Tesi: "Hydrocarbons"

1

Kandlbinder, Thomas. "Experimental investigation of forced convective boiling of hydrocarbons and hydrocarbon mixtures". Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/7918.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Lommatzsch, Martin. "Hydrocarbons as food contaminants:". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233297.

Testo completo

Abstract (sommario):

The contamination of foods with hydrocarbon mixtures migrating from food contact materials (FCM) was first observed for jute and sisal bags treated with batching oil in the 1990s. Since the millennium, the focus has shifted to printing inks and recycled cardboard packaging as most recognized sources for hydrocarbon contamination from FCM. Mineral oil containing printing inks can either release hydrocarbons directly from the printing of folding boxes into food or indirectly entering the recycling chain of cardboard material by printed products, such as newspapers. The contamination of dry foods with mineral oil hydrocarbons (MOH) from recycled fiber packaging has been reported to reach up to 100 mg/kg [1]. Using LC-GC-FID technique the MOH were categorized into mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). The molecular mass, which is assumed to be toxicological relevant, is derived from the GC retention times of accumulated MOSH in human tissues and is limited to n C16 to n-C35 [2]. MOSH is the most significant contaminant of the human body reaching 1-10 g per person, which is of particular concern since a formation of microgranulomas (causing inflammatory reactions) in the liver was observed in rats fed with saturated hydrocarbons [3]. Furthermore, some MOAH are assumed to be genotoxic analogous to polycyclic aromatic hydrocarbons [3]. In the latest draft of a German ‘Mineral Oil Regulation’ the following limits for the migration of MOH from recycled fiber are proposed: for MOSH C16-20 4.0 mg/kg, MOSH C21-35 2.0 mg/kg and for MOAH 0.5 mg per kg food [4]. Functional barriers reducing the migration of undesirable compounds from recycled cardboards (such as MOH and other contaminants) could be a part of the solution for this issue. Supporting that approach in this study, the boxes of recycled cardboard featuring a barrier layer on the internal surface or an integrated adsorbent available early in 2014 were investigated for their efficiency in reducing migration of mineral oil hydrocarbons into dry food. A practice-oriented one-year storage test was performed with wheat flakes in seven configurations: a box of virgin fibers, two boxes of unprotected recycled cardboard, three cardboards with barrier layers (a flexo-printed polyacrylate layer, a polyvinyl alcohol coating and a multilayer involving polyester) and a cardboard containing activated carbon. The highest migration of MOH (C16-24) was observed in the boxes of unprotected recycled cardboard (MOSH: 11.4 mg/kg, MOAH: 2.4 mg/kg). Of the three investigated barrier layers only two reduced migration of MOH into food below the limits of the 3rd draft of the German mineral oil ordinance (2014) until the end of shelf life. The cardboard box involving active carbon as adsorbent prevented detectable migration of mineral oil hydrocarbons (<0.1 mg/kg). In the case of virgin fiber, which was virtually free of MOH (<1 mg/kg), migration close to the proposed limits was detected (C16-24, MOSH: 1.5 mg/kg, MOAH: 0.4 mg/kg). Therefore, it has been proven that the transport box (corrugated board) substantially contributed to the transfer of MOH into food. Plastic FCM can also release hydrocarbons, such as polyolefin oligomeric hydrocarbons (POH), into food. These POH are of synthetic nature and are formed during the polymerization process of polyolefins (150 – 3000 mg/kg in granulates of homo/hetero polymers involving ethylene and propylene). This group of synthetic contaminants contain also saturated hydrocarbons (POSH) analogous to mineral oils, but contrary no aromatic hydrocarbons. Further, a significant amount (10 – 50%) of monounsaturated hydrocarbons (POMH) was determined in the oligomeric fraction of polyolefins, which are not detectable in mineral oil products. Therefore, these POMH can be used as a marker for POH migration. A method based on two-dimensional high performance liquid chromatography on-line coupled to gas chromatography (on-line HPLC-HPLC-GC) was developed to enable the separate analysis of saturated, monounsaturated and aromatic hydrocarbons in extracts of packaging materials like polyolefins or paperboard and foods, repectively. It is an extension of the HPLC-GC method for MOSH and MOAH [1] using an additional argentation HPLC column, since normal-phase HPLC on silica gel did not preseparate saturated from monounsaturated hydrocarbons. Further, this method and comprehensive two-dimensional GC (GCxGC) was used to investigate the concentration of different oligomer types in polypropylene (PP) and polyethylene (PE) based sealing layers as well as their corresponding granulates. The analyzed sealing layers contained 180-995 mg/kg POSH and 90-435 mg/kg POMH (C16-35). Only in sealing layers involving low-density PE, oxidized polyolefin oligomers as well as cyclic oligomers (alkylated cyclopentanes and hexanes) have been detected. The transfer of POH (C16-35) from the investigated sealing layers into food can be substantial (>50%) and can reach more than 2 mg per kg food. The level of contamination depends on the oligomer content of the sealing layer, the fat content of the food, the processing temperature and the surface-volume ratio. Hot melt adhesives are widely utilized to glue cardboard boxes used as food packaging material. The analysed raw materials of hot melts mainly consisted of paraffinic waxes, hydrocarbon resins and polyolefins. The hydrocarbon resins, functioning as tackifiers, were the predominant source of hydrocarbons of sufficient volatility to migrate via gaseous phase into dry foods. The 18 hydrocarbon resins analyzed contained 8.2-118 g/kg saturated and up to 59 g/kg aromatic hydrocarbons (C16-24). These synthetic tackfier resins, especially the oligomers ≤C24, have been characterized structurally and migration into food was estimated using a food simulant and by the analysis of real food samples. About 0.5-1.5 % of the potentially migrating substances (C16 24) of a hot melt were found to be transferred into food under storage conditions, which can result in a food contamination of approximately 1 mg/kg food in this case. The order of magnitude depends on the absolute amount of potentially migrating substances from the hot melt, the hot melt surface, contact time, amount and type of foods.

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Heck, Simone M. "Spontaneous ignition of hydrocarbons". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27297.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Blake, Nicola J. "Hydrocarbons in the troposphere". Thesis, University of East Anglia, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235923.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Mistry, Anish. "Non-Kekulé polyaromatic hydrocarbons". Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/88089/.

