Academic literature on the topic 'Co based oxides'
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Journal articles on the topic "Co based oxides"
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Neha, Neha, Ram Prasad, and Satya Vir Singh. "Simultaneous Catalytic Oxidation of a Lean Mixture of CO-CH4 over Spinel Type Cobalt Based Oxides." Bulletin of Chemical Reaction Engineering & Catalysis 15, no. 2 (June 12, 2020): 490–500. http://dx.doi.org/10.9767/bcrec.15.2.6499.490-500.
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A series of nickel-cobalt bimetal oxides in varying molar ratios and its single metal oxides were synthesized by reactive calcination of coprecipitated basic-carbonates. Several characterization techniques, such as: Bruneuer Emmett Teller (BET), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra Red (FTIR), and Hydrogen Temperature Programmed Reduction (H2-TPR), were performed over the oxides. Activities of oxides were evaluated in methane total oxidation in the presence or the absence of CO. The best catalytic performance was observed over NiCo catalyst with a Ni/Co molar ratio of 1:1, and the complete conversion of CO-CH4 mixture was achieved at 390 °C. Moreover, the presence of carbon monoxide improves CH4 total oxidation over nickel-cobalt mixed oxides. Structural analysis reveals that the insertion of nickel into the spinel lattice of cobalt oxide causes the structural disorder, which probably caused the increase of the amount of octahedrally coordinated divalent nickel cations that are responsible for catalytic activity. Stability of the best-performed catalyst has been tested in the two conditions, showing remarkable long-term stability and thermal stability, however, showed deactivation after thermally ageing at 700 °C. Copyright © 2020 BCREC Group. All rights reserved
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Da Silva, Paulo Roberto Nagipe, and Ana Brígida Soares. "Lanthanum based high surface area perovskite-type oxide and application in CO and propane combustion." Eclética Química Journal 34, no. 1 (January 23, 2018): 31. http://dx.doi.org/10.26850/1678-4618eqj.v34.1.2009.p31-38.
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The perovskite-type oxides using transition metals present a promising potential as catalysts in total oxidation reaction. The present work investigates the effect of synthesis by oxidant co-precipitation on the catalytic activity of perovskite-type oxides LaBO3 (B= Co, Ni, Mn) in total oxidation of propane and CO. The perovskite-type oxides were characterized by means of X-ray diffraction, nitrogen adsorption (BET method), thermo gravimetric and differential thermal analysis (ATG-DTA) and X-ray photoelectron spectroscopy (XPS). Through a method involving the oxidant co-precipitation it’s possible to obtain catalysts with different BET surface areas, of 33-44 m2/g, according the salts of metal used. The characterization results proved that catalysts have a perovskite phase as well as lanthanum oxide, except LaMnO3, that presents a cationic vacancies and generation for known oxygen excess. The results of catalytic test showed that all oxides have a specific catalytic activity for total oxidation of CO and propane even though the temperatures for total conversion change for each transition metal and substance to be oxidized.
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Cherepanova, Svetlana V., Egor G. Koemets, Evgeny Yu Gerasimov, Irina I. Simentsova, and Olga A. Bulavchenko. "Reducibility of Al3+-Modified Co3O4: Influence of Aluminum Distribution." Materials 16, no. 18 (September 14, 2023): 6216. http://dx.doi.org/10.3390/ma16186216.
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The reduction of Co-based oxides doped with Al3+ ions has been studied using in situ XRD and TPR techniques. Al3+-modified Co3O4 oxides with the Al mole fraction Al/(Co + Al) = 1/6; 1/7.5 were prepared via coprecipitation, with further calcination at 500 and 850 °C. Using XRD and HAADF-STEM combined with EDS element mapping, the Al3+ cations were dissolved in the Co3O4 lattice; however, the cation distribution differed and depended on the calcination temperature. Heating at 500 °C led to the formation of an inhomogeneous (Co,Al)3O4 solid solution; further treatment at 850 °C provoked the partial decomposition of mixed Co-Al oxides and the formation of particles with an Al-depleted interior and Al-enriched surface. It has been shown that the reduction of cobalt oxide by hydrogen occurs via the following transformations: (Co,Al)3O4 → (Co,Al)O → Co. Depending on the Al distribution, the course of reduction changes. In the case of the inhomogeneous (Co,Al)3O4 solid solution, Al stabilizes intermediate Co(II)-Al(III) oxides during reduction. When Al3+ ions are predominantly on the surface of the Co3O4 particles, the intermediate compound consists of Al-depleted and Al-enriched Co(II)-Al(III) oxides, which are reduced independently. Different distributions of elemental Co and Al in mixed oxides simulate different types of the interaction phase in Co3O4/γ-Al2O3-supported catalysts. These changes in the reduction properties can significantly affect the state of an active component of the Co-based catalysts.
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Zulfugarova, S. M., G. R. Azimova, Z. F. Aleskeroiva, G. M. Guseinli, and D. B. Tagiyev. "Catalytic activity of Co, Cu and Mn oxide catalysts synthesized by the sol-gel combustion method in the low-temperature oxidation of carbon oxide." Proceedings of the National Academy of Sciences of Belarus, Chemical Series 59, no. 2 (June 3, 2023): 105–14. http://dx.doi.org/10.29235/1561-8331-2023-59-2-105-114.
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The synthesis of catalysts based on cobalt, copper and manganese oxides by sol-gel method with combustion was carried out, and their catalytic activity was studied in the reaction of low-temperature oxidation of carbon monoxide to dioxide. Oxides of cobalt, copper and manganese, as well as their double oxides (Co–Mn, Cu–Mn and Co–Cu) were synthesized. X-ray phase analysis showed the formation of manganites and oxides of corresponding metals in the Co–Mn and Cu–Mn systems. It was revealed that in the Co–Cu system only oxides of separate metals are formed. It was found that cobaltmanganese and copper-manganese oxide systems synthesized by sol-gel combustion method exhibit high catalytic activity in the low-temperature (110–140 0C) conversion of carbon monoxide into dioxide. One-step synthesis of Cu–Mn/Al2O3 catalytic system was also carried out by sol-gel method with burning precursors with binder hydrogel (Al2O3), and its high activity in low-temperature conversion of carbon monoxide was revealed. The catalytic systems were investigated by X-ray diffraction, IR spectral methods, BET, SEM. The results obtained show the possibility of obtaining active multicomponent oxide catalysts in low-temperature oxidation of carbon monoxide by technologically simple sol-gel combustion method.
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Imamura, S., H. Minagawa, M. Ishihara, and S. Ishida. "Oxidation of CO on Ag-based composite oxides." Reaction Kinetics & Catalysis Letters 41, no. 1 (March 1990): 79–83. http://dx.doi.org/10.1007/bf02075485.
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Xu, Bin, Yi Cheng, and Jian Wu. "The Analysis about Harmful Emissions of Micro Combustor Based on Porous Medium." Advanced Materials Research 838-841 (November 2013): 2481–87. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.2481.
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According to the changes of the mixed gas flux ,porosity and burner structure,we measured the contents of CO, HC and Nitrogen Oxides in the harmful emissions of the methane burned in the micro combustor.In the micro scale, because the structure size of the burner is small, the combustion space and time is limited, CO and HC emissions are the products of incomplete combustion, nitrogen oxide are the products in local high temperature and oxygen enriched conditions.
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Fung, Kuan-Zong, Shu-Yi Tsai, Kenneth Fung, Yu-Hsuan Chen, Jen-Hao Yang, and Chia-Chin Chang. "Factors Affecting Performance of Single-Crystal Nickel-Rich Layered Oxides Cathode." ECS Meeting Abstracts MA2023-02, no. 2 (December 22, 2023): 287. http://dx.doi.org/10.1149/ma2023-022287mtgabs.
