkanes have been investigated. Currently, a MoVNbTe oxide is the most promising catalyst but it suffers from a long and difficult preparation method and the combination of four expensive metals. Nickel based catalysts have also shown great promise but are limited by the reactivity of the oxygen species on the surface of the catalyst. In this manuscript, the details for improving the activity of the nickel and altering the activation mechanism are outlined.Bulk CeNiNb oxide catalysts were shown to almost double the rate of ethylene yields at temperatures as low as 300°C. This is partially related to the improved rate of oxygen adsorption and transfer to the active oxygens on the nickel oxide via the ceria additive. However, with further characterization of these materials, it was shown that there is likely an interaction between the Ce and Nb, forming a Ce-O- Nb linkage that is also selective towards ethylene. This facilitates a higher activity of the catalyst by creating two redox active sites. The improved rates of ethylene formation observed with these catalysts led to the initial development of a commercially viable nickel based catalyst. The support interactions of NiO with a novel silica doped alumina support show higher yields than previously reported studies of NiO on alumina for ODH. These initial metal support interactions show that the addition of the niobium and ceria to this catalyst should give ethylene yields that are satisfactory for the commercialization of this catalyst.

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26

Dasgupta, Debasis. "Studies on the transport properties of tetraalkylammonium salts in 2- methoxy ethanol, 1, 2- dimethoxy ethane and their aqueous binary mixtures." Thesis, University of North Bengal, 1987. http://hdl.handle.net/123456789/713.

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27

Wang, Weigang. "Reduced kinetic mechanisms for premixed laminar flames." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337792.

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28

Amey, David M. "Directing influences in the intra- and inter-molecular meta photocycloaddition of ethenes to the benzene ring." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388465.

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29

Warren, Richard. "Towards in-situ analysis of liquefied natural gas with near infrared spectroscopy." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246257.

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30

Miller, Melanie Marie. "Multiphase equilibria behavior of carbon dioxide and ethane + hydrocarbon binary and ternary mixtures /." Access abstract and link to full text, 1988. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/8825490.

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31

Hodgetts, Robert William. "Excess enthalpies and excess volumes of binary mixtures containing carbon dioxide and ethane." Thesis, University of Bristol, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292452.

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32

Perez, Jeffrey A. "Evaluation of ethane as a power conversion system working fluid for fast reactors." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44836.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2008.
"June 2008."
Includes bibliographical references (p. 39-40).
A supercritical ethane working fluid Brayton power conversion system is evaluated as an alternative to carbon dioxide. The HSC® chemical kinetics code was used to study thermal dissociation and chemical interactions for ethane and other coolants under a variety of conditions. The NIST database was used for reaction rates. Overall results were not conclusive. The supercritical behavior of ethane at high pressures is not well documented, and the recombination rates of its dissociation reactions could prove very important. Ethane is known to crack into ethylene, but computer simulations show that it can, at equilibrium, also form significant amounts of hydrogen and methane. These reactions cracked more than 25% of the ethane above 300°C, even though high (20 MPa) pressure significantly reduced dissociation compared to results at 0.1 MPa. At high pressure it appears that ethane might recombine much faster than it dissociates, which would be highly advantageous. Further research and experimentation is encouraged. Simple experiments should be sufficient to identify the behavior of ethane at high temperatures and pressures. Ethane was calculated to have better heat transfer properties than carbon dioxide. In particular, heat exchanger sizes could be reduced by as much as a factor of three. On the other hand, more turbomachinery stages are needed. A simple experiment is proposed to determine whether recombination under compressor inlet conditions is sufficiently fast and complete to make the use of ethane a practical proposition. The chemical reaction of ethane with sodium, while it generates hydrogen, is endothermic, which may quench the reaction in the event of small heat exchanger leakage.
by Jeffrey A. Perez.
S.B.

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33

Mondal, K. C. "Oxidative or non−oxidative conversion of methane or ethane into value added products." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2004. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2904.