Testo completo

Abstract (sommario):

Non-Kekulé PAHs have been studied for a variety of applications due to the interesting chemistry they possess for such simple organic molecules. PAHs can have both closed and open-shell arrangements which have been of interest recently due to the potential magnetic and electronic properties they can acquire. Due to this, there has recently been a strong interest in graphene which can be viewed as a sheet of PAHs fused together. This thesis describes the formation of particular PAHs including open-shell compounds and how PAHs can be fully characterised using one technique. Chapter 2 describes the synthesis of 6H-benzo[cd]pyrene, the starting point of this project. Pentacene and perylene are other five fused ring structures like 6H-benzo[cd]pyrene which are commonly used due to their fluorescence, thus, this PAH could have interesting properties for material scientists. The production of the benzo[cd]pyrene radical by AFM/STM is then described. Chapter 3 describes peri-condensation reactions to form larger PAHs a technique which was commonly used in the 1900s for the addition of an aromatic ring, however, multiple ring additions have been reported to occur. In addition, carbon labelling experiments have been completed to confirm this and the mechanism by which multiple rings add have been discussed. STM/AFM has been used to characterise the compounds formed in the peri-condensation reactions as common techniques for characterisation do not provide enough structural data for compound determination. Chapter 4 discusses the synthesis of 3,8-dihydro-3H,8H-dibenzo[cd,mn]pyrene. Thereafter the use of AFM/STM is then utilised to dehydrogenate 3,8-dihydro-3H,8H-dibenzo[cd,mn]pyrene to form the non-Kekulé structure of triangulene which was simultaneously imaged for the first time.

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Tian, Zhenjiao. "Oxidation and Reduction Process for Polycyclic Aromatic Hydrocarbons and Nitrated Polycyclic Aromatic Hydrocarbons". The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1228333650.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Velugula, Hemakumar. "Impact of a prescribed forest burn on ambient hydrocarbon levels in Louisiana". Ohio : Ohio University, 2003. http://www.ohiolink.edu/etd/view.cgi?ohiou1175713579.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Stroud, Jacqueline L. "Bioavailability of hydrocarbons in soils". Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441365.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Crowley, Colin. "Fullerenes from polycyclic aromatic hydrocarbons". Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360582.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Lisle-Taylor, S. C. "Cavitation performance of pumped hydrocarbons". Thesis, Cranfield University, 1997. http://dspace.lib.cranfield.ac.uk/handle/1826/9676.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Koltuksuz, Gülsan Ülkü Semra. "Removal of hydrocarbons from wastewaters/". [s.l.]: [s.n.], 2002. http://library.iyte.edu.tr/tezler/master/kimyamuh/T000046.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Bastow, Trevor. "Sedimentary Processes Involving Aromatic Hydrocarbons". Thesis, Curtin University, 1998. http://hdl.handle.net/20.500.11937/833.

Testo completo

Abstract (sommario):

Sedimentary organic matter contains many compounds that have no obvious biogenic precursors, so their formation and occurrence are of geochemical interest. The first part of this thesis (chapters 2-5) discusses the results obtained from studying hydrocarbon racemates. Some of the compounds identified are also suggested as intermediates in the formation of alkylnaphthalenes identified in chapters 6-7. The second part of this thesis (chapters 6-11) covers the identification of a range of alkylnaphthalenes and alkylphenanthrenes in sedimentary organic matter. Possible pathways for the formation of these hydrocarbons are outlined and their application as probes into the processes of petroleum formation are described.In chapter 2 the use of permethylated cyclodextrin capillary gas chromatography columns to separate hydrocarbon racemates are reported. Chapter 3 reports the synthesis of 1,2,2,5-tetramethyltetralin and 1,2,2,5,6-pentamethyltetralin and identifies them as racemates in crude oil. They are proposed as intermediates in the formation of sedimentary alkylnaphthalenes (identified in chapters 6 and 7).The identification of isodihydro-ar-curcumene in sedimentary organic matter is described in chapters 4 and 5. It co-occurs in crude oil with dihydro-ar-curcumene and is suggested to originate from this compound via a sedimentary rearrangement process. Chiral GC-MS techniques have been used to show the presence of both enantiomers of these compounds in crude oils. The elution order of the enantiomers has been established using reference compounds of known configuration. The effects of maturity and biodegradation on dihydro-ar-curcumene and isodihydro-ar-curcumene enantiomers is reported. Optically pure dihydro-ar-curcumene from natural products undergoes rapid racemisation in the subsurface, yielding a racemic mixture before the onset of significant oil formation. 1,2-Alkyl shifts on the aromatic ring also begin at an early stage to yield isodihydro-ar-curcumene and these processes continue with increasing maturity. Laboratory experiments using proton and clay catalysts (Lewis acid catalyst) show that the alkyl shift reaction is catalysed by both proton and Lewis acids, and racemisation is only catalysed by Lewis acids. A moderately biodegraded crude oil has been shown to be depleted in the R enantiomer of dihydro-ar-curcumene and an extensively degraded oil has dihydro-ar-curcumene depleted relative to isodihydro-ar-curcumene.The identification of a number alkylnaphthalenes and their possible origins in sedimentary organic matter is described in chapters 6 and 7. In chapter 6 a previously unreported tetramethylnaphthalene (TeMN) was identified in petroleum. This compound is structurally similar to bicyclic compounds of microbial origin and these are suggested as a likely source, via a tetralin intermediate identified in chapter 3. In chapter 7 isomeric pentamethylnaphthalenes previously unreported in sedimentary organic matter are reported. These isomeric pentamethylnaphthalenes (PMNs) were identified in a number of crude oils and sediments, ranging in age from Proterozoic to Tertiary. 1,2,3,5,6-PMN is suggested to form predominantly from the aromatisation of drimanoid precursors via 1,2,2,5,6-pentamethyltetralin identified in chapter 3. In laboratory experiments, the other pentamethylnaphthalenes were generated from 1,2,3,5,6-PMN in proportions that reflect the relative stability of the isomers. By analogy, the other PMNs in sediments are suggested to arise via acid catalysed isomerisation or transalkylation processes. A maturity parameter was developed based on laboratory experiments in conjunction with observed distributions of pentamethylnaphthalenes.The formation of alkylnaphthalenes and alkylphenanthrenes through a methylation process is discussed in chapters 8-10. Several crude oils and shales which contain anomalously high concentrations of 1,6-dimethylnaphthalene, 1,2,5-trimethylnaphthalene, 1,2,7-trimethylnaphthalene, 1,2,3,5-tetramethylnaphthalene, 1,2,3,5,6-pentamethylnaphthalene, 2-methyl-6-isopropyl-1(4-methylpentyl)naphthalene, phenanthrene, 1-methylphenanthrene, 1,7-dimethylphenanthrene and retene have been shown to contain relatively high concentrations of their corresponding methylated counterparts. In laboratory experiments carried out under mild conditions, each of the alkylnaphthalenes and alkylphenanthrenes have been shown to be methylated in specific positions when heated with a methyl donor in the presence of a clay catalyst. These observations have been interpreted as evidence for a sedimentary methylation process.The effect of biodegradation on alkylnaphthalenes and alkylphenanthrenes formed from sedimentary methylation is described in chapter 11. Land-plant-derived aromatic hydrocarbons with a range of susceptibilities to reservoir biodegradation have been identified in crude oils. These compounds are the result of reactions of natural products involving aromatisation, rearrangement and methylation in the sediments (chapters 9 and 10). They are therefore suggested as markers for land-plants in severely biodegraded oils in which most of the other biologically derived compounds cannot be recognised. The order of biodegradability of these compounds has been assessed relative to their non-methylated counterparts namely 6-isopropyl-2-methyl-1-(4-methylpentyl)naphthalene and retene. The order of degradation of the four compounds is : retene < 9-methylretene ~ 6-isopropyl-2-methyl-1-(4-methylpentyl)naphthalene > 6-isopropyl-2,4-dimethyl-1-(4-methylpentyl)naphthalene. These results have been used to assess that a crude oil is a mixture of severely biodegraded and less biodegraded crude oil.

