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Disertační práce se zabývá syntézou, charakterizací a testováním směsných oxidů s různým chemickým složením ve valorizaci alkoholů a studiem možností použití butanolu jako kosolventu v transesterifikaci řepkového oleje. Směsné oxidy byly připraveny kalcinací hydrotalcitů, které byly syntetizovány pomocí koprecitační metody. Nejprve byl studován vliv složení MgAl a MgFe směsných oxidů dopovaných o další přechodový kov (Co, Ni, Cu, Mn, a Cr) na strukturu a katalytickou aktivitu ve valorizaci etanolu na látky s vyšší přidanou hodnotou. Reakce byla studována v mikro průtokovém reaktoru se zaměřením na analýzu vznikajících reakčních produktů, zejména butanol, hexanol, acetaldehyd, ethyl-acetát, atd. Na základě detailní analýzy produktů bylo navrženo reakční schéma jejich vzniku. Byl popsán vliv teploty a přechodového kovu na konverzi etanolu, selektivitu (a výtěžek) k vybraným produktům. Dále byl zkoumán vliv butanolu (produkt valorizace etanolu) jako kosolventu na transesterifikační reakci metanolu s řepkovým olejem za různých molárních poměrů složek, reakční teploty a množství katalyzátoru s použitím katalyzátoru homogenního (KOH) a heterogenního (MgFe směsný oxid). Posledním cílem bylo studium vlivu zinku v CuZnAl směsném oxidu na strukturní a texturní vlastnosti a katalytickou aktivitu při hydrogenolýze glycerolu (vzniká jako vedlejší produkt při transesterifikaci) na propan-1,2-diol., The doctoral thesis focuses on the synthesis, characterization, and testing of mixed oxides with different chemical compositions for the valorisation of alcohols. The interest was also focused on the investigation of using butanol (a product of ethanol valorisation) as a co-solvent in the transesterification of rapeseed oil. The mixed oxides were prepared by calcination of hydrotalcites, which were synthesized by a co-precipitation method. Firstly, the effect of the chemical composition of MgAl and MgFe mixed oxides doped with transition metals (Co, Ni, Cu, Mn, and Cr) on the structure and catalytic activity in ethanol valorisation was studied. The reactions were carried out in a microflow reactor at different reaction temperatures. The reaction scheme for the valorisation of ethanol using mixed oxides was proposed on the base of a detailed analysis of the products. Another task was to study the effect of butanol (a product of ethanol valorisation) on the transesterification reaction of methanol with rapeseed oil, considering different molar ratios of components, reaction temperatures, catalyst masses, and the use of homogeneous (KOH) and heterogeneous (MgFe mixed oxide) catalysts. The last task was to study the effect of zinc in CuZnAl mixed oxide on the structural and textural properties and catalytic activity in the hydrogenolysis of glycerol to propane-1,2-diol., Fakulta chemicko-technologická, Dokončená práce s úspěšnou obhajobou

The Mg-Al mixed oxides are an attractive acid-base catalyst with various activity published even for the same reaction under similar conditions. The differences in the results can be caused by impurities remaining after synthesis, which is very often omitted in papers. The influence of remaining sodium impurities (from 5 to 345 mu mol/g of hydrotalcite) on the catalysed transesterification of vegetable oil was studied. The novelty consists in the detailed description of the transformation of sodium species throughout synthesis of mixed oxides: the sodium nitrates, presented in hydrotalcites, were transformed to sodium oxide (during calcination), which reacted with water (present in oil and methanol) to sodium hydroxides. During transesterification, the sodium hydroxide leached to the liquid phase and so increased the ester yield as a homogeneous catalyst. The ester content was only 19 wt.% with the catalyst containing almost no sodium ions (5 mu mol/g), but only 18 mu mol/g caused increasing of ester content to 50 wt.%. Moreover, the sodium compounds rapidly increased the catalyst activity by changing the active sites. The reusability of the catalyst was caried out and the ester content decreased to only 22% after four cycles, because the sodium leached., Vliv zbytkového obsahu sodíkových iontů (v množství 5-345 mikro-mol/g hydrotalcitu) na katalytickou aktivitu směsných oxidů byl testován pro transesterifikaci rostlinných olejů. Detailně je popsán proces transformace sodíkových částic během syntézy směsného oxidu, vliv na reakci s vodou, typ katalýzy a výtěžek.

[ES] La presente tesis doctoral aborda el desarrollo de nuevos procesos catalíticos centrados en la valorización del glicerol, subproducto principal en la síntesis de biodiesel. El objetivo principal del trabajo consiste en utilizarlo como fuente de carbono para la producción de heterociclos nitrogenados de interés industrial, en concreto, para la producción de 2-metilpiperazina y 2-metilpirazina. Debido a la baja reactividad del glicerol y las drásticas condiciones de reacción que serían necesarias para llevar a cabo las transformaciones a estos heterociclos, se ha planteado como paso previo el estudio de la optimización y el entendimiento del proceso de deshidratación selectiva de glicerol a hidroxiacetona (o acetol). A través de la obtención de este compuesto intermedio, se han podido desarrollar procesos de producción de los heterociclos nitrogenados eficientes y selectivos, en condiciones de reacción moderadas. A este respecto, los precursores de hidrotalcitas del tipo Cu-Mg-Al dan lugar a una familia de materiales basados en óxidos mixtos Cu-Mg-Al capaces de llevar a cabo la deshidratación selectiva de glicerol a acetol en continuo con rendimientos del ¿40%. Además, estos catalizadores son estables durante más de 8 horas, mostrando también excelente capacidad de regeneración y reusabilidad. Del mismo modo, la combinación de centros ácido-base y redox exhibida por estos materiales ha permitido, a través de la combinación de estudios catalíticos y de caracterización, avanzar en el estado del arte en lo que respecta a la comprensión de esta reacción de deshidratación catalítica de glicerol. De esta forma, se ha podido comprobar el papel fundamental de las especies de Cu y, en concreto de las especies Cu(I) presentes en los catalizadores, en la generación de gliceraldehido como intermedio clave para la producción de acetol. Del mismo modo, los centros ácidos del catalizador facilitan la primera adsorción del glicerol, acelerando así la reacción. No obstante, la ne, [CA] La present tesi doctoral aborda el desenvolupament de nous processos catalítics centrats en la valorització del glicerol, subproducte principal en la síntesi de biodièsel, utilitzant-lo com a font de carboni per a la producció d'heterocicles nitrogenats d'interès industrial. En concret, per a la producció de 2-metilpiperazina i 2-metilpirazina. A causa de la baixa reactivitat del glicerol i les dràstiques condicions de reacció que serien necessàries per a dur a terme les transformacions a aquests heterocicles, s'ha plantejat com a pas previ un estudi detallat escometent l'optimització i l'enteniment del procés de deshidratació selectiva de glicerol a hidroxiacetona (o acetol). A través de l'obtenció d'aquest compost intermedi, s'han desenvolupat processos de producció dels heterocicles nitrogenats eficients i selectius, en condicions de reacció moderades. Referent a això, els precursors hidrotalcítics Cu-Mg-Al donen com a resultat una família de materials basats en òxids mixtos Cu-Mg-Al capaços de dur a terme la deshidratació selectiva de glicerol a acetol en continu amb rendiments del 40%. Així mateix, aquests catalitzadors són estables durant més de 8 hores, mostrant a més una excel·lent regenerabilitat i reusabilitat. De la mateixa manera, la combinació de centres àcid-base i redox exhibida per aquests materials ha permès, a través de la combinació d'estudis catalítics i de caracterització, avançar significativament en l'estat de l'art pel que fa a la comprensió d'aquesta reacció catalítica. D'aquesta manera, s'ha pogut comprovar el paper fonamental del Cu i, en concret del Cu(I), en la generació de gliceraldehid com a intermedi de reacció clau. Per altra banda, els centres àcids del catalitzador faciliten la primera adsorció del reactiu, accelerant així la reacció. No obstant això, la necessitat d'aconseguir productivitats de acetol més elevades per a assegurar l'èxit de l'estratègia global va motivar l'ús, en aquest procés de deshidratació selectiva de gli, [EN] This doctoral thesis addresses the development of new catalytic processes centered on glycerol valorization, which is the main by-product of biodiesel synthesis. In this sense, the main aim focused on using it as a carbon source to generate nitrogen heterocycles of industrial interest, specifically, to produce 2-methylpiperazine and 2-methylpyrazine. Due to the low reactivity of glycerol and the severe reaction conditions necessary to carry out the transformations towards these N-heterocycles, previous detailed research to optimize and understand the selective dehydration process of glycerol to hydroxyacetone (or acetol) was undertaken. Through obtaining this intermediate compound, it has been possible to develop efficient and selective nitrogen heterocycles production processes, under moderate reaction conditions. In this regard, Cu-Mg-Al hydrotalcite precursors give rise to a family of materials based on Cu-Mg-Al mixed oxides capable of carrying out the selective dehydration of glycerol to acetol continuously with yields of 40%. In addition, these catalysts are stable for more than 8 hours under operational conditions, showing excellent regeneration capacity and reusability. In the same way, through the combination of catalytic and characterization studies, the interesting mix of acid-base and redox centers exhibited by these materials has allowed for advancing significantly in the state of the art regarding understanding this glycerol catalytic dehydration reaction. Hence, it has been possible to verify the fundamental role of Cu species and, specifically, Cu(I) species present in the catalysts, in the generation of glyceraldehyde as a critical reaction intermediate for acetol production. Similarly, the acid centers of the catalyst facilitate the first adsorption of glycerol, thus accelerating the reaction. However, the need to achieve higher acetol productivities from glycerol to stand a chance to succeed in the overall strategy motivated the development an

[ES] La presente tesis doctoral aborda el desarrollo de nuevos procesos catalíticos centrados en la valorización del glicerol, subproducto principal en la síntesis de biodiesel. El objetivo principal del trabajo consiste en utilizarlo como fuente de carbono para la producción de heterociclos nitrogenados de interés industrial, en concreto, para la producción de 2-metilpiperazina y 2-metilpirazina. Debido a la baja reactividad del glicerol y las drásticas condiciones de reacción que serían necesarias para llevar a cabo las transformaciones a estos heterociclos, se ha planteado como paso previo el estudio de la optimización y el entendimiento del proceso de deshidratación selectiva de glicerol a hidroxiacetona (o acetol). A través de la obtención de este compuesto intermedio, se han podido desarrollar procesos de producción de los heterociclos nitrogenados eficientes y selectivos, en condiciones de reacción moderadas. A este respecto, los precursores de hidrotalcitas del tipo Cu-Mg-Al dan lugar a una familia de materiales basados en óxidos mixtos Cu-Mg-Al capaces de llevar a cabo la deshidratación selectiva de glicerol a acetol en continuo con rendimientos del ¿40%. Además, estos catalizadores son estables durante más de 8 horas, mostrando también excelente capacidad de regeneración y reusabilidad. Del mismo modo, la combinación de centros ácido-base y redox exhibida por estos materiales ha permitido, a través de la combinación de estudios catalíticos y de caracterización, avanzar en el estado del arte en lo que respecta a la comprensión de esta reacción de deshidratación catalítica de glicerol. De esta forma, se ha podido comprobar el papel fundamental de las especies de Cu y, en concreto de las especies Cu(I) presentes en los catalizadores, en la generación de gliceraldehido como intermedio clave para la producción de acetol. Del mismo modo, los centros ácidos del catalizador facilitan la primera adsorción del glicerol, acelerando así la reacción. No obstante, la ne, [CA] La present tesi doctoral aborda el desenvolupament de nous processos catalítics centrats en la valorització del glicerol, subproducte principal en la síntesi de biodièsel, utilitzant-lo com a font de carboni per a la producció d'heterocicles nitrogenats d'interès industrial. En concret, per a la producció de 2-metilpiperazina i 2-metilpirazina. A causa de la baixa reactivitat del glicerol i les dràstiques condicions de reacció que serien necessàries per a dur a terme les transformacions a aquests heterocicles, s'ha plantejat com a pas previ un estudi detallat escometent l'optimització i l'enteniment del procés de deshidratació selectiva de glicerol a hidroxiacetona (o acetol). A través de l'obtenció d'aquest compost intermedi, s'han desenvolupat processos de producció dels heterocicles nitrogenats eficients i selectius, en condicions de reacció moderades. Referent a això, els precursors hidrotalcítics Cu-Mg-Al donen com a resultat una família de materials basats en òxids mixtos Cu-Mg-Al capaços de dur a terme la deshidratació selectiva de glicerol a acetol en continu amb rendiments del 40%. Així mateix, aquests catalitzadors són estables durant més de 8 hores, mostrant a més una excel·lent regenerabilitat i reusabilitat. De la mateixa manera, la combinació de centres àcid-base i redox exhibida per aquests materials ha permès, a través de la combinació d'estudis catalítics i de caracterització, avançar significativament en l'estat de l'art pel que fa a la comprensió d'aquesta reacció catalítica. D'aquesta manera, s'ha pogut comprovar el paper fonamental del Cu i, en concret del Cu(I), en la generació de gliceraldehid com a intermedi de reacció clau. Per altra banda, els centres àcids del catalitzador faciliten la primera adsorció del reactiu, accelerant així la reacció. No obstant això, la necessitat d'aconseguir productivitats de acetol més elevades per a assegurar l'èxit de l'estratègia global va motivar l'ús, en aquest procés de deshidratació selectiva de gli, [EN] This doctoral thesis addresses the development of new catalytic processes centered on glycerol valorization, which is the main by-product of biodiesel synthesis. In this sense, the main aim focused on using it as a carbon source to generate nitrogen heterocycles of industrial interest, specifically, to produce 2-methylpiperazine and 2-methylpyrazine. Due to the low reactivity of glycerol and the severe reaction conditions necessary to carry out the transformations towards these N-heterocycles, previous detailed research to optimize and understand the selective dehydration process of glycerol to hydroxyacetone (or acetol) was undertaken. Through obtaining this intermediate compound, it has been possible to develop efficient and selective nitrogen heterocycles production processes, under moderate reaction conditions. In this regard, Cu-Mg-Al hydrotalcite precursors give rise to a family of materials based on Cu-Mg-Al mixed oxides capable of carrying out the selective dehydration of glycerol to acetol continuously with yields of 40%. In addition, these catalysts are stable for more than 8 hours under operational conditions, showing excellent regeneration capacity and reusability. In the same way, through the combination of catalytic and characterization studies, the interesting mix of acid-base and redox centers exhibited by these materials has allowed for advancing significantly in the state of the art regarding understanding this glycerol catalytic dehydration reaction. Hence, it has been possible to verify the fundamental role of Cu species and, specifically, Cu(I) species present in the catalysts, in the generation of glyceraldehyde as a critical reaction intermediate for acetol production. Similarly, the acid centers of the catalyst facilitate the first adsorption of glycerol, thus accelerating the reaction. However, the need to achieve higher acetol productivities from glycerol to stand a chance to succeed in the overall strategy motivated the development an

The production of higher alcohols (C4+) via ethanol liquid-phase condensation is studied in this work, screening catalysts with different acid/base properties, observing similarities but also relevant differences with respect to gas-phase reactions in the gas phase. The mechanistic analysis demonstrates the relevance of acidity, mainly to promote the dehydrogenation steps. In the same way, side reactions and hydrogenations have less relevance than in gas-phase, promoting the condensations and, subsequently, obtaining heavy compounds. The highest alcohol selectivity is reached with MgAl (2/1), with more than 79% of C4+ selectivity, but the activity of this material is conditioned by the low conversion obtained. The presence of water reduces the activity because of a competitive adsorption on the catalytic sites whereas the activity increases significantly when using bifunctional catalysts. The best results, obtained with 1% Cu/MgAl (2/1), allow rising the conversion up to more than 460% respect to the parent mixed oxide, with almost 44% of the alcohol mixture enriched in heavy compounds, mainly C6 and C8.

The production of higher alcohols (C4+) via ethanol liquid-phase condensation is studied in this work, screening catalysts with different acid/base properties, observing similarities but also relevant differences with respect to gas-phase reactions in the gas phase. The mechanistic analysis demonstrates the relevance of acidity, mainly to promote the dehydrogenation steps. In the same way, side reactions and hydrogenations have less relevance than in gas-phase, promoting the condensations and, subsequently, obtaining heavy compounds. The highest alcohol selectivity is reached with MgAl (2/1), with more than 79% of C4+ selectivity, but the activity of this material is conditioned by the low conversion obtained. The presence of water reduces the activity because of a competitive adsorption on the catalytic sites whereas the activity increases significantly when using bifunctional catalysts. The best results, obtained with 1% Cu/MgAl (2/1), allow rising the conversion up to more than 460% respect to the parent mixed oxide, with almost 44% of the alcohol mixture enriched in heavy compounds, mainly C6 and C8.

Hydrotalcites (HTCs) are promising solid base catalysts to produce advanced biofuels by aldol condensation. Their main potential lies in the tunability of their acid-base properties by varying their composition. However, the relationship between the composition of hydrotalcites, their basicity, and their catalytic performance has not yet been fully revealed. Here, we investigate systematically the preparation of HTCs with the general formula of Mg6M23+(OH)(16)CO3 center dot 4H(2)O, where M3+ stands for Al, Ga, Fe, and In, while keeping the Mg/M3+ equal to 3. We use an array of analytical methods including XRD, N-2 physisorption, CO2-TPD, TGA-MS, FTIR-ATR, and SEM to assess changes in the properties and concluded that the nature of M3+ affected the HTC crystallinity. We show that the basicity of the HTC-derived mixed oxides decreased with the increase in atomic weight of M3+, which was reflected by decreased furfural conversion in its aldol condensation with acetone. We demonstrate that all MgM3+ mixed oxides can be fully rehydrated, which boosted their activity in aldol condensation. Taking all characterization results together, we conclude that the catalytic performance of the rehydrated HTCs is determined by the ""host"" MgO component, rather than the nature of M3+., Hydrotalcity jsou nadějné materiály pro katalýzu v pevné fázi, která vede k produkci bionafty pomocí aldolové kondenzace. Jejich hlavním potenciálem je variabilita v jejich acidobazických vlastnostech závisející na složení. Nicméně vztah mezi složením hydrotalcitu, jeho acidobazickými vlastnostmi a jejich katalytickým účinkem není dosud plně objasněn.

Aldol condensation of furfural and acetone is often used as a model reaction to test acid-base properties of solid catalysts. The present study describes the effect of furfural acidity on the catalytic performance of MgAl mixed oxides. Three furfural sources differing in their acidity were used and compared in aldol condensation at T = 55 ?C and acetone to furfural molar ratio of 10. The furfural conversion over MgAl mixed oxides depended on the acidity of the furfural source, and the catalysts were partially consumed for neutralization of acid admixtures present in furfural. Only for some furfurals could the furfural conversion be improved by distilling the as-received furfural prior to the aldol condensation experiments. Moreover, the storage of the freshly distilled furfural during a few days, even in a closed flask and at a dark place, resulted in a substantial decrease in furfural conversion in aldol condensation. The results indicate that the distillation of the as-received furfural is an effective method to control the performance of basic catalysts at comparable reaction conditions only for some furfurals. Furthermore, the storage of the freshly distilled furfural has to be performed with care to avoid its re-oxidation., Aldolové kondenzace furfuralu a acetonu jsou často používanými modelovými reakcemi pro testování acidobazických vlastností pevných katalyzátorů. Tato studie popisuje vliv kyselosti furfuralu na katalytický účinek MgAl směsných oxidů.

This paper is focused on the catalytic synthesis of butanol from ethanol in a microflow reactor at a constant weight hour space velocity (4.5 h−1) and different reaction temperatures (280, 300 and 350 °C). The reaction was catalysed by Mg-Al mixed oxides (i) pure and (ii) with added transition metals such as Co, Ni, Cu, Mn and Cr (synthesis by coprecipitation). The solid materials were deeply characterised. Other products, such as ethylene, 1,1-diethoxyethane, ethyl acetate, 1-hexanol, etc. were also determined and the reaction pathway for their formation was examined. The metals Cr and Mn did not increase the catalyst activity, which was quite low (maximum 19% at 350 °C). However, the metals Co and Ni positively influenced butanol formation, while Cu positively influenced ethyl acetate formation. Moreover, ethanol conversion increased with increasing temperature, but at the same time the selectivity to butanol decreased., Článek je zaměřen na katalytickou syntézu butanolu z etanolu v mikroprůtokovém reaktoru při konstantním výhovém průtoku a odlišných reakčních teplotách. Reakce byla katalyzována směsnými oxidy Mg-Al s příměsí přechodových kovů jako jsou Co, Ni, Cu, Mn a Cr. Byla testována kompletní reakční cesta.

Bio-derived furfural and 5-hydroxymethylfurfural can be combined with acetone to yield aldol condensation products that may serve as biofuel and polymer precursors. We have explored different catalytic systems to obtain and purify each product in the most efficient way. The results of the catalytic tests of the cross-condensations and of the self-condensation of acetone allowed the comparison of the different reactivity of the two aldehydes. Online and in situ/operando ATR-IR was used to monitor the reaction over time and to study the interaction of the reaction species with the solid catalyst, especially the formation of deactivating organic matter that covers the surface, which is a major issue in heterogeneous condensation processes. In situ NMR was used to study the ongoing reaction, assessing its stereoselectivity, and to study the behavior of deuterated species in the catalytic system. Finally, the preparation of C14, a hetero-double-condensation product, was also explored.

[ES] La demanda de energía en el mundo presenta un continuo incremento, siendo la dependencia de combustibles fósiles (gas, petróleo, carbón) para producir esta energía cada vez más acentuada. El uso de combustibles fósiles genera una gran cantidad de emisiones de gases de efecto invernadero, principalmente dióxido de carbono (CO2), además de producir óxidos de nitrógeno (NOx) y dióxido de azufre (SO2) como resultado de la combustión. Una posible alternativa para disminuir la dependencia de los recursos fósiles es el uso de materias primas renovables para la producción de combustibles como, por ejemplo, la generación de biodiesel a partir de biomasa residual, disminuyendo también la emisión de gases de efecto invernadero. Además, el uso de combustibles renovables está orientado hacia la sostenibilidad, es decir, la capacidad de mantener el desarrollo de la calidad de vida, sin afectar la de futuras generaciones. La hidrogenación de aceites vegetales, tales como los aceites de palma, girasol, soja, colza, linaza, entre otros, es una tecnología actualmente aplicada a nivel industrial para la saturación de dobles enlaces presentes en los ésteres de ácidos grasos y de los triglicéridos constituyentes de los aceites, llegando incluso hasta la obtención de hidrocarburos (mediante reacciones de hidrólisis, hidrogenación y/o descarbonilación). Este trabajo de TFM se centra en el estudio del proceso de hidrogenación catalítica de ésteres de ácidos grasos y triglicéridos para la obtención de n-heptadecano (C17) y/o n-octadecano (C18). Estos hidrocarburos son de interés, ya que se encuentran en el rango de las fracciones de queroseno y diésel utilizados como combustibles de automoción. En particular, se evalúa la actividad catalítica en la hidrogenación selectiva de oleato de metilo (reactivo modelo de partida) de diferentes materiales basados en Ni soportado en óxidos metálicos, tales como Al2O3, TiO2 y ZrO2 y sus combinaciones en forma de óxidos mixtos. Estos catalizadores h, [EN] The world's energy demand is continuously increasing, and dependence on fossil fuels (gas, oil, coal) to produce energy is becoming more and more accentuated. In addition, the use of fossil fuels leads to greenhouse gases emissions in high amounts, mainly carbon dioxide (CO2), nitrogen oxide (NOx) and sulfur dioxide (SO2) because of combustion. A possible alternative to reduce the dependence on fossil resources is the use of renewable raw materials for fuel production, in particular, the generation of biodiesel from residual biomass, thus decreasing the emission of greenhouse gases. Furthermore, the use of renewable fuels is oriented towards sustainability, this meaning the ability to maintain the development of the life quality without affecting that of future generations. The hydrogenation of vegetable oils, such as palm, sunflower, soybean, rapeseed and linseed oils, among others, is a technology currently applied at industrial level for the saturation of double bonds present in fatty acid esters and triglycerides that make up the oils, even leading to obtain hydrocarbons (through hydrolysis, hydrogenation and/or decarbonylation reactions). The main objective of this work is to study the catalytic hydrogenation process of fatty acid esters and triglycerides to produce n-heptadecane (C17) and/or n-octadecane (C18). The latters are considered as products of interest, since they belong to the kerosene and diesel fractions, employed as automotive fuels. In particular, the starting model reagent was methyl oleate, and different Ni supported on metal oxides, such as Al2O3, TiO2 and ZrO2 and their combinations, were used as catalysts. These catalysts have been prepared at Instituto de Tecnología Química (ITQ), and characterized by different analytical techniques, such as: ICP, XRD and N2 physisorption, among others. These techniques allowed to determine their main physico-chemical and textural properties, and to correlate them with the observed catalytic activity.

[ES] La demanda de energía en el mundo presenta un continuo incremento, siendo la dependencia de combustibles fósiles (gas, petróleo, carbón) para producir esta energía cada vez más acentuada. El uso de combustibles fósiles genera una gran cantidad de emisiones de gases de efecto invernadero, principalmente dióxido de carbono (CO2), además de producir óxidos de nitrógeno (NOx) y dióxido de azufre (SO2) como resultado de la combustión. Una posible alternativa para disminuir la dependencia de los recursos fósiles es el uso de materias primas renovables para la producción de combustibles como, por ejemplo, la generación de biodiesel a partir de biomasa residual, disminuyendo también la emisión de gases de efecto invernadero. Además, el uso de combustibles renovables está orientado hacia la sostenibilidad, es decir, la capacidad de mantener el desarrollo de la calidad de vida, sin afectar la de futuras generaciones. La hidrogenación de aceites vegetales, tales como los aceites de palma, girasol, soja, colza, linaza, entre otros, es una tecnología actualmente aplicada a nivel industrial para la saturación de dobles enlaces presentes en los ésteres de ácidos grasos y de los triglicéridos constituyentes de los aceites, llegando incluso hasta la obtención de hidrocarburos (mediante reacciones de hidrólisis, hidrogenación y/o descarbonilación). Este trabajo de TFM se centra en el estudio del proceso de hidrogenación catalítica de ésteres de ácidos grasos y triglicéridos para la obtención de n-heptadecano (C17) y/o n-octadecano (C18). Estos hidrocarburos son de interés, ya que se encuentran en el rango de las fracciones de queroseno y diésel utilizados como combustibles de automoción. En particular, se evalúa la actividad catalítica en la hidrogenación selectiva de oleato de metilo (reactivo modelo de partida) de diferentes materiales basados en Ni soportado en óxidos metálicos, tales como Al2O3, TiO2 y ZrO2 y sus combinaciones en forma de óxidos mixtos. Estos catalizadores h, [EN] The world's energy demand is continuously increasing, and dependence on fossil fuels (gas, oil, coal) to produce energy is becoming more and more accentuated. In addition, the use of fossil fuels leads to greenhouse gases emissions in high amounts, mainly carbon dioxide (CO2), nitrogen oxide (NOx) and sulfur dioxide (SO2) because of combustion. A possible alternative to reduce the dependence on fossil resources is the use of renewable raw materials for fuel production, in particular, the generation of biodiesel from residual biomass, thus decreasing the emission of greenhouse gases. Furthermore, the use of renewable fuels is oriented towards sustainability, this meaning the ability to maintain the development of the life quality without affecting that of future generations. The hydrogenation of vegetable oils, such as palm, sunflower, soybean, rapeseed and linseed oils, among others, is a technology currently applied at industrial level for the saturation of double bonds present in fatty acid esters and triglycerides that make up the oils, even leading to obtain hydrocarbons (through hydrolysis, hydrogenation and/or decarbonylation reactions). The main objective of this work is to study the catalytic hydrogenation process of fatty acid esters and triglycerides to produce n-heptadecane (C17) and/or n-octadecane (C18). The latters are considered as products of interest, since they belong to the kerosene and diesel fractions, employed as automotive fuels. In particular, the starting model reagent was methyl oleate, and different Ni supported on metal oxides, such as Al2O3, TiO2 and ZrO2 and their combinations, were used as catalysts. These catalysts have been prepared at Instituto de Tecnología Química (ITQ), and characterized by different analytical techniques, such as: ICP, XRD and N2 physisorption, among others. These techniques allowed to determine their main physico-chemical and textural properties, and to correlate them with the observed catalytic activity.

[EN] Their complex surface chemistry and high oxygen lattice mobilities place mixed-metal oxides among the most important families of materials. Modulation of stoichiometry in mixed-metal oxides has been shown to be a very powerful tool for tuning optical and catalytic properties. However, accessing different stoichiometries is not always synthetically possible. Here, we show that the thermal decomposition of the recently reported metal-organic framework MUV-101(Fe, Ti) results in the formation of carbon-supported titanomaghemite nanoparticles with an unprecedented Fe/Ti ratio close to 2, not achievable by soft-chemistry routes. The resulting titanomaghemite phase displays outstanding catalytic activity for the production of CO from CO2 via the reverse water-gas shift (RWGS) reaction with CO selectivity values of ca. 100% and no signs of deactivation after several days on stream. Theoretical calculations suggest that the reaction proceeds through the formation of COOH¿ species, favoring in this way CO over other byproducts.

[EN] Their complex surface chemistry and high oxygen lattice mobilities place mixed-metal oxides among the most important families of materials. Modulation of stoichiometry in mixed-metal oxides has been shown to be a very powerful tool for tuning optical and catalytic properties. However, accessing different stoichiometries is not always synthetically possible. Here, we show that the thermal decomposition of the recently reported metal-organic framework MUV-101(Fe, Ti) results in the formation of carbon-supported titanomaghemite nanoparticles with an unprecedented Fe/Ti ratio close to 2, not achievable by soft-chemistry routes. The resulting titanomaghemite phase displays outstanding catalytic activity for the production of CO from CO2 via the reverse water-gas shift (RWGS) reaction with CO selectivity values of ca. 100% and no signs of deactivation after several days on stream. Theoretical calculations suggest that the reaction proceeds through the formation of COOH¿ species, favoring in this way CO over other byproducts.

Práce se zabývá vlivem zbytkových alkálií, přítomných ve směsných oxidech, na katalytickou aktivitu v transesterifikaci rostlinného oleje. Cílem bylo stanovit obsahu sodíku a zbytkových alkálií v hydrotalcitech a popsat jejich vliv na výtěžek methylesterů. V teoretické části byl popsána transesterifikace, hydrotalcity a směsné oxidy včetně syntézy a využití. Směsné oxidy byly připraveny kalcinací hydrotalcitů, které byly promyty různým množstvím redestilované vody, a tím obsahovaly odlišné množství zbylých alkálií a sodných iontů. Pro charakterizaci materiálů byly použity různé metody. Bylo zjištěno, že sodné ionty jsou vázány ve formě dusičnanu sodného vzniklého při syntéze. Kalcinací dochází k jeho rozpadu na oxid sodný, který s vodou obsaženou v reaktantech tvoří hydroxid sodný, jenž je jako homogenní katalyzátor zodpovědný za zvýšení výtěžku methylesterů. Snížení obsahu dusíku po kalcinaci bylo prokázáno elementární analýzou. Bylo navrženo reakční schéma přeměny aniontů vázaných na sodík, od vzniku hydroxidu k uvolňování při transesterifikaci., The aim of this work is to analyse the influence of residue alkali on the mixed oxides catalytic activity in transesterification of vegetable oil. Transesterification, hydrotalcites, mixed oxides and their preparation and synthesis was described. The mixed oxides were prepared by calcination of hydrotalcites, which were washed with different amounts of redestilled water, so they contained various amounts of sodium. The prepared materials were characterized by various methods. It was proved that sodium ions form nitrates in hydrotalcites. Through calcination, sodium nitrate decomposes, and forms sodium oxide. It then reacts with water in reactants to form sodium hydroxide, which is responsible for increased ester yields (acts as a homogenenous catalyst). The decomposition of nitrates was proved by elementary analysis. The reaction scheme of transformation of anions, bonded to sodium, was suggested., Fakulta chemicko-technologická, Diplomant přednesl prezentaci diplomové práce. Doc. Ing. Martin Hájek, Ph.D. přečetl posudek vedoucího práce a oponenta. Diplomant odpověděl na připomínky oponenta uvedené v posudku a otázky členů komise: prof. Ing. Roman Bulánek, Ph.D. - Máte nějaký důkaz, že dochází k blokaci pórů nánosy dusičnanu sodného?, Jestliže je katalyzátor připraven ex situ, nedochází k jeho přeměně vlivem vzduchu a vlhkosti při přenosu do reaktoru?; doc. Pavel Čičmanec, Ph.D. - Máte důkaz pro přítomnost oxidu sodného v katalyzátoru v reaktoru?; prof. Ing. Libor Čapek, Ph.D. - Jakého typu částic je sodík v katalyzátoru? A jaký vliv má jeho forma na katalýzu?, Připouštíte souběžný průběh homogenní a heterogenní katalýzy?; prof. Ing. Jiří Málek, DrSc. - Jaká byla rychlost ohřevu v případě termogravimetrického měření?, V jaké amosféře to bylo měřeno?, Dokončená práce s úspěšnou obhajobou

[ES] El objetivo principal del trabajo es el estudio de un proceso para la síntesis de productos nitrogenados de alto valor añadido a partir de glicerol empleando catalizadores heterogéneos sostenibles. En concreto, el trabajo se centra en la transformación del glicerol en compuestos nitrogenados del tipo piperazinas, importantes intermedios en síntesis orgánica. Para ello, se plantea un proceso en dos etapas que comprendería una deshidratación selectiva del glicerol para dar hidroxiacetona (o acetol) y una posterior aminación reductiva del acetol con etilendiamina. El estudio trata de optimizar cada etapa reactiva por separado, teniendo en cuenta la posibilidad de poder diseñar un proceso en una sola etapa. Para la deshidratación selectiva del glicerol, catalizadores basados en óxidos mixtos derivados de hidrotalcitas fueron preparados, caracterizados por DRX, análisis ICP y adsorción de N2 y probados en la reacción de interés, utilizando diversos sistemas de reacción. Por otro lado, Pd y Pt soportados sobre alúmina fueron los catalizadores escogidos en la reacción de aminación reductiva para producir la piperazina deseada, caracterizándose los mismos por análisis ICP y TEM. El trabajo proporciona una nueva ruta catalítica para el aprovechamiento del glicerol, ofreciendo nuevas posibilidades para la obtención de compuestos nitrogenados a partir de esta materia prima., [EN] The main purpose of this work is the study of a process for the synthesis of high-valued nitrogenated chemicals from glycerol by means of sustainable heterogeneous catalysts. Specifically, the work is focused on the transformation of glycerol into piperazines, which are basic chemical intermediates for organic synthesis. For the production of piperazines a two-step process is considered, involving selective dehydration of glycerol into hydroxyacetone (or acetol) and posterior reductive amination of acetol with ethylendiamine. The study intends to develop and optimize each single reaction step separately, taking into account the possibility of reaching a "one-pot" process, which is considered to be the most promising alternative. Mixed oxides derived from hydrotalcites were prepared, characterized by XRD, ICP analysis and N2 adsorption and tested for the selective dehydration of glycerol using different reaction systems. On the other hand, Pd and Pt supported on alumina were chosen as the catalysts to perform the reductive amination in order to yield the desired piperazine, being characterized by ICP analysis and TEM. This work opens up a new catalytic route for taking advantage of glycerol, thus offering new insights and possibilities to obtain nitrogenated compounds from this raw material.

[EN] The selective dehydration of glycerol to hydroxyacetone (acetol) was studied with Cu-based mixed oxides derived from hydrotalcite as catalysts in a continuous flow fix-bed reactor. Catalysts were prepared by co-precipitation and characterized by ICP, N-2 adsorption, XRD, NH3-TPD, CO2-TPD, TPR and TEM. Different parameters were investigated to develop the most appropriate material as well as to determine the function of every metallic species. The optimized Cu-Mg-AlOx offered approximate to 60% acetol selectivity at >90% glycerol conversion (approximate to 80% liquid yield, up to TOS = 9 h). The catalyst could be regenerated by calcination, achieving full activity recovery after five re-cycles. "In-situ" FTIR and XPS measurements evidenced that the presence of Cu, specially the most active Cu1+ species, was essential to carry out the dehydration to acetol with high reaction rates, and to form the preferred intermediate (with C=O group); although a minor contribution from Cu-0 and Cu2+ species could not be discarded.

[EN] The selective dehydration of glycerol to hydroxyacetone (acetol) was studied with Cu-based mixed oxides derived from hydrotalcite as catalysts in a continuous flow fix-bed reactor. Catalysts were prepared by co-precipitation and characterized by ICP, N-2 adsorption, XRD, NH3-TPD, CO2-TPD, TPR and TEM. Different parameters were investigated to develop the most appropriate material as well as to determine the function of every metallic species. The optimized Cu-Mg-AlOx offered approximate to 60% acetol selectivity at >90% glycerol conversion (approximate to 80% liquid yield, up to TOS = 9 h). The catalyst could be regenerated by calcination, achieving full activity recovery after five re-cycles. "In-situ" FTIR and XPS measurements evidenced that the presence of Cu, specially the most active Cu1+ species, was essential to carry out the dehydration to acetol with high reaction rates, and to form the preferred intermediate (with C=O group); although a minor contribution from Cu-0 and Cu2+ species could not be discarded.

[ES] El objetivo principal del trabajo es el estudio de un proceso para la síntesis de productos nitrogenados de alto valor añadido a partir de glicerol empleando catalizadores heterogéneos sostenibles. En concreto, el trabajo se centra en la transformación del glicerol en compuestos nitrogenados del tipo piperazinas, importantes intermedios en síntesis orgánica. Para ello, se plantea un proceso en dos etapas que comprendería una deshidratación selectiva del glicerol para dar hidroxiacetona (o acetol) y una posterior aminación reductiva del acetol con etilendiamina. El estudio trata de optimizar cada etapa reactiva por separado, teniendo en cuenta la posibilidad de poder diseñar un proceso en una sola etapa. Para la deshidratación selectiva del glicerol, catalizadores basados en óxidos mixtos derivados de hidrotalcitas fueron preparados, caracterizados por DRX, análisis ICP y adsorción de N2 y probados en la reacción de interés, utilizando diversos sistemas de reacción. Por otro lado, Pd y Pt soportados sobre alúmina fueron los catalizadores escogidos en la reacción de aminación reductiva para producir la piperazina deseada, caracterizándose los mismos por análisis ICP y TEM. El trabajo proporciona una nueva ruta catalítica para el aprovechamiento del glicerol, ofreciendo nuevas posibilidades para la obtención de compuestos nitrogenados a partir de esta materia prima., [EN] The main purpose of this work is the study of a process for the synthesis of high-valued nitrogenated chemicals from glycerol by means of sustainable heterogeneous catalysts. Specifically, the work is focused on the transformation of glycerol into piperazines, which are basic chemical intermediates for organic synthesis. For the production of piperazines a two-step process is considered, involving selective dehydration of glycerol into hydroxyacetone (or acetol) and posterior reductive amination of acetol with ethylendiamine. The study intends to develop and optimize each single reaction step separately, taking into account the possibility of reaching a "one-pot" process, which is considered to be the most promising alternative. Mixed oxides derived from hydrotalcites were prepared, characterized by XRD, ICP analysis and N2 adsorption and tested for the selective dehydration of glycerol using different reaction systems. On the other hand, Pd and Pt supported on alumina were chosen as the catalysts to perform the reductive amination in order to yield the desired piperazine, being characterized by ICP analysis and TEM. This work opens up a new catalytic route for taking advantage of glycerol, thus offering new insights and possibilities to obtain nitrogenated compounds from this raw material.

[ES] El objetivo principal del trabajo es el estudio de un proceso para la síntesis de productos nitrogenados de alto valor añadido a partir de glicerol empleando catalizadores heterogéneos sostenibles. En concreto, el trabajo se centra en la transformación del glicerol en compuestos nitrogenados del tipo piperazinas, importantes intermedios en síntesis orgánica. Para ello, se plantea un proceso en dos etapas que comprendería una deshidratación selectiva del glicerol para dar hidroxiacetona (o acetol) y una posterior aminación reductiva del acetol con etilendiamina. El estudio trata de optimizar cada etapa reactiva por separado, teniendo en cuenta la posibilidad de poder diseñar un proceso en una sola etapa. Para la deshidratación selectiva del glicerol, catalizadores basados en óxidos mixtos derivados de hidrotalcitas fueron preparados, caracterizados por DRX, análisis ICP y adsorción de N2 y probados en la reacción de interés, utilizando diversos sistemas de reacción. Por otro lado, Pd y Pt soportados sobre alúmina fueron los catalizadores escogidos en la reacción de aminación reductiva para producir la piperazina deseada, caracterizándose los mismos por análisis ICP y TEM. El trabajo proporciona una nueva ruta catalítica para el aprovechamiento del glicerol, ofreciendo nuevas posibilidades para la obtención de compuestos nitrogenados a partir de esta materia prima., [EN] The main purpose of this work is the study of a process for the synthesis of high-valued nitrogenated chemicals from glycerol by means of sustainable heterogeneous catalysts. Specifically, the work is focused on the transformation of glycerol into piperazines, which are basic chemical intermediates for organic synthesis. For the production of piperazines a two-step process is considered, involving selective dehydration of glycerol into hydroxyacetone (or acetol) and posterior reductive amination of acetol with ethylendiamine. The study intends to develop and optimize each single reaction step separately, taking into account the possibility of reaching a "one-pot" process, which is considered to be the most promising alternative. Mixed oxides derived from hydrotalcites were prepared, characterized by XRD, ICP analysis and N2 adsorption and tested for the selective dehydration of glycerol using different reaction systems. On the other hand, Pd and Pt supported on alumina were chosen as the catalysts to perform the reductive amination in order to yield the desired piperazine, being characterized by ICP analysis and TEM. This work opens up a new catalytic route for taking advantage of glycerol, thus offering new insights and possibilities to obtain nitrogenated compounds from this raw material.

[ES] El objetivo principal del trabajo es el estudio de un proceso para la síntesis de productos nitrogenados de alto valor añadido a partir de glicerol empleando catalizadores heterogéneos sostenibles. En concreto, el trabajo se centra en la transformación del glicerol en compuestos nitrogenados del tipo piperazinas, importantes intermedios en síntesis orgánica. Para ello, se plantea un proceso en dos etapas que comprendería una deshidratación selectiva del glicerol para dar hidroxiacetona (o acetol) y una posterior aminación reductiva del acetol con etilendiamina. El estudio trata de optimizar cada etapa reactiva por separado, teniendo en cuenta la posibilidad de poder diseñar un proceso en una sola etapa. Para la deshidratación selectiva del glicerol, catalizadores basados en óxidos mixtos derivados de hidrotalcitas fueron preparados, caracterizados por DRX, análisis ICP y adsorción de N2 y probados en la reacción de interés, utilizando diversos sistemas de reacción. Por otro lado, Pd y Pt soportados sobre alúmina fueron los catalizadores escogidos en la reacción de aminación reductiva para producir la piperazina deseada, caracterizándose los mismos por análisis ICP y TEM. El trabajo proporciona una nueva ruta catalítica para el aprovechamiento del glicerol, ofreciendo nuevas posibilidades para la obtención de compuestos nitrogenados a partir de esta materia prima., [EN] The main purpose of this work is the study of a process for the synthesis of high-valued nitrogenated chemicals from glycerol by means of sustainable heterogeneous catalysts. Specifically, the work is focused on the transformation of glycerol into piperazines, which are basic chemical intermediates for organic synthesis. For the production of piperazines a two-step process is considered, involving selective dehydration of glycerol into hydroxyacetone (or acetol) and posterior reductive amination of acetol with ethylendiamine. The study intends to develop and optimize each single reaction step separately, taking into account the possibility of reaching a "one-pot" process, which is considered to be the most promising alternative. Mixed oxides derived from hydrotalcites were prepared, characterized by XRD, ICP analysis and N2 adsorption and tested for the selective dehydration of glycerol using different reaction systems. On the other hand, Pd and Pt supported on alumina were chosen as the catalysts to perform the reductive amination in order to yield the desired piperazine, being characterized by ICP analysis and TEM. This work opens up a new catalytic route for taking advantage of glycerol, thus offering new insights and possibilities to obtain nitrogenated compounds from this raw material.

Manganese oxides are capable of releasing molecular oxygen and regenerate in air under determined conditions. This fact makes these materials interesting for applications in different areas, such as thermochemical energy storage processes, oxygen production by chemical looping air separation (CLAS) or CO2 capture-oriented processes, namely chemical looping combustion (CLC) or chemical looping with oxygen uncoupling (CLOU). In this work, the potential to release molecular oxygen and regenerate in air of different manganese‑titanium mixed oxides with mass fractions of titanium from 0 to 50%, were evaluated in a TGA apparatus. Besides, the reactivity of the mixed oxide samples to the main fuel gases (CO, H2 and CH4) has been also evaluated. Consecutive redox cycles have been performed at different temperatures (850 and 940 °C) using nitrogen during reduction and air in oxidation. The oxygen transport capacity as well as the rate index for oxygen uncoupling and gas-solid reactions have been determined and compared to that found for other materials reported in literature. Moreover, solid phase identification in the different mixed oxide samples by XRD has been addressed in order to determine the oxygen release/regeneration mechanism. Results show a great potential of these materials as low-cost and environmentally friendly oxygen carriers.

Mg-Al and Mg-Fe mixed oxides with a constant molar ratio (3:1) were tested in the transesterification of rapeseed oil with methanol in a fixed-bed reactor. The mixed oxides were obtained from parent layered double hydroxides by calcination at 500 degrees C. The synthesized materials were characterized by several experimental techniques such as XRD, TG-MS, TPD-CO2, DRIFT and SEM. The transesterification was carried out at different weight hour space velocities (WHSVs; 1, 2 and 3 h(-1)) and different reaction temperatures (115, 150 and 200'C), with every parameter tested for 32 h. Moreover, the stability of the catalysts was tested by the determination of the metal content in the reaction mixture. The ester yield increases with decreasing WHSV and with increasing reaction temperature. The Mg-Al mixed oxides were more active for all WHSVs and for temperatures of 115 degrees C and 150 degrees C due to the lower crystallite size and particularly higher concentration of basic species. For the reaction temperature of 200'C, the catalyst activity was almost the same for both catalysts. A long-term catalytic test (300 h) for the verification of the catalyst lifetime and stability was also carried out with insignificant leaching of metals. (C) 2019 Elsevier Ltd. All rights reserved., Mg-Al a Mg-Fe směsné oxidy s konstantním molárním poměrem (3:1) byly testovány při transesterifikaci řepkového oleje s metanolem v reaktoru s pevným ložem. Směsné oxidy byly získány z mateřských vrstevnatých podvojných hydroxidů kalcinací při 500 °C.

Práce se zabývá zlepšením katalytických vlastností směsných oxidů, které byly připraveny z hydrotalcitů. Hydrotalcity jsou chemické sloučeniny s vrstevnatou strukturou; jejich kalcinací dochází k rozpadu této struktury a vzniku směsných oxidů. Hydrotalcity se využívají jako nosiče léčiv, při výrobě nanokompozitů a syntetizují se z nich směsné oxidy, které se používají jako katalyzátory. Při syntéze hydrotalcitů bylo do směsi přidáno různé množství aktivního uhlí, kalcinací došlo k přeměně na směsné oxidy, jejichž vlastnosti byly studovány. Pro charakterizaci materiálů byly použity následující metody: Optická emisní spektrometrie, XRD, TGA-MS a N2 - adsorpční izotermie. Cílem práce bylo zjistit jak ovlivňuje přídavek aktivního uhlí vlastnosti směsných oxidů a jejich katalytickou aktivitu transesterifikací řepkového oleje s methanolem., The aim of this work is to improve catalytic properties of mixed oxides by addition of activated coal. Hydrotalcites have typical layered structure, that is destroyed, when calcinated to form mixed oxides. Hydrotalcites are used as drug carriers, in making nanocomposites and in formation mixed oxides. Mixed oxides are used as catalysts in biofuel production or in decomposition of N2O. The certain amount of active coal was added during the synthesis of hydrotalcites, then the hydrotalcites were calcinated and converted into mixed oxides. XRD, TGA-MS, N2 - adsorptive isothermy and optical emission spectrometry were used to compare properties of synthetized mixed oxides. The target of this work was to find optimal amount of activated coal to achieve the best catalytic properties. Catalyst activity was studied in transesterification reaction of rapeseed oil and methanol., Fakulta chemicko-technologická, Student úspěšně obhájil bakalářskou práci a zodpověděl všechny otázky zkušební komise. Otázky: srovnání transesterifikace za přítomnosti katalyzátoru a bez něj, vliv přídavku methanolu na výtěžek transesterifikace, způsob oddělení esterů od zbytku reakční směsi, Dokončená práce s úspěšnou obhajobou

La presente tesis de pregrado contribuye a la síntesis, caracterización, selección y orden de reacción de catalizadores preparados por el método de auto-combustión empleando metales de transición de Mn y/o Fe, evaluando así un posible efecto cooperativo entre estos metales y su interacción en cuanto a sus propiedades fisicoquímicas del material y su comportamiento catalítico de los mismos en la degradación de cristal violeta (CV) en medio acuoso diluido a condiciones moderadas.

La presente tesis de pregrado contribuye a la síntesis, caracterización, selección y orden de reacción de catalizadores preparados por el método de auto-combustión empleando metales de transición de Mn y/o Fe, evaluando así un posible efecto cooperativo entre estos metales y su interacción en cuanto a sus propiedades fisicoquímicas del material y su comportamiento catalítico de los mismos en la degradación de cristal violeta (CV) en medio acuoso diluido a condiciones moderadas.

La presente tesis de pregrado contribuye a la síntesis, caracterización, selección y orden de reacción de catalizadores preparados por el método de auto-combustión empleando metales de transición de Mn y/o Fe, evaluando así un posible efecto cooperativo entre estos metales y su interacción en cuanto a sus propiedades fisicoquímicas del material y su comportamiento catalítico de los mismos en la degradación de cristal violeta (CV) en medio acuoso diluido a condiciones moderadas.

La presente tesis de pregrado contribuye a la síntesis, caracterización, selección y orden de reacción de catalizadores preparados por el método de auto-combustión empleando metales de transición de Mn y/o Fe, evaluando así un posible efecto cooperativo entre estos metales y su interacción en cuanto a sus propiedades fisicoquímicas del material y su comportamiento catalítico de los mismos en la degradación de cristal violeta (CV) en medio acuoso diluido a condiciones moderadas.

La presente tesis de pregrado contribuye a la síntesis, caracterización, selección y orden de reacción de catalizadores preparados por el método de auto-combustión empleando metales de transición de Mn y/o Fe, evaluando así un posible efecto cooperativo entre estos metales y su interacción en cuanto a sus propiedades fisicoquímicas del material y su comportamiento catalítico de los mismos en la degradación de cristal violeta (CV) en medio acuoso diluido a condiciones moderadas.

Chemical and redox reaction between uranium (U) and zirconium (Zr) at high temperature under a reducing or oxidizing atmosphere were investigated to simulate fuel debris formed by Fukushima nuclear power plant accident. X-ray absorption spectroscopy (XAS) at U LIII-edge and Zr K edge and powder X-ray diffraction (XRD) of the mixed UO2/ZrO2 materials treated at high temperature from 1473 to 1873 K under reducing or oxidizing atmosphere were performed. For UO2-ZrO2 samples from1473 to 1873 K under the oxidizing atmosphere (Ar + 2% O2, 1h), it was found that the compounds were primarily consisted of five species including U3O8, UO2, U2Zr5O15, monoclinic-ZrO2, and tetragonal-ZrO2, whose fractions were calculated by principal component analysis (PCA) on both the X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) collected at both U LIII edge and Zr K edge. Here, the formation of U2Zr5O15, a pentavalent uranium compound, was confirmed by the U LIII edge-XANES between the temperature range from 1473 to 1573 K. These results were also supported by powder-XRD analysis. Under the reducing atmosphere (Ar + 10% H2, 1h), UO2 remained at the whole temperature range without reacting with ZrO2, whereas monoclinic- and tetragonal ZrO2 were formed at 1573 K (60- and 40%, respectively). This study can pave the way for understanding the interaction between nuclear fuels and cladding materials in damaged reactors, enabling to simulate possible decontamination procedures.

Chemical and redox reaction between uranium (U) and zirconium (Zr) at high temperature under a reducing or oxidizing atmosphere were investigated to simulate fuel debris formed by Fukushima nuclear power plant accident. X-ray absorption spectroscopy (XAS) at U LIII-edge and Zr K edge and powder X-ray diffraction (XRD) of the mixed UO2/ZrO2 materials treated at high temperature from 1473 to 1873 K under reducing or oxidizing atmosphere were performed. For UO2-ZrO2 samples from1473 to 1873 K under the oxidizing atmosphere (Ar + 2% O2, 1h), it was found that the compounds were primarily consisted of five species including U3O8, UO2, U2Zr5O15, monoclinic-ZrO2, and tetragonal-ZrO2, whose fractions were calculated by principal component analysis (PCA) on both the X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) collected at both U LIII edge and Zr K edge. Here, the formation of U2Zr5O15, a pentavalent uranium compound, was confirmed by the U LIII edge-XANES between the temperature range from 1473 to 1573 K. These results were also supported by powder-XRD analysis. Under the reducing atmosphere (Ar + 10% H2, 1h), UO2 remained at the whole temperature range without reacting with ZrO2, whereas monoclinic- and tetragonal ZrO2 were formed at 1573 K (60- and 40%, respectively). This study can pave the way for understanding the interaction between nuclear fuels and cladding materials in damaged reactors, enabling to simulate possible decontamination procedures.

Purpose - The aim of the work is to develop an anticorrosion pigment based on an oxide mixture with lamellar particles. The pigments are prepared from lamellar zinc, zinc oxide and magnetite by calcination. An alkaline earth carbonate is added when embedding a third cation in the lattice of the ferrite that forms the envelope of the lamellar zinc. The properties of the pigments are tested both in the powdered state and when embedded in an epoxy-ester system using different pigment volume concentrations (PVC). Design/methodology/approach - The properties of paints containing synthesised oxide mixture-based pigments at various volume concentrations and with the Q factor - Q = PVC/CPVC = 0.65 - were examined (where CPVC is critical pigment volume concentration). A series of isometric ferrite pigments were also synthesised for a comparison. Paints of both types with PVC = 10, 15 and 20 per cent were formulated. Steel panels coated with the paints were subjected to corrosion and mechanical tests., Cílem práce je vyvinout antikorozní pigment na bázi oxidové směsi s lamelárními částicemi. Pigmenty jsou připraveny z lamelárního zinku, oxidu zinečnatého a magnetitu kalcinací. Vlastnosti pigmentů se testují jak v práškovém stavu, tak v případě, že jsou zabudovány do systému epoxy-esterů s použitím různých objemových koncentrací pigmentů. Byly zkoumány vlastnosti nátěrů obsahující pigmenty na bázi syntetických oxidových směsí v různých objemových koncentracích OKP / KOKP = 0,65 (kde KOKP je kritická objemová koncentrace pigmentu). Pro srovnání byla také syntetizována řada izometrických feritových pigmentů. Byly formulovány barvy obou typů s OKP = 10, 15 a 20%. Připravené nátěrové filmy byly podrobeny korozním a mechanickým zkouškám.

La presente tesis de pregrado contribuye a la síntesis, caracterización, selección y orden de reacción de catalizadores preparados por el método de auto-combustión empleando metales de transición de Mn y/o Fe, evaluando así un posible efecto cooperativo entre estos metales y su interacción en cuanto a sus propiedades fisicoquímicas del material y su comportamiento catalítico de los mismos en la degradación de cristal violeta (CV) en medio acuoso diluido a condiciones moderadas.

La presente tesis de pregrado contribuye a la síntesis, caracterización, selección y orden de reacción de catalizadores preparados por el método de auto-combustión empleando metales de transición de Mn y/o Fe, evaluando así un posible efecto cooperativo entre estos metales y su interacción en cuanto a sus propiedades fisicoquímicas del material y su comportamiento catalítico de los mismos en la degradación de cristal violeta (CV) en medio acuoso diluido a condiciones moderadas.

The paper is focused on the description of the activity/selectivity of mesoporous silica based materials loaded with various types of active species in the esterification of tall oil free fatty acids. The metals such as aluminium, molybdenum, gallium and zinc, including their combinations were impregnated on the mesoporous silica, which was tested in esterification reaction. All these catalysts preserved its tall oil free fatty conversion in the first and the second catalytic cycles. However, while only insignificant amount of gallium or molybdenum was lost from the solid catalyst into the liquid phases, zinc leached from every studied solid catalyst. In contrast to impregnated gallium on mesoporous silica, which exhibited higher acidity and higher tall oil free fatty acids conversion in the first catalytic cycle, but its value was not preserved in the second catalytic test., Bio4Energy

U ovom radu proučavana je primena mehanohemije u sintezi prekursora aktivnih katalizatora reakcije transesterifikacije suncokretovog ulja. Ispitivan je uticaj različitih metoda sinteze – mehanohemijske, sa i bez dodatka vode i, radi poređenja, taložne – na osobine dobijenog prekursora CaZn2(OH)6·2H2O. Smeša prahova Ca(OH)2 i ZnO u molskom odnosu od 1:2 je podvrgnuta mlevenju u planetarnom mlinu tokom vremenskog perioda od 7 h, uz dodatak stehiometrijski potrebne količine vode, kao i bez dodatka vode. Izvršena je i sinteza prekursora katalizatora koprecipitacijom Ca(OH)2 i ZnO u vodenom rastvoru KOH radi poređenja. Prekursorski prahovi dobijeni u sve tri sinteze su višefazni, a njihova aktivacija izvršena je na temperaturi od 700 °C, čime su prevedeni u mešoviti oksid CaO·ZnO. Nakon kalcinacije, katalizatori su primenjeni u sintezi metil estara masnih kiselina (MEMK) suncokretovog ulja. Izvršena je i detaljna fizičko-hemijska karakterizaciju pripremljenih prahova, pre i posle kalcinacije: strukturna karakterizacija dobijenih prahova urađena je metodom rendgenske strukturne analize (XRD), dok je morfološka karakterizacija prahova nakon žarenja urađena skenirajućom elektronskom mikroskopijom (SEM/EDS). Takođe, primenjivana je i termijska analiza (TGA/DSC), i infracrvena (IC) spektroskopija radi dobijanja dodatnih informacija o strukturi i sastavu katalizatora. Kako pomenuti katalizatori daju različite prinose u reakciji transesterifikacije triglicerida sa metanolom, utvrđena je bitna povezanost između baznosti katalizatora pripremljenih različitim metodama i katalitičke efikasnosti. Mehanohemijska sinteza se, u odnosu na konvencionalnu koprecipitaciju, pokazala kao jednostavnija metoda koja ne uključuje rastvarač i dodatak alkalija koje mogu ometati uvid u stvarnu katalitičku aktivnost, a ujedno i kao efikasnija metoda za dobijanje aktivnih prekursora mešovitih oksida. Pored Ca(OH)2, kao polazni prah korišćen je i CaO, dobijen nakon žarenja Ca(OH)2 na 700 °C, kao i neg, The use of mechanochemical synthesis to obtain active catalyst precursors and testing their activity in transesterification of sunflower oil with methanol was investigated. The effect of different methods for preparation of catalytic precursor (CaZn2(OH)6·2H2O) – mechanochemical, with or without the addition of water and coprecipitation were investigated. A powder mixture of Ca(OH)2 and ZnO, with the molar ratio of 1:2, with, as well as without stoichiometrically required addition of water were milled in a planetary ball mill for a period of 7 hours. The classical coprecipitation procedure of Ca(OH)2 and ZnO powders in KOH solution was also performed for comparison. Precursor powders obtained after above mentioned procedures were multiphase, and their activation was carried out at temperature of 700 °C, in order to convert them to CaO·ZnO mixed oxide. After calcination, the catalytic activity was tested in the synthesis of fatty acid methyl esters (FAME) from sunflower oil. Structural characterization of obtained powders was done by X-ray diffraction (XRD) analysis, while morphology was observed by scanning electron microscopy (SEM/EDS). Thermal analysis (TG / DSC) was also applied, as well as infrared spectroscopy (IR) in order to obtain additional information on the structure and composition of the catalysts. The difference in the activity of mechanochemically synthesized catalysts and catalyst prepared by coprecipitation procedure could be related to the difference in their basicity. Mechanochemical synthesis has an advantage over the coprecipitation due to its relative simplicity – solid phase reactions without usage of solvents or precipitants which can interfere with catalytic activity. Using CaO, obtained after calcination of Ca(OH)2 at 700 °C, and lime as a starting powders was investigated in order to reduce the amount of carbonates present in the synthesized precursors. Influence of promoter (K2CO3) added to starting mixture of lime and ZnO for mechanochem

The aim of this work has been to compare the activity and selectivity of Mg-Fe mixed oxides in the aldol condensation of furfural with that of previously studied Mg-Al mixed oxides. Mg-Fe mixed oxides were prepared by thermal pre-treatment of hydrotalcites with a Mg/Fe molar ratio from 1.1 to 7.6. Structural and textural properties of Mg-Fe mixed oxides were analysed by using of XRD and N2-adsorption. It was found that Mg-Fe mixed oxides exhibited lower conversion of furfural in contrast to the Mg-Al mixed oxides, but being more selective to 4-(2-furyl)-3-buten-2-one (FAc). The difference in the conversion of furfural was relatively low among the Mg-Fe mixed oxides with the Mg/Fe molar ratio in the range of 1.1-5.5., Cílem práce bylo porovnat aktivitu a selektivitu směsných oxidů Mg-Fe v aldolové kondenzaci furfuralu s dříve zkoumanýmni směsnými oxidy Mg-Al.

Bakalářská práce se zabývá studiem anorganických pigmentů, se zaměřením na směsné oxidy s perovskitovou strukturou v zájmu ekologické charakteru. V teoretické části práce je nastíněno základní rozdělení antikorozních pigmentů a jednotlivé druhy netoxických pigmentů. Další část práce pojednává o pigmentech na bázi směsných oxidů, hlavní důraz je kladen zejména na perovskitové sloučeniny a jejich použití. V experimentální části práce byly připraveny dva pigmenty se strukturou perovskitu - oxidu strontnato-titaničitého. Připravené pigmenty se lišily typem výchozích látek. U vzorků pigmentů byly zkoumány fyzikálně chemické vlastnosti, především hustota, spotřeba oleje a kritická objemová koncentrace pigmentu. Struktura pigmentů byla zkoumána pomocí rentgenové difrakční a mikroskopické SEM analýzy., This bachelor thesis deals with study of inorganic pigments aimed at mixed oxides of perovskite structure in the interest of an ecological character. The theoretical part of thesis includes basic classification of anticorrosive pigments and information about andividual classes of nontoxic pigments. The other part of thesis is focused on pigments on the mixed oxides basis with emphasis on the perovskite type of compounds and their use. In experimental part two pigments of perovskite structure (strontium titanium oxide) were synthesized. The pigments differed in type of raw materials. The pigment samples were tested in term of physico-chemical properties, especially density, the oil absoption value and critical pigment volume concentration. The structure of pigments was investigated by X-ray diffraction and SEM analysis., Fakulta chemicko-technologická, Interpretace výsledků, souvislost práce se zvoleným oborem

Tato disertační práce je studií pojednávající o antikorozních pigmentech na bázi směsí oxidů. První část práce má charakter rešerše a zabývá se možnostmi přípravy a aplikace směsí oxidů s lamelárními částicemi. Syntetizované pigmenty se skládají z feritových částic, které jsou vázány na částečně naoxidované zinkové jádro, čímž vytváří nový typ pigmentů o složení MexZn1-xFe2O4/Zn. Jsou zde uvedeny i různé další způsoby přípravy pigmentů jak na bázi směsí oxidů, tak na bázi směsných oxidů. Jsou podány informace o metodách charakterizace připravených pigmentů, jak v práškovém stavu, tak i přehled metod stanovení vlastností těchto pigmentů v naformulovaných systémech pigment-pojivo. Druhá část práce popisuje syntézu směsí oxidů s lamelárními částicemi a je věnována charakterizaci vlastností připravených pigmentů v práškovém stavu, včetně stanovení morfologie částic pigmentu, distribuční křivky, chemického složení a aplikovatelnosti v nátěrových hmotách. Série izometrických feritů byla též syntetizována pro srovnání vlastností. Vlastní testování antikorozních i mechanických charakteristik bylo provedeno pro nátěry formulované při třech různých hodnotách OKP = 10 % , 15% a 20% a při hodnotě parametru Q = OKP/KOKP = 0,65. Konstantní hodnota parametru Q (celková pigmentace) byla udržována pomocí přídavku titanové běloby. Shrnutí výsledků a antikorozní účinnost pigmentů je diskutována v závěru disertační práce. Pomocí SEM analýzy bylo zjištěno, že připravené pigmenty na bázi směsí oxidů obsahují lamelární částice s povrchovou vrstvou. Připravené práškové směsi oxidů mají rovněž charakteristické široké distribuční křivky velikosti částic. Jednotlivé obsažené oxidy v těchto pigmentech působí různými antikorozními mechanismy a výsledný antikorozní efekt je dán kombinací těchto mechanismů. Nejlepších výsledků bylo dosaženo s pigmenty na bázi směsí oxidů s lamelárními částicemi při OKP = 10% a 15%., This Ph.D. thesis is a study regarding a new type of mixed oxide anticorrosion pigment MexZn1-xFe2O4/Zn. As a specialty this new pigment has spinel ferrite particles bonded/deposited on a partly oxidized lamellar zinc core. Because of this, the new pigment combines the anticorrosion effect of both lamellar zinc oxide/zinc and ferrite. The first part of the study provides information about the different types of both mixed oxides and ferrite pigments and describes various means of preparation and application areas. A description of methods used for characterization of the prepared pigment?s properties in the powder state as well as the methods used for testing paint systems? binder-pigment are included in the first part of the work. The second part of the work is devoted to the preparation process for this new mixture-based pigment and deals with the determination of the pigment properties in a pulverized state and the properties of paints containing synthesized oxide mixture-based pigments at various volume concentrations and with the Q factor Q = PVC/CPVC = 0.65. A series of isometric ferrite pigments were also synthesized for comparison. Paints of both types with PVC = 10%, 15%, and 20% were used. The Q factor was kept constant by adding titanium white. The pigment properties examined included applicability in paints, morphology, particle size distribution, and pigment composition. Steel panels coated with the paints were subjected to corrosion and mechanical tests. The measured data were processed into charts, evaluated and the results discussed. The oxide mixtures with lamellar particles were subjected to particle size analysis and found to make up a broad distribution curve. Electron microscopy photographs confirmed that the oxide mixture pigments contained lamellar particles with a surface layer. A high anticorrosion effect was achieved owing to the combination of different oxide types. The best results were achieved with paints pigmented with oxide mixture-ba, Fakulta chemicko-technologická

Fe (III)-modified Titania and Fe (III)-Ti (IV) binary oxides have received much less attention as possible catalysts compared to their parent single-metal oxides, Fe2O3 and TiO2. This could be due to the difficulty of obtaining pure desired monophases. In addition, the effect of different preparative conditions on the textural properties of sol-gel-prepared Ti-Fe mixed oxides was rarely studied. Furthermore, the effect of the composition on the reducibility and the catalytic activity of these composites was never studied. In the present work, Ti-Fe mixed oxides were prepared using a modified sol-gel method and their textural properties as well as their reducibility and their catalytic activity were investigated and were compared with those of parent single-metal oxides. The use of propylene oxides (PO) as a gelation promoter as well as the presence of hetero-ions was found to play a key role in promoting gel formation at certain concentrations. While in the presence of a single metal, colloidal solutions and very fine precipitates were obtained, gels formed readily from mixed solutions containing 5-15% Fe(III) in the presence of PO, and from solutions containing 40 and 66.7% Fe(III) even in the absence of PO. While Fe (III) concentration as high as 10% was well dispersed in the Titania lattice, which was also associated with enhanced stability of the anatase structure, higher concentrations resulted in the formation of anatase and pserudorutile (Pr) initially, which converted to rutile and pseudobrookite (Pb) upon heating at elevated temperatures. The preparation of a pure Pr phase was possible under the employed preparative conditions starting with a solution containing 40% Fe (III). However, the presence of higher concentrations resulted in the formation of some segregated α- Fe2O3. Xerogel and aerogel mixed oxides possessed significantly higher surface areas than their parent single metal oxi

Non-edible oils and waste cooking oils are alternatives to uphold a sustainable large scale production of biodiesel considering large volumes and by-products. Babassu oil (Attalea speciosa) offers a challenging case study scenario for the preparation of a heterogeneous catalytic material. This study shows the binary synthesis of calcium and stannic oxide (CaO/SnO2) catalysts for transesterification of oils with high content of free fatty acids (FFAs). The catalysts were prepared with several mass ratios of CaO:SnO2 in the proportions of 1:4, 4:1, 7:3 and 1:1. The catalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and N2-physisorption analyses. Biodiesel production was tested using a 23 full factorial design with variables such as temperature, methanol/oil molar ratio, and catalyst weight relative to oil. Such design statistically proved that there was no significant effect over the response variable. Furthermore a Box-Behnken design surface response analysis using the same three variables with three levels was performed with MATLAB showing a non-linear relation and statistical response of the optimal conditions for biodiesel production. The optimal experimental conditions were found to be 54.1°C, agitation speed at 250rpm with 6wt.% of CaO/SnO2 (7:3 mass ratio of the binary catalyst) and 10:1 (methanol:oil) molar ratio. The catalyst has shown a high potential for conversion of Babassu oil by fine-tuning as a single step by simultaneous esterification and transesterification to biodiesel., QC 20160627

The heterometallic complexes (NH4)2[Co(H2O)6]2[V10O28]·4H2O (1) and (NH4)2[Co(H2O)5(β-HAla)]2[V10O28]·4H2O (2) have been synthesized and used for the preparation of mixed oxides as catalysts for water oxidation. Thermal decomposition of 1 and 2 at relatively low temperatures (<500 °C) leads to the formation of the solid mixed oxides CoV2O6/V2O5 (3) and Co2V2O7/V2O5 (4). The complexes (1, 2) and heterogeneous materials (3, 4) act as catalysts for photoinduced water oxidation. A modification of the thermal decomposition procedure allowed the deposition of mixed metal oxides (MMO) on a mesoporous TiO2 film. The electrodes containing Co/V MMOs in TiO2 films were used for electrocatalytic water oxidation and showed good stability and sustained anodic currents of about 5 mA cm−2 at 1.72 V versus relative hydrogen electrode (RHE). This method of functionalizing TiO2 films with MMOs at relatively low temperatures (<500 °C) can be used to produce other oxides with different functionality for applications in, for example, artificial photosynthesis.

Ruthenium-based materials are investigated for the simultaneous removal of soot and NOx and their behavior is compared with that of model Pt-Ba/Al2O3 and Pt-K/Al2O3 catalysts.; The materials, 1%wt Ru-10%wt AM/MO (AM = Ba or K; MO= Ce0.8Zr0.2O2, O-2, Al2O3), have been prepared by incipient wetness impregnation and characterized by BET, XRD, HRTEM and TPR experiments. The catalytic activity for diesel soot combustion is studied under loose contact conditions by means of TPO (Temperature Programmed Oxidation) while the reactivity in the NO, removal is investigated by Isothermal Concentration Step Change experiments.; All the ruthenium-based formulations are active in the combustion of diesel soot, particularly potassium-doped materials that show low onset temperatures, near 230 degrees C. The catalytic activity in the simultaneous removal of soot and NOx shows that Ru-based catalysts are very efficient in the oxidation of soot also under isothermal conditions and that their NOx removal capacity (i.e. storage capacity) is almost comparable to that of traditional Pt-based LNT systems. However, the NOx reduction efficiency of the Ru-containing catalysts is lower than that of traditional LNT Pt-based catalysts. (C) 2016 Elsevier B.V. All rights reserved., Postprint (author's final draft)

Dehydrogenation promoters greatly enhance the performance of SiO2-MgO catalysts in the Lebedev process. Here, the effect of preparation method and order of addition of Cu on the structure and performance of Cu-promoted SiO2-MgO materials is detailed. Addition of Cu to MgO via incipient wetness impregnation (IWI) or coprecipitation (CP) prior to wet-kneading with SiO2 gave similar butadiene yields (similar to 40%) as when Cu was added to the already wet-kneaded catalyst. In contrast, the catalyst prepared by impregnation of Cu on SiO2 first proved to be the worst catalyst of the series. TEM, XRD, and XPS analyses suggested that, for all catalyst materials, Cu2+ forms a solid solution with MgO. This was confirmed by UV-vis, XANES, and EXAFS data, with Cu being found in a distorted octahedral geometry. As a result, the acid base properties, as determined by Pyridine- and CDCl3-IR as well as NH3-TPD, are modified, contributing to the improved performance. Operando XANES and EXAFS studies of the evolution of the copper species showed that Cu2+, the only species initially present, is extensively reduced to a mixture of Cu-0 and Cu+, leaving only a limited amount of unreduced Cu2+. This formation of Cu-0 is the result of the reducing environment of the Lebedev process and is thought to be mainly responsible for the improved performance of the Cu-promoted catalysts.

The effect of ruthenium on the physico-chemical properties of CeZr and CeZrCo mixed oxides for H2 production by glycerol steam reforming reaction has been studied. The combination of in situ Raman spectroscopy under both reductive and oxidative conditions, H2/O2 pulses and XRD, Raman, BET analysis, H2-TPR and TPD-TPO analyses contributed to the determination of the structural and textural properties, redox behavior, re-oxidation capacity and resistance to carbon deposition of the synthesized catalysts. The results show that the catalytic activity is improved by the (positive) cooperative and complementary effect between cobalt and ruthenium that favors the selectivity toward the steam reforming, selective to H2, with respect to the unselective thermal decomposition of glycerol. Ruthenium stabilizes the cobalt cations inserted in the fluorite structure preventing its rejection as Co3O4; and provides the necessary hydrogen to reduce Ce4+. The combination cobalt-ruthenium modifies positively the redox properties of the catalysts, increases the re-oxidation capacity (OSC) and promotes the gasification of the carbon deposits. Under the reaction conditions, the decrease in glycerol conversion came along with a change of selectivity. The formation of H2 and CO2 were strongly decreased, while the formation of CO, C2H4 and condensable products (mainly hydroxyacetone) increase. The differences in the catalytic stability and activity of the catalysts are related to the capability of the catalysts to activate H2O under the reaction conditions, favoring the steam reforming reaction over the thermal decomposition.

In this paper a novel synthetic route, being a paradigm of the "direct synthesis" approach, is proposed for the preparation of heterometallic Mn/V compounds by a one-pot reaction. Two synthesized complexes, (NH4)(2)[Mn-2(HGly)(H2O)(10)][V10O28]center dot(HGlY)center dot 2H(2)O (1) and (NR4)(2)[Mn(beta-HAIa)(H2O)(5)](2)[V10O28]center dot 2H(2)O (2) (HGly = glycine, beta-HAla = beta-alanine) have been fully characterized by elemental analysis, single-crystal X-ray diffraction, cyclic voltammetry, magnetic susceptibility, FTIR and EPR spectroscopy. Thermal degradation of these compounds lead to the formation of porous, solid mixed oxides V2O5/MnV2O6 in a ratio of 3:2, which were analyzed by X-ray phase analysis and scanning electron microscopy with energy dispersive X-ray microanalysis (SEM/EDX). Additionally the ability of 1 and 2 to act as oxygen evolving water oxidation catalysts under visible light-driven conditions have been studied in a Clark type cell and by ex situ EPR spectroscopy.

The effect of ruthenium on the physico-chemical properties of CeZr and CeZrCo mixed oxides for H2 production by glycerol steam reforming reaction has been studied. The combination of in situ Raman spectroscopy under both reductive and oxidative conditions, H2/O2 pulses and XRD, Raman, BET analysis, H2-TPR and TPD-TPO analyses contributed to the determination of the structural and textural properties, redox behavior, re-oxidation capacity and resistance to carbon deposition of the synthesized catalysts. The results show that the catalytic activity is improved by the (positive) cooperative and complementary effect between cobalt and ruthenium that favors the selectivity toward the steam reforming, selective to H2, with respect to the unselective thermal decomposition of glycerol. Ruthenium stabilizes the cobalt cations inserted in the fluorite structure preventing its rejection as Co3O4; and provides the necessary hydrogen to reduce Ce4+. The combination cobalt-ruthenium modifies positively the redox properties of the catalysts, increases the re-oxidation capacity (OSC) and promotes the gasification of the carbon deposits. Under the reaction conditions, the decrease in glycerol conversion came along with a change of selectivity. The formation of H2 and CO2 were strongly decreased, while the formation of CO, C2H4 and condensable products (mainly hydroxyacetone) increase. The differences in the catalytic stability and activity of the catalysts are related to the capability of the catalysts to activate H2O under the reaction conditions, favoring the steam reforming reaction over the thermal decomposition.

The goal of this study was to prepare a CaO·ZnO catalyst containing a small amount of K2CO3 and analyze its activity for biodiesel synthesis. The catalyst was prepared using the following procedure: CaO and ZnO (mole ratio of 1:2), water and K2CO3 (in various amounts) were mechanochemically treated and after milling heated at 700°C in air atmosphere for obtaining mixed CaO·ZnO/xK2CO3 oxides (x = 0, 1, 2 and 4 mol of K2CO3 per 10 mol of CaO). All the samples were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), scanning electron microscopy/ energy-dispersive spectroscopy (SEM/EDS), particle size laser diffraction (PSLD) distribution, solubility measurement of Ca, Zn and K ions in methanol as well as by determination of their alkalinity (Hammett indicator method). Prepared CaO·ZnO/xK2CO3 composite powders were tested as catalysts for methanolysis of sunflower oil at 70 °C using mole ratio of sunflower oil to methanol of 1:10 and with 2 mass% of catalyst based on oil weight. The presence of K2CO3 in prepared samples was found to increase the activity of catalyst, and that such effect is caused by homogeneous-heterogeneous catalysis of biodiesel synthesis., Cilj ovih istraživanja bio je da se pripremi CaO·ZnO katalizator koji sadrži malu količinu K2CO3 i analizira njegova aktivnost u sintezi biodizela. Katalizator je pripremljen prema sledećoj proceduri: CaO i ZnO (molski odnos 1:2), voda i K2CO3 (u različitoj količini) su tretirani mehanohemijski i nakon mlevenja zagrevani na 700 °C u atmosferi vazduha da bi se dobila smeša oksida CaO·ZnO/xK2CO3 (x = 0, 1, 2 i 4 mol K2CO3 na 10 mol CaO). Karakterizacija pripremljenih katalizatora izvršena je metodama rendgenske difrakcije (XRD), indukovane kuplovane plazme (ICP), spektroskopije fotoelektrona dobijenih X-zracima (XPS), termogravimetrijske analize (TGA), infracrvene spektroskopije (FTIR), skenirajuće elektronske mikroskopije i energetske disperzione spektroskopije (SEM/EDS), raspodele veličine čestica (PSLD), merenjem rastvorljivosti katalizatora odnosno Ca, Zn i K jona u metanolu, kao i određivanjem njihove baznosti (metodom Hametovih indikatora). Pripremljeni CaO·ZnO/xK2CO3 kompozitni prahovi testirani su kao katalizatori u reakciji metanolize suncokretovog ulja na 70 °C, pri molarnom odnosu suncokretovog ulja i metanola od 1:10 i sa 2 mas.% katalizatora u odnosu na masu ulja. Pokazano je da prisustvo K2CO3 u pripremljenim uzorcima povećava aktivnost katalizatora i da je takav efekat posledica homogeno-heterogene katalize u sintezi biodizela.

The goal of this study was to prepare a CaO·ZnO catalyst containing a small amount of K2CO3 and analyze its activity for biodiesel synthesis. The catalyst was prepared using the following procedure: CaO and ZnO (mole ratio of 1:2), water and K2CO3 (in various amounts) were mechanochemically treated and after milling heated at 700 °C in air atmosphere for obtaining mixed CaO·ZnO/xK2CO3 oxides (x = 0, 1, 2 and 4 mol of K2CO3 per 10 mol of CaO). All the samples were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), particle size laser diffraction (PSLD) distribution, solubility measurement of Ca, Zn and K ions in methanol as well as by determination of their alkalinity (Hammett Indicator method). Prepared CaO·ZnO/xK2CO3 composite powders were tested as catalysts for methanolysis of sunflower oil at 70 °C using mole ratio of sunflower oil to methanol of 1:10 and with 2 mass% of catalyst based on oil weight. The presence of K2CO3 in prepared samples was found to increase the activity of catalyst, and that such effect is caused by homogeneous-heterogeneous catalysis of biodiesel synthesis. © 2015, CI and CEQ. All Rights Reserved.

The goal of this study was to prepare a CaO·ZnO catalyst containing a small amount of K2CO3 and analyze its activity for biodiesel synthesis. The catalyst was prepared using the following procedure: CaO and ZnO (mole ratio of 1:2), water and K2CO3 (in various amounts) were mechanochemically treated and after milling heated at 700 °C in air atmosphere for obtaining mixed CaO·ZnO/xK2CO3 oxides (x = 0, 1, 2 and 4 mol of K2CO3 per 10 mol of CaO). All the samples were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), particle size laser diffraction (PSLD) distribution, solubility measurement of Ca, Zn and K ions in methanol as well as by determination of their alkalinity (Hammett Indicator method). Prepared CaO·ZnO/xK2CO3 composite powders were tested as catalysts for methanolysis of sunflower oil at 70 °C using mole ratio of sunflower oil to methanol of 1:10 and with 2 mass% of catalyst based on oil weight. The presence of K2CO3 in prepared samples was found to increase the activity of catalyst, and that such effect is caused by homogeneous-heterogeneous catalysis of biodiesel synthesis. © 2015, CI and CEQ. All Rights Reserved.