Bibliografie tematiche / Sulfure de zirconium

Letteratura scientifica selezionata sul tema "Sulfure de zirconium"

Autore: Grafiati

Pubblicato: 22 giugno 2024

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Articoli di riviste sul tema "Sulfure de zirconium":

Zhang, Juan Juan, Yue Qin Song, Xiao Long Zhou, Cheng Lie Li, Jin An Wang e Long Ya Xu. "Effect of Hydrothermal Conditions on Isomerization Activity of Pt/SO₄^2--ZrO₂". Advanced Materials Research 132 (agosto 2010): 183–91. http://dx.doi.org/10.4028/www.scientific.net/amr.132.183.

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Pt/SO42--ZrO2 catalysts (PSZ) were prepared by using a series of hydrous zirconia as support synthesized via a hydrothermal method. The catalytic performances of these catalysts were evaluated in the n-hexane isomerization in a fixed bed reactor. The crystalline structure, acidity, reduction properties, textural texture, and sulfur content were characterized by XRD, NH3-TPD, H2-TPR, N2 adsorption and thermal analysis. The experimental results indicated that the hydrothermal ageing of zirconium hydroxide led to great changes in the crystalline structure of hydrous zirconia support, sulfur content, and the acidity of PSZ. The abundant strong acid sites and high sulfur content were essential but insufficient to achieve a PSZ catalyst with high isomerization activity. Too weak or too strong interaction between sulfur species and zirconia in the catalysts was unfavorable to the isomerization reaction. The presence of considerable sulfate species interacting moderately with zirconia was crucial to high isomerization activity.

Al-Tabbakh, Dr Ban A. Ahmed, e Maan M. Dawood. "Synthesis and Characterization of Sulfated Zirconia Catalyst for Light Naphtha Isomerization Process". Journal of Petroleum Research and Studies 12, n. 1(Suppl.) (21 aprile 2022): 186–98. http://dx.doi.org/10.52716/jprs.v12i1(suppl.).630.

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The platinum-loaded zirconium oxide (Pt/SO4-2/ZrO2) catalyst was developed for the light naphtha atoms over the reaction temperature range of 160 to 220 °C, 1 and 3 h-1 LSHV and 10 bar. Platinum improved the stability of the catalyst by preventing the formation of a coke precursor at the strong acid site of sulfur zirconium. The acidity of the catalyst was characterized by of NH3-TPD and the effect of sulfur and calcination temperature on the surface area of the final prepared zirconia was studied. The prepared catalyst shows high structural similar activity at temperature between 200 and 210°C for two types of light naphtha feed.

Maresz, Katarzyna, Agnieszka Ciemięga, Patryk Bezkosty, Kamil Kornaus, Maciej Sitarz, Maciej Krzywiecki e Julita Mrowiec-Białoń. "Insight into Structural and Physicochemical Properties of ZrO2-SiO2 Monolithic Catalysts with Hierarchical Pore Structure: Effect of Zirconium Precursor". Catalysts 13, n. 12 (16 dicembre 2023): 1516. http://dx.doi.org/10.3390/catal13121516.

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Zirconia–silica monolithic catalysts with hierarchical micro/macroporous structure were obtained in a sol-gel process combined with phase separation using inorganic salts, i.e., oxychloride, oxynitrate and sulphate, as a zirconium source. It was found that the use of zirconium oxychloride and prehydrolysis of tetraethoxysilane (TEOS) resulted in materials characterized by a well-developed continuous structure of macropores with a diameter of ca. 10 μm. For zirconium oxynitrate and sulfate modified materials, the prehydrolysis hardly affected the macropore size. The micropores with a diameter of 1.5 nm in the skeleton of all materials provided a large surface area of 550–590 m2/g. A high dispersion of zirconia in the silica skeleton in all studied materials was shown. However, the largest surface concentration of Lewis and Brönsted acid sites was found in the monolith synthesized with zirconium oxychloride. The monoliths were used as a core for continuous-flow microreactors and high catalytic activity was confirmed in the deacetalization of benzylaldehyde dimethyl acetal. The process was characterized by a high efficiency at low temperature, i.e., 35 °C.

Zhuang, Quan, e Jack M. Miller. "One-pot sol-gel synthesis of sulfated ZrO2-SiO2 catalysts for alcohol dehydration". Canadian Journal of Chemistry 79, n. 8 (1 agosto 2001): 1220–23. http://dx.doi.org/10.1139/v01-109.

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Sulfated ZrO2SiO2 catalysts were synthesized by one-pot sol-gel method using ammonium sulfate, zirconium propoxide, and tetraethyl orthosilicate as precursors. The catalysts were characterized by N2 adsorption and DRIFTS. On calcining the gel at elevated temperature, the ammonium sulfate decomposed, giving a sulfated zirconiasilica catalyst. By adding ammonium sulfate to the sol-gel synthesis system, the surface area, pore size, and pore volume of the resultant catalyst were increased. The one-pot sol-gel synthesized catalyst with an optimum loading of SO42 14 mol% showed significantly higher catalytic activity, with a selectivity of 100%, for isopropanol dehydration when compared to the impregnated catalyst. The one-pot sol-gel synthesis method is an effective way to prepare sulfated zirconia catalyst.Key words: sulfated zirconia, sol-gel synthesis, acid catalyst, alcohol dehydration, N2 adsorption, DRIFT.

