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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Yield Optimization of Nitrogen Vacancy Centers in Diamond

Chen, Jeson 2011 August 1900 (has links)
To fully exploit the capability of NV centers in diamond as magnetic sensors and quantum bits, the optimum production recipe as well as the method to enhance its optical performance has been studied in this work. The NV centers in bulk diamond were prepared by ion implantation and electron irradiation, and the optimum dose and temperature are found by comparing its optical and magnetic performance both experimentally and theoretically. In addition, the enhancement of optical performance and size characterization of NV centers in nanodiamonds will be discussed in this work.
22

Étude de catalyseurs à base d’oxyde de titane et d’oxyde de vanadium sulfatés pour l’oxydation sélective du méthanol en diméthoxyméthane (DMM) / Sulfated vanadia-based and titania-based catalysts for selective oxidation of methanol to dimethoxymethane (DMM)

Zhao, Hongying 28 June 2010 (has links)
Ce travail est en relation avec la thématique "Energies Propres". Le diméthoxyméthane estun composé adapté au stockage de l’hydrogène pour des applications mobiles, de par saforte teneur en hydrogène, sa très faible toxicité et son faible impact sur l'environnement.De ce fait, des catalyseurs mixtes, à base d’oxyde de vanadium et d’oxyde de titanesulfatés ont été préparés et testés dans la réaction d'oxydation sélective du méthanol enDMM, en vue de la production d'hydrogène. Les propriétés acides et redox de surface ontété corrélées aux performances catalytiques. Les mécanismes de réaction et l'identificationdes facteurs limitant l'activité et la sélectivité des catalyseurs ont été aussi étudiés. / This work is related to the subject “Clean Energy”. Dimethoxymethane (DMM) is asuitable H2 storage material for mobile application because of its high content of hydrogen,extremely low toxicity and environmentally benign. Therefore, sulfated vanadia-titania,sulfated binary vanadia-based and titania-based catalysts were prepared and evaluated inthe reaction of selective oxidation of methanol to DMM and further production ofhydrogen. The surface acidic and redox properties of the studied catalysts were correlatedto their catalytic performance. In addition, the reaction mechanisms and the identificationof factors limiting the activity and selectivity of catalysts were also studied.
23

Modélisation de l'évolution de la composition du substrat au cours de l'oxydation sélective des alliages à haute température / Modelling of substrate depletion during the high temperature selective oxidation of binary alloys

Marrier, Etienne 17 December 2015 (has links)
L'oxydation sélective conduit à un appauvrissement du substrat qui contribue aux phénomènes de corrosion sous contrainte. Afin de prédire cet appauvrissement en élément oxydable, un modèle basé sur la diffusion dans le substrat et l'équilibre des flux au niveau de l'interface alliage/oxyde a été développé. La cinétique d'oxydation du matériau est utilisée comme donnée d'entrée du modèle et permet de piloter le déplacement de l'interface alliage/oxyde.Le modèle d'appauvrissement développé a été validé dans la cas de l'oxydation de l'alliage binaire Pt-Ni à 850 °C, en reproduisant la solution analytique du modèle de Wagner. L'utilisation de la méthode des différences finies a permis de lever les hypothèses d'une concentration à l'interface alliage/oxyde et d'un coefficient d'interdiffusion constants.L'appauvrissement initial en élément oxydable d'un alliage binaire (passivation, pré-oxydation) a peu d'influence sur l'évolution de l'appauvrissement de l'alliage lors de son oxydation à haute température. En revanche, lorsque le coefficient d'interdiffusion de l'alliage est plus grand en subsurface qu'en volume de cet alliage (écrouissage), la concentration en élément oxydable au niveau de l'interface alliage/oxyde décroit au cours de l'oxydation. Les profils d'appauvrissement présentent alors un point d'inflexion dû à une diffusion plus rapide au voisinage de l'interface.Enfin, le modèle a été appliqué à l'oxydation en milieu aqueux à une température de 290 °C pour étudier la déchromisation de l'alliage 690 en milieu primaire des REP. Ceci a permis de conforter la cinétique d'oxydation logarithmique directe proposée dans la littérature pour cet alliage. / High temperature selective oxidation of alloys usually results in substrate depletion. This phenomenon can be at the origin of stress corrosion cracking (SCC) initiation. To predict the depletion of the oxidizable element, a model based on diffusion in the substrate and fluxes balance at the oxide/alloy interface has been developed. The oxidation kinetics is used as input data of the model in order to drive the oxide/alloy interface displacement when the oxidizable element is "consumed" from the alloy.The depletion model presented in this work has been validated in the case of the oxidation at 850 °C of the Pt-Ni binary alloy by reproducing the Wagner's analytical solution. The two assumptions of a fixed concentration at the oxide/alloy interface, and of a diffusion coefficient homogeneous in the substrate and constant during oxidation, have been relaxed using finite difference method.An initial depletion of a binary alloy in oxidizable element (passivation, pre-oxidation) has a low impact on the substrate depletion evolution during high temperature oxidation. However, when the interdiffusion coefficient in the alloy is greater in subsurface than in the bulk (work-hardening), the oxidizable element concentration at the oxide/alloy interface decreases during the oxidation. Depletion profiles show an inflexion point due to faster diffusion close to the interface.Finally, the model has been applied to oxidation in aquaous media at a temperature of 290 °C to study Cr-depletion of alloy 690 in PWR primary water. The direct logarithmic oxidation kinetics proposed in the literature has been validated
24

