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[{"key": "dc.contributor.author", "value": "Aho, Kaisa", "language": null, "element": "contributor", "qualifier": "author", "schema": "dc"}, {"key": "dc.date.accessioned", "value": "2013-10-14T17:59:10Z", "language": null, "element": "date", "qualifier": "accessioned", "schema": "dc"}, {"key": "dc.date.available", "value": "2013-10-14T17:59:10Z", "language": null, "element": "date", "qualifier": "available", "schema": "dc"}, {"key": "dc.date.issued", "value": "2013", "language": null, "element": "date", "qualifier": "issued", "schema": "dc"}, {"key": "dc.identifier.other", "value": "oai:jykdok.linneanet.fi:1284588", "language": null, "element": "identifier", "qualifier": "other", "schema": "dc"}, {"key": "dc.identifier.uri", "value": "https://jyx.jyu.fi/handle/123456789/42331", "language": null, "element": "identifier", "qualifier": "uri", "schema": "dc"}, {"key": "dc.description.abstract", "value": "The usage of fossils fuels has increased carbon dioxide emissions, and the carbon dioxide is responsible for global warming and sea level rising. One of the most promising ways of carbon capturing from the power plants is chemical looping combustion (CLC). CLC is based on the alternating oxidation and reduction reactions on the air and fuel reactors. Oxygen and energy needed for combustion between the reactors is transferred by an oxygen carrier. Oxygen carrier is usually made of metal or metal oxide. One big hindrance towards commercial use of CLC is slow reaction kinetics of oxygen carriers. One possible solution for the problem is to replace the conventional carriers by nanoscale oxygen carriers. Use of nanostructures as oxygen carriers has been investigated in this master's thesis both theoretically and numerically.\n\nThere are little research about nanocarriers available in the literature, but the results are very promising. In particular very few numerical studies has been published. Based on the literature nanostructures improve reaction kinetics thus solving one major obstacle towards commercialization. A clear disadvantage of the nanostructures is a low temperature resistance, which can be enhanced by using suitable support materials. On the whole nanostructures are seen as a promising alternative to the oxygen carriers for the CLC on the basis of the current literature .\n\nIn the numerical part of the study diffusion and formation energies of vacancies on the bulk and on the surface of a metal oxide are investigated using the GPAW software, which is based on density functional theory. As the nanosturctures have more surface, comparison of these results reveals whether the nanostructures are suitable oxygen carriers or not. Finally temperature and pressure effects are investigated applying atomistic thermodynamics, because temperatures at CLC are very high. Investigated oxygen carriers are copper (CuO and Cu_2O) and manganese based (Mn_3O_4 ja Mn_2O_3) metal oxides.\n\n\nResults from the calculations are very promising: both vacancy formation and diffusion are easier on the surface than on the bulk. Thus the nanosturctures can solve the problem of slow reaction kinetics. Mn_3O_4 makes an exception for the results, vacancy formation is easier on the Mn_3O_4 bulk than on the surface. Although the results are very promising, further research is needed in order to for example, explain the different behaviour of vacancy formation in Mn_3O_4. In addition it should be find out how the location of the vacancy and the number of vacancies affect the vacancy formation energies and diffusion.", "language": "en", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Fossiilisten polttoaineiden polttamisen seurauksena hiilidioksidip\u00e4\u00e4st\u00f6t ovat kasvaneet. Hiilidioksidi taas on vastuussa ilmaston l\u00e4mpenemisest\u00e4 ja merenpinnan noususta. Yksi lupaavimmista teknologioista hiilidioksidin talteenottoon