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Bastow, Trevor. "Sedimentary Processes Involving Aromatic Hydrocarbons". Curtin University of Technology, School of Applied Chemistry, 1998. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=9379.

Testo completo

Abstract (sommario):

Sedimentary organic matter contains many compounds that have no obvious biogenic precursors, so their formation and occurrence are of geochemical interest. The first part of this thesis (chapters 2-5) discusses the results obtained from studying hydrocarbon racemates. Some of the compounds identified are also suggested as intermediates in the formation of alkylnaphthalenes identified in chapters 6-7. The second part of this thesis (chapters 6-11) covers the identification of a range of alkylnaphthalenes and alkylphenanthrenes in sedimentary organic matter. Possible pathways for the formation of these hydrocarbons are outlined and their application as probes into the processes of petroleum formation are described.In chapter 2 the use of permethylated cyclodextrin capillary gas chromatography columns to separate hydrocarbon racemates are reported. Chapter 3 reports the synthesis of 1,2,2,5-tetramethyltetralin and 1,2,2,5,6-pentamethyltetralin and identifies them as racemates in crude oil. They are proposed as intermediates in the formation of sedimentary alkylnaphthalenes (identified in chapters 6 and 7).The identification of isodihydro-ar-curcumene in sedimentary organic matter is described in chapters 4 and 5. It co-occurs in crude oil with dihydro-ar-curcumene and is suggested to originate from this compound via a sedimentary rearrangement process. Chiral GC-MS techniques have been used to show the presence of both enantiomers of these compounds in crude oils. The elution order of the enantiomers has been established using reference compounds of known configuration. The effects of maturity and biodegradation on dihydro-ar-curcumene and isodihydro-ar-curcumene enantiomers is reported. Optically pure dihydro-ar-curcumene from natural products undergoes rapid racemisation in the subsurface, yielding a racemic mixture before the onset of significant oil formation. ++
1,2-Alkyl shifts on the aromatic ring also begin at an early stage to yield isodihydro-ar-curcumene and these processes continue with increasing maturity. Laboratory experiments using proton and clay catalysts (Lewis acid catalyst) show that the alkyl shift reaction is catalysed by both proton and Lewis acids, and racemisation is only catalysed by Lewis acids. A moderately biodegraded crude oil has been shown to be depleted in the R enantiomer of dihydro-ar-curcumene and an extensively degraded oil has dihydro-ar-curcumene depleted relative to isodihydro-ar-curcumene.The identification of a number alkylnaphthalenes and their possible origins in sedimentary organic matter is described in chapters 6 and 7. In chapter 6 a previously unreported tetramethylnaphthalene (TeMN) was identified in petroleum. This compound is structurally similar to bicyclic compounds of microbial origin and these are suggested as a likely source, via a tetralin intermediate identified in chapter 3. In chapter 7 isomeric pentamethylnaphthalenes previously unreported in sedimentary organic matter are reported. These isomeric pentamethylnaphthalenes (PMNs) were identified in a number of crude oils and sediments, ranging in age from Proterozoic to Tertiary. 1,2,3,5,6-PMN is suggested to form predominantly from the aromatisation of drimanoid precursors via 1,2,2,5,6-pentamethyltetralin identified in chapter 3. In laboratory experiments, the other pentamethylnaphthalenes were generated from 1,2,3,5,6-PMN in proportions that reflect the relative stability of the isomers. By analogy, the other PMNs in sediments are suggested to arise via acid catalysed isomerisation or transalkylation processes. A maturity parameter was developed based on laboratory experiments in conjunction with observed distributions of pentamethylnaphthalenes.The formation of alkylnaphthalenes and alkylphenanthrenes through a ++
methylation process is discussed in chapters 8-10. Several crude oils and shales which contain anomalously high concentrations of 1,6-dimethylnaphthalene, 1,2,5-trimethylnaphthalene, 1,2,7-trimethylnaphthalene, 1,2,3,5-tetramethylnaphthalene, 1,2,3,5,6-pentamethylnaphthalene, 2-methyl-6-isopropyl-1(4-methylpentyl)naphthalene, phenanthrene, 1-methylphenanthrene, 1,7-dimethylphenanthrene and retene have been shown to contain relatively high concentrations of their corresponding methylated counterparts. In laboratory experiments carried out under mild conditions, each of the alkylnaphthalenes and alkylphenanthrenes have been shown to be methylated in specific positions when heated with a methyl donor in the presence of a clay catalyst. These observations have been interpreted as evidence for a sedimentary methylation process.The effect of biodegradation on alkylnaphthalenes and alkylphenanthrenes formed from sedimentary methylation is described in chapter 11. Land-plant-derived aromatic hydrocarbons with a range of susceptibilities to reservoir biodegradation have been identified in crude oils. These compounds are the result of reactions of natural products involving aromatisation, rearrangement and methylation in the sediments (chapters 9 and 10). They are therefore suggested as markers for land-plants in severely biodegraded oils in which most of the other biologically derived compounds cannot be recognised. The order of biodegradability of these compounds has been assessed relative to their non-methylated counterparts namely 6-isopropyl-2-methyl-1-(4-methylpentyl)naphthalene and retene. The order of degradation of the four compounds is : retene < 9-methylretene ~ 6-isopropyl-2-methyl-1-(4-methylpentyl)naphthalene > 6-isopropyl-2,4-dimethyl-1-(4-methylpentyl)naphthalene. These results have been used to assess that a crude oil is a mixture of severely biodegraded and ++
less biodegraded crude oil.