Lugo del Ángel, F. E., R. Silva-Rodrigo, A. Vázquez Rodríguez, R. García Alamilla, J. Navarrete Bolaños, A. Castillo Mares, José Aarón Melo-Banda, Eduardo Térres-Rojas e J. L. Rivera Armenta. "Studies on the Catalytic Activity of Sulfated Zirconia Promoted with Cerium Oxide". Advanced Materials Research 132 (agosto 2010): 149–61. http://dx.doi.org/10.4028/www.scientific.net/amr.132.149.

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Pure zirconia, sulfated zirconia and sulfated zirconia modified with 2, 3, 5 and 10 wt. % of cerium oxide were synthesized by sol-gel method. Pt phase was impregnated on the supports using the incipient wet technique. Sulfated zirconium oxide showed tetragonal phase only. Addition of cerium to sulfated zirconia did not modify the tetragonal phase but produced a marked effect on the surface area. Low cerium content may greatly increase the surface area; however, too high cerium content (10 wt.%) may decrease the surface area. Pore size had influence on the catalytic activity and ZrO2 acidity was favored by the sulfate ion incorporation. All catalysts having Brönsted and Lewis acid sites were active in the n-hexane isomerization. The highest n-hexane conversion (40%) and selectivity towards DMB (26%), 2-methyl pentane (61%) and 3-methyl pentane (13%) were reached over the catalyst with 10 wt. % cerium oxide. In addition, sulfated zirconium oxide presented high selectivity of light products (< C6), which indicated that the addition of this doping agent (CeO2) made the catalysts more selective toward the desired reaction products.

Ma, Yiqian, Srecko Stopic, Xuewen Wang, Kerstin Forsberg e Bernd Friedrich. "Basic Sulfate Precipitation of Zirconium from Sulfuric Acid Leach Solution". Metals 10, n. 8 (13 agosto 2020): 1099. http://dx.doi.org/10.3390/met10081099.

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H2SO4 was ensured to be the best candidate for Zr leaching from the eudialyte. The resulting sulfuric leach solution consisted of Zr(IV), Nb(V), Hf(IV), Al(III), and Fe(III). It was found that ordinary metal hydroxide precipitation was not feasible for obtaining a relatively pure product due to the co-precipitation of Al(III) and Fe(III). In this reported study, a basic zirconium sulfate precipitation method was investigated to recover Zr from a sulfuric acid leach solution of a eudialyte residue after rare earth elements extraction. Nb precipitated preferentially by adjusting the pH of the solution to around 1.0. After partial removal of SO42− by adding 120 g of CaCl2 per 1L solution, a basic zirconium sulfate precipitate was obtained by adjusting the pH to ~1.6 and maintaining the solution at 75 °C for 60 min. Under the optimum conditions, the loss of Zr during the SO42− removal step was only 0.11%, and the yield in the basic zirconium sulfate precipitation step was 96.18%. The precipitate contained 33.77% Zr and 0.59% Hf with low concentrations of Fe and Al. It was found that a high-quality product of ZrO2 could be obtained from the basic sulfate precipitate.

Utami, Maisari, Karna Wijaya e Wega Trisunaryanti. "Effect of Sulfuric Acid Treatment and Calcination on Commercial Zirconia Nanopowder". Key Engineering Materials 757 (ottobre 2017): 131–37. http://dx.doi.org/10.4028/www.scientific.net/kem.757.131.

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The modification of commercial zirconia nanopowder by sulfuric acid and heat treatment was conducted. The aim of this present research was to obtain a stable modified zirconia nanopowder chemically and thermally by studying the effect of sulfuric acid treatment and calcination temperature on commercial zirconia nanopowder. The material was prepared by dispersing the commercial zirconia nanopowder into 0.2, 0.5 and 0.8 M sulfuric acid solutions, followed by calcination at varied temperatures, i.e. 600, 700, 800 and 900 °C. The so called sulfated zirconias then were characterized their physicochemical properties using FT-IR, XRD and SEM-EDX analysis methods. The optimized condition for that modification was obtained by using sulfuric acid of 0.8 M and calcination temperature of 600 °C. The characterization results also revealed that using ammonia adsorption method, the acidity of the catalyst was found to be 1.06 mmol/g.

Beschkov, Venko N., Elena N. Razkazova-Velkova, Martin S. Martinov e Stefan M. Stefanov. "Performance of Sulfide-Driven Fuel Cell Aerated by Venturi Tube Ejector". Catalysts 11, n. 6 (30 maggio 2021): 694. http://dx.doi.org/10.3390/catal11060694.

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Hydrogen sulfide is frequently met in natural waters, like mineral springs, but mostly it is found in marine water with low renewal rate. The Black Sea has extremely high hydrogen sulfide content. It can be utilized in different ways, but the most promising one is direct conversion into electricity. This result can be attained by a sulfide-driven fuel cell (SDFC), converting sulfide to sulfate thus releasing electric energy up to 24 GJ/t. One of the most important problems is the mass transfer limitation on oxygen transfer in the cathode space of the fuel cell. This problem can be solved using a gas diffusion electrode or highly efficient saturation by oxygen in an ejector of the Venturi tube type. This work presents experimental data in laboratory-scale SDFC for sulfide conversion into sulfate, sulfite and polysulfide releasing different amounts of electric energy. Two types of aeration are tested: direct air blow and Venturi-tube ejector. Besides pure graphite, two catalysts, i.e., cobalt spinel and zirconia-doped graphite were tested as anodes. Experiments were carried out at initial sulfide concentrations from 50 to 300 mg/L. Sulfate, sulfite and thiosulfate ions were detected in the outlet solutions from the fuel cell. The electrochemical results show good agreement with the chemical analyses. Most of the results show attained high efficiencies of the fuel cell, i.e., up to 80%. The practical applications of this method can be extended for other purposes, like treatment of polluted water together with utilization as energy.

Platero, E. Escalona, e M. Pe�arroya Mentruit. "IR characterization of sulfated zirconia derived from zirconium sulfate". Catalysis Letters 30, n. 1-4 (1995): 31–39. http://dx.doi.org/10.1007/bf00813670.

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Amin, Amalia Kurnia, Wega Trisunaryanti e Karna Wijaya. "Effect of Promoters and Calcination Temperature on Surface and Acidity of Modified Zirconia". Journal of Nano Research 57 (aprile 2019): 31–39. http://dx.doi.org/10.4028/www.scientific.net/jnanor.57.31.

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The effect of sulfating agent concentration, calcination temperature, and Ni incorporation on commercial zirconia have been evaluated. Sulfation of commercial zirconia was prepared by wet impregnation with different amounts of sulfuric acid (0.2, 0.5 and 0.8 M) then calcined at 400, 500, 600, 700, 800 and 900°C for 4 h. Ni was incorporated by refluxing over sulfated zirconia, followed by calcination-reduction process. All samples were characterized by XRD, FTIR, ammonia sorption, SEM-EDX, TEM, and AAS. The presence of sulfate has been added to acidic strength of the sulfated zirconia, the more sulfuric acid were used the stronger the acidic property. There has been degradation of sulfate groups that was adrift in sulfated zirconia by calcination treatment above 600°C. The best physicochemical properties of sulfated zirconia were modification with 0.8 M sulfuric acid and on calcination at 400°C. The 0.8SZ-400 has exhibited the highest Brønsted acidic sites with total acidity of 1.71 mmol/g. The impregnation of Ni enhanced the Lewis acidic sites on the surface of the 0.8SZ-400 which NiSZ gave 2.71 mmol/g of total acidity. All prepared materials consisted of nearly spherical shape of nanocrystal with mostly aggregated particles.

Più fonti

Tesi sul tema "Sulfure de zirconium":

Abdoulmoumine, Nourredine. "Sulfate and Hydroxide Supported on Zirconium Oxide Catalysts for Biodiesel Production". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/33873.

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Biodiesel is currently produced by homogeneous catalysis. More recently however, heterogeneous catalysis is being considered as a cheaper alternative to the homogeneous process. In this research project, heterogeneous catalysts of zirconium oxide were produced by impregnation. Zirconium oxide impregnation with sulfuric acid produced acidic solid catalysts. It was determined that impregnation and calcination at 550^oC (SO₄/ZrO₂-550^oC) produced the best catalyst for palmitic acid esterification with 10 wt % as the optimum concentration in esterification of palmitic acid. SO₄/ZrO₂-550^oC was successfully recycled for eight consecutive runs before permanent deactivation. Its sulfur content was 1.04 wt % using SEM-EDS and 2.05 wt % using XPS for characterization. BET surface area was 90.89 m2/g. The reaction mechanism over BrÃ¸nsted acid (SO₄/ZrO₂-550^oC) and Lewis acid (Al₂O₃) catalysts obeyed Eley-Rideal kinetics with palmitic acid and methanol adsorbed on the active site respectively. Zirconium oxide was also impregnated with sodium hydroxide to produce basic catalysts. The best catalyst was produced when zirconium oxide was impregnated with 1.5 M NaOH and calcined at 600^oC. Soybean oil was completely converted to biodiesel with 10 wt % catalyst and 1:6 oil to methanol. A mixture of the base catalyst with 30 wt % SO₄/ZrO₂-550^oC effectively converted soybean oil containing 5% oleic acid indicating that this mixture could be used for waste oils. The reaction was first order with respect to triglyceride and second order with respect to methanol. The activation energy was 49.35 kJ/mol and the reaction mechanism obeyed Langmuir-Hinshelwood kinetics.
Master of Science

Sharp, Conor Hays. "Fundamental Studies of the Uptake and Diffusion of Sulfur Mustard Simulants within Zirconium-based Metal-Organic Frameworks". Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102928.

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The threat of chemical warfare agent (CWA) attacks has persisted into the 21st century due to the actions of terror groups and rogue states. Traditional filtration strategies for soldier protection rely on high surface area activated carbon, but these materials merely trap CWAs through weak physisorption. Metal-organic frameworks (MOFs) have emerged as promising materials to catalyze the degradation of CWAs into significantly less toxic byproducts. The precise synthetic control over the porosity, defect density, and chemical functionality of MOFs offer exciting potential of for use in CWA degradation as well as a wide variety of other applications. Developing a molecular-level understanding of gas-MOF interactions can allow for the rational design of MOFs optimized for CWA degradation. Our research investigated the fundamental interfacial interactions between CWA simulant vapors, specifically sulfur mustard (HD) simulants, and zirconium-based MOFs (Zr-MOFs). Utilizing a custom-built ultrahigh vacuum chamber with infrared spectroscopic and mass spectrometric capabilities, the adsorption mechanism, diffusion energetics, and diffusion kinetics of HD simulants were determined. For 2-chloroethyl ethyl sulfide (2-CEES), a widely used HD simulant, infrared spectroscopy revealed that adsorption within Zr-MOFs primarily proceeded through hydrogen bond formation between 2-CEES and the bridging hydroxyls on the secondary building unit of the MOFs. Through the study of 1-chloropentane and diethyl sulfide adsorption, we determined that 2-CEES forms hydrogen bonds through its chlorine atom likely due to geometric constraints within the MOF pore environment. Temperature-programmed desorption experiments aimed at determining desorption energetics reveal that 2-CEES remain adsorbed within the pores of the MOFs until high temperatures, but traditional methods of TPD analysis fail to accurately measure both the enthalpic and entropic interactions of 2-CEES desorption from a single adsorption site. Infrared spectroscopy was able to measure the diffusion of adsorbates within MOFs by tracking the rate of decrease in overall adsorbate concentrations at several temperatures. The results indicate that 2-CEES diffusion through the pores of the MOFs is a slow, activated process that is affected by the size of the pore windows and presence of hydrogen bonding sites. We speculate that diffusion is the rate limiting step in the desorption of HD simulants through Zr-MOFs at lower temperatures. Stochastic simulations were performed in an attempt to deconvolute TPD data in order to extract desorption parameters. Finally, a combination of vacuum-based and ambient-pressure spectroscopic techniques were employed to study the reaction between 2-CEES and an amine-functionalized MOF, UiO-66-NH2. Although the presence of water adsorbed within UiO 66 NH2 under ambient conditions may assist in the reactive adsorption of 2-CEES, the reaction proceeded under anhydrous conditions.
Doctor of Philosophy

Makhlouf, Sandy. "Modélisation et simulation de la structure électronique de petites molécules environnementales : Un exemple : les halogénures et monoxydes de Lanthanides (Ce et Lu)". Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR042.

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Nos travaux de recherche portent sur l’étude théorique de la structure électronique de molécules diatomiques environnementales telles que le monoxyde de cérium et de lutétium (CeO et LuO), le monofluorure de cérium (CeF) et le monosulfure de zirconium (ZrS). Pour réaliser ces études, nous avons eu recours aux méthodes ab initio de chimie quantique qui englobent les méthodes de Hartree-Fock, la méthode du champ auto-cohérent complet de l'espace actif (CASSCF) et les méthodes d'interaction de configuration multi-référence (MRCI) à simple et double excitation. Le progiciel MOLPRO a été utilisé pour les calculs sans et en incluant le couplage spin-orbite, avec la correction de Davidson et en symétrie C2v. Pour chaque molécule des fonctions de bases atomiques spécifiques ont été déterminées et différents modèles théoriques testés. Les courbes d’énergie potentielle des états électroniques 2S+1L+/- et des composantes O+/- ont été tracées sur un intervalle de distance internucléaire conséquent puis ajustées au potentiel de Morse pour en déduire les constantes spectroscopiques (l’énergie électronique à l’équilibre Te, la distance internucléaire d’équilibre Re, les constantes vibrationnelles harmonique ωe et anharmonique ωeXe et, la constante rotationnelle Be). Les moments dipolaires de transition et permanents ont ensuite été calculés pour les états 2S+1L+/-. Pour identifier les composantes O+/-, la composition en pourcentages des états parents S-L+/- ont été obtenus via le calcul tenant compte du couplage spin-orbite.Nos résultats sans et avec spin-orbite sont comparés à ceux trouvés expérimentalement et montrent un bon accord. Globalement, une erreur relative inférieure à 6% est retrouvée pour toutes les constantes spectroscopiques des molécules étudiées
Our research work focuses on the theoretical investigation of the electronic structure of environmental diatomic molecules such as the cerium and the lutetium monoxides (CeO and LuO), the cerium monofluoride (CeF) and the zirconium monosulfide (ZrS). For these studies, we used ab initio quantum chemistry methods which encompass the Hartree-Fock methods, the complete active space self-consistent field (CASSCF) method and the multi-reference configuration interaction methods (ICMR) with single and double excitation. The MOLPRO software package is used to perform the calculations with and without the inclusion of the spin-orbit coupling. The Davidson's correction is considered and the calculations are elaborated in the C2v symmetry. For each molecule, corresponding atomic basis functions are adopted and theoretical models are tested. As result, the potential energy curves are plotted and then fitted to the Morse potential in order to determine the spectroscopic constants (the equilibrium electronic energy Te, the equilibrium internuclear distance Re, the harmonic ωe and anharmonic ωe vibrational constants and the rotational constant Be) of the electronic states 2S+1Lambda+/- and the respective Omega+/- components. The transition and permanent dipole moments are estimated for the Lambda+/- states. The Omega+/- components and the mixing percentages that provide the parental states Lambda+/- are obtained from the ICMRSD(+Q) calculations including the spin-orbit coupling.Our results with and without taking into consideration the spin-orbit effect are very satisfactory. They are compared with the experimental data and show good agreement and in general the relative error is found of less than 6% for all the spectroscopic constants of the studied molecules

Romano, Esteban Javier. "A surface science approach to understanding emission control catalyst deactivation due to sulfation of ceria-zirconia mixed-metal oxides". Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-03252004-162922.

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Romano, Esteban Javier. "In-situ surface science studies of the interaction between sulfur dioxide and two-dimensional palladium loaded-cerium/zirconium mixed metal oxide model catalysts". Diss., Mississippi State : Mississippi State University, 2005. http://library.msstate.edu/etd/show.asp?etd=etd-04062005-093500.

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Armendariz, Herrera Hector. "Préparation par méthode sol-gel et activation de catalyseurs zircone-sulfate pour l'hydroisomérisation d'alcanes". Montpellier 2, 1997. http://www.theses.fr/1997MON20009.

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La methode sol-gel a ete utilisee pour effectuer la synthese de zro#2 et de composes mixtes sio#2-zro#2 sulfates. L'incorporation du zr dans le reseau de la silice a conduit a des oxydes mixtes sio#2-zro#2 avec un accroissement de l'acidite de brnsted. Ces solides montrent une activite elevee, exprimee par site de zr, dans l'hydroisomerisation du n-hexane. Ceci confirmerait l'hypothese selon laquelle les atomes de zr de faible coordination sont a l'origine des centres acides les plus actifs. En utilisant la methode sol-gel, noua avons developpe une methode de synthese en une seule etape de zircones sulfatees, par incorporation du sulfate dans le reseau du gel de zircone au moment de sa preparation. Ces solides sont catalytiquement actifs pour l'hydroisomerisation du n-hexane a 150c. Dans ces memes conditions une zircone sulfatee preparee en deux etapes selon une methode plus conventionnelle, par sulfatation ulterieure d'un gel de zircone, se revele peu active. Les caracterisations par tpd-nh#3 et spectroscopies drifts et rmn mas #1h montrent que l'activite catalytique est plutot liee a la nature et la force qu'au nombre des sites acides des solides. Ainsi, la presence de groupements -oh, caracterises par une bande ir large a 3280 cm#-#1 et un pic de resonance rmn a 5. 85 ppm, etablissant une liaison de type hydrogene avec les oxygenes superficiels de la zircone est mis en evidence. Ces types de groupements oh absents sur l'echantillon prepare en deux etapes, semblent jouer un role determinant dans les proprietes catalytiques des zircones sulfatees. L'interaction du benzene avec ces solides montre que ces types de -oh possedent une force acide capable d'effectuer l'echange isotopique h-d avec la molecule de c#6d#6 a temperature ambiante.

González, Arcos Angélica Viviana. "RhPt and Ni based catalysts for fuel reforming in energy conversion". Doctoral thesis, KTH, Kemisk teknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-160026.

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Although current trends in global warming are of great concern, energy demand is still increasing, resulting in increasing pollutant emissions. To address this issue, we need reliable renewable energy sources, lowered pollutant emissions, and efficient and profitable processes for energy conversion. We also need to improve the use of the energy, produced by existing infrastructure. Consequently, the work presented in this thesis aims at investigating current scientific and technological challenges in energy conversion through biomass gasification and the alternative use of fossil fuels, such as diesel, in the generation of cleaner electricity through auxiliary power units in the transport sector. Production of chemicals, syngas, and renewable fuels is highly dependent on the development and innovation of catalytic processes within these applications. This thesis focuses on the development and optimization of catalytic technologies in these areas. One of the limitations in the commercialization of the biomass gasification technology is the effective catalytic conversion of tars, formed during gasification. Biomass contains high amounts of alkali impurities, which pass on to the producer gas. Therefore, a new material with alkali tolerance is needed. In the scope of this thesis, a new catalyst support, KxWO3 – ZrO2 with high alkali resistance was developed. The dynamic capability of KxWO3 – ZrO2 to store alkali metals in the crystal structure, enhances the capture of alkali metals "in situ". Alkali metals are also important electronic promoters for the active phase, which usually increases the catalysts activity and selectivity for certain products. Experimental results show that conversion of 1-methylnaphathalene over Ni/KxWO3 – ZrO2 increases in the presence of 2 ppm of gas-phase K (Paper I). This support is considered to contribute to the electronic equilibrium within the metal/support interface, when certain amounts of alkali metals are present. The potential use of this support can be extended to applications in which alkali "storage-release" properties are required, i.e. processes with high alkali content in the process flow, to enhance catalyst lifetime and regeneration. In addition, fundamental studies to understand the adsorption geometry of naphthalene with increasing temperature were performed in a single crystal of Ni(111) by STM analyses. Chapter 9 presents preliminary studies on the adsorption geometry of the molecule, as well as DFT calculations of the adsorption energy. In relation to the use of clean energy for transport applications, hydrogen generation through ATR for FC-APUs is presented in Papers II to V. Two promoted RhPt bimetallic catalysts were selected in a previous bench scale study, supported on La2O3:CeO2/d – Al2O3 and MgO : Y2O3/CeO2 – ZrO2. Catalyst evaluation was performed in a fullscale reformer under real operating conditions. Results showed increased catalyst activity after the second monolithic catalyst due to the effect of steam reforming, WGS reaction, and higher catalyst reducibility of the RhxOy species in the CeO2 – ZrO2 mixed oxide, as a result of the improved redox properties. The influence of sulfur and coke formation on diesel reforming was assessed after 40 h on stream. Sulfur poisoning was evaluated for the intrinsic activity related to the total Rh and Pt area observed after exposure to sulfur. Sulfur concentration in the aged catalyst washcoat was observed to decrease in the axial direction of the reformer. Estimations of the amount of sulfur adsorbed were found to be below the theoretical equilibrated coverage on Rh and Pt, thus showing a partial deactivation due to sulfur poisoning.

QC 20150213

Hill, Melinda Lou. "Polymeric and Polymer/Inorganic Composite Membranes for Proton Exchange Membrane Fuel Cells". Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/37597.

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Several types of novel proton exchange membranes which could be used for both direct methanol fuel cells (DMFCs) and hydrogen/air fuel cells were investigated in this work. One of the main challenges for DMFC membranes is high methanol crossover. Nafion, the current perfluorosulfonic acid copolymer benchmark membrane for both DMFCs and hydrogen/air fuel cells, shows very high methanol crossover. Directly copolymerized disulfonated poly(arylene ether sulfone)s copolymers doped with zirconium phosphates and phenyl phosphonates were synthesized and showed a significant reduction in methanol permeability. These copolymer/inorganic nanocomposite hybrid membranes show lower water uptake and conductivity than Nafion and neat poly(arylene ether sulfone)s copolymers, but in some cases have similar or even slightly improved DMFC performance due to the lower methanol permeability. These membranes also show advantages for high temperature applications because of the reinforcing effect of the filler, which helps to maintain the modulus of the membrane, allowing the membrane to maintain proton conductivity even above the hydrated glass transition temperature (Tg) of the copolymer. Sulfonated zirconium phenyl phosphonate additives were also synthesized, and membranes incorporating these materials and disulfonated poly(arylene ether sulfone)s showed promising proton conductivity over a wide range of relative humidities. Single-Tg polymer blend membranes were studied, which incorporated disulfonated poly(arylene ether sulfone) with varied amounts of polybenzimidazole. The polybenzimidazole served to decrease the water uptake and methanol permeability of the membranes, resulting in promising DMFC and hydrogen/air fuel cell performance.
Ph. D.

Kurdi, Mohamad. "Sur l'utilisation des sulfures en catalyse d'hydrotraitement le trisulfure du niobium /". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376148133.

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Sinha, Majumdar Sreshtha. "Catalytic Reduction of Nitrogen Oxide Emissions with Lower Hydrocarbons for Natural gas-fired Lean-burn Engines". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471602998.

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Libri sul tema "Sulfure de zirconium":

United States. National Aeronautics and Space Administration., a cura di. The effect of sulfur and zirconium co-doping on the oxidation of NiCrAl. [Washington, DC]: National Aeronautics and Space Administration, 1987.

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Capitoli di libri sul tema "Sulfure de zirconium":

Tsuchiya, Hiroaki, Jan M. Macak, Irina Sieber e Patrik Schmuki. "Anodic Porous Zirconium Oxide Prepared in Sulfuric Acid Electrolytes". In Materials Science Forum, 205–10. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-996-2.205.

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Dekhtyar, Yu, R. Reisfeld, M. Romanova, T. Saraidarov e I. Surkova. "Influence of Ultraviolet and Electron Radiation on Photoelectron Emission Spectra of Lead Sulfide Nanoparticles Embedded in a Matrix of Zirconium Oxide". In First European Biomedical Engineering Conference for Young Investigators, 56–59. Singapore: Springer Singapore, 2015. http://dx.doi.org/10.1007/978-981-287-573-0_14.

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Fontani, Marco, Mariagrazia Costa e Mary Virginia Orna. "The Forerunners of Celtium and Hafnium: Ostranium, Norium, Jargonium, Nigrium, Euxenium, Asium, and Oceanium". In The Lost Elements. Oxford University Press, 2014. http://dx.doi.org/10.1093/oso/9780199383344.003.0012.

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Abstract (sommario):

Of the naturally occurring nonradioactive elements, hafnium was the next to last to be discovered, preceding the discovery of rhenium by 3 years. It can boast of holding a very strange record: the number of claims for its discovery over the years is unequaled by any other element. This record was the cause of frustration for many scientists who, over the years, took turns in attempts to isolate it. The reason that hafnium remained undiscovered until 1922 lay not so much in that its presence in nature (long known to be quite scarce) wasn’t looked for, but in its peculiar chemical properties that bound it up intimately with zirconium. Toward the end of the 18th century, Martin Heinrich Klaproth melted some forms of yellow-green and red zirconium with sodium hydroxide and then digested the residue several times with hydrochloric and sulfuric acids to eliminate the extraneous silicon. The solution, thought to contain a number of elements, produced, upon addition of potassium carbonate, a generous precipitate. The oxide that Klaproth collected did not seem to belong to any known substance, and he called it terra zirconia. With the passing of the years, he and many other chemists, among them the renowned Jons Jacob Berzelius, determined the elemental composition of zircon and of its correlative minerals. Far from being simply ZrSiO4, zircon contained traces of iron, aluminum, nickel, cobalt, lead, bismuth, manganese, lithium, sodium, zinc, calcium, magnesium, and uranium and small amounts of the rare earths. Some impurities persistently resisted separation from zirconium oxide or zirconia and were taken erroneously for oxides of new elements (new earths). In 1825, Johann Friedrich August Breithaupt (1791–1873) reported the presence of a new element, ostranium, isolated from ostranite, a mineral similar to zircon. Twenty years later, the Swedish chemist, mineralogist, and metallurgist Lars Fredrik Svanberg (1805–78) announced the discovery of a new element. In his publication of 1845, he asserted that the zirconium oxide obtained from a variety of Siberian, Norwegian, and Indian zircon samples was in reality composed of two earths: one, zirconia, already noted, and another unknown earth.

Ogawa, C., e S. Kobayashi. "Using Zirconium(IV) Tetrakis(dodecyl sulfate)". In Water in Organic Synthesis, 1. Georg Thieme Verlag KG, 2012. http://dx.doi.org/10.1055/sos-sd-206-00437.

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Rayner, C. M., e M. A. Graham. "Zirconium-Mediated Coupling of Aryllithium Reagents with Alkynes and Sulfur Dichloride". In Fused Five-Membered Hetarenes with One Heteroatom, 1. Georg Thieme Verlag KG, 2001. http://dx.doi.org/10.1055/sos-sd-010-00204.

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Ben Chaabene, S., L. Bergaoui, A. Ghorbel e J. F. Lambert. "Non-aggressive way using zirconium acetate for preparation of zirconium pillared clay developing high sulfur thermal stability over 830°C". In Studies in Surface Science and Catalysis, 1053–62. Elsevier, 2000. http://dx.doi.org/10.1016/s0167-2991(00)80751-x.

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Katada, Naonobu, Jun-ichi Endo, Kei-ichi Notsu, Naoko Yasunobu, Norihiro Naito e Miki Niwa. "Super acidity confirmed on a monolayer of sulfate species loaded on zirconia". In Studies in Surface Science and Catalysis, 3213–18. Elsevier, 2000. http://dx.doi.org/10.1016/s0167-2991(00)80517-0.

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Moreno, J. A., e G. Poncelet. "n-Butane isomerization over Al-promoted sulfated zirconias. Influence of the sulfate content". In Studies in Surface Science and Catalysis, 1003–10. Elsevier, 2000. http://dx.doi.org/10.1016/s0167-2991(00)80745-4.

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Strukul, G., M. Signoretto, F. Pinna, A. Benedetti, G. Cerrato e C. Morterra. "Aerogel Synthesis as an Improved Method for the Preparation of Platinum-Promoted Zirconia—Sulfate Catalysts". In Advanced Catalysts and Nanostructured Materials, 143–63. Elsevier, 1996. http://dx.doi.org/10.1016/b978-012508460-4/50008-5.

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Sohn, J. R., E.-H. Park e J.-G. Kim. "Preparation of new solid super-acid catalyst, titanium sulfate supported on zirconia and its acid catalytic properties". In Studies in Surface Science and Catalysis, 377–85. Elsevier, 2000. http://dx.doi.org/10.1016/s0167-2991(00)80678-3.

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Atti di convegni sul tema "Sulfure de zirconium":

Li, Li, Li Kai, Ma Lan e Luan Zhiqiang. "Activated carbon impregnated with zirconium hydroxide for sulfur dioxide removal". In The 3rd International Conference on Application of Materials Science and Environmental Materials (AMSEM2015). WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789813141124_0007.

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Harris, William M., Jeffrey J. Lombardo, George J. Nelson, Wilson K. S. Chiu, Barry Lai, Steve Wang, Joan Vila-Comamala, Mingfei Liu e Meilin Liu. "Examining Effects of Sulfur Poisoning on Ni/YSZ Solid Oxide Fuel Cell Anodes Using Synchrotron-Based X-Ray Imaging Techniques". In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63972.