voimalaitoksista on kemikaalikiertopolttoprosessi (CLC). CLC perustuu vuorotteleviin hapetus- ja pelkistysreaktioihin ilma- ja polttoainereaktoreissa. Palamiseen tarvittavaa happea ja energiaa reaktorien v\u00e4lill\u00e4 kuljettaa hapenkantaja, joka on yleens\u00e4 metalli tai metallioksidi. Ennen CLC-prosessin kaupallistamista on selvitett\u00e4v\u00e4 miten hapenkantajien reaktiokinetiikkaa voidaan parantaa. Yksi mahdollinen ratkaisu hitaaseen reaktiokinetiikkaan on korvata hapenkantajat nanokokoluokan hapenkantajilla. Nanorakenteiden k\u00e4ytt\u00f6\u00e4 hapenkantajina CLC-prosessissa on tutkittu t\u00e4ss\u00e4 opinn\u00e4ytety\u00f6ss\u00e4 sek\u00e4 kirjallisuuden perusteella ett\u00e4 numeerisesti.\n\nTutkimus nanorakenteiden k\u00e4yt\u00f6st\u00e4 CLC-prosessissa on v\u00e4h\u00e4ist\u00e4, mutta tulokset ovat hyvin lupaavia. Erityisesti laskennallista tutkimusta on saatavilla hyvin v\u00e4h\u00e4n. Kirjallisuuden perusteella nanorakenteita k\u00e4ytt\u00e4m\u00e4ll\u00e4 reaktiokinetiikka parantuu ratkaisten n\u00e4in yhden suuren esteen kaupallistumisen tiell\u00e4. Nanorakenteiden selke\u00e4n\u00e4 haittapuolena on niiden heikko l\u00e4mp\u00f6tilakest\u00e4vyys, jota voidaan kuitenkin parantaa erilaisilla tukimateriaaleilla. Kokonaisuutena nanorakenteet n\u00e4hd\u00e4\u00e4n kirjallisuuden perusteella hyvin lupaavina vaihtoehtoina hapenkantajiksi CLC-prosessiin.\n\nTy\u00f6n numeerisessa osuudessa tutkitaan metallioksidien diffuusioita ja vakanssinmuodostusenergioita sek\u00e4 metallioksidissa ett\u00e4 metallioksidipinnalla tiheysfunktionaaliteoriaan (DFT) pohjautuvan GPAW-ohjelmiston avulla. Koska nanorakenteissa on enemm\u00e4n pintaa, n\u00e4it\u00e4 tuloksia vertaamalla voidaan p\u00e4\u00e4tell\u00e4 ovatko nanorakenteet toimivia hapenkantajia. Koska CLC-prosessissa l\u00e4mp\u00f6tilat ovat hyvin korkeita, lopuksi tutkitaan my\u00f6s l\u00e4mp\u00f6tilan ja paineen vaikutusta vakanssinmuodostukseen ja pintojen stabiilisuuteen atomistisen termodynamiikan avulla. Tutkitut hapenkantajat ovat kupari- (CuO ja Cu_2O) ja mangaanipohjaisia (Mn_3O_4 ja Mn_2O_3) metallioksideja.\n\nLaskujen perusteella saadut tulokset ovat hyvin lupaavia, sek\u00e4 vakanssinmuodostus ett\u00e4 diffuusio on helpompaa pinnalla ja pinnan alla kuin bulkissa. Nanorakenteiden k\u00e4ytt\u00f6 voisi siis ratkaista hitaan reaktiokinetiikan. Poikkeuksen t\u00e4h\u00e4n tulokseen tekee Mn_3O_4, jossa vakanssinmuodostus on helpompaa bulkissa. Vaikka tulokset ovat hyvin lupaavia my\u00f6s laskennallista tutkimusta tarvitaan lis\u00e4\u00e4, jotta voidaan esimerkiksi selitt\u00e4\u00e4 Mn_3O_4-oksidin erilainen k\u00e4yt\u00f6s vakanssinmuodostuksessa. Lis\u00e4tutkimuksissa tulisi my\u00f6s selvitt\u00e4\u00e4 vakanssin paikan ja vakanssien m\u00e4\u00e4r\u00e4n vaikutusta vakanssin muodostumisenergiaan ja diffuusioon.", "language": "fi", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted using Plone Publishing form by Kaisa Aho (kamakaah) on 2013-10-14 17:59:07.853069. Form: Pro gradu -lomake (1 tekij\u00e4) (https://kirjasto.jyu.fi/julkaisut/julkaisulomakkeet/pro-gradu-lomake-1-tekijae). JyX data:", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted by jyx lomake-julkaisija (jyx-julkaisija@noreply.fi) on 2013-10-14T17:59:10Z\nNo. of bitstreams: 2\nURN:NBN:fi:jyu-201310142467.pdf: 4884004 bytes, checksum: 3a704803ea7579ebd92862d978b9b17a (MD5)\nlicense.html: 107 bytes, checksum: a7d86e598caa500b1b433bbb9dc8ef1c (MD5)", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Made available in DSpace on 2013-10-14T17:59:10Z (GMT). No. of bitstreams: 2\nURN:NBN:fi:jyu-201310142467.pdf: 4884004 bytes, checksum: 3a704803ea7579ebd92862d978b9b17a (MD5)\nlicense.html: 107 bytes, checksum: a7d86e598caa500b1b433bbb9dc8ef1c (MD5)\n Previous issue date: 2013", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.format.extent", "value": "1 verkkoaineisto.", "language": null, "element": "format", "qualifier": "extent", "schema": "dc"}, {"key": "dc.format.mimetype", "value": "application/pdf", "language": null, "element": "format", "qualifier": "mimetype", "schema": "dc"}, {"key": "dc.language.iso", "value": "eng", "language": null, "element": "language", "qualifier": "iso", "schema": "dc"}, {"key": "dc.rights", "value": "In Copyright", "language": "en", "element": "rights", "qualifier": null, "schema": "dc"}, {"key": "dc.subject.other", "value": "CLC", "language": "", "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "nano", "language": "", "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "oxygen carrier", "language": "", "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.title", "value": "Use of nanostructures as oxygen carriers in chemical looping combustion", "language": null, "element": "title", "qualifier": null, "schema": "dc"}, {"key": "dc.type", "value": "master thesis", "language": null, "element": "type", "qualifier": null, "schema": "dc"}, {"key": "dc.identifier.urn", "value": "URN:NBN:fi:jyu-201310142467", "language": null, "element": "identifier", "qualifier": "urn", "schema": "dc"}, {"key": "dc.type.dcmitype", "value": "Text", "language": "en", "element": "type", "qualifier": "dcmitype", "schema": "dc"}, {"key": "dc.type.ontasot", "value": "Pro gradu -tutkielma", "language": "fi", "element": "type", "qualifier": "ontasot", "schema": "dc"}, {"key": "dc.type.ontasot", "value": "Master\u2019s thesis", "language": "en", "element": "type", "qualifier": "ontasot", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Matemaattis-luonnontieteellinen tiedekunta", "language": "fi", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Faculty of Sciences", "language": "en", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.department", "value": "Fysiikan laitos", "language": "fi", "element": "contributor", "qualifier": "department", "schema": "dc"}, {"key": "dc.contributor.department", "value": "Department of Physics", "language": "en", "element": "contributor", "qualifier": "department", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "University of Jyv\u00e4skyl\u00e4", "language": "en", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "Jyv\u00e4skyl\u00e4n yliopisto", "language": "fi", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Fysiikka", "language": "fi", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Physics", "language": "en", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "dc.date.updated", "value": "2013-10-14T17:59:10Z", "language": null, "element": "date", "qualifier": "updated", "schema": "dc"}, {"key": "dc.type.coar", "value": "http://purl.org/coar/resource_type/c_bdcc", "language": null, "element": "type", "qualifier": "coar", "schema": "dc"}, {"key": "dc.rights.accesslevel", "value": "openAccess", "language": "fi", "element": "rights", "qualifier": "accesslevel", "schema": "dc"}, {"key": "dc.type.publication", "value": "masterThesis", "language": null, "element": "type", "qualifier": "publication", "schema": "dc"}, {"key": "dc.subject.oppiainekoodi", "value": "4021", "language": null, "element": "subject", "qualifier": "oppiainekoodi", "schema": "dc"}, {"key": "dc.subject.yso", "value": "hiilidioksidin talteenotto ja varastointi", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "hiilidioksidi", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "happi", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "nanorakenteet", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.format.content", "value": "fulltext", "language": null, "element": "format", "qualifier": "content", "schema": "dc"}, {"key": "dc.rights.url", "value": "https://rightsstatements.org/page/InC/1.0/", "language": null, "element": "rights", "qualifier": "url", "schema": "dc"}, {"key": "dc.type.okm", "value": "G2", "language": null, "element": "type", "qualifier": "okm", "schema": "dc"}]
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