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The superior properties of carbon nanotubes (CNTs) are best manifest in bulk materials when the CNTs are organized in tandem and embedded in a continuous matrix. Decorating the CNTs with magnetic nanoparticles (MNPs) facilitates their expedient organization with a magnetic field. One of the most convenient methods for their decoration is to first treat the CNTs with oxidative acids, and then coprecipitated MNPs in situ. This method results magnetized CNTs that are covalently functionalized with the MNPs. The associated destruction in the CNTs required running a comparative study of this protocol to identify the influence of the acid treatment on the decoration of multiwalled CNTs (MWNTs). Further, we explore means to tune the physical properties of these magnetized CNTs (mMWNTs) by varying the (1) MNP material composition, and (2) MNP:MWNT (w/w) magnetization weight ratio (γ). The resulted composite materials (mMWNTs) are utilized to synthesize a novel and hitherto unreported class of colloidal suspensions (MCCs) for which the dispersed phase, which consists of MWNTs decorated with MNPs, is both magnetoresponsive and electrically conductive. Synthesis of the dispersed phase merges processes for producing ferrofluids and mMWNTs. Later, these MCCs are adapted and engineered to produce a biological ink containing MWNTs that are twice functionalized, first with MNPs and thereafter with the anti-c-Myc monoclonal antibodies (Abs). The ink is pipetted and dynamically self-organized by an external magnetic field into a dense electrically conducting sensor strip that measures the decrease in current when a sample containing c-Myc antigens (Ags) is deposited on it. On the other side, a nondestructive methods to magnetize MWNTs and provide a means to remotely manipulate them is through the electroless deposition of magnetic nickel nanoparticles on their surfaces. The noncovalent bonds between Ni nanoparticles and MWNTs produce a Ni-MWNT hybrid material (NiCH) that is electrically conductive and has an enhanced magnetic susceptibility and elastic modulus. Raising γ (Ni:MWNT weight ratios) increases the coating layer thickness, which influences the NiCH magnetic properties and tunes its elastic modulus. The NiCH was used to fabricate Ni-MWNT macrostructures and tune their morphologies by changing the direction of an applied magnetic field. Leveraging the hydrophilic Ni-MWNT outer surface, a water-based conductive ink was created and used to print a conductive path that had an electrical resistivity of 5.9 Ωm, illustrating the potential of this material for printing electronic circuits. Further, the NiCHs are introduced into an epoxy matrix at low 0.25-1% volume fractions and aligned along the direction of an applied magnetic field, which produces anisotropic bulk properties. However, nanoparticles aligned in perpendicular directions in sequential layers result in an effectively isotropic composite material. Furthermore, the subsequent annealing of the NiCH in the presence of air oxidizes nickel to nickel oxide whereas carbon is released as gaseous carbon dioxide, which leads to a novel approach for the fabrication of nickel oxide nanotubes (NiONTs) based on MWNTs as a sacrificial template. New chelating polyelectrolytes are used as dispersing agents to achieve high colloidal stability both for NiCH and NiONTs. A gravimetric specific capacitance of 245.3 F g-1 and areal capacitance of 3.28 F cm-2 at a scan rate of 2 mV s-1 is achieved with an electrode fabricated using nickel oxide nanotubes as the active element with a mass loading of 24.1 mg/cm2. / Thesis / Doctor of Philosophy (PhD) / The superior properties of carbon nanotubes (CNTs) are best manifested in bulk materials when the CNTs are organized axially and in tandem, and embedded in a continuous matrix. Decorating the CNTs with magnetic nanoparticles (MNPs) facilitates their organization through “action from a distance” with a magnetic field. The attachment of MNPs to the surfaces of CNTs can be realized through covalent or non-covalent (i.e. physical) bonding. This work develops both methodologies to investigate how the physical properties of magnetized CNT (mCNT) can be tuned and produce new CNT-based nanostructures for particular applications. First, mCNTs are utilized to synthesize a hitherto unreported class of colloidal suspensions based on which a magnetic bio-ink is fabricated to print a fast-response biological sensor. Next, nickel-coated CNTs prepared using electroless deposition are used in the form of a filler at low volume fractions in an epoxy matrix, where they are aligned along multiple-direction using a magnetic field, producing either anisotropic or isotropic bulk properties on demand. Finally, subsequent annealing of nickel-coated CNTs in air oxidizes nickel to nickel oxide while carbon is released in the form of gaseous carbon dioxide. This leads to another novel approach for the fabrication of nickel oxide nanotubes, which are demonstrated to be an alternate viable material to fabricate electrodes for use in supercapacitors.