アミドアニオン配位単核非ヘム鉄錯体を触媒とする選択酸化反応に関する研究 / アミドアニオン ハイイ タンカク ヒヘムテツ サクタイ オ ショクバイ トスル センタク サンカ ハンノウ ニカンスル ケンキュウ

荒川 健吾, Kengo Arakawa 22 March 2014 (has links)
博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University
25

Ανάπτυξη καταλυτικής διεργασίας για την εκλεκτική οξείδωση του CO παρουσία περίσσειας H2 / Development of a catalytic process for the selective oxidation of CO in excess H2

Αυγουρόπουλος, Γεώργιος Α. 24 June 2007 (has links)
Τα τελευταία χρόνια διεξάγεται µια έντονη ερευνητική προσπάθεια µε στόχο την ανά- πτυξη αποτελεσµατικών καταλυτών για την εκλεκτική οξείδωση του CO παρουσία περίσσειας H2. Το ενδιαφέρον για αυτήν την διεργασία εντοπίζεται στην εφαρµογή της για τον καθαρισµό από το περιεχόµενο CO, πλούσιων σε Η2 αέριων µιγµάτων τα οποία χρησιµοποιούνται ως καύσιµο σε κυψελίδες καυσίµου τύπου PEM. Στην παρούσα διδακτορική διατριβή εξετάστηκαν οι καταλυτικές ιδιότητες τριών συ- στηµάτων: Au/α-Fe2O3, Pt/γ-Al2O3 και CuO-CeO2, για την εν λόγω διεργασία. Η µελέτη εντοπί- στηκε, κατά κύριο λόγο, στους καταλύτες CuO-CeO2, οι οποίοι δε περιέχουν πολύτιµο µέταλλο. Στους εν λόγω καταλύτες, παράµετροι της µελέτης ήταν η µέθοδος παρασκευής, η φόρτιση των καταλυτών σε ενεργό φάση και η θερµοκρασία ενεργοποίησής τους. Σε κάθε περίπτωση εξετά- στηκε η ενεργότητα, εκλεκτικότητα και σταθερότητα των καταλυτών, καθώς και η ανθεκτικότητά τους στην παρουσία CO2 και Η2Ο στην τροφοδοσία. Για το χαρακτηρισµό των καταλυτών χρησι- µοποιήθηκαν: α) φασµατοσκοπία ατοµικής απορρόφησης, β) ρόφηση Ν2, γ) περίθλαση ακτίνων Χ, δ) ηλεκτρονική µικροσκοπία, ε) θερµοσταθµική ανάλυση, στ) φασµατοσκοπία φωτοηλεκτρο- νίων ακτίνων Χ και ζ) δυναµικά πειράµατα µε προγραµµατισµό θερµοκρασίας. Επιπλέον, κινητι- κές µελέτες πραγµατοποιήθηκαν σε επιλεγµένα δείγµατα CuO-CeO2. Οι καταλύτες CuO-CeO2 βρέθηκαν να έχουν σχεδόν ιδανική εκλεκτικότητα σε θερµο- κρασίες µικρότερες από 130οC. Ενεργοί και εξαιρετικά εκλεκτικοί καταλύτες CuO-CeO2 παρα- σκευάστηκαν µε διαφορετικές τεχνικές, και εµφάνισαν µεγάλη σταθερότητα µε το χρόνο αντί- δρασης και ικανοποιητική ανθεκτικότητα στην παρουσία Η2Ο και CO2. H σειρά ενεργότητας των καταλυτών, µε βάση τη µέθοδο παρασκευής τους, ήταν: (sol-gel) > (καύση) > (κιτρικά-υδρο- θερµική) > (συγκαταβύθιση) > (εµποτισµός). Ο βέλτιστος καταλύτης CuO-CeO2, ο οποίος παρα- σκευάστηκε µε τεχνική sol-gel, έδωσε ~99% µετατροπή του CO, µε ~87% εκλεκτικότητα, στους 175οC, σε συνθήκες εκλεκτικής οξείδωσης του CO (παρουσία CO2 και Η2Ο). Γενικά, η ένταση της αλληλεπίδρασης CuO-CeO2 βρέθηκε να εξαρτάται από τη θερµοκρασία ενεργοποίησης των καταλυτών. Σε χαµηλές θερµοκρασίες ενεργοποίησης η προω- θητική δράση της δηµήτριας εντοπίζεται στην αύξηση της ειδικής επιφάνειας των καταλυτών και στη δηµιουργία νέων ενεργών κέντρων, πιθανά στη διεπιφάνεια των δύο φάσεων. Απ’ την άλλη πλευρά, η ένταση της αλληλεπίδρασης ενισχύεται σε υψηλές θερµοκρασίες ενεργοποίησης, µε συνέπεια την αύξηση της εγγενούς ενεργότητας των ενεργών κέντρων. Στα περισσότερα καταλυ- τικά δείγµατα το οξείδιο του χαλκού βρισκόταν πολύ καλά διασπαρµένο στην επιφάνεια της δηµήτριας. Επιπλέον, η παρουσία και σταθεροποίηση ιόντων Cu1+ στους καταλύτες που παρα- σκευάστηκαν µε