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Safa, Behnam. "Role of the aromatic hydrocarbon receptor in the suppression of cytochrome P450 2C11 by polycyclic aromatic hydrocarbons". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0022/MQ33953.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Makhubele, Marvel M. H. "The role of salt tectonics in the hydrocarbon potential of the post-salt deposits (Albian to Recent), offshore Gabon". Thesis, University of Western Cape, 2014. http://hdl.handle.net/11394/3497.

Testo completo

Abstract (sommario):

Magister Scientiae - MSc
Following successful discovery and production of hydrocarbons, Gabon is one of the key hydrocarbon target countries in Africa. Located in the Lower Congo Basin, the study area is based in Etame Marin Permit (EMP), which is licensed to VAALCO Energy Inc., and has been producing hydrocarbons since 2002. The currently explored and producing reservoirs are in the pre-salt sandstones of the Aptian Gamba Formation, charged with hydrocarbons sourced from the syn-rift lacustrine shale of the pre-Aptian Melania Formation. With the aim of finding potential petroleum plays in the post-salt successions and by using 3D prestack depth migration (PSDM) seismic sections and wireline logs, a detailed study of the post-Aptian stratigraphy and salt tectonics of the EMP was undertaken. Eight distinct reflectors were identified based on gamma ray signatures, stratal terminations and isopach trends. Sediment distribution patterns and the relative sea level history of the succession were determined by applying principles of sequence stratigraphy and salt tectonics. Furthermore, two potential plays have been outlined in the post-salt carbonates of the Albian Madiela Formation as well as in sandstones of the Turonian Azile Formation. These reservoirs might have been charged with hydrocarbons from the pre-salt shale of the Melania Formation and/or potentially also enriched from the Albian and Cenomanian shales. For these post-salt hydrocarbon reservoirs to be charged by the pre-salt source rocks, windows within the extensive evaporitic sealing of the Aptian Ezanga Formation were required. 3D PSDM seismic sections attest that diapirism of the Aptian salt unit generated ample hydrocarbon migration pathways from the pre-salt source rocks to post-salt reservoirs. Five well-developed potential salt windows have been identified, two of which have good probability to have facilitated the upward migration of hydrocarbons, because these salt windows are located up dip of oil producing wells. However, even if hydrocarbons are found in the post-salt reservoirs, similarly to the Yombo Field (located offshore Congo, south of the EMP), these shallow reservoirs in the EMP are likely to produce heavy oils due to biodegradation.

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Olariu, Romeo Iulian. "Atmospheric oxidation of selected aromatic hydrocarbons". [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964170299.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Safinowski, Michael. "Anaerobic biodegradation of polycyclic aromatic hydrocarbons". kostenfrei, 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=97648627X.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Robertson, Charles Ray. "Chemistry towards curved polycyclic aromatic hydrocarbons". abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1438911.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Wanene, Wilson Kamau. "Toward curved polycyclic aromatic hydrocarbons (PAHs)". abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1445914.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Erwe, Karolin. "Selective Diesel Oxidation Catalysts for Hydrocarbons". Thesis, KTH, Skolan för kemivetenskap (CHE), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145857.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Spink, Robert C. H. "Functionalisation of hydrocarbons using fluorinated alkenes". Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5336/.

Testo completo

Abstract (sommario):

Functionalisation of hydrocarbons is a field of continuing activity and a variety of approaches to this field, have been taken. This thesis is concerned with the functionalisation of the carbon-hydrogen bond, in hydrocarbons, using fluorinated alkenes via a free radical chain mechanism. Addition of the nucleophilic alkyl radical to the electrophilic fluorinated alkene, specifically hexafluoropropene, occurs readily to give incorporation of the polyfluoroalkyl group into a number of hydrocarbons, including aliphatic, mono-, bi- and polycyclic systems. Further chemistry of these polyfluoroalkylated systems has been investigated, including dehydrofluorination of the polyfluoralkyl group to give a series of novel mono- di- and poly-enes with polyfluoroalkenyl groups. Perfluorination of the polyfluoroalkylated systems, using high valency metal fluorides, produced a range of new perfluorocarbons of interest and the monocyclic polyfluoroalkylated systems' were further functionalised, by radical chemistry, to give isomeric products.

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Gleisner, Florian Hans. "Bacterial degradation of polycyclic aromatic hydrocarbons". Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247752.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Leggetter, Steven Alexander. "The computer simulation of absorbed hydrocarbons". Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280866.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Peters, Andrew John. "Polycyclic aromatic hydrocarbons in seasonal snowcover". Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315520.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Sritongkam, Pornpimol. "Electrochemical measurement of polycyclic aromatic hydrocarbons". Thesis, Cranfield University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274039.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Bird, Robert. "Reactions of hydrocarbons on oxide catalysts". Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/11979.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Nowicka, Ewa. "Selective oxidation of polynuclear aromatic hydrocarbons". Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/40092/.

