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Статті в журналах з теми "K-Fe catalysts":
1
Xiang, Minglin, and Juan Zou. "CO Hydrogenation over Transition Metals (Fe, Co, or Ni) Modified K/Mo2C Catalysts." Journal of Catalysts 2013 (September 3, 2013): 1–5. http://dx.doi.org/10.1155/2013/195920.
Анотація:
Transition metals (Fe, Co, or Ni) modified K/Mo2C catalysts were prepared and investigated as catalysts for CO hydrogenation. The addition of Fe, Co, or Ni to K/Mo2C catalyst led to a sharp increase in both the activity and selectivity of C2+OH, but the promotion effects were quite different and followed the sequence: Ni > Co > Fe for the activity and Fe > Co > Ni for the alcohol selectivity. For the products distributions, it also displayed some differences; Co promoter showed much higher C5+ hydrocarbon selectivity than Fe or Ni promoter, but Fe or Co promoter gave lower methane selectivity than Ni promoter, and Fe promoter showed the highest C2=-C4= selectivity.
2
Aluha, James, Stéphane Gutierrez, François Gitzhofer, and Nicolas Abatzoglou. "Use of Plasma-Synthesized Nano-Catalysts for CO Hydrogenation in Low-Temperature Fischer–Tropsch Synthesis: Effect of Catalyst Pre-Treatment." Nanomaterials 8, no. 10 (October 12, 2018): 822. http://dx.doi.org/10.3390/nano8100822.
Анотація:
A study was done on the effect of temperature and catalyst pre-treatment on CO hydrogenation over plasma-synthesized catalysts during the Fischer–Tropsch synthesis (FTS). Nanometric Co/C, Fe/C, and 50%Co-50%Fe/C catalysts with BET specific surface area of ~80 m2 g–1 were tested at a 2 MPa pressure and a gas hourly space velocity (GHSV) of 2000 cm3 h−1 g−1 of a catalyst (at STP) in hydrogen-rich FTS feed gas (H2:CO = 2.2). After pre-treatment in both H2 and CO, transmission electron microscopy (TEM) showed that the used catalysts shifted from a mono-modal particle-size distribution (mean ~11 nm) to a multi-modal distribution with a substantial increase in the smaller nanoparticles (~5 nm), which was statistically significant. Further characterization was conducted by scanning electron microscopy (SEM with EDX elemental mapping), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The average CO conversion at 500 K was 18% (Co/C), 17% (Fe/C), and 16% (Co-Fe/C); 46%, 37%, and 57% at 520 K; and 85%, 86% and 71% at 540 K respectively. The selectivity of Co/C for C5+ was ~98% with 8% gasoline, 61%, diesel and 28% wax (fractions) at 500 K; 22% gasoline, 50% diesel, and 19% wax at 520 K; and 24% gasoline, 34% diesel, and 11% wax at 540 K, besides CO2 and CH4 as by-products. Fe-containing catalysts manifested similar trends, with a poor conformity to the Anderson–Schulz–Flory (ASF) product distribution.
3
Kim, ChoHwe, and YoungChul Kim. "Promotional Effect of Iron on Nickel-Based Catalyst for Combined Steam-Carbon Dioxide Reformation of Methane." Journal of Nanoscience and Nanotechnology 20, no. 9 (September 1, 2020): 5506–9. http://dx.doi.org/10.1166/jnn.2020.17632.
Анотація:
In this study, the effect by Iron with nickel-based catalyst for the combined steam and carbon dioxide reforming of methane was investigated. Fe-promoted and un-promoted Ni–Mg–Ce/γ-Al2O3 catalysts were prepared by co-impregnation and evaluated in a quartz fixed-bed reactor at H2O:CO2:CH4 ratios of 0.9:1:1 and a temperature of 1073 K under atmospheric pressure. The physicochemical properties of the catalysts were investigated by N2 adsorption–desorption, XRD, H2-TPR, CO2-TPD, TGA and FE-SEM. The iron-supported catalysts showed improved resistance to carbon deposition and suppressed sintering of nickel. As a result, NMC-Fe(5) showed the lowest coke and high stability over 70 h among all other catalysts.
4
Ribeiro, Mirtha Z. Leguizamón León, Joice C. Souza, Muthu Kumaran Gnanamani, Michela Martinelli, Gabriel F. Upton, Gary Jacobs, and Mauro C. Ribeiro. "Fischer–Tropsch Synthesis: Effect of the Promoter’s Ionic Charge and Valence Level Energy on Activity." Reactions 2, no. 4 (October 10, 2021): 408–26. http://dx.doi.org/10.3390/reactions2040026.
Анотація:
In this contribution, we examine the effect of the promoter´s ionic charge and valence orbital energy on the catalytic activity of Fe-based catalysts, based on in situ synchrotron X-ray powder diffraction (SXRPD), temperature-programmed-based techniques (TPR, TPD, CO-TP carburization), and Fischer–Tropsch synthesis catalytic testing studies. We compared the promoting effects of K (a known promoter for longer-chained products) with Ba, which has a similar ionic radius but has double the ionic charge. Despite being partially “buried” in a crystalline BaCO3 phase, the carburization of the Ba-promoted catalyst was more effective than that of K; this was primarily due to its higher (2+) ionic charge. With Ba2+, higher selectivity to methane and lighter products were obtained compared to the K-promoted catalysts; this is likely due to Ba´s lesser capability of suppressing H adsorption on the catalyst surface. An explanation is provided in terms of a more limited mixing between electron-filled Ba2+ 5p and partially filled Fe 3d orbitals, which are expected to be important for the chemical promotion, as they are further apart in energy compared to the K+ 3p and Fe 3d orbitals.
5
Gujjar, Soumya J., Avinashkumar V. Karre, Alaa Kababji, and Dady B. Dadyburjor. "Effect of Changing Amounts of Promoters and Base Fe Metal in a Multicomponent Catalyst Supported on Coal-Based Activated Carbon for Fischer–Tropsch Synthesis." Reactions 2, no. 1 (February 1, 2021): 11–29. http://dx.doi.org/10.3390/reactions2010003.