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For the past decades, multi-element layered oxide such as Li(Ni,Co,Mn)O2 has been processed by a very popular co-precipitation method. Recently, layered oxides obtained by a single-crystal process has received great attention. The oxides prepared by co-precipitation typically show very uniform and fine particles in nm range <500nm. However, very fine co-precipitated oxide particles with large specific area may suffer from reaction with liquid electrolyte. When the grain size of Ni-rich layered oxides reaches µm range, they tend to show better cycling performance with better structural integrity and less volume change during charge/discharge cycles. Toward the formation of single crystal Ni-rich layered oxides, it may involve decomposition, chemical reactions, diffusion, oxidation, sintering, grain-growth. As a result, factors such as temperature, annealing period and atmospheres may be critical for high-performance cathode. Thus, the objective of this study is (1) to identify what are key factors; (2) the role of key factors; (3) optimization of key factors for better performance. For factor verification and understanding of single crystal process, the resulted electrical, optical, structural, and electrochemical properties of layered oxides will be analyzed and discussed based on defect chemistry consideration. During the different stages of processing, the structural, microstructural and electrical properties of decomposed precursors and resultant layered oxides will be examined using XRD, SEM and DC/AC impedance measurements. CV and charge/discharge tests from assembled coin cells will be used to evaluate electrochemical properties of single-crystal Ni-rich layered oxides.
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Park, Kyoung Ryeol, Jae Eun Jeon, Ghulam Ali, Yong-Ho Ko, Jaewoong Lee, HyukSu Han, and Sungwook Mhin. "Oxygen Evolution Reaction of Co-Mn-O Electrocatalyst Prepared by Solution Combustion Synthesis." Catalysts 9, no. 6 (June 24, 2019): 564. http://dx.doi.org/10.3390/catal9060564.
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High-performance oxygen evolution reaction (OER) electrocatalysts are needed to produce hydrogen for energy generation through a carbon-free route. In this work, the solution combustion synthesis (SCS) method was employed to synthesize mixed phases of Co- and Mn-based oxides, and the relationships between the crystalline structure and the catalytic properties in the mixed phases were established. The mixed phases of Co- and Mn-based oxides shows promising OER properties, such as acceptable overpotential (450 mV for 10 mA∙cm−2) and Tafel slope (35.8 mV∙dec−1), highlighting the use of the mixed phases of Co- and Mn-based oxides as a new efficient catalysts for water splitting. Electronic structure of the mixed phases of Co- and Mn based oxides is studied in detail to give insight for the origin of high catalytic activities. In addition, excellent long-term stability for OER in alkaline media is achieved for the mixed phase of Co- and Mn based oxides.
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Hyun, Hyejeong, and Jongwoo Lim. "Elucidating degradation mechanisms of Co-free high-Ni layered oxide cathodes for Li-ion batteries via advanced X-ray-based characterization methods." Ceramist 26, no. 1 (March 31, 2023): 138–57. http://dx.doi.org/10.31613/ceramist.2023.26.1.10.
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High-Ni layered oxide cathodes without Co are being investigated as potential cathode materials for Li-ion batteries with high energy density. By decreasing the Co content, these cathodes not only boost energy density but also alleviate concerns about the supply instability and fluctuating cost of Co raw materials. However, the elevated Ni content in the layered oxides causes distinct chemo-mechanical degradation mechanisms that inhibit their commercial application. In order to gain insight into the degradation process at various scales, from the atomic to the particle and the electrode levels, and to devise ways to prevent degradation, multi-scale characterization methods are essential. In this review, we critically evaluate the role of Co substitution in high-Ni layered oxides and the impact of Co content on the chemo-mechanical degradation process. Furthermore, the use of advanced X-ray-based characterization methods, which have helped shed light on the degradation mechanisms of high-Ni cathodes, is also discussed.
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Jetpisbayeva, G. D., B. K. Massalimova, and A. B. Daulet. "SYNTHESIS OF PEROFSKITE-LIKE Co-CONTAINING CATALYST." SERIES CHEMISTRY AND TECHNOLOGY 2, no. 440 (April 15, 2020): 115–19. http://dx.doi.org/10.32014/2020.2518-1491.31.
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There are several approaches to the preparation of catalysts with a developed surface based on oxides with a perovskite structure. Perovskites, due to the possibility of easy variation of chemical composition, make it possible to choose the optimal composition of the catalyst and surface area, and as a result it is possible to influence effectively the selectivity. Perovskite-like LaMeO3 oxides are one of the most promising catalysts for many oxidation processes due to their high activity in oxidative reactions and the stability in aggressive environment. Pekini method (polymer complexes method) and its simplified variant - citrate method are the most widely used for the synthesis of perovskite-like oxides. This article reports about the synthesis of perovskite-like complex oxide LaCoO3 obtained in two ways: hydrothermal, using ethylene glycol, and the citrate method using the template – mesoporous silica KIT-6. The structure of the samples obtained was determined by the XRD method. As a result, it was found that the catalysts have a perovskite structure. Key words: LaCoO3 , perovskite, KIT-6.
Dissertations / Theses on the topic "Co based oxides"
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Duan, Yan. "Understanding the oxygen evolution reaction (OER) for Co based transition metal oxides / hydroxides in alkaline electrolytes." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS416.
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Le développement d'électrocatalyseurs efficaces pour la réaction de libération d'oxygène (OER) est important pour améliorer l'efficacité globale du processus d'électrolyse de l'eau. Les oxydes / hydroxydes de métaux de transition présentent une activité et une stabilité raisonnables lorsqu’utilisés dans un milieu alcalin. Ils ont le potentiel de remplacer les oxydes à base d'Ir et de Ru. Comprendre la réaction d’OER pour les oxydes / hydroxydes de métaux de transition dans les électrolytes alcalins aide à la conception d'électrocatalyseurs peu coûteux et très efficaces. Avec trois travaux différents sur les oxydes / hydroxydes à base de Co, cette thèse approfondit la compréhension des propriétés de surface des matériaux et des propriétés interfaciales sur la cinétique de la réaction d’OER. Tout d'abord, la substitution au fer régule par exemple la configuration des cations métalliques dans LaCoO3. Cela ajuste la covalence de la liaison oxygène 2p – métal 3d et améliore les performances. Deuxièmement, la substitution au Ni dans ZnCo2O4 modifie la position relative du centre de la bande O 2p et du centre de la bande métallique dans un environnement octahédrique MOh. Cela modifie la stabilité et la possibilité pour l'oxygène du réseau de participer à la réaction de dégagement d’oxygène. Enfin, en étudiant les séries La1-xSrxCoO3, CoOOH et CoOOH contenant Fe, l'impact de l'électrolyte sur les paramètres de la cinétique de réaction a été exploré. Avec une meilleure compréhension de la façon dont les propriétés des matériaux et l'environnement dynamique influencent l'activité et le mécanisme des OER, nous pouvons obtenir des catalyseurs de OER plus efficaces pour une meilleure infrastructure énergétiqueThe development of efficient electrocatalysts to lower the overpotential of oxygen evolution reaction (OER) is of fundamental importance in improving the overall efficiency of fuel production by water electrolysis. Among a plethora of catalysts being studied on, transition metal oxides / hydroxides that exhibit reasonable activity and stability in alkaline electrolyte have been identified as catalysts to potentially overpass the activity of expensive Ir- and Ru- based oxides. Understanding the OER for transition metal oxides / hydroxides in alkaline electrolytes paves the way for better design of low cost and highly efficient electrocatalysts. This dissertation, with three different work on Co-based oxides / hydroxides, studies and deepens the understanding of the bulk properties, surface properties of materials and interfacial properties on OER. Firstly, with Fe substitution, it addresses tuning the eg configuration of metal cations in LaCoO3 where adjusting the metal 3d oxygen 2p covalency can bring benefits to the OER performance. Secondly, with Ni substitution in ZnCo2O4, it demonstrates a change in relative position of O p-band and MOh d-band centre which induces a change in stability as well as the possibility for lattice oxygen to participate in the OER. Finally, with La1-xSrxCoO3 series, CoOOH and Fe-containing CoOOH as examples, the impact of the electrolyte has been explored by the study of reaction kinetics parameters. With a better understanding of how material properties and dynamic environment influence the OER activity and mechanism, we can obtain more efficient OER catalysts for better energy infrastructure
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Anghel, Clara. "Modified oxygen and hydrogen transport in Zr-based oxides." Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4095.