Testo completo

Abstract (sommario):

This thesis targets the selective oxidation of polynuclear aromatic compounds, which is considered as a preliminary step of upgrading of heavy oils, resids and bitumens to higher value materials in the liquid phase using different catalytic systems. Oxidation studies concentrated on simple model polyaromatic compounds and their alkylated derivatives. Ruthenium ion catalyzed oxidation chemistry has the potential to selectively oxidize PAHs and this system was studied in great detail with particular attention made to the reaction solvent system. Through careful studies it was found that the use of a monophasic solvent system led to the selective oxidative opening of an aromatic ring to produce the dialdehyde derivative. It was demonstrated that under standard conditions the rate of oxidation increased with the size of the fused ring system. 1H NMR methodology was developed to quantify the percentage of alkyl chain hydrogens preserved after reaction. It was found that the ruthenium based system demonstrated a high affinity for the oxidation of aromatic carbon with a low tendency to oxidise aliphatic carbon. These studies formed the basis of a detailed investigation into the mechanism of ruthenium ion catalyzed oxidation of PAHs. Investigation into another catalytic system which uses a homogeneous tungsten catalyst with hydrogen peroxide as the oxidant was also performed. Early studies showed that the H2WO4/H2O2 catalytic system exhibits high solvent dependant selectivity towards preferential oxidation of aromatic carbon. What is more, studies using alkylated aromatics with a alkyl chain greater than C8 showed that even in a non polar solvent the selectivity of oxidation is directed towards the aromatic carbon. A range of catalytic systems containing tungsten, ruthenium, heteropolyacids and their heterogenised equivalents were also applied to the oxidation of PAHs. Au-Pd supported catalysts in combination with molecular oxygen and H2WO4 were also used for the oxidation of PAHs and the results obtained opened a new path in the research of PAHs. Studies on the oxidative desulfurization, denitrogenation of heteroaromatics and the demetallation of nickel and vanadium porphyrines was also performed and are reported in this thesis.

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Henderson, Janice E. "Catalytic reactions of hydrocarbons over zeolites". Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/17006.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Rismanchian, Azadeh. "Electrochemical and Photocatalytic Oxidation of Hydrocarbons". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1415799133.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Wang, Cong. "Synthesis of Polyaromatic Hydrocarbons via Mechanochemistry". University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563525733261563.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Matthewman, Richard. "Hydrocarbons as recorders of cosmic environments". Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9290.

Testo completo

Abstract (sommario):

Hydrocarbons are ubiquitous in the Cosmos. Carbon stars jettison large amounts of hydrocarbons into interstellar space and these are incorporated into forming planetary systems alongside newly synthesized hydrocarbon material. The structure of a hydrocarbon reveals its origin with non-biological, biological, low temperature, high temperature, reduced, oxidised and aqueously altered hydrocarbons all having structural features that imply their provenance. These features are explored throughout this work, with a focus on the insoluble macromolecular organic carbon of meteorites and comparative terrestrial samples. Analytical pyrolysis of macromolecular material in meteorites is a well established technique. By subjecting samples to multiple heating steps, rather than the more usual single step, new insights into the structure and composition of the macromolecular material have been obtained. In addition, simple typing of chondrites and a reconstruction of the conditions experienced on their asteroid parent bodies is possible using the products of pyrolysis. It is the carbonaceous chondrites that have received the most attention for their organic content but some ordinary chondrites also contain appreciable quantities of organic materials. The organic inventory of both carbonaceous and ordinary chondrites has been explored in this study. Carbonaceous chondrites contain authentic abiotic organic material and are in great demand for scientific analysis and experimentation. Yet these objects are extremely rare and valuable and there is a need for analogue materials that are available in larger quantities and on which specific experiments can be carried out. Uses of effective meteorite organic analogues include the training of personnel, testing of analytical methods, contamination studies, and optimisation of space mission instruments. Most of the carbon in carbonaceous chondrites is a non-biological aromatic and intractable macromolecular material and previously unsatisfactory analogues have included coals and other so-called type III kerogens. Following a comparison of a number of candidate materials a new analogue has been identified in reworked fossil soils from the Jurassic of southern England. This type IV kerogen displays great similarities to the macromolecular material in meteorites and can be employed to lessen the burden on our curated collections of rare carbonaceous meteorites. The thermal and chemical stability of hydrocarbons ensures that they exhibit excellent preservation potential and can often be found when other molecular information carriers have long since perished. This feature is important when studying planetary environments for indicators of biogenicity. Yet there is a multitude of information to process and the organic signals can often be confusing owing to diagenesis, catagenesis, oxidation and weathering. In this study a wide range of terrestrial and extraterrestrial materials have been examined using statistical techniques to develop a method for the discrimination of abiotic from biotic macromolecular materials, based only upon the distributions of simple aromatic hydrocarbons and related compounds. This has important implications for life-detection missions destined for Mars, which are currently under development.

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Khan, Rafi Ullah. "Vacuum gas carburizing - fate of hydrocarbons". [S.l. : s.n.], 2008. http://digbib.ubka.uni-karlsruhe.de/volltexte/1000009264.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Kapinus, Vadym A. Beauchamp Jesse L. "Photophysical properties of protonated aromatic hydrocarbons /". Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-01252005-123917.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Tokunaga, Ken. "Studies on vibronic coupling in hydrocarbons". 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136243.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Mashino, Michio. "Photoinduced Chemical Reaction of Halogenated Hydrocarbons". 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147629.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Bose, Suranjana. "Manganese corrole catalyzed oxygenation of hydrocarbons". Thesis, University of North Bengal, 2013. http://hdl.handle.net/123456789/958.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Mejeha, Obioma Kelechi. "Biodegradation of petroleum hydrocarbons in soils co-contaminated with petroleum hydrocarbons and heavy metals derived from petroleum". Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3391.