Анотація:
The effect of varying the amounts of metals Fe, Cu, K, and Mo was studied on a catalyst supported on activated carbon (AC), which is an item of novelty of this paper. The base-case catalyst contains 16% Fe, 0.9% K, 6% Mo, and 0.8% Cu relative to the AC support. For all of the catalysts used, alcohol production is small. The production of hydrocarbons depends upon the amount of Fe and other promoters used. The amount of Fe was increased from 0% to 32% on the catalyst containing base-case amounts of the other materials. While 0% Fe shows no activity towards Fischer–Tropsch synthesis (FTS), 32% Fe shows a marginal increase in FTS activity when compared with 16% Fe. Furthermore, the amount of K was increased from 0% to 1.8%, with the other metals in their base-case amounts. The selectivity of C1–C4 decreases with the addition of K, while the selectivity of C5+ increases. Analogously, the amount of Mo was increased from 0% to 12%. A small amount of Mo results in an increase in FTS activity but decreases with the addition of more Mo. Cu on the catalyst was increased from 0% to 1.6%, with 0.8% Cu proving optimum for FTS.
6
Ku, YuPing, Konrad Ehelebe, Markus Bierling, Florian Dominik Speck, Dominik Seeberger, Karl J. J. Mayrhofer, Simon Thiele, and Serhiy Cherevko. "The Interplay of Oxygen Reduction Reaction and Iron Dissolution from Fe-N-C Electrocatalysts." ECS Meeting Abstracts MA2022-01, no. 35 (July 7, 2022): 1486. http://dx.doi.org/10.1149/ma2022-01351486mtgabs.
Анотація:
Fe-N-C catalysts are regularly proposed as promising earth-abundant and cheap catalysts replacing platinum group metal catalysts for fuel cells (FCs). Besides the activity, especially the stability of those materials remains challenging. It was found that the electrochemical activity and durability of Fe-N-C catalysts are superior in alkaline compared to acidic media, [1-3] yet most of their degradation studies are done in acidic media. [4-9] Moreover, although these are systematic works, discrepancies in these results from aqueous model systems (AMS) [5,6] and FC testing [7-9] remain puzzling. For example, the origin of the dissolved Fe species was found to be from poorly active sites in AMS [5] yet from highly active sites in operating FCs. [7,8] Additionally, the harmful effects of reactive oxygen species (ROS) on Fe-N-C catalysts are proven in AMS [6] but not directly correlated to the durability in FCs. [9] To bridge this gap, a gas diffusion electrode (GDE) half-cell coupled with inductively coupled plasma mass spectrometry (ICP-MS) has been developed to study on-line dissolution in realistic catalyst layers. [10] In this work, using a GDE-ICP-MS, we investigate the impacts of oxygen reduction reaction (ORR) on Fe leaching from realistic Fe-N-C alkaline catalyst layers. [11] For the first time, Fe dissolution is measured online at current densities above -100 mA·cm-2. The novel results show that compared to the model Ar-saturated environment, the Fe dissolution is dramatically higher during ORR. Furthermore, between 0.6 and 1.0 VRHE, we unveil an interesting correlation between Fe dissolution and charge transfer events. This subsequently leads to our hypothesis that the instability of the coordinated Fe during Fe3+/Fe2+ redox transitions is responsible for Fe leaching from Fe-N-C catalysts in alkaline media in this potential region. The novel insights into Fe-N-C catalyst degradation in realistic conditions can lead to rational design of this promising platinum group metal free catalyst for efficient, durable, and affordable FCs. References: [1] Santori, P. G. et al. Effect of pyrolysis atmosphere and electrolyte pH on the oxygen reduction activity, stability and spectroscopic signature of FeNx moieties in Fe-N-C catalysts. J. Electrochem. Soc. 2019, 166: F3311. [2] Holby, E. F. et al. Acid stability and demetalation of PGM-Free ORR electrocatalyst structures from density functional theory: a model for “single-atom catalyst” dissolution. ACS Catal. 2020, 10: 14527-14539. [3] Bae, G. et al. PH effect on the H2O2-induced deactivation of Fe-N-C catalysts. ACS Catal. 2020, 10: 8485-8495. [4] Kumar, K. et al. On the influence of oxygen on the degradation of Fe‐N‐C catalysts. Angew. Chem. 2020, 132: 3261-3269. [5] Choi, C. H. et al. Stability of Fe‐N‐C catalysts in acidic medium studied by operando spectroscopy. Angew. Chem. Int. Ed. 2015, 54: 12753-12757. [6] Choi, C. H. et al. The Achilles' heel of iron-based catalysts during oxygen reduction in an acidic medium. Energy Environ. Sci. 2018, 11: 3176-3182. [7] Li, J. et al. Identification of durable and non-durable FeNx sites in Fe–N–C materials for proton exchange membrane fuel cells. Nat. Catal. 2021, 4: 10-19. [8] Chenitz, R. et al. A specific demetalation of Fe–N4 catalytic sites in the micropores of NC_Ar + NH3 is at the origin of the initial activity loss of the highly active Fe/N/C catalyst used for the reduction of oxygen in PEM fuel cells. Energy Environ. Sci. 2018, 11: 365-382. [9] Zhang, Gaixia, et al. Is iron involved in the lack of stability of Fe/N/C electrocatalysts used to reduce oxygen at the cathode of PEM fuel cells? Nano Energy, 2016, 29: 111-125. [10] Ehelebe, K. et al. Platinum dissolution in realistic fuel cell catalyst layers. Angew. Chem. Int. Ed. 2021, 60: 8882-8888. [11] Ku, Y.-P. et al. Oxygen reduction reaction causes iron leaching from Fe-N-C electrocatalysts. 2021 Submitted, DOI: 10.21203/rs.3.rs-1171081/v1.
7
Calizzi, Marco, Robin Mutschler, Nicola Patelli, Andrea Migliori, Kun Zhao, Luca Pasquini, and Andreas Züttel. "CO2 Hydrogenation over Unsupported Fe-Co Nanoalloy Catalysts." Nanomaterials 10, no. 7 (July 11, 2020): 1360. http://dx.doi.org/10.3390/nano10071360.