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Hung, Jocelyn. "Effects of propane or ethane additives on laminar burning velocity of methane-air mixtures." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26297.

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Laminar burning velocities of stoichiometric methane-air, ethane-air, propane-air as well as methane with propane and ethane additives have been determined from pressure-time records during combustion in a constant-volume spherical combustion bomb with central ignition. Additives up to 20 volume percent were used. Initial pressure ranged from 1 to 8 atm. Results show that these additives increase the burning velocity of methane-air by an amount depending on the concentration and initial pressure. Ethane appeared to be more effective than propane for the same volume percent. Two analytical methods were used to deduce the laminar burning velocity: Metghalchi and Keck (M and K) model and linear model. The M and K model is a procedure to satisfy the conservation of mass and energy for a mixture consisting of two homogeneous regions, burnt and unburnt, separated by a flame of negligible thickness. The linear model, from the assumption that the fractional pressure rise is linearly proportional to the fractional mass burnt, calculates the burning velocity based on the mass conservation equation. Results from these two methods agree to within 5%. Dissociation reactions, when neglected, were found to give values of burning velocities that are 10% too low. Ionization probes were used to detect flame arrival times at specific radial locations. Experimental and calculated results agree to within 2%.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

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Harris, Jonathan James Whithey. "Molecular beam study of the dissociation and reactivity of ethane on Pt{110}-(1x2)." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603753.

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Supersonic molecular beam techniques were used to study the dissociative adsorption of ethane, C₂H₆, on Pt{110}-(1 x 2). The initial sticking probability of C₂H₆ was measured using a novel form of the King and Wells method, for incident translational energies (E_t) of 3.5 to 65 kJ mol^-1. In addition to the high energy pathway reported previously, dissociation occurs through two lower-energy pathways, both of which are direct and activated. For E_t £ 15 kJ mol^-1, dissociation is strongly inhibited by vibrational excitation. For E_t = 15 to 40 kJ mol^-1, the initial dissociative sticking probability (s₀) is independent of E_t and enhanced by excitation of the ethane asymmetric CH₃ deformation vibrational modes. For the surface temperature range of 350-400 K, the stable dissociation product of ethane on Pt{110}- (1 x 2) is ethylilidyne, C₂H₂, at all coverages. Temperature-programmed reaction (TPR) experiments shows that C₂H₂ decomposes to C₂H above 400 K, and to surface carbon at higher temperatures. For T_S ³ 800 K, ethane dissociation leads to the formation of carbonaceous multilayers. We show that surface CCH species is readily oxidized to CO₂ and H₂O at surface temperatures of 450 K or above, while the dehydrogenated C₂ species reacts with oxygen at the same temperature much more slowly. When ethane dissociates on oxygen-covered Pt{110} at T_S = 370 K, O_a reacts exclusively with surface hydrogen. At T_S = 600 K, the reaction between gas-phase C₂H₆ and O_a produces CO₂ and H₂O. We propose a mechanism in which ethane first decomposes to form C_a and H_a; the initial reaction intermediates are CO_a and OH_a. CO oxidation is catalyzed by surface OH groups.

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36

Edwards, Gillian. "Some studies of Leydig cell cytotoxicity ethane-1,2-dimethane sulphonate in the male rat." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328323.

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Walker, Brian Christopher. "SHOCK-TUBE INVESTIGATION OF IGNITION DELAY TIMES OF BLENDS OF METHANE AND ETHANE WITH OXYGEN." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3473.

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The combustion behavior of methane and ethane is important to the study of natural gas and other alternative fuels that are comprised primarily of these two basic hydrocarbons. Understanding the transition from methane-dominated ignition kinetics to ethane-dominated kinetics for increasing levels of ethane is also of fundamental interest toward the understanding of hydrocarbon chemical kinetics. Much research has been conducted on the two fuels individually, but experimental data of the combustion of blends of methane and ethane is limited to ratios that recreate typical natural gas compositions (up to ~20% ethane molar concentration). The goal of this study was to provide a comprehensive data set of ignition delay times of the combustion of blends of methane and ethane at near atmospheric pressure. A group of ten diluted CH4/C2H6/O2/Ar mixtures of varying concentrations, fuel blend ratios, and equivalence ratios (0.5 and 1.0) were studied over the temperature range 1223 to 2248 K and over the pressure range 0.65 to 1.42 atm using a new shock tube at the University of Central Florida Gas Dynamics Laboratory. Mixtures were diluted with either 75 or 98% argon by volume. The fuel blend ratio was varied between 100% CH4 and 100% C2H6. Reaction progress was monitored by observing chemiluminescence emission from CH* at 431 nm and the pressure. Experimental data were compared against three detailed chemical kinetics mechanisms. Model predictions of CH* emission profiles and derived ignition delay times were plotted against the experimental data. The models agree well with the experimental data for mixtures with low levels of ethane, up to 25% molar concentration, but show increasing error as the relative ethane fuel concentration increases. The predictions of the separate models also diverge from each other with increasing relative ethane fuel concentration. Therefore, the data set obtained from the present work provides valuable information for the future improvement of chemical kinetics models for ethane combustion.
M.S.A.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Aerospace Engineering MSAE

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38

Jawad, Shadwan Hamid. "Thermal conductivity of polyatomic gases." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367922.

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Pham, Thi Lan Huong. "Synthèse et caractérisation des carbures de tungstène : application à l'isomérisation du n-heptane." Paris 6, 2002. http://www.theses.fr/2002PA066501.

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40

Kierkegaard, Amelie. "PBDEs in the Environment : Time trends, bioaccumulation and the identification of their successor, decabromodiphenyl ethane." Doctoral thesis, Stockholm : Department of Applied Environmental Science (ITM), Stockholm University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6779.

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Fröhlich, Thomas [Verfasser], and Ernst [Akademischer Betreuer] Wagner. "Novel, sequence-defined oligo (ethane amino) amides for siRNA delivery / Thomas Fröhlich. Betreuer: Ernst Wagner." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/1022791117/34.

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Chua, Li Min. "Deactivation of PtH-ZSM-5 bifunctional catalysts by coke formation during benzene alkylation with ethane." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518282.

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The alkylation of benzene with ethane was studied at 370 oC over two Pt-containing ZSM-5 catalysts with SiO2/Al2O3 ratios of 30 and 80. While the benzene and ethane conversion decreased with time-on-stream for the PtH-ZSM-5(30) catalyst, the PtH-ZSM-5(80) catalyst demonstrated a stable performance. The deactivation of the PtH-ZSM-5(30) catalyst was found to be more significant, when compared to the PtH-ZSM-5(80) catalyst as a result of differences in the formation of coke. Results from gas sorption and x-ray diffraction experiments showed that coke is preferentially formed within the channel segments of the PtH-ZSM-5(30) catalyst as opposed to coke deposition on the outside surface of the PtH-ZSM-5(80) crystallites, subsequently blocking entrance to the zeolite channels.
The location of the coke deposition was found to affect the product selectivity of the two PtH-ZSM-5 catalysts. The accessibility functions, derived from nitrogen and argon sorption data, suggested that, with prolonged time-on-stream, the coke molecules build up from the middle of the zeolite crystallites outwards towards the surface, as the reaction was carried out over the PtH-ZSM-5(30) catalyst. Partial blockage of the internal pore structure of the PtH-ZSM-5(30) catalyst decreased the diffusion length within the crystallites. In contrast to the typical effect of coking, where the selectivity of para- isomers would be enhanced with coke deposition, the effect of the reduction in the diffusion length of the PtH-ZSM-5(30) crystallites is consistent with the decreasing para-selectivity of the diethylbenzene (DEB) isomers with time-on-stream.
n investigation of the causes of coke locations was conducted, and the results suggested that, the spatial distribution of Pt metal was responsible for the different locations of coke observed. Surface reactions initiated coking in the intercrystalline region of the PtH-ZSM-5(80) catalyst, as the Pt particles on the surface of the PtH-ZSM-5(80) crystallites increased the difficulty of access for reactants to the interior of the crystallites. Within the PtH-ZSM-5(30) catalyst, ethane dehydrogenation and benzene alkylation took place in the micropore network as a result of preferential intracrystalline deposition of Pt metal. Further conversions on the active sites within the PtH-ZSM-5(30) crystallites thus lead intracrystalline coking.

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Mulla, S. A. R. "Oxidative conversion of methane, ethane or natural gas to ethylene in an energy efficient manner." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1997. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3233.

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44

Glasier, Greg F. "Molecular growth, aerosol formation and pyrolytic carbon deposition during the pyrolysis of ethane at high conversion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0034/NQ66664.pdf.

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45

Lam, Daniel H. "Multiphase equilibrium behavior of ethane, nitrous oxide and carbon dioxide + n-alkanol binary and ternary mixtures /." Access abstract and link to full text, 1990. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/9034205.

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46

Zhou, Zheng. "The Investigation of Functionalized Carbon Nanotubes for the Carbon Dioxide Capture and Ethane Oxidative Dehyrogenation Catalysts." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8417.

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Carbon nanotubes (CNT) have gained interest for wide use as both support and catalyst due to the ease of uniquely tunable surface chemistry. Increasingly severe greenhouse effects have attracted attention to novel materials and technologies capable of capturing carbon dioxide (CO2). In this context, we develop a CNT based solid state amine for the CO2 capture. CNT are functionalized under various methods as a support for polymeric amines. Polyethyleneimine are physically adsorbed on CNT and are further characterized and studied for reversible CO2 capture. We obtain a high CO2 capture capacity (6.78 mmol∙g-1) for linear polyethyleneimine (LPEI) and 6.18 mmol∙g-1 for branched polyethyleneimine (BPEI). Based on the study of pore structure, we also demonstrate that in a steam post-combustion environment, supported polymeric amines on CNT show higher stability than traditional metal oxides. Besides the increased stability of the support in steam, we also improve the stability of amines under steam conditions by developing a covalent modification method. The CO2 capture capacity of the covalent bonded materials under steam conditions improved by 14% compared to dry conditions. In addition, the loading, chemical properties of PEI, and the surface chemistry of CNT remained stable under steam conditions compared to physically adsorbed PEI on CNT. These results suggest that covalent bonded PEI on CNT can be more suitable for CO2 capture in post-combustion processes. A different CNT application is as a catalyst for oxidative dehydrogenation (ODH) of ethane, and herein we develop a new processing technique for tuning the surface chemistry of the CNT-based catalyst. A one-step, gas-phase hydrogen (H2) surface modification is used to reduce carboxylic groups to phenolic groups on carbon nanotube (CNT) materials. This technique is greener and more facile for large-scale industrial catalysts than what has previously been reported. This method uses fundamental principles of CNT surface chemistry to efficiently reduce the unselective oxidation sites and enhances the active sites used for alkane oxidative dehydrogenation. The resulting catalyst improves the ethylene selectivity and yield by at most 81% and 28% respectively compared to the non-modified catalyst. A clear linear correlation between the functional groups and catalytic activity reveals the effect of specific oxygen species on performance. As the catalyst surface area increases, pretreatments generate more selective active sites instead of over-oxidation sites, providing a guideline for catalyst optimization. We suggest that the gas-phase H2 method is general for reducing carbon catalysts to increase selective oxidation sites for gas phase reactions.

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47

Fuller, Anshuman. "Novel Perovskite-based electro-catalysts for Oxidative Dehydrogenation (ODH) of Ethane in an Electrochemical Membrane Reactor." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1439880541.

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48

Etoumi, Assma S. Abdalla. "Hybrid membrane-distillation separation for ethylene cracking." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/hybrid-membranedistillation-separation-for-ethylene-cracking(aee59d9f-61a3-4edf-8d22-0123fb6e942e).html.