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Yes / Production of clean fuel has recently become one of the most important goals for petroleum refining industries. The objective of this work is to obtain such clean fuel using simple and easy process under safe conditions. For this purpose, batch oxidative desulfurization (ODS) process is considered here to remove sulfur compounds found in light gas oil using a new composite synthetic homemade nano-catalyst. First the support for the new catalyst, which is HY zeolite nanoparticles, is prepared using sol-gel method. The support is then employed to generate the synthetic composite nano-catalyst which is made of copper oxide and nickel oxide using the impregnation method with different proportions of the active components such as: 5% CuO +25 % NiO, 10 % CuO +20 % NiO, 15 % CuO +15 % NiO, 20 % CuO +10 % NiO and 25 % CuO +5% NiO. An excellent distribution of the active metals with high surface area and pore volume as a result high activity has obtained. A fully automated batch reactor is used for the oxidative desulphurization of sulfur compounds and the performance of the new nano-catalyst at different safe reaction conditions (reaction temperature from 353−413 K, reaction time from 30−90 min) is evaluated in terms of sulfur removal.

Yes / In this paper, oxidative desulfurization (ODS) process is studied for the purpose of removing the sulfur components from light gas oil (LGO) via experimentation and process modeling. A recently developed (by the authors) copper and nickel oxide based composite nano-catalyst is used in the process. The ODS experiments are conducted in a batch reactor and air is used as an oxidizer under moderate operation conditions. Determination of the kinetic parameters with high accuracy is necessary of the related chemical reactions to develop a helpful model for the ODS operation giving a perfect design of the reactor and process with high confidence. High conversion of 92% LGO was obtained under a reaction temperature of 413 K and reaction time of 90 min for synthesized Cu Ni /HY nano-catalyst. Here model based optimization technique incorporating experimental data is used to estimate such parameters. Two approaches (linear and non-linear) are utilized to estimate the best kinematic parameters with an absolute error of less than 5% between the predicted and the experimental results. An environmentally friendly fuel is regarded the main goal of this study, therefore the optimization process is then employed utilizing the validated model of the prepared composite nano-catalyst to get the optimal operating conditions achieving maximum conversion of such process. The results show that the process is effective in removing more than 99% of the sulfur from the LGO resulting in a cleaner fuel.

[ES] La presente tesis doctoral se sitúa en el marco de la actual transición energética, que plantea la sustitución progresiva de materias primas de origen fósil por fuentes renovables, tanto para la obtención de productos químicos como para la producción de combustibles. En este contexto de transición paulatina a las renovables, y teniendo en cuenta los últimos pronósticos, las fuentes fósiles (fundamentalmente gas natural) y derivados de la biomasa, jugarán un papel fundamental durante el cambio. Se ha llevado a cabo un estudio sobre el empleo de óxidos metálicos (basados en bronces de wolframio o en óxido de níquel), como catalizadores para: i) la transformación de derivados de biomasa: de glicerol a acroleína/ácido acrílico; y de compuestos oxigenados de cadena corta presentes en efluentes acuosos (procedentes de tratamientos de extracción de bio-aceites de pirolisis) a combustibles; y ii) la transformación de componentes del gas natural, concretamente la obtención de etileno a partir de etano, mediante deshidrogenación oxidativa (ODH). El trabajo se presenta desde una perspectiva de la química de materiales, haciendo hincapié en las propiedades fisicoquímicas de los distintos sistemas catalíticos, empleando técnicas de caracterización convencionales e in situ, además de reacciones modelo (transformación de metanol y etanol), con el objetivo de entender las funciones catalíticas presentes en cada caso. Tanto para la transformación de glicerol en fase gas, como para la valorización de mezclas acuosas de compuestos oxigenados de cadena corta, se han utilizado catalizadores basados en bronces de wolframio. Se ha tratado de poner de manifiesto la gran versatilidad composicional y estructural (con el consiguiente control de las propiedades funcionales), que presentan este tipo de materiales. En este sentido, las propiedades ácidas y redox de catalizadores