Анотація:
The thermo-catalytic synthesis of hydrocarbons from CO2 and H2 is of great interest for the conversion of CO2 into valuable chemicals and fuels. In this work, we aim to contribute to the fundamental understanding of the effect of alloying on the reaction yield and selectivity to a specific product. For this purpose, Fe-Co alloy nanoparticles (nanoalloys) with 30, 50 and 76 wt% Co content are synthesized via the Inert Gas Condensation method. The nanoalloys show a uniform composition and a size distribution between 10 and 25 nm, determined by means of X-ray diffraction and electron microscopy. The catalytic activity for CO2 hydrogenation is investigated in a plug flow reactor coupled with a mass spectrometer, carrying out the reaction as a function of temperature (393–823 K) at ambient pressure. The Fe-Co nanoalloys prove to be more active and more selective to CO than elemental Fe and Co nanoparticles prepared by the same method. Furthermore, the Fe-Co nanoalloys catalyze the formation of C2-C5 hydrocarbon products, while Co and Fe nanoparticles yield only CH4 and CO, respectively. We explain this synergistic effect by the simultaneous variation in CO2 binding energy and decomposition barrier as the Fe/Co ratio in the nanoalloy changes. With increasing Fe content, increased activation temperatures for the formation of CH4 (from 440 K to 560 K) and C2-C5 hydrocarbons (from 460 K to 560 K) are observed.
8
Fidelis, Michel, Eduardo Abreu, Onélia Dos Santos, Eduardo Chaves, Rodrigo Brackmann, Daniele Dias, and Giane Lenzi. "Experimental Design and Optimization of Triclosan and 2.8-Diclorodibenzeno-p-dioxina Degradation by the Fe/Nb2O5/UV System." Catalysts 9, no. 4 (April 8, 2019): 343. http://dx.doi.org/10.3390/catal9040343.
Анотація:
This study describes the experimental design and optimization of the photocatalytic reaction using the immobilized catalyst Fe/Nb2O5 in the degradation of Triclosan and 2.8-DCDD. The techniques employed to characterize the photocatalysts were: specific surface area, average pore volume, average pore diameter, photo-acoustic spectroscopy (PAS), X-ray diffraction (XRD), and scanning electron microscopy (SEM/EDS). The reaction parameters studied were pH, catalyst concentration, catalyst calcination temperature, and nominal metallic charge. The results indicated that the immobilized Fe/Nb2O5 catalysts were efficient in the degradation of Triclosan and 2.8-dichlorodibenzene-p-dioxin. The catalysts with nominal metal loading of 1.5% Fe calcined at 873 K showed the highest constant reaction rate and the lowest half-life 0.069 min−1 and 10.04 min. Tests in different matrices indicated that the photocatalytic reaction using aqueous solution containing Cl− is faster when compared with the ultrapure water matrix.
9
Nam, Sang-Sung, Gurram Kishan, Myung-Woo Lee, Myoung-Jae Choi, and Kyu-Wan Lee. "Selective Synthesis of C2–C4 Olefins and C5+ Hydrocarbons over Unpromoted and Cerium-promoted Iron Catalysts Supported on Ion Exchanged (H, K) Zeolite-Y." Journal of Chemical Research 23, no. 5 (May 1999): 344–45. http://dx.doi.org/10.1177/174751989902300524.
Анотація:
Hydrogenation of CO2 to hydrocarbons is carried out on unpromoted and Ce-promoted iron catalysts supported on ion exchanged (H, K) zeolite-Y; the results suggest that the Fe–Ce/KY catalyst has significant advantages being highly selective for C2–C4 olefins and C5+ hydrocarbons.
10
Cai, Binxiang, Huazhang Liu, and Wenfeng Han. "Solution Combustion Synthesis of Fe2O3-Based Catalyst for Ammonia Synthesis." Catalysts 10, no. 9 (September 7, 2020): 1027. http://dx.doi.org/10.3390/catal10091027.
Анотація:
Fe2O3-based catalysts were prepared by solution combustion synthesis (SCS) with metal nitrates (Fe, K, Al, Ca) as the precursors and glycine as the fuel. The activities of catalysts were evaluated in terms of ammonia synthesis reaction rate in a fixed bed reactor similar to the industrial reactors. The results indicate that the precursor of catalyst prepared by SCS is Fe2O3 which facilitates the high dispersion of promoters to provide high activity. The catalysts exhibit higher activity for ammonia synthesis than that of traditional catalysts, and the reaction rate reaches 138.5 mmol g−1 h−1. Fe2O3 prepared by SCS could be favorable precursor for ammonia synthesis catalyst. The present study provides a pathway to prepare catalyst for ammonia synthesis.
Дисертації з теми "K-Fe catalysts":
1
EDUARDO, Raphael da Silva. "Avaliação dos catalisadores Fe/Cu/K/SBA-15TEOS e Fe/Cu/K/SBA-15CCA na síntese de Fischer-Tropsch." Universidade Federal de Campina Grande, 2014. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/528.
Анотація:
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-30T16:52:44Z
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Capes
A síntese de Fischer-Tropsch, reação de polimerização de gás de síntese na presença de um catalisador, se apresenta como uma oportunidade sustentável de geração de combustíveis de alta qualidade. Diante da necessidade de desenvolvimento de novos materiais, este trabalho tem como objetivo avaliar o desempenho de catalisadores Fe/Cu/K/SBA-15TEOS e Fe/Cu/K/SBA-15CCA na síntese de Fischer-Tropsch. Os catalisadores foram preparados utilizando peneiras moleculares do tipo SBA-15 como suporte, sintetizadas com diferentes fontes de sílica (tetraortosilicato-TEOS e cinzas da casca de arroz-CCA). Os metais foram impregnados por via úmida, utilizando sais como precursores metálicos. As peneiras moleculares SBA-15TEOS e SBA-15CCA foram caracterizadas por Difração de raios X (DRX), Espectrometria de raios x de Energia Dispersiva (EDX), Microscopia Eletrônica de Varredura (MEV) e Capacidade de Adsorção Física de Nitrogênio (BET). Os catalisadores Fe/Cu/K/SBA-15TEOS e Fe/Cu/K/SBA-15CCA foram caracterizados por Difração de raios X (DRX), Espectrometria de raios x de Energia Dispersiva (EDX), Capacidade de Adsorção Física de Nitrogênio (BET) e Redução a Temperatura Programada (RTP). Pelos resultados obtidos, a peneira molecular SBA-15CCA se assemelhou à SBA-15TEOS, sendo caracterizadas como materiais mesoporosos de morfologia típica, porém com resultados distintos de área específica (490 m2/g para SBA-15TEOS e 112 m2/g para SBA-15CCA). Os catalisadores apresentaram composições de sílica, ferro, cobre e potássio nas proporções pré-definidas e boa dispersão sobre a peneira molecular, a qual manteve sua estrutura mesoporosa, porém com redução de área específica após impregnação (257,3 m2/g para Fe/Cu/K/SBA-15TEOS, 91,7 m2/g para Fe/Cu/K/SBA15CCA). Pelos resultados de RTP, foi possível verificar as faixas de temperatura de redução típicas das fases óxidas do ferro e a influência do cobre nesse processo. A avaliação catalítica na síntese de Fischer-Tropsch foi satisfatória na razão molar H2/CO de 1:1, convergindo a altas frações de hidrocarbonetos líquidos. O catalisador Fe/Cu/K/SBA-15TEOS proporcionou excelente conversão a hidrocarbonetos de frações mais pesadas C10+ (78,18%); o catalisador Fe/Cu/K/SBA-15CCA apresentou moderada conversão a hidrocarbonetos líquidos C5+ (54,47%).
The Fischer-Tropsch polymerization reaction of synthesis gas in the presence of a catalyst, is presented as a sustainable opportunity to generate high quality fuels. Given the need for development of new materials, this work aims to evaluate the performance of catalysts Fe/Cu/K/SBA-15TEOS and Fe/Cu/K/SBA-15CCA in Fischer-Tropsch synthesis. The catalysts were prepared using molecular sieves type SBA-15 as support, synthesized with different silica sources (TEOS - tetraortosilicate and rice husk ash - CCA). The metals were impregnated wet method using metal salts as precursors. The molecular sieves SBA-15TEOS and SBA-15CCA were characterized by X-ray diffraction (XRD), X-ray Spectrometry Energy Dispersive (EDX), Scanning Electron Microscopy (SEM) and Physical Adsorption Capacity of Nitrogen (BET). The Fe/Cu/K/SBA-15TEOS and Fe/Cu/K/SBA-15CCA catalysts were characterized by X-ray diffraction (XRD), X-ray Spectrometry Energy Dispersive (EDX), Physical Adsorption Capacity of Nitrogen (BET) and Temperature Programmed Reduction (TPR). From the results obtained, the molecular sieve SBA15CCA resembled the SBA-15TEOS, being characterized as mesoporous materials typical morphology, but with different results of specific area (490 m2/g for SBA15TEOS and 112 m2/g for SBA- 15CCA). The catalysts showed compositions of sílica, iron, potassium and copper in pre-defined and good dispersion of the molecular sieve, which retained its mesoporous structure proportions, but with reduced specific area after impregnation (257.3 m2/g for Fe/Cu/K/SBA-15TEOS 91.7 m2/g for Fe/Cu/K/SBA-15CCA); By the TPR results, it was possible to check the temperature ranges typical reduction of iron oxides phases and the influence of copper in this process. The catalytic reviewed in Fischer-Tropsch synthesis was satisfactory molar ratio H2/CO of 1:1, the converging high fractions of liquid hydrocarbons. The catalyst Fe/Cu/K/SBA-15TEOS provided excellent conversion to hydrocarbons heavier fractions C10+ (78.18%); Fe/Cu/K/SBA-15CCA catalyst showed moderate conversion to liquid hydrocarbons C5+ (54.47%).
2
Panzone, Carlotta. "Etude et optimisation du procédé d’hydrogénation du dioxyde de carbone en hydrocarbures gazeux et liquides." Thesis, Lyon, 2021. https://tel.archives-ouvertes.fr/tel-03789618.