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Gas separations are often required in chemical processes, e.g. air separation, ethylene production, etc. These are often challenging and costly processes because of the low temperature and high pressure needed if vapour-liquid phase separations are involved. This thesis focuses on hybrid membrane-distillation separations as an opportunity to develop more energy-efficient separation processes. In a typical ethylene plant, recovery, the separation and purification of the cracked product are economically important. The focus of this thesis is on the ‘C2splitter’ which separates the desired product, ethylene, from ethane. Cryogenic distillation, which is currently used to separate the binary ethylene-ethane mixture, is extremely expensive in terms of both capital and operating costs, especially because of refrigerated cooling requirements. Hybrid membrane-distillation processes are able to effectively separate low-boiling compounds and close-boiling mixtures and to reduce energy consumption, relative to cryogenic distillation. However, hybrid membrane-distillation processes present challenges for process modelling, design and operation. There are two major challenges associated with the modelling of hybrid processes for low temperature separations: i) the complex interaction between the process and the refrigeration system and ii) the large number of structural options, e.g. conventional column, membrane unit or hybrid membrane-distillation separation, where the distillation column can be integrated with the membrane unit to form a sequential, parallel, ‘top’or ‘bottom’ hybrid scheme. This thesis develops a systematic methodology to design, screen, evaluate and optimise various design alternatives. Schemes are evaluated with respect to energy consumption, i.e. power consumption of process and refrigeration compressors, or energy costs. In the methodology, process options are screened first for feasibility, based on numerous simulations and sensitivity analyses. Then, the feasible options are evaluated in terms of energy consumption and compared to the performance of a conventional distillation column. Finally, economically viable schemes are optimised to identify the most cost-effective heat-integrated structure and operating conditions. The methodology applies models for multi-feed and multi-product distillation columns, the membrane, compressor and refrigeration system; heat recovery opportunities are systematically captured and exploited. For the separation of relatively ideal mixtures, modified shortcut design methods, based on the Fenske-Underwood-Gilliland method are appropriate because they allow fast evaluation without needing detailed specification of column design parameters (i.e. number of stages, feed and side draw stage locations and reflux ratio). The modifications proposed by Suphanit (1999) for simple column design are extended to consider multi-feed and/or multi-product columns. The complex column designs based on the approximate calculations method are validated by comparison with more rigorous simulations using Aspen HYSYS. To design the hybrid system, a reliable and robust membrane model is also needed. To predict the performance of the module model, this work applies and modifies detailed membrane model (Shindo et al., 1985) and approximate method (Naylor and Backer, 1955) to avoid the need for initial estimates of permeate purities and to facilitate convergence. Heat integration opportunities are considered to reduce the energy consumption of the system, considering interactions within the separation process and with the refrigeration system. A matrix-based approach (Farrokhpanah, 2009) is modified to assess opportunities for heat integration. The modified heat recovery model eliminates the need to design the refrigeration cycle and uses a new simple, linear model that correlates the ideal (Carnot) and a more accurately predicted coefficient of performance. This work develops a framework for optimising important degrees of freedom in the hybrid separation system, e.g. permeate pressure, stage cut, side draw molar flow rate and purity, column feed and side draw locations. Heat recovery options between: i) column feeds and products; ii) the membrane feed and products and iii) the associated refrigeration system are considered. A deterministic and a stochastic optimisation algorithm are applied and compared for their efficiency of solving the resulting nonlinear optimisation problem. The new approach is demonstrated for the design and optimisation of heat-integrated sequential and parallel hybrid membrane-distillation flowsheets. Case study results show that hybrid scheme can reduce energy cost by 11%, compared to distillation, and that parallel schemes have around 8% lower energy costs than sequential hybrid schemes. These results suggest hybrid membrane-distillation processes may be competitive with distillation when applied for ethylene-ethane separations, but that further development of suitable membranes may still be needed.

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Sigurbjornsson, Omar Freyr. "Vibrational dynamics of icy aerosol particles : phase transitions and intrinsic particle properties." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2795.

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Phase transitions and other intrinsic properties (shape, size, architecture) of molecularly structured aerosol particles are important for understanding their role in planetary atmospheres and for technical applications. By combining bath gas cooling with time resolved mid-infrared spectroscopy and modeling, information is obtained on dynamic processes and intrinsic properties of fluoroform and ethane aerosol particles. The distinct infrared spectral features of fluoroform aerosol particles make it a particularly suitable model system. Homogeneous crystallization rates of the sub-micron sized aerosol particles are determined (JV = 10⁸ - 10¹⁰ cm-³s-¹ or JS = 10³ – 10⁵ cm-²s-¹ at a temperature of T = 78 K), and the controversial question regarding volume versus surface nucleation in freezing aerosols is addressed. It is demonstrated that current state of the art measurements of droplet ensembles cannot distinguish between the two mechanisms due to inherent experimental uncertainties. The evolution of particle shape from spherical supercooled droplets to cube-like crystalline particles and eventually to elongated crystalline particles is recorded and analyzed in detail with the help of vibrational exciton model calculations. Phase behaviour of pure ethane aerosols and ethane aerosols formed in the presence of other ice nuclei under conditions mimicking Titan’s atmosphere provide evidence for the formation of supercooled liquid ethane aerosol droplets, which subsequently crystallize. The observed homogeneous freezing rates (JV = 10⁷ – 10⁹ cm-³s-¹) imply that supercooled ethane could play a similar role in ethane rich regions of Titan’s atmosphere as supercooled water does in the Earth’s atmosphere.

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Kakou, Yao Rita Carolina Angora. "Ethane et 1,2-dideutérioéthane : Spectre IR-TF et photoisomérisation induite par irradiation infrarouge sélective en matrices cryogéniques." Aix-Marseille 1, 1990. http://www.theses.fr/1990AIX11285.

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La photorotamerisation induite par irradiation infrarouge selective du 1,2-dideuterioethane ch#2d-ch#2d piegee en matrices de gaz rare pose le double probleme de la relaxation intramoleculaire du mode excite sur le mode de rotation interne et de la relaxation intermoleculaire par interaction de l'espece excitee avec son environnement. Cette molecule presente deux conformeres stables (une forme gauche de symetrie c#2 et une forme trans(anti) de symetrie c#2#h). Nous avons montre que la molecule piegee en matrice de xenon presente un mode b a 1046,85 cm#8#1 de la forme gauche du ch#2d-ch#2d resonnant avec la raie p20 du laser co#2. On peut supposer que la barriere autour de la liaison c-c est peut differente de celle de l'ethane, c'est-a-dire 12,1 kj. Mol##1 soit 1012 cm##1. C'est-a-dire une energie de l'ordre de grandeur de celle du photon co#2. Le processus de photoconversion gauche-trans induite par l'absorption d'un photon infrarouge conduit a une forte modification des populations entre les differents conformeres. L'analyse de la cinetique d'idomerisation met en evidence deux phenomenes majeurs: l'existence d'un effet et tunnel permettant l'isomerisation inverse sans irradiation a travers la barriere de potentiel; l'existence d'un couplage non selectif entre les modes vibrationnels trans, gauche et la rotation interne, lorsque la molecule est irradiee par une source a large bande. Les etudes preliminaires de sites de piegeage traduisant l'interaction de la matrice sur la molecule active ont ete realisees avec l'ethane dont la symetrie d#3#d est parfaitement bien adaptee a celle d'un site monosubstitue dans un cristal cubique a faces centrees. L'hypothese d'un site disubstitue est aussi envisagee. Dans ce cas l'apparence des spectres et leur comparaison avec ceux de l'ethane gazeux permettent d'envisager l'hypothese d'une rotation de la molecule dans le site d'argon. La ro

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Dissertations / Theses on the topic 'Ethane'

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