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Abstract (sommario):

Fuel flexibility is widely considered one of the most significant advantages of solid oxide fuel cells (SOFC). However, the presence of small amounts of sulfur or other impurities in the gas stream can have a serious impact on cell performance [1–10]. Under certain conditions, hydrogen sulfide (H2S), even at the ppm level, can lead to the formation of bulk nickel-sulfides within the conventional Ni–yttria-stabilized zirconia (Ni-YSZ) anode of SOFC’s [9]. Understanding the distribution of these sulfides is critical to describing their effects on the electrochemical activity of the cell.

Yang, Liao, Li Yan, Tong Peijie, Zhao Shilin e Liao Xuepin. "A Novel Fibrous Zirconium Sulfate Solid Acid Catalyst for Esterification Reaction". In 2011 International Conference on Computer Distributed Control and Intelligent Environmental Monitoring (CDCIEM). IEEE, 2011. http://dx.doi.org/10.1109/cdciem.2011.114.

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Ruslan, Khairuddin, J. Hardi e M. Mirzan. "Characterization of zirconia-pillared clay with sulfate acid activation". In THE 8TH INTERNATIONAL CONFERENCE OF THE INDONESIAN CHEMICAL SOCIETY (ICICS) 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0001508.

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Strangman, T. E., e J. Schienle. "Tailoring Zirconia Coatings for Performance in a Marine Gas Turbine Environment". In ASME 1989 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1989. http://dx.doi.org/10.1115/89-gt-269.

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Abstract (sommario):

Zirconia coatings represent an advanced materials technology that offers significant durability and performance benefits for marine gas turbines. Thin zirconia coatings offer superior resistance to hot corrosion attack from fuel (sulfur, vanadium and sodium) and air (sea salt) impurities present in marine engine environments. Thicker zirconia coatings reduce transient thermal stresses and heat transferred into air-cooled components. This paper describes the development of zirconia coatings, applied by the electron beam evaporation - physical vapor deposition process, that are tailored to provide superior durability in a marine engine environment.

Nagaraj, B. A., e D. J. Wortman. "Burner Rig Evaluation of Ceramic Coatings With Vanadium-Contaminated Fuels". In ASME 1989 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1989. http://dx.doi.org/10.1115/89-gt-270.

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Abstract (sommario):

The performance of yttria stabilized zirconia (YSZ), ceria stabilized zirconia (CSZ), and magnesia stabilized zirconia (MSZ) coatings was evaluated using an atmospheric burner rig; the test environment contained compounds of vanadium, sodium and sulfur. The coatings were deposited by plasma spraying and electron beam physical vapor deposition (EB-PVD); sputtered sealant layers of hafnia, alumina and platinum were deposited on the yttria stabilized zirconia coating (YSZ). The tests were performed for up to 500 hours at 1650°F and 1300°F. The tests were designed to simulate the deposit chemistry and sulfur trioxide partial pressures expected in a marine gas turbine engine operating on contaminated fuel. YSZ, CSZ, and MSZ coatings all underwent reaction in the burner rig environment; the reaction products and their effects on spallation were varied. MSZ was by far the most reactive, readily forming MgSO4 in both 1650°F and 1300°F tests. The observed reaction products provided a measure of “protection” for the bond coat by preventing molten salt infiltration in the duration of the test. The mechanism of ceramic spallation is discussed. Sputtered overlayers of platinum, hafnia and alumina did not prevent salt infiltration and reaction with the underlying ceramic, although no reaction product between the overlayer and the salt was observed.

Verdier, S., V. Harle, A. Huang, E. Rohart, O. Larcher e M. Allain. "Doped Zirconia with High Thermal Stability, for High Sulfur Resistance Diesel Oxidation Catalysts". In SAE 2006 World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2006. http://dx.doi.org/10.4271/2006-01-0031.

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Oleiwi, Ahmed H., Akram R. Jabur e Qusay F. Alsalhy. "Morphology of polystyrene nano-fiber membranes reinforced with copper oxide and zirconium oxide nanoparticles as a sulfur absorbent materials". In TECHNOLOGIES AND MATERIALS FOR RENEWABLE ENERGY, ENVIRONMENT AND SUSTAINABILITY: TMREES22Fr. AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0129144.

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Alsaiari, H. A., M. Al-Khaldi, I. Al-Taie, Q. Wang, G. Alabedi, F. Zhang, Z. Zhang et al. "Effect of Crosslinkers on the Performance of Calcium Sulfate Scale Inhibitors at High Temperature: Impact of Zirconium". In SPE International Oilfield Scale Conference and Exhibition. Society of Petroleum Engineers, 2016. http://dx.doi.org/10.2118/179878-ms.

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Shkurenok, V. A., O. V. Dzhikiya, M. D. Smolikov, D. I. Kir'yanov e A. S. Belyi. "Isomerization of C6-C7 alkanes over zirconia catalysts modified by tungstate and sulfate anions". In INTERNATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF COMBUSTION AND PROCESSES IN EXTREME ENVIRONMENTS (COMPHYSCHEM’20-21) and VI INTERNATIONAL SUMMER SCHOOL “MODERN QUANTUM CHEMISTRY METHODS IN APPLICATIONS”. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0032755.

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