Анотація:
Cette thèse porte sur l'étude de la réaction d'hydrogénation du dioxyde de carbone vers des hydrocarbures gazeux et liquides sur un catalyseur supporté K-Fe/Al2O3. Le sujet s'inscrit dans le cadre des technologies Power-to-X qui visent à stocker les excès d’énergie électrique issue des énergies renouvelables sous forme de composés chimiques gazeux et liquides. En particulier, l'électricité est utilisée pour produire de l'hydrogène via l’électrolyse de l'eau, puis l'hydrogène obtenu est utilisé pour convertir le dioxyde de carbone en hydrocarbures. Ces hydrocarbures peuvent avoir des applications comme matière première dans l'industrie chimique ou comme carburants dans le domaine des transports. L'hydrogénation du dioxyde de carbone est une réaction catalytique, généralement réalisée sur des catalyseurs à base de fer, et s’effectue en deux étapes : d'abord, le dioxyde de carbone est converti en monoxyde de carbone via la réaction inverse de conversion eau-gaz (RWGS), puis le monoxyde de carbone est transformé en hydrocarbures via la synthèse Fischer-Tropsch (FT). L'une des principales contraintes de cette réaction est sa faible sélectivité, car une grande variété d'hydrocarbures peut être obtenue. Pour une éventuelle application de ce procédé à l'échelle industrielle, il est nécessaire de comprendre comment la sélectivité de la réaction pourrait être orientée vers la formation des produits visés. Dans ce travail, une étude expérimentale à l'échelle du laboratoire a été réalisée dans un lit fixe continu et un protocole analytique qui permet la quantification de tous les produits obtenus a été développé. De plus, nous avons développé un modèle macro-cinétique qui décrit avec une approche semi-empirique la formation de tous les produits considérés ; et un modèle micro-cinétique, qui contribue à apporter un éclairage sur les mécanismes de réaction possibles. Enfin, nous avons modélisé un réacteur à plus grande échelle avec des approches hétérogène et pseudo-homogène et nous avons simulé le procédé global pour estimer son bilan carbone et son efficacité énergétiqueThis thesis is focused on the study of the carbon dioxide hydrogenation reaction towards gaseous and liquid hydrocarbons over a supported K-Fe/Al2O3 catalyst. The subject is part of the framework of the Power-to-X technologies that aim at storing surplus electric power derived from renewable energy into the form of gaseous and liquid chemical compounds. In particular, the electricity is used to perform the water electrolysis to produce hydrogen, then the obtained hydrogen is used to convert carbon dioxide into hydrocarbons. These hydrocarbons can have applications as feedstock in the chemical industry or as fuels in the transport field. The carbon dioxide hydrogenation is a catalytic reaction, generally performed over Fe-based catalysts, consisting in two steps: first, carbon dioxide is converted into carbon monoxide via the reverse water-gas shift reaction (RWGS), and then it is further transformed into hydrocarbons via the Fischer-Tropsch synthesis (FT). One of the main constraints of this reaction is its low selectivity, as a variety of hydrocarbons can be obtained. For an eventual application of this process at the industrial scale, it is necessary to deeper understand and better describe the selectivity of the reaction to optimize the productivity of the desired products. In this work, we have carried out an experimental study of the reaction in a lab-scale fixed bed reactor and developed an analytic protocol that allows the quantification of all the products obtained. Moreover, we have developed a macro-kinetic model that describes with a semi-empirical approach the formation of all the products considered; and a micro-kinetic model, that contributes to give insights about the reaction mechanism. Finally, we have modelled a scaled-up reactor with a heterogeneous and a pseudo-homogeneous approach and we have simulated the global process to estimate its carbon and energy efficiencies
3
Farias, Francisco Edson Mesquita. "ProduÃÃo de Hidrocarbonetos atravÃs da SÃntese de Fischer-Tropsch utilizando Catalisadores de Fe/K." Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=1273.
Анотація:
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorA reaÃÃo de sÃntese de Fischer-Tropsch tem merecido grande atenÃÃo pelo seu interesse tecnolÃgico e cientÃfico. Este interesse està associado a conversÃo do gÃs natural em produtos lÃquidos de alta qualidade (gasolina e diesel) e elevado valor agregado. No presente trabalho à descrito a metodologia empregada na sÃntese e caracterizaÃÃo de catalisadores de ferro usados na sÃntese de Fischer-Tropsch, com Ãnfase nos catalisadores suportados em sÃlica e catalisadores industriais (utilizados na sÃntese de amÃnia) promovidos com potÃssio e cobre. Pretende-se com esta discussÃo, identificar possÃveis vias para o desenvolvimento de catalisadores mais ativos e seletivos, variando a composiÃÃo do promotor estrutural para fins de otimizar a distribuiÃÃo dos produtos em fraÃÃes de hidrocarbonetos especÃficos (gasolina, diesel e graxa). A reaÃÃo foi conduzida em um reator de leito de lama. O estudo seguiu um planejamento experimental do tipo fatorial quadrado com ponto central e os resultados foram analisados baseados na metodologia dos grÃficos de superfÃcie de respostas. Os efeitos das diferentes condiÃÃes operacionais (temperatura e pressÃo) e dos diferentes teores de potÃssio na distribuiÃÃo dos produtos lÃquidos foram comparados baseados nos cromatogramas, nÃmero mÃdio de carbono (Nn) e no grau de dispersÃo dos produtos. Para todos os catalisadores de ferro empregados neste trabalho, observou-se um aumento no Ãndice que representa o comprimento da cadeia de hidrocarboneto (Nn) com o aumento do teor de potÃssio. Indicando um maior grau de polimerizaÃÃo para os catalisadores de ferro suportados com 18K em ralaÃÃo aos outros (12K, 6K e industrial). Os resultados mostram que, para catalisadores suportados, em pressÃes elevadas (25 e 30atm) favorecem a produÃÃo de graxa, enquanto a seletividade para hidrocarbonetos lÃquidos à favorecida a baixa pressÃo (20atm) e baixa temperatura (240ÂC). Para os catalisadores industriais, observou-se um aumento na fraÃÃo graxa em baixas temperaturas (240-255ÂC) e elevadas pressÃes (30atm). Contudo, os resultados de todas as corridas para o catalisador suportado e o industrial promovido e nÃo-promovido apresentaram quantidades significativas de n-parafinas com no mÃximo 35 Ãtomos de carbono que pode ser causados atravÃs das limitaÃÃes geomÃtricas e espaciais dentro dos poros do catalisador que tambÃm podem explicar o motivo pelo qual o Ãndice de dispersÃo da distribuiÃÃo de hidrocarbonetos serem mais baixos para um maior nÃmero de carbonos mÃdio.
The Fischer-Tropsch synthesis has been focus of attention of the scientific and industrial community. This interest is related to the conversion of natural gas into high quality liquid products, such as gasoline and diesel, which have high commercial value. In this work the methodology applied to synthesize and characterize iron-based catalyst used in the Fischer-Tropsch synthesis was described. Emphasis was given to catalysts supported in silica and to industrial catalysts (used in the synthesis of ammonia) impregnated with potassium and copper. The catalysts were tested to identify more active and selective catalysts, changing the amount of structural promoter in order to optimize the product distribution of specific hydrocarbons (gasoline, diesel, wax). The reaction was carried out in a slurry phase reactor. The experiments followed a 22 factorial experimental planning with central point and the results were analyzed based on the surface response methodology. The effects of the operating conditions (temperature and pressure) and of the amount of potassium in the catalyst on the liquid product distribution were compared based on the chromatographs, number average number of carbons (Nn) and distribution dispersion. In all iron based catalyst used in the research, the number average number of carbons (Nn) increased with increasing amount of potassium in the catalyst formulation. This result indicates that the catalyst with 18 K supported in silica showed the highest degree of polymerization in comparison with all other catalysts produced in this research. The results showed that for the catalyst supported in silica high pressures (25 to 30 atm) favor the production of wax, while higher selectivity towards liquid fuels was favored by low pressure (20 atm) and low temperature (240ÂC). For the industrial catalyst, an increase in the wax cat was observed at low temperatures (240-255ÂC) and high pressures (30 atm). The experiments carried out with the both catalysts (silica-supported and alumina-supported) have presented significant amounts of n-paraffins with a maximum of 35 carbons and low dispersion of the product distribution which can be caused by space limitations within the catalyst pores.
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Farias, Francisco Edson Mesquita. "ProduÃÃo de hidrocarbonetos atravÃs da sÃntese de Fischer-Tropsch utilizando catalisadores bimetÃlicos de Fe/Co dopados com K e Cu." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8322.
Анотація:
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorA reaÃÃo de sÃntese de Fischer-Tropsch tem merecido grande atenÃÃo pela sua aplicaÃÃo no Ãmbito tecnolÃgico e cientÃfico. Este interesse està associado à conversÃo do gÃs natural em produtos lÃquidos de alta qualidade (gasolina e diesel) e elevado valor agregado. No presente trabalho à descrito a metodologia empregada na sÃntese e caracterizaÃÃo de catalisadores bimetÃlicos, com alto teor da fase ativa de ferro e cobalto, usados na sÃntese de Fischer-Tropsch, suportados em sÃlica promovidos com potÃssio e cobre com diferentes proporÃÃes em base molar. O uso de catalisadores de ferro utilizados na sÃntese de Fischer-Tropsch tem sido estudado por muitos pesquisadores, os resultados tÃm mostrado que estes possuem um desempenho satisfatÃrio na produÃÃo de combustÃveis lÃquidos. Entretanto, pesquisas mostram que os catalisadores de cobalto sÃo mais eficientes na produÃÃo de hidrocarbonetos de cadeia longa e linear em relaÃÃo ao ferro. Contudo, catalisadores a base de cobalto sÃo mais caros comparados aos de ferro. Uma relaÃÃo custo/benefÃcio tem que ser atingida na fabricaÃÃo de catalisadores de tal forma que tenhamos uma otimizaÃÃo da produÃÃo de combustÃveis sintÃticos de elevado peso molecular sem muitos gastos com o catalisador. Pretende-se com esta discussÃo, identificar possÃveis vias para o desenvolvimento de catalisadores mais ativos e seletivos, variando a composiÃÃo do promotor estrutural para fins de otimizar a distribuiÃÃo dos produtos (diesel e graxa). A reaÃÃo foi conduzida em um reator de leito de lama. O estudo seguiu um planejamento experimental do tipo fatorial quadrado com ponto central e os resultados foram analisados baseados na metodologia de anÃlises de superfÃcies de respostas. Os efeitos das diferentes condiÃÃes operacionais (temperatura e pressÃo) e dos diferentes teores de potÃssio e cobre na distribuiÃÃo dos produtos lÃquidos foram comparados baseados nos cromatogramas, nÃmero mÃdio de carbono (Nn). Diante dos testes realizados com os catalisadores bimetÃlicos (Fe/Co) dopados com diferentes teores de potÃssio e/ou cobre, chegou-se a uma melhor relaÃÃo entre os metais (K,Cu) para sÃntese de um catalisador mais eficiente (50Fe/50Co/12K/5Cu/139SiO2). Sendo que o objetivo desta formulaÃÃo bimetÃlica, obter vantagens de possÃveis efeitos sinergÃticos entre os dois metais (Fe/Co) e seus promotores estruturais.
The reaction of Fischer-Tropsch synthesis has received great attention for its application in technology and science. This interest is associated with conversion of natural gas into high quality liquid products (gasoline and diesel) and high added value. In the present paper describes the methodology employed in the synthesis and characterization of bimetallic catalysts with high levels of the active phase of iron and cobalt, used in the synthesis of Fischer-Tropsch, supported on silica promoted with potassium and copper with different ratios on a molar basis. The use of iron catalysts used in the Fischer-Tropsch synthesis has been studied by many researchers, the results have shown that these have a satisfactory performance in the production of liquid fuels. However, studies have shown that cobalt catalysts are most effective in producing long-chain hydrocarbons and linear with respect to iron. However, the cobalt-based catalysts are more expensive compared to iron. A cost / benefit ratio has to be reached in the manufacture of catalysts which have such an optimization of production of synthetic fuels of high molecular weight inexpensively with the catalyst. The intention with this discussion, identify possible pathways for the development of more active and selective catalysts, varying the composition of the promoter structure for purposes of optimizing the distribution of products (diesel and grease). The reaction was conducted in a reactor bed of mud. The study followed an experimental planning factorial central square and the results were analyzed based on the methodology of the analysis of response surfaces. The effects of different operating conditions (temperature and pressure) and different concentrations of potassium and copper in the distribution of liquid based on the chromatograms were compared, average carbon number (Nn). Before the tests with the bimetallic catalysts (Fe / Co) doped with different concentrations of potassium and / or copper, it was a better relationship between the metals (K, Cu) for the synthesis of a more efficient catalyst (50Fe/50Co/12K/5Cu/139SiO2). Since the goal of this formulation bimetallic take advantage of possible synergistic effects between the two metals (Fe / Co) and its structural promoters.
Частини книг з теми "K-Fe catalysts":
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Venter, J., M. Kaminsky, G. L. Geoffroy, and M. A. Vannice. "Preparation of Carbon-Supported K-Fe-Mn and Fe-Mn Catalysts Using Carbonyl Clusters." In Preparation of Catalysts IV, Proceedings of the Fourth International Symposium, 479–91. Elsevier, 1987. http://dx.doi.org/10.1016/s0167-2991(08)65430-0.
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Kaŀucki, K., A. W. Morawski, and w. Arabczyk. "Preparation of K-C-Fe/Al2O3 catalysts for ammonia synthesis at mild conditions." In Studies in Surface Science and Catalysis, 131–40. Elsevier, 1995. http://dx.doi.org/10.1016/s0167-2991(06)81750-7.
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Dziewiçcki, Z., and E. Ozdoba. "Some Remarks on the Preparation of Fe-K/Ca-Cr Catalyst for Styrene Production." In Preparation of Catalysts V - Scientific Bases for the Preparation of Heterogeneous Catalysts, Proceedings of the Fifth International Symposium, 113–22. Elsevier, 1991. http://dx.doi.org/10.1016/s0167-2991(08)64578-4.
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Park, S. E., E. K. Shim, K. W. Lee, and P. S. Kim. "Formation of methylformate during hydrogenation of CO2 over Cu/ZnO/Al2O3 and K-Fe/L zeolite catalysts." In Studies in Surface Science and Catalysis, 1595–602. Elsevier, 1994. http://dx.doi.org/10.1016/s0167-2991(08)63708-8.
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Li, Senzi, George D. Meitzner, and Enrique Iglesia. "Fischer-Tropsch synthesis catalysts based on Fe oxide precursors modified by Cu and K: structure and site requirements." In Natural Gas Conversion VI, 387–92. Elsevier, 2001. http://dx.doi.org/10.1016/s0167-2991(01)80334-7.
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Ma, Wenping, Edwin L. Kugler, and Dady B. Dadyburjor. "Effect of Mo Loading and Support Type on Hydrocarbons and Oxygenates Produced Over Fe-Mo-Cu-K Catalysts Supported on Activated Carbons." In Studies in Surface Science and Catalysis, 125–40. Elsevier, 2007. http://dx.doi.org/10.1016/s0167-2991(07)80476-9.
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Badani, M. V., L. M. Eshelman, and W. N. Delgass. "Acetonitrile Synthesis from CO, H2 and NH3 Over Fe/C and K,Fe/C." In Studies in Surface Science and Catalysis, 1223–34. Elsevier, 1993. http://dx.doi.org/10.1016/s0167-2991(08)64446-8.
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Dalton, David R. "The Soil." In The Chemistry of Wine. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190687199.003.0012.
Анотація:
The widespread practices of viniculture (the study of production of grapes for wine) and oenology (the study of winemaking) affirm the generalization that grapevines have fewer problems with mineral deficiency than many other crops. Only occasionally is the addition of iron (Fe), phosphorus (P), magnesium (Mg), and manganese (Mn) supplements to the soil needed. Addition of potassium (K), zinc (Zn), and boron (B) to the soil is more common. And, of course, nitrogen (N) is critical for the production of proteins. Over the years, various transition metals (metals in groups three through twelve [3– 12] of the periodic table, Appendix 1) have been shown to be generally important. These groups include iron (Fe), magnesium (Mg), manganese (Mn), zinc (Zn), and copper (Cu). Many metals are bound to organic molecules that are important for life. Some of the metals, such as copper (Cu) and iron (Fe), are important in electron transport while others, including manganese (Mn) and iron (Fe), inhibit reactive oxygen (O) species (ROSs) that can destroy cells. Metals serve both to cause some reactions to speed up, called positive catalysis while caus¬ing others (e.g., unwanted oxidation) to slow down (negative catalysis). It is not uncommon to add nitrogen (N), in the form of ammonium salts such as ammonium nitrate (NH4NO3), as fertilizer to the soil in which the vines are growing. It is also common to increase the nitrogen (N) content in the soil by planting legumes (legumes have roots that are frequently colonized by nitrogen-fixing bacteria). Nitrogen- fixing bacteria convert atmospheric nitrogen (N2), which plants cannot use, to forms, such as ammonia (NH3) or its equivalent, capable of absorption by plants. Nitrogen, used in plant proteins, tends to remain in the soil after harvest or decomposition. With sufficient nitrogen present in the soil the growth cycle can begin again in the following season without adding too much fertilizer. In a more general sense, however, it is clear (as mentioned earlier) that the soil must be capable of good drainage so the sub-soil parts of the plant do not rot and it must be loose enough to permit oxygen to be available to the growing roots.
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Longya, Xu, Wang Qingxia, Liang Dongbai, Wang Xing, Lin Liwu, Cui Wei, and Xu Yide. "CO2 Hydrogenation for the Production of Light Alkenes over K-Fe-Mn/silicalite-2 catalyst." In Natural Gas Conversion V, Proceedings ofthe 5th International Natural Gas Conversion Symposium,, 221–26. Elsevier, 1998. http://dx.doi.org/10.1016/s0167-2991(98)80435-7.
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Taber, Douglass. "Best Synthetic Methods: Oxidation." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0005.
Анотація:
Although the enantioselective oxidation of alkyl aryl sulfides is well developed, much less is known about dialkyl sulfides. Tsutomu Katsuki of Kyushu University has designed (J. Am. Chem. Soc. 2007, 129, 8940) an Fe(salan) complex that combines with aqueous H2O2 to oxidize alkyl methyl sulfides in high ee. The oxidation of alcohols to aldehydes and ketones is one of the most widely practiced of synthetic transformations. Ge Wang of the University of Science and Technology in Beijing has developed (Chem. Lett. 2007, 36, 1236) a Mo catalyst that used aqueous H2O2 to effect this transformation. Secondary alcohols are oxidized more rapidly than primary alcohols. Vinod K. Singh of the Indian Institute of Technology, Kanpur, has found (Synth. Comm. 2007, 37, 4099) that the solid, inexpensive 6 can take the place of oxalyl chloride in the Swern oxidation. Viktor V. Zhdankin of the University of Minnesota, Duluth has devised (J. Org. Chem. 2007, 72, 8149) a polymer-bound hypervalent iodine reagent that is easily separated after use, and reoxidized for reuse. Enones such as 11 are versatile intermediates for organic synthesis. Makoto Tokunaga, now at Kyushu University, and Yasushi Tsuji, now at Kyoto University, have found (Tetrahedron Lett. 2007, 48, 6860) a Pd catalyst that, in the presence of O2 , will oxidize a cyclic ketone such as 10 to the enone. The direct oxidation of an alcohol to the acid is not always an efficient process, so the conversion of 12 to 13 would often be carried out over at least three steps. David Milstein of the Weizmann Institute of Science has devised (Science 2007, 317, 790) a Ru catalyst that effected the transformation in a single step, generating H2 as a byproduct as the oxidation proceeded. The oxidation of an aldehyde to the corresponding amide is also a useful transformation. Noritaka Mizuno of the University of Tokyo has designed (Angew. Chem. Int. Ed. 2007, 46, 5202) a Rh catalyst that can combine, in water, the aldehyde 14 and NH2OH to give the primary amide 15 . Johann Chan of Amgen Inc., Thousand Oaks, CA has found (J. Am. Chem. Soc. 2007, 129, 14106) a different Rh catalyst that mediated the oxidation of a sulfonamide to the nitrene, which under the reaction conditions inserted into the aldehyde H to give the amide 17.
Тези доповідей конференцій з теми "K-Fe catalysts":
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Oyinbo, Sunday Temitope, Tien-Chien Jen, Patrick Ehi Imoisili, and Peter Ozaveshe Oviroh. "An Atomic-Scale Investigation of the Temperature Influence on the Reactivity of Alkaline Water Electrolysis on an Optimized Nickel-Iron Catalyst Surface for the Hydrogen Generation." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-68795.
Анотація:
Abstract The temperature influence on the reactivity of alkaline potassium hydroxide (KOH) solution on a heterometallic NiFe surface was investigated with the aid of ReaxFF potential is performed using reactive molecular dynamics (RMD) simulations, with a particular focus on H2 generation. In this study, the hydrogen generation in the presence of Ni-doped with transition metals such as Fe in the temperature range 500–1500 K through steam water electrolysis was investigated. The composition of the surface was systematically altered by the integration of the second metal (Fe) into the monometallic (Ni) surfaces. A series of well-dispersed and uniform NiFe heterometallic nanocrystals with a 50 % surface ratio were successfully prepared by size control as model catalysts. Systematic electrochemical assessments found that the reactivity of the alkaline hydrogen evolution reaction was strongly dependent on the temperature increase to achieve optimum efficiency. Hydrogen molecules are also the most formed species at all temperature. The alloy catalyst efficiency in H2 generation rate increases with temperature. Hence, this study highlights the significance of temperature in the process of steam-water electrolysis, an important step towards successful H2 formation as a clean energy source.
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Atibeh, Ehsan Abbasi, and Ahmet Yozgatligil. "Combustion Characteristics of Biomass Ash and Lignite Blend Under Oxy-Fuel Conditions." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-65182.
Анотація:
In this study an attempt was done to profoundly explore the pyrolysis and combustion behaviors and emission characteristics of lignite samples in O2/N2 and O2/CO2 (oxy-fuel conditions) ambients. A special focus was allocated to the effects of three inorganic materials, potassium (K), calcium (Ca) and iron (Fe) on combustion characteristics of Turkish lignite using non-isothermal Thermo-gravimetric Analysis (TGA) technique combined with Fourier Transform Infrared (FTIR) spectroscopy and the effects of ambient gases and various oxygen mole fractions were considered. Eventually the co-processing combustion tests of lignite and the ash contents of different biomass fuels were investigated and the possible way of using biomass as a potential source of inexpensive catalysts in combustion processes were discussed. Co-processing combustion tests of lignite and biomass ash contents indicated that the hazelnut shell and walnut shell ash contents were significantly effective in increasing the char reactivity of lignite due to high concentration of potassium based oxides during combustion tests carried out in both air and 30% O2 in CO2 ambients. Furthermore the catalytic reactivity of wheat straw and cattle manure ash contents were observed in the second region of combustion regarding volatile matter release and combustion in both air and 30% O2 in CO2 ambients. These results are thought to be due to high concentrations of Alkali and Alkaline earth metals existed in the impregnated lignite samples with wheat straw and cattle manure ash contents and especially Na-based oxides in the cattle manure form. Finally in the case of lignite sample impregnated with saw dust ash content, it was observed that the impregnated lignite was significantly more reactive in devolatalization process in 30% O2 in CO2 ambients. These results revealed that the ash contents of walnut and hazelnut shell biomass fuels can be used as a potential source of inexpensive K-based catalysts in the co-processing of coal and biomass ash. Furthermore high concentrations of Alkali and Alkaline earth metals existed in the ash contents of biomass fuels like wheat straw, cattle manure and saw dust can make them suitable sources of inexpensive catalysts and develop a step forward in economic aspects of catalytic coal combustion.
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Aluvihara, Suresh, C. S. Kalpage, and P. W. S. K. Bandaranayake. "The elementary characterization of anthill clay for composite materials." In The 8th International Conference on Advanced Materials and Systems. INCDTP - Leather and Footwear Research Institute (ICPI), Bucharest, Romania, 2020. http://dx.doi.org/10.24264/icams-2020.i.2.
Анотація:
Anthill clay is a distinct soil/clay genre among common soil types because of the extraordinary stockpiling method. The small particles are carried in and erected an anthill by a small creature that it is called as termite. In generally, clay is a conspicuous raw material for industrial applications greatly and the assay of expediencies of anthill clay for advanced material applications were the prospects of the existing research. Carefully collected anthill clay samples were characterized under the physically and chemically using standard procedures and instruments. The mechanical characteristics of prepared bricks from anthill clays under 8000C were investigated. As the major outcomes of the existing investigation of raw clays, there were looked to 5.56 of PH value, 15% of natural moisture content, gap graded and symmetrically distributed arrangement of grains, 60% finer particle percentage (<0.075mm) according to the weight, composition of Fe, Ti, Ba and K based compounds including Fe minerals with large sorption capacity for other metals. In addition that 25% of water absorption, 2.62 of bulk specific gravity, 65% of apparent porosity, 21 Mpa compressive strength and 0.4 Mpa splitting tensile strength were observed with respect to the bricks which were prepared from the anthill clay. Based on the behaviors of such anthill clay it should be an influential material in the advanced material manufacturing in the industrial purposes such as the water treatments, rigid materials, catalysts and refractors.