Testo completo

Abstract (sommario):

The biodegradation of sites co-contaminated by organic pollutants and Heavy Metals is often a challenge due to the inhibition of microbial activities. Microbes play important role in the mineralization of petroleum hydrocarbons to CO2 by utilizing petroleum hydrocarbons as a carbon/ energy source. Heavy metals are often constituents of petroleum. Petroleum spills may result to the release associated metals (e.g. Ni, Cd, Pb, As) into the environment. Subsequent spills may cause an increase in metal concentrations in soils that may build to concentrations above intervention values. This may result to the inhibition of important biological activities such as the biodegradation of organic contaminants. This research investigates the effects of Ni, Cd and Pb contamination on biodegradation of petroleum hydrocarbons in complex soil system using a microbiological approach combined with geochemical approach. Such an approach will provide a more detailed understanding of the patterns of oil degradation under different and increasing metal stresses and how microbial communities change in such environments. Results indicated that Ni has stimulatory or no effects on biodegradation of petroleum hydrocarbons in soils depending on the chemical form of added Ni. The stimulatory effect was observed in Ni-Porphyrin contaminated soils and declined with increasing Ni concentration. In NiO soils, no effects occurred at low concentrations and increased concentration of Ni resulted to increased inhibition of biodegradation. This is unlike NiCl2 amended soils where Ni effects on biodegradation were neutral irrespective of Ni concentration. The microbial diversity study of the microbial soil community indicated that there was a selective enrichment of species in the soil communities. Phylogenetic study indicated that the dominant microorganism in the community is a strain of Rhodococcus (100%), which was closely related to most Rhodococcus strains isolated from hydrocarbon-contaminated environments, metal contaminated environments and extreme environments. Results indicated that Cd inhibited biodegradation of crude oil in soils, irrespective of Cd form or concentrations. The inhibitory effect increased with increasing concentrations. Also, the microbial diversity study of the microbial soil community indicated that there was a selective enrichment of species in the soil communities. Similar to Ni, Phylogenetic study indicated that the dominant microorganism in the community is a strain of Rhodococcus. Also biodegradation of petroleum was significantly reduced in crude oil degrading short-term Pb contaminated soils, irrespective of Pb form or concentration. However, in long-term Pb contaminated soils, while maximal rate of petroleum degradation reduced at high- Pb concentration, no effect was observed at low lead concentration. Also, the microbial diversity study of the microbial soil community indicated that there was a selective enrichment of species in the soil communities. Two dominating specie were identified in Pb-soils depending on soil. Both are closely related to a strain belonging to Bacillales that were originally isolated Rock, Scopulibacillus darangshiensis strain (98%) and oil contaminated soil Bacillus circulans (99%). While the former dominated in Pb -short-term contaminated soils as well as Pb-long term contaminated soil at high concentration, the later dominated long-term-Pb contaminated soil at low concentration.

Gli stili APA, Harvard, Vancouver, ISO e altri

38

Labib, Sarah. "Utility of Toxicogenomics Tools for the Toxicological Assessment of Polycyclic Aromatic Hydrocarbons and Complex Polycyclic Aromatic Hydrocarbon Mixtures". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35342.

Testo completo

Abstract (sommario):

Human exposures to polycyclic aromatic hydrocarbons (PAHs) occur as components of complex mixtures. Evaluations of health risks posed by complex mixtures containing PAHs rely on the toxicological knowledge of prioritized PAH mixture components, assuming that these PAHs share a common mode of action and that the sum of the contributions of these PAHs equals the toxic potency of the mixture (i.e., additivity). Traditional toxicity testing methods emphasizing apical endpoints have had limited success at evaluating the validity of these assumptions. Toxicogenomic tools that are able to rapidly generate toxicologically-relevant and mechanistic information have gained acceptance in the regulatory arena for individual chemicals; however, the applicability of these tools for chemical mixtures has been inadequately addressed. This thesis used toxicogenomic tools to (1) improve the understanding of mechanisms underlying the adverse, toxicological responses induced by individual PAHs and (2) evaluate the contention that transcriptional profiles and pathway information can be used to critically examine interactions between individual PAHs in PAH-containing mixtures, and the assumption of additivity. Microarrays were used to profile gene expression changes (transcriptomes) in forestomach, liver, and lung tissues (targets of PAH exposure) from mice orally exposed to three doses of eight individual PAHs, two defined PAH mixtures, and one complex PAH-containing mixture (coal tar). The results revealed that each PAH induced transcriptional changes that were significantly associated with several pathways implicated in carcinogenesis. However, despite a uniform ability to induce DNA damage (i.e., DNA adducts), mutations, and increases in enzyme activity, the pathways differ across PAHs and tissues. A novel strategy that employs single-PAH transcriptome data to models of additivity revealed that the assumption of additivity in PAH mixtures is valid at the pathway level; however, the independent action model of additivity yielded better estimates compared to concentration addition (used in human health risk assessment of PAH mixtures) or generalized concentration addition. Additionally, predicted and observed coal tar-induced transcriptional benchmark doses were comparable to those derived from previously published coal tar-induced murine lung tumour incidence data. Overall, this thesis demonstrates the utility of toxicogenomic data to expand the current understanding regarding the toxic potential of individual PAHs and PAH-containing complex mixtures.

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Tsai, Wai Yan. "Non-methane hydrocarbon characteristics of motor vehicular emissions in the Pearl River Delta region". online access from Digital Dissertation Consortium, 2006. http://libweb.cityu.edu.hk/cgi-bin/er/db/ddcdiss.pl?3282320.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Ouellette, Mélanie. "Gas-phase Ion Chemistry of Hydroxy and Amino-substituted Interstellar Polycyclic Aromatic Hydrocarbons and Protonated Polycyclic Aromatic Hydrocarbons". Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31349.