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Cole, Kieran John. "Copper manganese based mixed oxides for ambient temperature co-oxidation and higher temperature oxidation reactions." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54689/.
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The catalytic oxidation of carbon monoxide is an important reaction in heterogeneous catalysis. Copper manganese mixed oxides in the form of Hopcalite, CuMn2C4, is used as a catalyst for the oxidation at ambient temperature and is important in respiratory protection, particularly in mining industries. These types of catalysts are prepared by a co-precipitation method variables in this preparation procedure are known to control catalytic activity. Previous work has shown that the addition of a cobalt dopant metal to the catalyst structure can have a positive effect on activity towards CO oxidation. This thesis furthers the work of dopant addition by studying the effects of zinc on the copper manganese catalyst. Catalyst testing for CO oxidation showed that the addition of the zinc dopant metal increases the stability of catalytic activity. Temperature Programmed Reduction studies show that the addition of zinc has an effect on the redox properties of the catalyst. Prepared copper manganese oxide catalysts were used as supports for gold catalysts. Gold supported CuMnOx was prepared by a deposition precipitation method. The addition of gold to these active materials leads to a marked increase in the catalytic activity. Scanning Electron Microscopy (SEM) showed that the morphology of the support used, played an important role in producing a highly active catalyst. Also, the ageing time of the catalyst precursor was shown to influence catalytic activity. The most effective catalyst for CO oxidation was found to be a 1 wt% Au supported catalyst. The presence of moisture in the gas feed is known to be detrimental to a Hopcalite catalyst for ambient temperature CO oxidation. The effect of moisture on the copper manganese mixed oxide catalysts highlighted the improvement in moisture tolerance with the addition of gold. The method of depositing gold onto an oxide support was shown to be applicable to a commercially available catalyst. The gold supported CuMnOx catalysts prepared were tested for oxidation reactions at higher temperatures. The reactions investigated were ethylene oxide oxidation and preferential oxidation (PROX) of carbon monoxide. Studies showed the addition of gold to the CuMnOx catalysts, improves activity compared to an undoped catalyst.
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Gupta, Himanshu. "NOx reduction by Carbonaceous Materials and CO₂ separation using regenerative metal oxides from fossil fuel based flue gas /." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486399160107212.
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Buselli, Lorenzo. "Study of Co-based hydrotalcite-derived mixed metal oxides partially modified with silver as potential catalysts for N2O decomposition." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11930/.
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Co-Al-Ox mixed metal oxides partially modified with Cu or Mg, as well as Ag were successfully prepared, characterized and evaluated as potential catalysts for the N2O decomposition. The materials were characterized by the following techniques: X-Ray Diffraction, Thermogravimetric Analysis (TGA), N2 Physisorption, Hydrogen Temperature-Programmed Reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). Ag-modified HT-derived mixed oxides showed enhanced activity compared to the undoped materials, the optimum composition was found for (1 wt.% Ag)CHT-Co3Al. The catalyst characterization studies suggested that the improved catalytic activity of Ag-promoted catalysts were mainly because of the altered redox properties of the materials.
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Popoola, Olalekan Abdul Muiz. "Studies of urban air quality using electrochemical based sensor instruments." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/243620.
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Poor air quality has been projected to be the world’s top cause of environmental premature mortality by 2050 surpassing poor sanitation and dirty water (IGBP / IGAC press release, 2012 ). One of the major challenges of air quality management is how to adequately quantify both the spatial and temporal variations of pollutants for the purpose of implementing necessary mitigation measures. The work described in this thesis aims to address this problem using novel electrochemical based air quality (AQ) sensors. These instruments are shown to provide cost effective, portable, reliable, indicative measurements for urban air quality assessment as well as for personal exposure studies. Three principal pollutants CO, NO and NO2 are simultaneously measured in each unit of the AQ instrument including temperature / RH measurements as well as GPS (for time and position) and GPRS for data transmission. Laboratory studies showed that the electrochemical sensor nodes can be highly sensitive, showing linear response during calibration tests at ppb level (0-160 ppb). The instrumental detection limits were found to be < 4 ppb (CO and NO) and < 1 ppb for NO2 with fast response time equivalent to t90 < 20 s. Several field studies were carried out involving deployment of both the mobile and static electrochemical sensor nodes. Results from some short-term studies in four different cities including Cambridge (UK), London (UK), Valencia (Spain) and Lagos (Nigeria) are presented. The measurements in these cities represent snapshot of the pollution levels, the stark contrast between the pollution level especially CO (mean mixing ratio of 16 ppm over 3 hrs) in Lagos and the other three cities is a reflection of the poor air quality in that part of the world. Results from long-term AQ monitoring using network of 46 static AQ sensors were used to characterise pollution in different environments ranging from urban to semi-urban and rural locations. By coupling meteorological information (wind measurements) with pollution data, pollution sources, and phenomena like the street canyon effect can be studied. Results from the long-term study also revealed that siting of the current fixed monitoring stations can fail to represent the actual air quality distribution and may therefore be unrepresentative. This work has shown the capability of electrochemical based AQ sensors in complementing the existing fixed site monitors thus demonstrating an emerging measurement paradigm for air quality monitoring and regulation, source attribution and human exposure studies.
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Zheng, Jian. "Model electrocatalysts for fuel cells: a surface science based study." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3424615.
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The present thesis focuses on studying structure/morphology/activity relationships in bimetallic Pt-Sn nanostructured electrodes for proton exchange membrane (PEM) fuel cells by adopting a rigorous surface science approach where:
i) Model electrocatalysts are prepared in ultra-high-vacuum (UHV) conditions as ultrathin (UT) films (PtSnx/Pt(110) and SnOx/Pt(110)) to ensure a very reproducible control down to the atomic level;
ii) Composition, morphology and structure of the UT nanostructured films are studied in situ by adopting state-of-the-art characterization tools;
iii) Quantum mechanical calculations are carried out adopting the density functional theory (DFT) in order to determine the atomic structure of the UT films.
A systematic search for possible Sn alloy or oxides on Pt(110) surface phases was carried out. Three surface alloys (including one already reported surface alloy) and two surface oxides on Pt(110) surface were identified.
The two novel surface alloys: p(3×1)PtSn/Pt(110) and p(6×1) PtSn/Pt(110) can be prepared by means of UHV Sn deposition on Pt(110) at different thickness and by a subsequent annealing at proper temperature. Besides, two SnOx oxides surfaces, namely the c(2×4)SnOx/Pt(110) and the c(4×2) SnOx/Pt(110), were prepared by oxidizing the surface alloys. With optimization of the preparation conditions, a phase diagram for the surface alloys and surface oxides on Pt(110) was outlined.
The two novel surface alloys were characterized by low energy electron diffraction (LEED), scanning tunnelling microscopy (STM) and synchrotron radiation photoemission spectroscopy (SRPES). STM images of the two surface alloys are characterized by a highly corrugated row structure whereas photoemission data indicate a complex intermixing between Pt and Sn which leads to the formation of extended near-surface alloys. Some models for the two surfaces were proposed on the basis of the experimental evidences. These models were then compared with DFT calculations and the simulated STM images of the models were used as final assessment of their validity. The reactivity of the surface alloys with CO was investigated both experimentally by thermal programmed desorption (TPD) and theoretically by DFT calculations. The results reveal a scarce reactivity towards CO on the two surfaces due the lower adsorption energy with respect to pure Pt(110) surface, indicating their use as highly CO tolerant catalysts. Based on the DFT results, the surfaces can have also an improved performance in CO oxidation reaction (COOR) on the basis of the calculated d-band centroid value.
The two surface oxides (c(2×4)SnOx/Pt(110) and c(2×4)SnOx/Pt(110) ) were investigated by LEED, STM and SRPES. Some models for the two surfaces were proposed based on the experimental results, and investigated by DFT calculations. The good agreement between the simulated STM images with the experimental data suggests a good reliability of the proposed structures.
The reactivity towards CO for the two oxidised phases was also investigated. The c(4×2) structure, constituted by a slightly oxidised Sn overlayer, demonstrated to be scarcely reactive, whereas the more oxidized c(2×4) phase proved to be able to efficiently oxidize CO. These results were also confirmed by DFT. The decomposition of methanol on c(2×4) surface was also investigated by TPD and SRPES, indicating that the methanol can be oxidised efficiently into CO2 and H2O. However the body of our experimental data points to a quite complex oxidation mechanism whose selectivity changes dynamically according to the experimental conditions. The fully oxidised c(2×4) can efficiently oxidise methanol to CO2 at low temperature, but this reaction path is progressively suppressed as soon as the phase is reduced. In this regime the methanol is oxidized to CO2 at higher temperature and less efficiently, the microscopic mechanism of the reaction implies the supply of oxygen by c(2×4) islands on reduced Pt or PtSn areas by spillover, where the actual reaction takes place. When the spillover is not anymore possible, because the methanol decomposition has removed most oxygen, methanol is simply oxidatively dehydrogenated to CO and H2, similarly to what happens on the clean Pt(110) surface but at a slightly lower temperature.La presente tesi si concentra sullo studio della relazione struttura / morfologia / reattività in elettrodi bimetallici nanostrutturati Pt - Sn per celle a combustibile a membrana a scambio protonico (PEM), adottando un rigoroso approccio di scienza delle superfici sviluppato come segue: i) sistemi modello di elettrocatalizzatori sono stati preparati in condizioni di ultra - alto vuoto (UHV) depositando via epitassia da fasci molecolari (MBE) strati ultrasottili (UT) di PtSnx e SnOx su superfici di Pt monocristallino orientate (110), al fine di garantire un controllo fine e riproducibile su scala atomica; ii ) composizione, morfologia e struttura dei film nanostrutturati UT sono stati studiati in situ mediante l'adozione di strumenti di caratterizzazione in linea con le più avanzate tecniche offerte dallo stato dell’arte; iii ) calcoli quanto-meccanici basati sulla teoria del funzionale densità (DFT) sono quindi stati effettuati per determinare la struttura atomica dei film UT, in modo da razionalizzare e supportare i risultati sperimentali ottenuti al punto precedente. Una ricerca sistematica è stata effettuata allo scopo di identificare nuove possibili fasi di superficie di Sn o ossidi di Sn supportate su Pt (110). In questo modo, tre leghe di superficie (di cui una risulta già nota in letteratura) e due ossidi di superficie su Pt (110) sono stati identificati. Le due innovative leghe da film UT, la p(3 × 1) PtSn / Pt (110) e la p(6 × 1) PtSn / Pt (110) possono essere sintetizzate mediante deposizione di Sn su Pt (110), preparando spessori diversi e sottoponendo le superfici così ottenute a trattamenti termici effettuati a diverse temperature. Conseguentemente, l’ossidazione ad alta temperatura delle leghe superficiali ha permesso l’ottenimento di due nuove fasi ossidate di superficie, la (c(2 × 4) SnOx / Pt (110) e la c(4 × 2) SnOx / Pt (110). Infine, data l’elevata flessibilità delle tecniche di preparazione e caratterizzazione offerte dalla scienza delle superfici, è stato possibile delineare con grande accuratezza un diagramma di fase sia per le leghe che per gli ossidi di superficie sopra descritti. Le due nuove leghe superficiali sono state caratterizzate mediante diffrazione di elettroni a bassa energia cinetica (LEED), microscopia a scansione ad effetto tunnel (STM) e spettroscopia di fotoemissione da radiazione di sincrotrone (SRPES). Le immagini STM delle due leghe superficiali sono caratterizzate da una struttura a righe altamente corrugata; i dati di fotoemissione indicano inoltre un complesso intermixing tra Pt e Sn che porta alla formazione di leghe localizzate in prossimità della superficie. Alcuni modelli per le due superfici così ottenute sono state proposte sulla base delle evidenze sperimentali. Tali modelli sono stati poi confrontati con calcoli DFT; in particolare, sono state generate simulazioni di immagini STM che sono state quindi confrontate con i dati sperimentali ed usate come valutazione finale della validità dei modelli proposti. La reattività delle leghe di superficie rispetto al CO è stata studiata sia sperimentalmente, mediante desorbimento termico programmato (TPD), sia ricorrendo a calcoli DFT. I risultati rivelano una scarsa reattività delle due superfici nei confronti del CO a causa dell’energia di adsorbimento inferiore rispetto alla stessa superficie di Pt (110) presa come riferimento; tale fenomenologia indica pertanto il promettente impiego di tali sistemi come catalizzatori caratterizzati da elevata tolleranza al CO. Come già descritto per le leghe di superficie, i due ossidi superficiali (c(2 × 4) SnOx / Pt (110 ) e c(4 × 2) SnOx / Pt (110) ), sono stati studiati mediante LEED, STM e SRPES. Alcuni modelli per le due superfici sono stati proposti sulla base dei risultati sperimentali, la cui validità è stata supportata da calcoli DFT. Il buon accordo tra le immagini STM simulate e i dati sperimentali suggeriscono una buona affidabilità delle strutture proposte. La reattività verso il CO per le due fasi ossidate è stata inoltre indagata mediante TPD supportata da calcoli quantomeccanici. La struttura c(4 × 2), costituita da uno strato UT di SnOx sub-stechiometrico, ha dimostrato di essere poco reattiva, mentre la fase più ossidata c(2 × 4) ha dimostrato di essere in grado di ossidare efficacemente il CO. Lo studio della decomposizione del metanolo sulla fase c(2 × 4), effettuato mediante TPD e SRPES, indica come il metanolo possa essere ossidato in modo efficiente a CO2 e H2O. Tuttavia, i dati sperimentali indicano un meccanismo di ossidazione piuttosto complesso, la cui selettività cambia dinamicamente in base alle condizioni sperimentali. Ad ogni modo, la fase completamente ossidata c(2 × 4) può facilmente ossidare il metanolo a CO2 già a bassa temperatura, tuttavia tale reattività viene progressivamente soppressa non appena inizia la riduzione della fase con la perdita di ossigeno reticolare. In questo regime l’ossidazione del metanolo a CO2 richiede temperature più elevate; in particolare, il meccanismo microscopico della reazione implica la fornitura di ossigeno da parte della fase c(2 × 4) ad isole ridotte di Pt o PtSn, siti nei quali avviene effettivamente la reazione di ossidazione. Con il procedere della decomposizione del metanolo, il progressivo consumo di ossigeno porta ad una drastica soppressione della diffusione di superficie di quest’ultimo. In questo modo, il metanolo viene semplicemente deidrogenato a CO e H2 analogamente a quanto accade sulla superficie pulita di Pt (110), sebbene a temperature inferiori.
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Dhanasekaran, Venkatesan. "Oxide supported Au-Pd nanoparticles for CO oxidation reaction." Thesis, Sorbonne Paris Cité, 2017. https://theses.md.univ-paris-diderot.fr/DHANASEKARAN_Venkatesan_1_va_20170629.pdf.
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Les nanoparticules (NPs) bimétalliques Au-Pd ont été étudiées pour leur activité catalytique dans la réaction d'oxydation du CO. La technique de préparation, la taille et la composition des nanoparticules ont un grand impact sur le comportement catalytique du système. Ici, des nanoparticules de 3 et 5nm de diamètre Au1-xPdx (x = 0, 0.25, 0.5, 0.75, 1) ont été utilisées pour étudier l'effet de la taille et de la composition. Les échantillons ont été synthétisés par nano-lithographie à base de micelles, technique bien adaptée pour obtenir des particules ayant une distribution en taille étroite. Afin d’obtenir une répartition homogène des micelles chargées en ions métalliques sur des substrats de SiO2/Si(001), nous avons eu recours à la méthode de « spin-coating » et obtenu une organisation quasi-hexagonales des micelles observable en SEM. Un plasma d'oxygène ou d'hydrogène a été utilisé pour éliminer le polymère, réduire les ions métalliques et permettre la formation de nanoparticules. Nous avons entrepris une approche systématique pour étudier l'effet du plasma sur la structure et la morphologie des NPs à l'aide des techniques de diffusion des rayons X. L'oxydation et l'activité catalytique des NPs Au1-xPdx pour l'oxydation du CO ont été étudiées à 300 °C et 0.5 bar dans le réacteur à flux XCAT disponible sur la ligne de lumière SixS du Synchrotron SOLEIL, France. Les mesures de l'activité d'oxydation du CO ont montré que les NPs préparées en utilisant le plasma d'oxygène présentent un taux de conversion en CO2 plus élevé que les NPs préparées à l'aide de plasma d'hydrogène pour une composition donnée. Les nanoparticules de Pd préparées avec du plasma d'O2 se sont révélées être le catalyseur le plus actif : aucun effet synergique n'a été observé pour les nanoparticules bimétalliques pour la réaction d'oxydation du COAu-Pd bimetallic nanoparticles (NPs) have been studied for their catalytic activity in CO oxidation reaction. The preparation technique, size and composition of the nanoparticles have great impact on the catalytic behaviour of the system. Here, 3 and 5nm diameter Au1-xPdx (x = 0, 0.25, 0.5, 0.75, 1) nanoparticles were employed to study the effect of size and composition. The samples were synthesized by micelle nanolithography, a technique well adapted to yield narrow size distribution of nanoparticles. To achieve monodisperse metal-loaded micelles on SiO2/Si(001) substrates we employed spin-coating and observe quasi-hexagonal ordered micelles in SEM. Oxygen or hydrogen plasma were used to remove the polymer, reduce the metal ions and enable nanoparticle formation. We made a systematic approach to study the effect of plasma on the structure and morphology of the NPs by means of surface x-ray scattering techniques. The oxidation behavior and CO oxidation activity of the Au1-xPdx NPs were studied at 300°C and 0.5 bar in the flow reactor XCAT available at the SixS Beamline, Synchrotron SOLEIL, France. The CO oxidation activity measurements showed that the NPs prepared using the oxygen plasma present higher CO2 conversion rate than the NPs prepared using hydrogen plasma for a given composition. The Pd nanoparticles prepared using O2 plasma were found to be the most active catalyst: no synergetic effects were observed for bimetallic nanoparticles for the CO oxidation reaction
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Luo, Wenjia. "First-Principles Study of Ethanol and Methanol Steam Reforming on Co-based Materials." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429188977.
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Zhang, Wei. "Simulation of Solid Oxide Fuel Cell - Based Power Generation Processes with CO2 Capture." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/946.
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The Solid Oxide Fuel Cell (SOFC) is a promising technology for electricity generation. It converts the chemical energy of the fuel gas directly to electricity energy and therefore, very high electrical efficiencies can be achieved. The high operating temperature of the SOFC also provides excellent possibilities for cogeneration applications. In addition to producing power very efficiently, the SOFC has the potential to concentrate CO2 with a minimum of an overall efficiency loss. Concentration of CO2 is a desirable feature of a power generation process so that the CO2 may be subsequently sequestered thus preventing its contribution to global warming. The primary purpose of this research project was to investigate the role of the SOFC technology in power generation processes and explore its potential for CO2 capture in power plants. This thesis introduces an AspenPlusTM SOFC stack model based on the natural gas feed tubular internal reforming SOFC technology. It was developed utilizing existing AspenPlusTM functions and unit operation models. This SOFC model is able to provide detailed thermodynamic and parametric analysis of the SOFC operation and can easily be extended to study the entire process consisting of the SOFC stack and balance of plant.
Various SOFC-based power generation cycles were studied in this thesis. Various options for concentrating CO2 in these power generation systems were also investigated and discussed in detail. All the processes simulations were implemented in AspenPlusTM extending from the developed natural gas feed tubular SOFC stack model. The study shows that the SOFC technology has a promising future not only in generating electricity in high efficiency but also in facilitating CO2 concentration, but the cost of the proposed processes still need be reduced so SOFCs can become a technical as well as economic feasible solution for power generation.
Books on the topic "Co based oxides"
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IEEE International Workshop on Defect Based Testing (2000 Montréal, Québec). 2000 IEEE International Workshop on Defect Based Testing: April 30, 2000, Montreal, Canada : proceedings. Los Alamitos, Calif: IEEE Computer Society, 2000.
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Malaiya, Yashwant K., Sankaran M. Menon, Quebec) IEEE VLSI Test Symposium (2000 :. Montreal, and Manoj Sachdev. 2000 IEEE International Workshop on Defect Based Testing: April 30, 2000 Montreal, Canada : Proceedings. Institute of Electrical & Electronics Enginee, 2000.
Find full textBook chapters on the topic "Co based oxides"
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Risch, Marcel, Katharina Klingan, Ivelina Zaharieva, and Holger Dau. "Water Oxidation by Co-Based Oxides with Molecular Properties." In Molecular Water Oxidation Catalysis, 163–85. Chichester, UK: John Wiley & Sons, Ltd, 2014. http://dx.doi.org/10.1002/9781118698648.ch9.
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Riza, F., G. Ch Kostogloudis, and Ch Ftikos. "Preparation and Characterization of Pr-Sr-Co-Fe-Al-O Based Perovskite Oxides for SOFC Cathodes." In Functional Materials, 193–98. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2006. http://dx.doi.org/10.1002/3527607420.ch33.
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Carry, Claude, Emre Yalamaç, and Sedat Akkurt. "Co-Sintering Behaviors of Oxide Based Bi-Materials." In Ceramic Transactions Series, 305–20. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2010. http://dx.doi.org/10.1002/9780470599730.ch30.
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Mukherji, Rana, Vishal Mathur, and Manishita Mukherji. "Image Analysis of SEM Micrograph of Co-doped ZnO-Based Oxide Semiconductors." In Advances in Intelligent Systems and Computing, 321–24. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8618-3_34.
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Lu, D., Z. Sheng, B. Yan, and Z. Jiang. "Co-effects of Graphene Oxide and Silica Fume on the Rheological Properties of Cement Paste." In Lecture Notes in Civil Engineering, 251–58. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_26.
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AbstractPolycarboxylate superplasticizer is typically used to prepare a high-quality graphene oxide (GO) solution before mixing with cement grains. However, even if GO is well dispersed in water, they tend to re-agglomerate in the alkaline cement hydration environment, thus seriously decreasing the workability of the fresh mixture. In this study, we propose a more targeted method by synthesizing GO-coated silica fume (SF) to promote the utilization of GO in cement-based materials. Specifically, the surface of pristine SF was modified to convert their zeta potential (modified SF: MSF), then GO-coated SF (i.e., MSF@GO) was prepared via electrostatic adsorption of GO onto the MSF surface. The experimental results revealed that adding 5MSF@GO hybrid (0.04% GO and 5% MSF, by weight of binder) significantly reduced yield stress and plastic viscosity by 51.5% and 26.2%, respectively, relative to the 0.04% GO-modified sample. These findings indicated that application of GO-coated SF is an effective and environmentally friendly way to develop sustainable cementitious composites.
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Itkulova, Sh S. "The Bimetallic Co-Containing Supported on Alumina Catalysts in the Synthesis on the Base of Carbon Oxides." In Principles and Methods for Accelerated Catalyst Design and Testing, 407–15. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0554-8_28.
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de Marco, Ario. "Cytoplasmic Production of Nanobodies and Nanobody-Based Reagents by Co-Expression of Sulfhydryl Oxidase and DsbC Isomerase." In Methods in Molecular Biology, 145–57. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2075-5_7.
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Chouhan, Neelu, and Kazuhiro Marumoto. "Modified Graphene-Based Compound: Hydrogen Production through Water Splitting." In Graphene-based Carbocatalysts: Synthesis, Properties and Applications (Volume 2), 81–135. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815136050123020007.
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Solar hydrogen production from water splitting can solve two big issues i.e. energy and environmental pollution. Since the discovery of graphene, its importance has been proven in many fields including light-driven hydrogen generation from water. This chapter offers a contemporary overview of the progress of graphene-based materials including graphene oxide, reduced graphene oxide and graphene oxide quantum dots for hydrogen evolution from photocatalytic water splitting. This chapter begins with a concise introduction to the current status of hydrogen energy generation from water. The chemical and physical characteristics of this extraordinary plasmonic metamaterial were also elaborated. Afterwards, the synthesis methods, various models, and associated properties of the tailored graphene oxides, reduced graphene oxide and graphene oxide quantum dots in the forms of pristine, binary and ternary compounds are discussed for their application in hydrogen production. In these modified compounds, the graphene acts as a surfactant, a charge-carrier recombination suppressor, an electron-sink and transporter, a co-catalyst, a photocatalyst, and a photosensitizer which, are elaborated . Finally, the chapter ends with a concluding remark on the challenges and future perspectives in this promising field.<br>
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Belaid, Walid, Amina Houimi, Shrouk E. Zaki, and Mohamed A. Basyooni. "Sol-Gel Production of Semiconductor Metal Oxides for Gas Sensor Applications." In Sol-Gel Method - Recent Advances [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.111844.
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As they are widely utilized in industries including the food packaging industry, indoor air quality testing, and real-time monitoring of man-made harmful gas emissions to successfully combat global warming, reliable and affordable gas sensors represent enormous market potential. For environmental monitoring, chemical safety regulation, and many industrial applications, the detection of carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), and methane (CH4) gases is essential. To reliably and quantitatively detect these gases, much-improved materials and methods that are adaptable to various environmental factors are needed using low-cost fabrication techniques such as sol–gel. The advantages of employing metal oxide nanomaterials-based chemoresistive for creating high-performance gas sensors are shown by key metrics such as selectivity, sensitivity, reaction time, and detection. The primary sensing methods are also grouped and thoroughly covered. In light of the current constraints, anticipated future developments in the field of sol–gel nanomaterial-based chemoresistive gas sensors are also highlighted.
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Daniel, Likius Shipwiisho, Veikko Uahengo, and Ateeq Rahman. "Factors Influencing TiO2-based Composites for Water Decolorization: A Systematic Review." In Novel Materials and Water Purification, 256–97. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/9781837671663-00256.
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The widespread use of synthetic dyes and their release into aquatic environments poses significant risks to human health and ecosystems. As a process for dye removal that is environmentally benign and green, photocatalysis has gained a lot of interest. Composites made of TiO2 have demonstrated potential as photocatalytic materials for water decolorization. In this study, we used key phrase analysis, keyword co-occurrence, and bibliographic couplings to examine 131 articles from the Scopus database (2017–2023). We investigated how TiO2-based composites—including doped TiO2, mixed metal oxides and supporting substrates—could be categorized based on composition. We studied various factors, such as pH, temperature, coexisting compounds, reaction time, light intensity, and initial dye concentration. These factors were found to influence the performance and stability of TiO2-based composites in water decolorization. It was discovered that doping is a method for improving light absorption of TiO2 by reducing its bandgap. The relationships between these variables also imply that the ideal photocatalytic conditions may differ based on the particular composite, dye, and environmental conditions used. Consequently, optimizing these parameters is crucial for obtaining the best photocatalytic activity.
Conference papers on the topic "Co based oxides"
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Huang, Dong, Yingli Shi, and Francis C. Ling. "Enhancing the dielectric constant of oxides via acceptor-donor co-doping." In Oxide-based Materials and Devices XII, edited by Ferechteh H. Teherani, David C. Look, and David J. Rogers. SPIE, 2021. http://dx.doi.org/10.1117/12.2586393.
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Huang, Xiao. "Effect of Co-Doping on Microstructure, Thermal and Mechanical Properties of Ternary Zirconia-Based Thermal Barrier Coating Materials." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59007.
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7YSZ (yttria stabilized zirconia) was co-doped with metal oxides of different valence, ionic radius and mass in order to investigate microstructural and property changes as a result of co-doping. Mechanical alloying process was used to produce the powder blends which were subsequently sintered at 1500°C for 120 hours. The results from SEM, XRD and DSC showed that the microstructures of the co-doped ternary oxides were affected by the amount of oxygen vacancies in the system, the co-dopant cation radius and mass. Increasing the number of oxygen vacancies by the addition of trivalent co-dopant (Yb2O3 and Sc2O3) as well as the use of larger cations promoted the stabilization of cubic phase. The tetravalent co-dopant (CeO2), on the other hand, had the effect of stabilizing tetragonal phase which may transform into monoclinic phase during cooling, depending on the concentration of tetravalent co-dopant and the mass. Smaller cation mass had the effect of reducing the transformation temperature from tetragonal to monoclinic phase. Pentavalent co-dopants (Nb2O5 and Ta2O5) were found to stabilize the tetragonal phase at high temperature; however, the stability of the tetragonal phase upon cooling was determined by the mass and ionic radius of the co-dopants. Cation clustering was observed during cooling in trivalent oxide co-doped 7YSZ while clustering of trivalent and pentavalent cations in pentavalent co-doped 7YSZ was not detected. Additionally, from the thermal conductivity measurement results, it was found that trivalent oxides exhibited the most significant effect on reducing the thermal conductivity of ternary oxides; this trend was followed by pentavalent co-doping oxides whereas the tetravalent CeO2 co-doped 7YSZ showed marginal effect. A semi-empirical thermal conductivity model was established based on defect cluster model and the predicted room temperature thermal conductivity values were found to be consistent with that measured experimentally. Furthermore, the incorporation of co-dopant oxide in 7YSZ was observed to substantially modify the elastic modulus of the ternary oxides. More specifically, the addition of co-dopant with larger cation radius was found to reduce the elastic modulus of 7YSZ due to the increase in lattice parameter(s).
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André, Laurie, Stéphane Abanades, and Laurent Cassayre. "Mixed Co, Cu and Mn-based metal oxides for thermochemical energy storage application." In SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems. Author(s), 2018. http://dx.doi.org/10.1063/1.5067124.
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Rokni, Emad, Hsun Hsien Chi, and Yiannis A. Levendis. "In-Furnace Sulfur Capture by Co-Firing Coal With Alkali-Based Sorbents." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65549.
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Over the last quarter of a century, since the 1990 US Clean Air Act Amendments were enacted the gaseous sulfur emission, in the form of sulfur dioxide, have been reduced [1] by a factor of 4, by switching to lower sulfur content coals, installation of flue gas desulfurization (FGD) sorbents or switching altogether to natural gas as a fuel. Penetration of alternative energy generation also has had a positive impact. However, current emissions of sulfur dioxide are still voluminous, amounting to 3,242,000 short tons annually in the USA [2]. As wet flue gas desulfurization is both real-estate- and capital-intensive, infurnace dry sorbent injection has been considered over the years to be a viable alternative. However there is still uncertainty on the best selection of the sorbents for particular coals and furnace operating conditions. This is particularly the case when it is economically attractive for the power-plant operator to burn locally-sourced high-sulfur coal, such as the case of Illinois bituminous coals. This manuscript presents experimental results on the reduction of sulfur oxide emissions from combustion of a high-sulfur content pulverized bituminous coal (Illinois #6 Macoupin). The coal particles were in the size range of 90–125 μm and were blended with dry calcium-, sodium-, potassium-, and magnesium-containing powdered sorbents at different proportions. The alkali/S molar ratios were chosen to be at stoichiometric proportions (Ca/S = 1, Mg/S = 1, Na2/S = 2, and K2/S = 2) and the effectiveness of each alkali or alkali earth based sorbent was evaluated separately. Combustion of coal took place in a drop-tube furnace, electrically-heated to 1400 K under fuel-lean conditions. The evolution of combustion effluent gases, such as NOx, SO2 and CO2 were monitored and compared among the different sorbent cases. The use of these sorbents helps to resolve the potential of different alkali metals for effective in-furnace sulfur oxide capture and possible NOx reduction. It also assesses the effectiveness of various chemical compounds of the alkalis, such as oxides, carbonates, peroxides and acetates.
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Boichuk, T., and S. Orlyk. "Influence of composition (Pd) In-, Co-containing aluminia- and zirconia-based catalysts on simultaneous reduction of nitrogen(I, II) oxides by CO." In Chemical technology and engineering. Lviv Polytechnic National University, 2019. http://dx.doi.org/10.23939/cte2019.01.265.
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Ramis, Gianguido, Guido Busca, Tania Montanari, Michele Sisani, and Umberto Costantino. "Ni-Co-Zn-Al Catalysts From Hydrotalcite-Like Precursors for Hydrogen Production by Ethanol Steam Reforming." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33034.
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A series of well crystallized Ni-Co-Zn-Al LDHs materials has been prepared by the urea hydrolysis method as precursors of mixed oxide catalysts for the Ethanol Steam Reforming (ESR) reaction. The calcination of the layered precursors gives rise to high surface area mixed oxides, mainly a mixture of rock-salt phase (NiO), wurtzite phase (ZnO) and spinel phase. Both precursors and mixed oxides have been throughtfully characterized and the steam reforming of ethanol has been investigated over the calcined catalysts in flow reactor and in-situ FT-IR experiments. The data here reported provide evidence of the good catalytic activity of Co-Zn-Al and Co-Ni-Zn-Al catalysts prepared from hydrotalcite-like LHD precursors for ethanol steam reforming. At 823 K the most active Co/Ni catalyst containains a predominant spinel phase with composition near Zn0.58Ni0.42[Al0.44Co0.56]2O4 and small amounts of NiO and ZnO. On the other side, at 873 K the selectivity to hydrogen increases with cobalt content. In particular, the presence of cobalt increases selectivity to H2 and CO2 and decreases selectivity to methane in the low temperature range 720–870 K. The most selective catalyst is the Ni-free Co-Zn-Al mixed oxide essentially constituted by a single spinel type phase Zn0.55Co0.45[Al0.45Co0.55]2O4. Cobalt catalysts appear consequently to behave better than nickel based catalysts in this temperature range. The key feature for high selectivity to hydrogen is proposed to be associated to a stability of a relatively high oxidation state at the catalyst surface, the most relevant selectivity determining step being constituted by the evolution of surface acetate species. In fact, over oxidized catalyst surface the acetate species evolve producing carbon dioxide and hydrogen while over a more reduced surface they evolve giving rise to methane and COx. Water is supposed to have the main role of allowing surface sites to stay in an unreduced state at least in the temperature range 720–870 K.
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Calzolari, Arrigo, and Alessandra Catellani. "Doping, co-doping, and defect effects on the plasmonic activity of ZnO-based transparent conductive oxides." In SPIE OPTO, edited by Ferechteh H. Teherani, David C. Look, and David J. Rogers. SPIE, 2017. http://dx.doi.org/10.1117/12.2250736.
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Tillmann, W., L. Hagen, and D. Duda. "A Study on the Tribological Behavior of Arc Sprayed Vanadium Doped Stellite Coatings." In ITSC2017, edited by A. Agarwal, G. Bolelli, A. Concustell, Y. C. Lau, A. McDonald, F. L. Toma, E. Turunen, and C. A. Widener. DVS Media GmbH, 2017. http://dx.doi.org/10.31399/asm.cp.itsc2017p0354.
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Abstract Due to good performance in abrasive and sliding wear and enhanced oxidation behavior, coatings based on Co-Cr-W alloys are widely used in industrial applications, where the material is exposed to high temperature. Within the scope of this study, a Co-based alloy similar to commercial Stellite 6, which additionally contains 20.6 wt.% of vanadium, was deposited by Twin Wire Arc Spraying (TWAS). Multi-criteria optimization using statistical design of experiments (DoE) have been carried out in order to produce adequate coatings. The produced coatings have been analyzed with respect to their tribological behavior at elevated temperatures. Dry sliding experiments were performed in the temperature range between 25°C and 750°C. Oxide phases were identified in the investigated temperature range by X-ray diffraction (XRD) using synchrotron radiation. The V-doped Stellite-based coating possesses a reduced coefficient of friction (COF) of about 0.37 at elevated temperatures (above 650°C), which was significant lower when compared to conventional Stellite 6 coating that serves as reference. In contrast, both produced coatings feature a similar COF under room temperature. X-ray diffraction reveals the formation of cobalt vanadate and vanadium oxides above 650°C. The formation of vanadium oxides exhibits the ability of self-lubricating behavior, thus leading to enhanced tribological properties.
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Engblom, Markus, Pia Kilpinen, Fredrik Klingstedt, Kari Era¨nen, and Ranjit Katam Kumar. "NOx and N2O Emission Formation Tendency From Multifuel CFB-Boilers: A Further Development of the Predictor." In 18th International Conference on Fluidized Bed Combustion. ASMEDC, 2005. http://dx.doi.org/10.1115/fbc2005-78116.
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Present paper is a part of our on-going model development activities with aim to predict formation tendency of gaseous emissions from CFB combustion of different fuels, and especially, fuel-mixtures in real furnaces of various scale. The model is based on detailed description of homogeneous, catalytic, and heterogeneous chemical kinetics, and a sound but simple 1.5D representation of fluid dynamics. Temperature distribution is assumed known. With the tool, different fuels and fuel mixtures can be compared in respect to their tendency to form nitrogen oxides (NOx, N2O). In this paper the model was tested to predict nitrogen oxide emissions from mono- or co-combustion of coal, wood, and sludge. The plants simulated were the 12MWth CFB combustor located at Chalmers Technical University (A = 2.25m2, h = 13.6m) and the pilot scale CFB unit at the Technical University Hamburg-Harburg (d = 0.1m, h = 15m). The results gave reasonable representation of the measured emission data, and reflected correctly to the changes in the fuel characteristics and in the furnace operating conditions in most cases. An extensive laboratory fixed-bed reactor study was also performed in order to obtain input values for the kinetic constants of the catalytic reactions for the reduction and decomposition of nitrogen oxides. In literature, there is a limited data available regarding the catalytic activity of CFB solids during combustion of wood- and waste-derived fuels, especially at co-firing conditions. The kinetics for the NO reduction by CO in the temperature range of 780–910°C was determined to be of the following form (NO = 300ppm, CO = 5000ppm): −rNO=k·[NO]0.48·[CO]0.55mol/g-s with k=8.15·exp(−8869/T)m3/kg-s(emptyreactoreffectincluded)ork=830·exp(−14930/T)(emptyreactoreffectexcluded), when using a bed sample (250–355 μm) taken from the transport zone in the CTH boiler while burning a mixture of wood pellets and a pre-dried municipal sewage sludge. The role of char particle size and shape as well as the incorporation of energy balance on the char reactivity and the formation of nitrogen oxides is further illustrated by single char particle oxidation simulations.
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Song, Shigeng, Sijia Cai, Daxing Han, Carlos García Nuñez, Gong Zhan, Gavin Wallace, Lewis Fleming, et al. "Tantalum Oxide and Silica Mixture Coatings Deposited Using Microwave Plasma Assisted Co-sputtering for Optical Mirror Coatings in Gravitational Wave Detectors." In Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/oic.2022.wb.2.
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This work presents the characterisation of optical and mechanical properties of thin films based on (Ta2O5)1-x(SiO2)x mixed oxides deposited by microwave plasma assisted co-sputtering to demonstrate their potential as optical coatings in gravitational wave detectors.
Reports on the topic "Co based oxides"
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McHale, Yalin, and Olsen. PR-179-13203-R01 Real Time Laser Sensor for Nitrogen Oxides and Carbon Monoxide. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), August 2014. http://dx.doi.org/10.55274/r0010020.
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Performance of current NOx sensors is problematic, in particular drift and cross-sensitivity to other species. Many lean burn engines are operated based on earlier calibrations. Operators must allow for drift and use large margins to meet emissions. Laser sensors (based on absorption at target wavelengths) are self-calibrating and immune to interferences. In particular, recently developed Quantum Cascade Lasers (QCLs) allow measurements at mid-infrared (MIR) wavelengths thereby allowing stronger signals, better schemes to mitigate interferences, and fast time response. This project evaluated a commercial QCL-based NOx (NO, NO2) and CO sensor for use in gas engine applications. The project also developed and performed bench top testing of a custom sensor which uses a �pitch and catch� design.
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Kudin, Roman, Prabhat Chand, and Anura Bakmeedeniya. Mitigating Nitrogen Oxides Exhaust Emissions from Petrol Vehicles by Application of a Fuel Additive. Unitec ePress, August 2020. http://dx.doi.org/10.34074/rsrp.083.
Full textAbstract:
This research has been commissioned by Eco Fuel Global Limited, a New Zealand-based company, to further evaluate the effects of their fuel-additive product on the tailpipe exhaust emissions of petrol cars. At the time this research was conducted (end of 2018), the product was still in development and had not been released to the market. Prior to the testing in this research, an initial pilot test was done for the same product on a single car (Nissan Pulsar 1998), which showed favourable results, with a reduction in hydrocarbons and oxides of nitrogen at the tailpipe by more than 70%. The current research included five test cars, all running on RON 95 fuel, with the years of manufacture ranging between 1994 and 2006, and the odometer readings between 112,004 km and 264,001 km. The effects of the fuel-additive product were assessed by comparing the emissions from a car running on standard fuel with the emissions from the same car after it completed a road run (250±20 km) on the additive-treated fuel. The exhaust emissions were measured using the AVL series 4000 Emission Tester, which analyses five components: carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen (NOX), hydrocarbons (HC) and oxygen (O2). The most noticeable outcome of using the fuel-additive product was the reduction in the concentration of oxides of nitrogen in the tailpipe exhaust (by up to 27.7%), when compared with the same cars running on standard fuel. In addition, the results showed a decrease in residual oxygen concentration, which normally indicates more complete utilisation of O2 as an oxidising agent. Mitigating Nitrogen Oxides Exhaust Emissions from Petrol Vehicles by Application of a Fuel Additive Dr Roman Kudin, Prabhat Chand and Anura Bakmeedeniya 2 The changes for other emission parameters were either relatively small (below 1%) or were not statistically significant. The application of such fuel-additive products could be beneficial for mitigating nitrogen oxides exhaust emissions from petrol vehicles in countries with ageing car fleets. These include New Zealand, which has a relatively high proportion of old cars in use, with no government-run scrappage scheme, and without a mandatory objective emissions testing.
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Chepeliev, Maksym. Development of the Air Pollution Database for the GTAP 10A Data Base. GTAP Research Memoranda, June 2020. http://dx.doi.org/10.21642/gtap.rm33.
Full textAbstract:
The purpose of this note is to document data sources and steps used to develop the air pollution database for the GTAP Data Base Version 10A. Emissions for nine substances are reported in the database: black carbon (BC), carbon monoxide (CO), ammonia (NH3), non-methane volatile organic compounds (NMVOC), nitrogen oxides (NOx), organic carbon (OC), particulate matter 10 (PM10), particulate matter 2.5 (PM2.5) and sulfur dioxide (SO2). The dataset covers four reference years – 2004, 2007, 2011 and 2014. EDGAR Version 5.0 database is used as the main data source. To assist with emissions redistribution across consumption-based sources, IIASA GAINS-based model and IPCC-derived emission factors are applied. Each emission flow is associated with one of the four sets of emission drivers: output by industries, endowment by industries, input use by industries and household consumption. In addition, emissions from land use activities (biomass burning) are estimated by land cover types. These emissions are reported separately without association with emission drivers.
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Chapman and Toema. PR-266-07209-R01 Phase 2 - Assessment of the Robustness and Transportability of the Gas Turbine Model. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 2010. http://dx.doi.org/10.55274/r0010719.
Full textAbstract:
This report presents the modeling study of a gas turbine combustor based on first engineering principles to fully characterize the nitrogen oxides (NOx) and carbon monoxide emissions (CO). The model is mainly focused on the emissions from the widely used lean-premixed, dry low-NOx combustor. The combustor is divided into several zones where each zone can be considered as a plug-flow reactor. Each of these zones is assumed to have a uniform pressure, temperature and perfect mixing between combustion species. The temperature of each zone is calculated using mass and energy balances along with heat transfer through the combustor liner. The emissions are calculated using well-know pollutant reaction schemes such as the Zeldovich mechanism in addition to other well-established semi-empirical correlations.
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Corriveau, L., J. F. Montreuil, O. Blein, E. Potter, M. Ansari, J. Craven, R. Enkin, et al. Metasomatic iron and alkali calcic (MIAC) system frameworks: a TGI-6 task force to help de-risk exploration for IOCG, IOA and affiliated primary critical metal deposits. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/329093.
Full textAbstract:
Australia's and China's resources (e.g. Olympic Dam Cu-U-Au-Ag and Bayan Obo REE deposits) highlight how discovery and mining of iron oxide copper-gold (IOCG), iron oxide±apatite (IOA) and affiliated primary critical metal deposits in metasomatic iron and alkali-calcic (MIAC) mineral systems can secure a long-term supply of critical metals for Canada and its partners. In Canada, MIAC systems comprise a wide range of undeveloped primary critical metal deposits (e.g. NWT NICO Au-Co-Bi-Cu and Québec HREE-rich Josette deposits). Underexplored settings are parts of metallogenic belts that extend into Australia and the USA. Some settings, such as the Camsell River district explored by the Dene First Nations in the NWT, have infrastructures and 100s of km of historic drill cores. Yet vocabularies for mapping MIAC systems are scanty. Ability to identify metasomatic vectors to ore is fledging. Deposit models based on host rock types, structural controls or metal associations underpin the identification of MIAC-affinities, assessment of systems' full mineral potential and development of robust mineral exploration strategies. This workshop presentation reviews public geoscience research and tools developed by the Targeted Geoscience Initiative to establish the MIAC frameworks of prospective Canadian settings and global mining districts and help de-risk exploration for IOCG, IOA and affiliated primary critical metal deposits. The knowledge also supports fundamental research, environmental baseline assessment and societal decisions. It fulfills objectives of the Canadian Mineral and Metal Plan and the Critical Mineral Mapping Initiative among others. The GSC-led MIAC research team comprises members of the academic, private and public sectors from Canada, Australia, Europe, USA, China and Dene First Nations. The team's novel alteration mapping protocols, geological, mineralogical, geochemical and geophysical framework tools, and holistic mineral systems and petrophysics models mitigate and solve some of the exploration and geosciences challenges posed by the intricacies of MIAC systems. The group pioneers the use of discriminant alteration diagrams and barcodes, the assembly of a vocab for mapping and core logging, and the provision of field short courses, atlas, photo collections and system-scale field, geochemical, rock physical properties and geophysical datasets are in progress to synthesize shared signatures of Canadian settings and global MIAC mining districts. Research on a metamorphosed MIAC system and metamorphic phase equilibria modelling of alteration facies will provide a foundation for framework mapping and exploration of high-grade metamorphic terranes where surface and near surface resources are still to be discovered and mined as are those of non-metamorphosed MIAC systems.