καύση, συγκαταβύθιση και sol-gel, και ενεργοποιήθηκαν σε υψηλές θερµοκρασίες, αποτελεί ένδειξη ισχυρής αλληλεπίδρασης ανάµεσα στο οξείδιο του χαλκού και στη δηµήτρια, µε αποτέλεσµα την εισχώρηση ιόντων Cu1+ στα πρώτα επιφανειακά στρώµατα της δηµήτριας. Κινητικά µοντέλα βασιζόµενα σε έναν οξειδοαναγωγικό µηχανισµό, µπορούν να περι- γράψουν τις αντιδράσεις οξείδωσης του CO και του Η2, τόσο στο καθαρό CuO, όσο και στους κα- ταλύτες CuO-CeO2. H αλληλεπίδραση ανάµεσα στο CuO και τη δηµήτρια έχει ως αποτέλεσµα την ευκολότερη αναγωγή των οξειδωµένων ενεργών κέντρων, σε σχέση µε το καθαρό CuO. Η ευχερέστερη αναγωγή αυτών των κέντρων από το CO, σε σχέση µε το Η2, είναι η αιτία της υψη- λής εκλεκτικότητας των καταλυτών CuO-CeO2. Η ενεργότητα των καταλυτών Au βρέθηκε να εξαρτάται από την επιφανειακή συγκέ- ντρωση του Au, γεγονός που καταδεικνύει τη σηµασία ύπαρξης καλώς διασπαρµένων νανοσωµα- τιδίων Au (µεγέθους ~3 nm), για την επίτευξη υψηλής καταλυτικής ενεργότητας. Την καλύτερη συµπεριφορά παρουσίασε το δείγµα µε 2.94 wt% Au, για το οποίο προσδιορίστηκε η µεγαλύτερη τιµή επιφανειακής συγκέντρωσης Au. Με αυτό το δείγµα επιτεύχθηκε µετατροπή του CO µεγαλύτερη από 99% (µε 52% εκλεκτικότητα), στους 100οC, σε ρεαλιστικές συνθήκες εκλεκτικής oξείδωσης του CO (παρουσία CO2 και Η2Ο). Η σύγκριση της καταλυτικής συµπεριφοράς καταλυτών Au/α-Fe2O3, Pt/γ-Al2O3 και CuOCeO2 έδειξε ότι σε σχετικά χαµηλές θερµοκρασίες λειτουργίας (<80oC) ο καταλύτης Au/α-Fe2O3 εµφανίζει τη βέλτιστη συµπεριφορά για την εκλεκτική οξείδωση του CO. Σε υψηλότερες θερµοκρασίες, καλύτερα αποτελέσµατα έδωσαν οι καταλύτες CuO-CeO2, ο οποίοι ήταν αντί- στοιχα ενεργοί, και σε κάθε περίπτωση πιο εκλεκτικοί από τον καταλύτη Pt/γ-Al2O3. Η παρουσία H2O και CO2 στο αντιδρόν µίγµα προκάλεσε σηµαντική µείωση στην ενεργότητα των καταλυτών Au/α-Fe2O3 και CuO-CeO2, αλλά δεν επηρέασε, τουλάχιστον αρνητικά, την ενεργότητα του Pt/γ- Al2O3. Οι καταλύτες CuO-CeO2 και Pt/γ-Al2O3 παρουσίασαν σταθερή καταλυτική συµπεριφορά για το χρονικό διάστηµα που εξετάστηκαν σε ρεαλιστικές συνθήκες αντίδρασης (7-8 ηµέρες), σε αντίθεση µε τον καταλύτη Au/α-Fe2O3. / The development of efficient catalysts for the selective oxidation of CO in the presence of excess H2 is the goal of intense research effort during the last years, due to the application of this process in removal of CO from H2-rich gas mixtures, which are used as fuel in PEM fuel cells. The catalytic properties of three systems: Au/α-Fe2O3, Pt/γ-Al2O3 και CuO-CeO2, were investigated for the title process of the present thesis. The study was focused mainly on the CuOCeO2 catalysts, which do not contain a noble metal. Parameters of the study were: the preparation method, the metal loading and the activation temperature. The activity, selectivity and stability of catalysts, and also their tolerance in the presence of CO2 and Η2Ο in the feed, were examined. The catalysts were characterized by: a) atomic adsorption spectroscopy, b) N2 adsorption, c) X-ray diffraction, d) electron microscopy, e) thermogravimetry, f) X-ray photoelectron spectroscopy and g) temperature-programmed dynamic tests. Additionally, kinetic studies were performed with selected CuO-CeO2 samples. CuO-CeO2 catalysts were found to be almost ideally selective in temperatures lower than 130οC. Active and selective CuO-CeO2 catalysts were prepared with various techniques, and showed high stability with time on stream and good resistance towards Η2Ο and CO2. Based on the preparation method, the activity ranking of the catalysts was: (sol-gel) > (combustion) > (citrate- hydrothermal) > (coprecipitation) > (impregnation). The best CuO-CeO2 catalyst, prepared with a sol-gel technique, showed ~99% CO conversion, with ~87% selctivity, at 175οC (in the presence of CO2 and Η2Ο). The interaction intensity between copper oxide and ceria was generally found to depend on the activation temperature of the catalysts. At low activation temperatures, the promoting effect of ceria causes enhancement of surface area and creation of additional active sites, probably at the interface of the two phases. On the other hand, the interaction is enhanced at high activation temperatures, resulting in increase of intrinsic activity of active sites. In most of the catalytic samples, copper oxide was well dispersed on the ceria surface. In addition, the presence and stabilization of Cu1+ ions in the catalysts that were prepared with combustion, coprecipitation and sol-gel, and were activated at high temperatures, indicates the presence of strong interaction between copper v oxide and ceria, resulting to the penetration of Cu1+ ions into the first surface layers of ceria. Kinetic models, based on the redox mechanism, can describe the oxidation reactions of CO and Η2, for both pure CuO and CuO-CeO2 catalysts. The interaction between CuO and ceria results in easier reduction of oxidized active sites, compared to pure CuO. The easier reduction of these sites from CO, compared to Η2, is the cause of high selectivity of CuO-CeO2 catalysts. The activity of gold catalysts was found to depend on the surface concentration of Au, implying that well-dipersed gold nanoparticles (size of ~3 nm) are essential for the achievement of high catalytic activity. The best performance was found for the sample with 2.94 wt% Au, which had the highest value of surface concentration of gold. In this case, CO conversion higher than 99% (with 52% selectivity) was obtained at 100οC, under realistic conditions of selective CO oxidation (in the presence of CO2 and Η2Ο). Comparison of the catalytic performance of Au/α-Fe2O3, Pt/γ-Al2O3 and CuO-CeO2 catalysts, showed that the Au/α-Fe2O3 catalyst is superior for the selective oxidation of CO at relatively low operation temperatures (<80oC). At higher temperatures, best results were obtained with the CuO-CeO2 catalysts, which proved to be comparably active, and in any case more selective than the Pt/γ-Al2O3 catalyst. The presence of H2O and CO2 in the reactant mixture caused a significant decrease in the catalytic activity of Au/α-Fe2O3 and CuO-CeO2 catalysts, but didn’t affect, at least negatively, the activity of Pt/γ-Al2O3. With the exception of Au/α-Fe2O3, the CuO-CeO2 and Pt/γ-Al2O3 catalysts exhibited a stable catalytic performance for at least 7-8 days under realistic reaction conditions.
26