Testo completo

Abstract (sommario):

The gas-phase ion chemistry of hydroxyl- and amino-substituted polycyclic aromatic hydrocarbons (PAHs) and their protonated counterparts were studied using mass spectrometry. Ions were generated using an electron ionization (EI) source and the unimolecular chemistry of metastable ions was studied by performing mass-analysed ion kinetic energy spectrometry (MIKES) experiments with a magnetic sector tandem mass spectrometer. Collision-induced dissociation (CID) experiments were used in conjunction with MIKES experiments to determine ion structure. The ten molecules studied were: 1-naphthol, 2-naphthol, 1-naphthylamine, 2-naphthylamine, 1-aminoanthracene, 2-aminoanthracene, 1-phenanthrol, 9-phenanthrol, 1-hydroxypyrene and 1-aminopyrene. Since it is believed that larger PAHs, on the order of more than 50 carbon atoms, populate the interstellar medium, the goal of this study was to attempt to extrapolate the results from smaller systems to larger ones. The trends found include: hydroxy-substituted PAH radical cations lose carbon monoxide spontaneously and amino-substituted PAH radical cations lose HCN. Mechanisms for both processes are proposed, and it appears from the present results that this process should extrapolate to larger PAHs. Another trend found was that all the remaining fragment ions were always a closed ring. Protonated amino-substituted PAHs were generated by electrospray ionization using a quadruple time-of-flight mass spectrometer. By protonating 1-naphthol and 2-naphthol using methane in the high-pressure EI source, it was found that they lost exclusively H2O. As for 2-naphthylamine, 1-aminoanthracene and 2-aminoanthracene, it was found that 2-naphthylamine lost NH3 and a hydrogen atom, NH3being the dominant channel. However, as the ion size 3 increases, the hydrogen-loss channel became the dominant channel. This means that larger PAHs will likely lose exclusively a hydrogen atom to reform the parent radical cation.

Gli stili APA, Harvard, Vancouver, ISO e altri

41

Lopez, Soto Liza. "Studies of the Mars van Krevelen mechanism in hydrocarbon selective oxidation". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 384 p, 2007. http://proquest.umi.com/pqdweb?did=1362532021&sid=37&Fmt=2&clientId=8331&RQT=309&VName=PQD.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

42

Öström, Henrik. "Chemical Bonding of Hydrocarbons to Metal Surfaces". Doctoral thesis, Stockholm University, Department of Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-171.

Testo completo

Abstract (sommario):

Using x-ray absorption spectroscopy (XAS), x-ray emission spectroscopy (XES) and x-ray photoelectron spectroscopy (XPS) in combination with density functional theory (DFT) the changes in electronic and geometric structure of hydrocarbons upon adsorption are determined. The chemical bonding is analyzed and the results provide new insights in the mechanisms responsible for dehydrogenation in heterogeneous catalysis.

In the case of alkanes, n-octane and methane are studied. XAS and XES show significant changes in the electronic structure upon adsorption. XES shows new adsorption induced occupied states and XAS shows quenching of CH*/Rydberg states in n-octane. In methane the symmetry forbidden gas phase lowest unoccupied molecular orbital becomes allowed due to broken symmetry. New adsorption induced unoccupied features with mainly metal character appear just above the Fermi level in XA spectra of both adsorbed methane and n-octane. These changes are not observed in DFT total energy geometry optimizations. Comparison between experimental and computed spectra for different adsorbate geometries reveals that the molecular structures are significantly changed in both molecules. The C-C bonds in n-octane are shortened upon adsorption and the C-H bonds are elongated in both n-octane and methane.

In addition ethylene and acetylene are studied as model systems for unsaturated hydrocarbons. The validity of both the Dewar-Chatt-Duncanson chemisorption model and the alternative spin-uncoupling picture is confirmed, as well as C-C bond elongation and upward bending of the C-H bonds.

The bonding of ethylene to Cu(110) and Ni(110) are compared and the results show that the main difference is the amount of back-donation into the molecular π* orbital, which allows the molecule to desorb molecularly from the Cu(110) surface, whereas it is dehydrogenated upon heating on the Ni(110) surface.

Acetylene is found to adsorb in two different adsorption sites on the Cu(110) surface at liquid nitrogen temperature. Upon heating the molecules move into one of these sites due to attractive adsorbate-adsorbate interaction and only one adsorbed species is present at room temperature, at which point the molecules start reacting to form benzene. The bonding of the two species is very similar in both sites and the carbon atoms are rehybridized essentially to sp².

Gli stili APA, Harvard, Vancouver, ISO e altri

43

Gunbas, Duygu Deniz. "Functionalization Of Saturated Hydrocarbons: High Temperature Bromination". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607307/index.pdf.

Testo completo

Abstract (sommario):

ABSTRACT FUNCTIONALIZATION OF SATURATED HYDROCARBONS: HIGH TEMPERATURE BROMINATION Gü
nbaS, Duygu Deniz M.S., Department of Chemistry Supervisor: Prof. Dr. Metin Balci June 2006, 174 pages Although saturated hydrocarbons are readily available and extremely cheap starting materials, they can not be used in synthetic chemistry without prior activation. Efficient functionalization of alkanes leading to the production of useful organic chemicals in an industrial scale is of considerable interest for the chemical and pharmaceutical industries and remains a long-term challenge for chemists. In this respect, halogenations of hydrocarbons which leads to a variety of useful synthetic intermediates is an open avenue which deserves special attention. It is also noteworthy to mention that efficient methods for selective functionalization of saturated bicyclic hydrocarbons still remains elusive, albeit a number of methods employing various reagents have been developed for the C&
#8211
H bond activation of open chain and monocyclic alkanes. Herein, we will investigate the high temperature bromination reactions as a method for functionalization of saturated bicyclic hydrocarbons such as octahydropentalene (1), octahydro-1H-indene (2) and 1a,2,7,7a-tetrahydro-1H-cyclopropa[b]naphthalene (3). The scope and the limitations of the reaction will reveal the regio-and stereoselectivity. Furthermore, formation mechanism of the products will be discussed and the chemistry of these compounds will be extended for further functionalization

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Phillips, Pamela June. "Microbial degradation of hydrocarbons in aqueous systems". Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/842666/.