W-V-O pueden ser moduladas, para una misma concentración de vanadio, mediante el control de la relación de fases cristalinas (hexagonal y monoclínica) del óxido de wolframio. Este efecto se ha estudiado empleando la transformación aeróbica de metanol como reacción "test", y tiene una gran influencia en la deshidratación oxidativa de glicerol a ácido acrílico. A su vez, mediante la sustitución isomórfica de wolframio por niobio (en el sistema WO3-Nb2O5) es posible controlar la relación de centros ácidos de tipo Brönsted y Lewis en la superficie de los materiales. Por un lado, los catalizadores con una alta relación Brönsted/Lewis se han mostrado más efectivos en la deshidratación de glicerol a acroleína, mientras que los catalizadores con altas concentraciones de centros de tipo Lewis presentan altos rendimientos a productos de condensación de compuestos oxigenados de cadena corta. Adicionalmente se han estudiado las diferencias entre catalizadores (bien óxidos mixtos W-V-O o W-Nb-O) preparados mediante un método hidrotermal o mediante reflujo, así como el efecto de la utilización de un soporte mesoporoso (KIT-6), sobre sus propiedades catalíticas en la transformación aeróbica en fase gaseosa de etanol y glicerol. Finalmente, en lo que concierne a la transformación de componentes del gas natural, se han empleado materiales basados en óxido de níquel (soportado sobre distintos óxidos y/o promovido con distintos metales) como catalizadores para la ODH de etano. En este caso el estudio se ha centrado fundamentalmente en dilucidar los efectos de promotores y soportes en la naturaleza y propiedades fisicoquímicas del óxido de níquel, los cuales dan lugar a un cambio drástico en sus propiedades catalíticas. Así, se ha observado que modificando la reducibilidad y las características superficiales del óxido de níquel es posible transformar un catalizador muy poco selectivo en la ODH de etano (como es el NiO, con una selectividad a etileno del 30 %) en uno de los catalizadores más selectivos para llevar a cab / [CA] Aquesta tesi doctoral es situa dins del marc de l'actual transició energètica, la qual planteja la substitució progressiva de les primeres matèries d'origen fòssil per fonts renovables, tant per a l'obtenció de productes químics com per a la producció de combustibles. En aquest context de transició gradual a les renovables, i tenint en compte els últims pronòstics, les fonts fòssils (principalment el gas natural) i els derivats de la biomassa, exerciran un paper fonamental durant aquest canvi. S'ha dut a terme un estudi sobre la utilització d'òxids metàl·lics (basats en bronzes de wolframi o en òxid de níquel), com a catalitzadors per a: i) la transformació de derivats de la biomassa: de glicerol a acroleïna/àcid acrílic; i de compostos oxigenats de cadena curta presents en efluents aquosos (procedents de tractaments d'extracció de bio-olis de la piròlisi) a combustibles; i ii) la transformació de components del gas natural, concretament l'obtenció d'etilè a partir d'età, mitjançant la deshidrogenació oxidativa. El treball es presenta des del punt de vista de la química de materials, posant l'accent en les propietats fisicoquímiques dels diferents sistemes catalítics, utilitzant tècniques de caracterització convencionals i in situ, a més de reaccions model, amb l'objectiu d'entendre les funcions catalítiques presents en cadascun dels casos. Tant per a la transformació del glicerol en fase gasosa com per a la valorització de les mescles aquoses de compostos oxigenats de cadena curta, s'han utilitzat catalitzadors basats en bronze de wolframi. S'ha intentat posar de manifest la gran versatilitat de composicions i estructures (amb el conseqüent control de les propietats funcionals) que presenten aquest tipus de materials. En aquest sentit, les propietats àcides i redox dels catalitzadors de W - V - O poden ser modulades, per a una mateixa concentració de vanadi, mitjançant el control de la relació de fases cristal·lines (hexagonal i monoclínica) de l'òxid de wolframi. Aquest efecte s'ha estudiat utilitzant la transformació aeròbica de metanol com a reacció "test", i presenta una gran influència en la deshidratació oxidativa de glicerol a àcid acrílic. Al mateix temps, mitjançant la substitució isomòrfica de wolframi per niobi (en el sistema WO3 - Nb2O5), és possible controlar la relació de centres àcids de tipus Brönsted i Lewis en la superfície dels materials. Per una part, els catalitzadors que presenten una relació Brönsted / Lewis alta s'han mostrat més efectius en la deshidratació de glicerol a acroleïna, mentre que els catalitzadors amb unes altes concentracions de tipus Lewis presenten alts rendiments a productes de condensació de compostos oxigenats de cadena curta. Addicionalment, s'han estudiat les diferències entre catalitzadors (ja siguin òxids mixtos W-V-O o W-Nb-O) preparats mitjançant un mètode hidrotermal o mitjançant un mètode de reflux, així com l'efecte que presenta la utilització d'un suport mesoporós (KIT-6), sobre les seves propietats catalítiques en la reacció de transformació aeròbica en fase gasosa d'etanol i glicerol. Finalment, pel que fa referència a la transformació de components del gas natural, s'han utilitzat materials basats en òxid de níquel (suportat sobre diferents òxids i/o promoguts amb diferents metalls) i catalitzadors per a la deshidrogenació oxidativa d'età. En aquest cas, l'estudi s'ha focalitzat principalment en dilucidar els efectes de promotors i suports en la naturalesa i propietats fisicoquímiques de l'òxid de níquel, els quals impliquen un canvi dràstic en les seves propietats catalítiques. Així doncs, s'ha observat que modificant la reductibilitat i les característiques superficials de l'òxid de níquel és possible transformar un catalitzador molt poc selectiu en la deshidrogenació oxidativa de l'età (com és el cas del NiO, amb una selectivitat a l'etilè del 30%) en un dels cata / [EN] The present doctoral thesis is set within the scope of the current energy transition, which considers the progressive substitution of non-renewable fossil sources by renewable feedstocks for the production of chemicals and fuels. In this context of gradual transition, and according to recent energy outlooks, fossil sources (especially natural gas) and biomass feedstocks will play a key role during the shift. A study on the use of metal oxides (based on tungsten bronzes or nickel oxides) as catalysts for different reactions has been conducted. Particularly, they have been studied as catalytic materials for: i) the transformation of biomass-derived feedstocks: glycerol transformation into acrolein/acrylic acid, and the transformation of short-chain oxygenates present in aqueous effluents (derived from extraction processes of pyrolysis bio-oils) into fuels; and ii) the valorization of natural gas components, i.e. the transformation of ethane into ethylene by oxidative dehydrogenation. The work is presented from a materials chemistry perspective, emphasizing the physicochemical characteristics of the different catalytic systems by using conventional and in situ characterization techniques and model reactions (gas phase methanol and ethanol transformation); with the aim of understanding the specific catalytic functionalities present in each case. For both gas phase glycerol transformation and the valorization of short-chain oxygenates aqueous mixtures, catalyst based on tungsten oxide bronzes have been used. The compositional and structural versatility of this structural types (with the subsequent control of their functional properties) will be highlighted. In this sense, the acid-redox properties of W-V-O catalysts can be modulated by controlling the crystalline phase composition in the materials (i.e. hexagonal and monoclinic polymorphs of tungsten oxide) at a fixed V concentration. This effect has been studied by using the gas-phase aerobic transformation of methanol as a surface test reaction. The concentration of the hexagonal and monoclinic polymorphs in the catalysts has also an important influence in the gas-phase transformation of glycerol into acrylic acid. Also, it is possible to control the Brönsted/Lewis acid nature of the surface by the isomorphic substitution of Nb for W in WO3-Nb2O5 system. On the one hand, catalysts showing a higher proportion of Brönsted acid sites are more effective in the glycerol dehydration to acrolein. On the other hand, materials with a higher concentration of Lewis acid sites display high yields to condensation products in the aqueous phase valorization of short chain oxygenates. Additionally, the differences between W-V-O and W-Nb-O catalysts prepared by both reflux and hydrothermal methods have been studied. Also the effect of adding a mesoporous KIT-6 silica as support on the catalytic performance in the gas phase transformation of ethanol and glycerol will be underlined. Considering the transformation of natural gas components, nickel oxide-based materials were chosen (either supported on different oxides and/or promoted with different metals) to perform the oxidative dehydrogenation (ODH) of ethane. In this case the study has been focused on elucidating the effects of both promoters and supports on the nature and physicochemical features of nickel oxide, which lead to a drastic change in the catalytic behavior of these materials. This way, it has been observed that by the modification of the reducibility and the chemical nature of nickel oxide, it is possible to transform an apparently non-selective catalyst in the ODH of ethane (like NiO, showing a selectivity to ethylene of ca. 30 %) into one of the most selective catalysts reported in the literature (presenting a selectivity to ethylene of ca. 90 %). / También me gustaría agradecerle al Prof. Avelino Corma, investigador principal del proyecto SEV-2012-0267, a través del cual he podido realizar mi tesis doctoral enel Instituto de Tecnología Química (SVP-2014-068669). / Delgado Muñoz, D. (2019). Catalytic valorization of natural gas and biomass-derived feedstocks by metal oxides [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/122298

This work investigates fabrication methods of nickel oxide thin films and their use in organic electronics. Two fabrication techniques were studied: UV-ozone oxidation of pure nickel films and reactive RF magnetron sputtering. The former was used to produce Ni/Ni2O3 bi-layer anodes to use as a substitute for the de facto standard ITO anode. OLEDs fabricated using Ni/Ni2O3 bi-layer anodes exhibited comparable device performance to standard ITO devices. UV-ozone oxidation was also used to fabricate Ni2O3 buffer layers for OPVs. Solar cells fabricated using Ni2O3 coated ITO exhibited an enhanced power conversion efficiency of up to 90%. RF magnetron sputtering was used to produce NiOx buffer layers with tunable conductivity and optical transparency for OPVs. Solar cells fabricated using NiOx coated ITO exhibited an enhanced power conversion efficiency of up to 60%. Nickel oxide films have been characterized with various techniques: sheet resistance measurements, optical transmission, XPS, UPS, AFM, and TEM.

This work investigates fabrication methods of nickel oxide thin films and their use in organic electronics. Two fabrication techniques were studied: UV-ozone oxidation of pure nickel films and reactive RF magnetron sputtering. The former was used to produce Ni/Ni2O3 bi-layer anodes to use as a substitute for the de facto standard ITO anode. OLEDs fabricated using Ni/Ni2O3 bi-layer anodes exhibited comparable device performance to standard ITO devices. UV-ozone oxidation was also used to fabricate Ni2O3 buffer layers for OPVs. Solar cells fabricated using Ni2O3 coated ITO exhibited an enhanced power conversion efficiency of up to 90%. RF magnetron sputtering was used to produce NiOx buffer layers with tunable conductivity and optical transparency for OPVs. Solar cells fabricated using NiOx coated ITO exhibited an enhanced power conversion efficiency of up to 60%. Nickel oxide films have been characterized with various techniques: sheet resistance measurements, optical transmission, XPS, UPS, AFM, and TEM.

Volatile organic compounds (VOCs) in the indoor air have adverse effects on the dwellers residing in a building or a vehicle. One of these effects is called sick building syndrome (SBS). SBS refers to situations in which the users of a building develop acute health effects and discomfort depending on the time they spend inside some buildings without having any specific illness. Furthermore, monitoring volatile organic compounds could lead to early diagnosis of specific illnesses through breath analysis. Among those VOCs formaldehyde, acetaldehyde can be listed. In this thesis, VOC detecting thin film sensors have been investigated. Such sensors have been manufactured using semiconducting metal oxides, ligand activated gold nanoparticles and Graphene/TiO2 mixtures. Advanced gas deposition unit, have been used to produce NiO thin films and Au nanoparticles. DC magnetron sputtering has been used to produce InSnO and VO2 thin film sensors. Graphene/TiO2 sensors have been manufactured using doctor-blading. While presenting the results, first, material characterization details are presented for each sensor, then, gas sensing results are presented. Morphologies, crystalline structures and chemical properties have been analyzed using scanning electron microscopy, X-ray diffraction and X-ray photo electron spectroscopy. Furthermore, more detailed analyses have been performed on NiO samples using extended X-ray absorption fine structure method and N2 adsorption measurements. Gas sensing measurements were focused on monitoring formaldehyde and acetaldehyde. However, responses ethanol and methane were measured in some cases to monitor selectivity. Graphene/TiO2 samples were used to monitor NO2 and NH3. For NiO thin film sensors and Au nano particles, fluctuation enhanced gas sensing is also presented in addition to conductometric measurements.

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