[en] CONTROLLED SYNTHESIS OF CE OXIDE FOR CATALYTIC CONVERTER / [pt] SÍNTESE CONTROLADA DE NANOFIOS DE ÓXIDO DE CÉRIO DECORADOS COM NANOPARTÍCULAS DE OURO PARA CATÁLISE OXIDATIVA DO TIOANISOL

TAISSA FELISBERTO ROSADO 23 March 2021 (has links)
[pt] O controle de parâmetros físicos e químicos das nanopartículas, tais quais, forma, composição e tamanho, além da interação entre metal e suporte, são fatores determinantes no desenvolvimento de um nanocatalisador com uma boa performance. Desse modo, nanopartículas de ouro foram incorporadas em nanofios de céria e utilizados como nanocatalisador para a oxidação seletiva do tioanisol. Sendo a sua morfologia 1D, com grande área superficial específica, diâmetros finos, alta concentração de vacância de oxigênio e pequenas NPs de Au uniformemente distribuídas na superfície do CeO2, além de espécies oxidadas de ouro, temos em nosso material características que o torna favorável a reação de oxidação. Os nanofios de CeO2-Au demonstraram uma melhora na performance da oxidação seletiva do tioanisol quando comparados aos nanofios de céria puros, e ao material comercial com e sem a deposição de NPs de Au. Os nanofios de céria obtiveram uma seletividade de 100 porcento para o metil fenil sulfóxido, e uma conversão de 53 porcento em 2 h de reação. O impacto da temperatura também foi observado, demonstrando que esse é, também, um fator importante na análise da atividade de um catalisador. / [en] The control over physical and chemical parameters of nanoparticles, such as shape, composition and size as well as the interactions between metal and support, are important factors in the development of a nanocatalyst with high activity. In this context, gold nanoparticles were incorporated the surface of ceria nanowire for application as nanocatalysts towards the selective oxidation of thioanisole. Considerin their one-dimensional morphology, high specific surface area, thin diameters, significant concentration of oxygen vacancies, and small Au NPs uniformly deposited at the CeO2 nanowires surface, our material displayed characteristics that makes them favorable for oxidations reactions. The CeO2-Au nanowires showed improved catalytic performances in the selective oxidation of thioanisol relative to pure CeO2 nanowires and commercial CeO2 with and without Au NPs deposited. CeO2-Au nanowires catalyzed the desired product with 100 percent of selectivity and 53 percent of conversion. The impact of temperature, such as the solvent, were also observed revealing that these factors also influences in the activity of these nanocatalyst.
27

Coating of High Strength Steels with a Zn-1.6Al-1.6Mg Bath / Selective Oxidation and Reactive Wetting of High Strength Steels by a Zn-1.6Al-1.6Mg Bath

De Rango, Danielle M. January 2019 (has links)
Recently, Zn-XAl-YMg coatings have emerged as lighter-weight substitutes for traditional Zn-based coatings for the corrosion protection of steels; however, little is currently known concerning the interactions between the oxides present on advanced high strength steel (AHSS) surfaces and the Zn-Al-Mg bath. In the current contri- bution, the selective oxidation and reactive wetting of a series of C-Mn AHSS were determined with the objective of providing a quantitative description of this pro- cess. The process atmosphere pO2 was varied using dew points of −50◦C, −30◦C and −5◦C. The surface oxide chemistry and morphology were analysed by means of SEM and XPS techniques. Reactive wetting of the selectively oxidized surfaces using a Zn-1.6 wt.% Al-1.6 wt.% Mg bath was monitored as a function of annealing time at 60 s, 100 s and 140 s at 800◦C. The resulting bare spot defects in the Zn-1.6 wt.% Al-1.6 wt.% Mg coating were assessed by means of SAM-AES and FIB, while coating adhesion was analysed by 180◦ bend tests. Annealing the steel substrates resulted in the formation of surface MnO, which varied based on pO2 and Mn alloy content, and that this MnO greatly reduced the wettability of the steel by the Zn-1.6 wt.% Al- 1.6 wt.% Mg bath, resulting in bare spot defects. It was determined that the reactive wetting of the steel substrate was dependant on the oxide morphology and oxidation mode, which was a function of both alloying content of Mn in the steel and annealing pO2 process atmosphere (dew point). Finally, it was concluded that the bare spot area percentage on the coated panels was statistically invariant for annealing times of between 60 s and 140 s at 800◦C. / Thesis / Master of Applied Science (MASc) / Metallic coatings are applied to steels that are not naturally corrosion resistant. The aim of this research was to determine how well a coating containing zinc, aluminum and magnesium adhered to high strength automotive steel. It was deter- mined that manganese oxides formed on the steel during heating prior to applying the metallic coating. The manganese oxides prevented good adhesion between the steel and the coating, resulting in bare spot defects in the coating. The bare spot defects are undesirable as they leave the steel exposed and therefore susceptible to corrosion and are unsightly when painted.
28

Synthesis, adsorption and catalysis of large pore metal phosphonates

Pearce, Gordon M. January 2010 (has links)
The synthesis and properties of metal phosphonates prepared using piperazine-based bisphosphonic acids have been investigated. The ligands N,N’-piperazinebis(methylenephosphonic acid) (H₄L), and the 2-methyl (H₄L-Me) and 2,5-dimethyl (H₄L 2,5-diMe) derivatives have been prepared using a modified Mannich reaction. Hydrothermal reaction of gels prepared from metal (II) acetates and the bisphosphonic acids results in the synthesis of four structures: STA-12, Ni VSB-5, Co H₂L.H₂O and Mg H₂L. STA-12, synthesised by reaction of Mn, Fe, Co or Ni acetate with H₄L or H₄L-Me, has been investigated further. STA-12 crystallises in the space group R⁻₃, and Ni STA-12 is the most crystalline version. Its structure was solved from synchrotron data (a = b = 27.8342(1) Å, c = 6.2421(3) Å, α = β = 90°, γ = 120°), and it has large 10 Å hexagonal shaped pores. Helical chains of Ni octahedra are coordinated by the ligands, resulting in phosphonate tetrahedra pointing towards the pore space. Water is present, both coordinated to the Ni²⁺ cations and physically adsorbed in the pores. Mixed metal structures based on Ni STA-12, where some Ni is replaced in the gel by another divalent metal (Mg, Mn, Fe or Co) can also be synthesised. Dehydration of STA-12 results in two types of behaviour, depending on the metal present. Rhombohedral symmetry is retained on dehydration of Mn and Fe STA-12, the a cell parameter decreasing compared to the as-prepared structures by 2.42 Å and 1.64 Å respectively. Structure solution of dehydrated Mn STA-12 indicates changes in the torsion angles of the piperazine ring bring the inorganic chains closer together. Fe and Mn STA-12 do not adsorb N₂, which is thought to be due to the formation of an amorphous surface layer. Dehydration of Ni and Co STA-12 causes crystallographic distortion. Three phases were isolated for Ni STA-12: removal of physically adsorbed water results in retention of rhombohedral symmetry, while dehydration at 323 K removes some coordinated water forming a triclinic structure. A fully dehydrated structure (dehydrated at 423 K) was solved from synchrotron data (a = 6.03475(5) Å, b = 14.9156(2) Å, c = 16.1572(7) Å, α = 112.5721(7)°, β = 95.7025(11)°, γ = 96.4950(11)°). The dehydration mechanism, followed by UV-vis and Infra-red spectroscopy, involves removal of water from the Ni²⁺ cations and full coordination of two out of three of the phosphonate tetrahedra forming three crystallographically distinct Ni and P atoms. No structural distortion takes place on dehydration of Ni and Co STA-12 prepared using the methylated bisphosphonate, and the solids give a higher N₂ uptake as a result. Dehydrated Ni and Co STA-12 were tested for adsorption performance for fuel related gases and probe molecules. Investigations were undertaken at low temperature with H₂, CO and CO₂, and ambient temperature with CO₂, CH₄, CH₃CN, CH₃OH and large hydrocarbons. Due to the presence of lower crystallinity, Co STA-12 has an inferior adsorption performance to Ni STA-12, although it has similar adsorption enthalpies for CO₂ at ambient temperature (-30 to -35 kJ mol⁻¹). Ni STA-12 adsorbs similar amounts of CO₂ and N₂ at low temperature, indicating the adsorption mechanisms are similar. Also, it adsorbs 10 × more CO₂ than CH₄ at low pressure, meaning it could be used for separation applications. Ni STA-12 adsorbs 2 mmol g⁻¹ H₂ with an enthalpy of -7.5 kJ mol⁻¹, the uptake being due to adsorption on only one-third of the Ni²⁺ cations. The uptake for CO is 6 mmol g⁻¹, with adsorption enthalpies ranging from -24 to -14 kJ mol⁻¹. This uptake is due to adsorption on all the Ni²⁺, meaning the adsorption enthalpies are high enough to allow the structure to relax. This is also observed for adsorption of CH₃CN and CH₃OH, where there is a return to rhombohedral symmetry after uptake. The adsorption sites in dehydrated Ni and Co STA-12 were investigated via Infra-red spectroscopic analysis of adsorbed probe molecules (H₂, CO, CO₂, CH₃CN and CH₃OH). The results indicate the adsorption sites at both low and ambient temperature are the metal cations and the P=O groups. The metal cation sites are also characterised as Lewis acids with reasonable strength. STA-12 was shown to have acidic activity for the liquid phase selective oxidations of 1-hexene and cyclohexene, although there is evidence active sites are coordinated by products and/or solvents during the reaction. STA-12 also demonstrates basic activity for the Knoevenagel condensation of ethyl cyanoacetate and benzaldehyde. Modification of STA-12 by adsorption of diamine molecules causes a slight increase in the basicity, and the highest conversions are where water and diamine molecules are both present.

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