Testo completo

Abstract (sommario):

There is a vast worldwide consumption of petroleum hydrocarbons and accidental release in to the environment is common. For example petroleum forecourt retail outlets have 'interceptors' to prevent release of hydrocarbons into the environment. The aim of this study was to investigate options for in-situ bioremediation of the hydrocarbon substrates within these 'interceptors' in a laboratory model. The initial studies on bioremediation were undertaken with diesel as the substrate. It was shown that the addition of nitrogen and phosphorus to the system increased hydrocarbon mineralisation by a factor of 16, resulting in increased carbon dioxide evolution. There was strong evidence indicating that nitrogen and phosphorus were the limiting factor for hydrocarbon metabolism in this aqueous system. Trichoderma harzianum and a soil bacterial isolate LFC D1 FI were assessed and shown to degrade hexadecane and pristane. The positive affect of adding a cosubstrate was evident in flask studies; the rates of degradation by LFC D1 FI and T. harzianum were approximately doubled and tripled respectively in the presence of glucose compared to treatments without glucose. Previous attention has focused on the ability of Phanerochaete chrysosporium to degrade polycyclic aromatic hydrocarbons; in this study the degradation of aliphatics was investigated. Spores from P. chrysosporium induced on the hydrocarbon substrate were found to be necessary to degrade hexadecane. Pseudomonas putida was unable to grow in liquid media containing hydrocarbons, however on solid media and in an aqueous environment containing acid-washed sand, degradation of hydrocarbons was evident, hi the presence of sand P. putida degraded both hexadecane and pristane by 70% of the initial concentration added; in the absence of sand no degradation in the aqueous system was seen. This suggests surface attachment plays an important role in hydrocarbon degradation by P. putida. The attachment and use of the sessile P. putida in aliphatic hydrocarbon degradation is discussed.

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Liu, Bonan. "Methanol conversion to hydrocarbons via acidic catalysts". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:2314ba14-8367-4334-8f53-2ec1c05f0e16.

Testo completo

Abstract (sommario):

Methanol has long been advanced as a high-energy-density, widely-obtained (from non-oil sources such as coal, and biomass) material with potential as a replacement for the limitedly-distributed, finite-in-current-storage oil resources. Given the fact that effective methanol conversion has been observed over the acidic, zeolite based catalytic materials, e.g. H-ZSM-5, since the 1970s, it is almost certain that extra catalytic properties, such as an enhanced C-H bond activation, govern by the introduced non-zeolitic promoters, e.g. metal oxide species, could further modify the reaction pathways, with potentially-achievable, lower energy costs, higher selectivity (or yields) to many valuable hydrocarbon products (e.g. olefins) and other benefits. On the other hand, a big step is to successful convert the laboratory achievements, e.g. a selected good performance zeolite sample, into the larger-scale applications. Such a process requires the involvement of catalyst binders, and when zeolite particle comes to the nano-scale, the corporation of binder phases, e.g. Al2O3, with the parent nano zeolite plays the most important role in determining the following methanol conversion. Another critical issue is the binder-incorporated, shaped zeolite catalysts would be better tested in larger reactors which are not often seen in the regular laboratory, and the scale-up also increases the research budgets. It should be mentioned that catalyst deactivation is another crucial limitation in this research area; particularly, the reaction formed cokes especially the higher-density, and deeply dehydrogenated graphitized compounds deopsiting deeply inside the zeolite cavities/channels give many difficulties not only in the effective methanol conversion but also in detecting and measuring their quantity and compositions. This thesis aims to help in solving the above mentioned challenges in an effective methanol catalytic conversion, and can be accordingly divided into 3 aspects: 1) a method to further improve the C-H bond activations for higher olefin and aromatic yields, via modification of H-ZSM-5 (Si/Al=25, industrial) with MoO3 promoters, prepared at a lower-than-usual temperature of 400 °C (routinely 500 °C or higher temperatures are employed for the calcination of metal oxide modified zeolites); 2) an attempt to scale up the laboratory methanol-to-hydrocarbon reaction, obtained over Al2O3 incorporated nano H-ZSM-5 samples (the parent nano zeolites have Si/Al ratios of 20, 60 and 120), with a customized larger fixed-bed reactor that allows catalyst loadings of 20g packed in the shaped forms; 3) a technique based on microwave perturbation measurements in a resonant cavity, inside which coked zeolite samples are analyzed, and different coking levels as well as coke compositions are evaluated based on the sample dielectric loss values that can be calculated from the measured perturbation data. Our efforts herein are made for the soul of "Science should be applied", for a sustainable future, in a great certain to be sparked by the utilization of methanol in the industries.

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Zhang, Fengjun. "Hydrogenation of unsaturated hydrocarbons on metal surfaces". Thesis, Queen's University Belfast, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.728838.

Testo completo

Abstract (sommario):

In this thesis, we have focused on achieving insights into the heterogeneous hydrogenation of benzoic acid and acetylene. DFT calculations have enabled us to understand the reaction mechanism towards different products. Chapter 3 and Chapter 4 present detailed analyses of benzoic acid and formic acid hydrogenation over various metal surfaces; based on the computational results, we have achieved to understand the bi-phase Pt/SnO2-x catalysts that make up the deficiencies of singe metal catalysts regarding the selectivity of hydrogenation of benzoic acid towards phenyl methanol. Computationally, the formation mechanism of ethylene and ethane was investigated in Chapter 5 and a systematic analysis of the selective hydrogenation of acetylene over 16 metal surfaces based on DFT calculations was presented. Chapter 6 reports the ZPE corrections and coverage-dependent analysis for all 16 metal surfaces and we only presented the micro-kinetic modelling for Rh(111). The micro-kinetic modelling for all other 15 metal surfaces may be worth being carried out in the future.

Gli stili APA, Harvard, Vancouver, ISO e altri

47

Hagey, H. Louis. "Kinetic modelling of synthesis gas into hydrocarbons". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58214.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Pizzul, Leticia. "Degradation of polycyclic aromatic hydrocarbons by actinomycetes /". Uppsala : Department of Microbiology, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200650.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Eriksson, Mikael. "Biodegradation of hydrocarbons in soil and water /". Stockholm : Tekniska högsk, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3072.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

50

Öström, Henrik. "Chemical bonding of hydrocarbons to metal surfaces /". Stockholm : Fysikum, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-171.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Hydrocarbons"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili