Academic literature on the topic 'Carbène NHC'
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Journal articles on the topic "Carbène NHC"
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Alauddin, Mohammad, and Mazharul M. Islam. "A computational characterization of N-heterocyclic carbenes for catalytic and nonlinear optical applications." Zeitschrift für Naturforschung B 79, no. 4 (2024): 215–23. http://dx.doi.org/10.1515/znb-2023-0092.
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Abstract Very recently, N-heterocyclic carbenes (NHCs) have found a wide range of applications in the fields of catalysis and nonlinear optics. Herein, we have employed 1,3-bis-(1(S)-benzyl)-4,5-dihydro-imidazol-based carbene as a reference molecule and substituted one H atom from each CH2 of the benzyl groups in both sides by CH3, NH2, and CF3 to study the thermodynamic and opto-electronic properties of NHCs theoretically. It was observed that the enthalpy (H), Gibb’s free energy (G), specific heat capacity (C v), and entropy (S) increase significantly in the presence of the electron-withdrawing groups compared to the electron-donating groups. The IR active in-plane bending vibrations of the CH (NHC) group are shifted to the higher frequency region for the considered substituted molecules compared to the reference carbene. The analysis of the electronic properties shows that the CH3-substituted carbene is more reactive for catalytic activities compared to other NHCs. The calculated nonlinear optical (NLO) properties reveal that the NH2-substituted NHC has the largest hyperpolarizability value whereas the CH3-substituted NHC has the largest dipole moment and polarizability among all, making them potential candidates for the development of NLO materials.
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Mokfi, Moloud, Jörg Rust, Christian W. Lehmann, and Fabian Mohr. "Facile N9-Alkylation of Xanthine Derivatives and Their Use as Precursors for N-Heterocyclic Carbene Complexes." Molecules 26, no. 12 (2021): 3705. http://dx.doi.org/10.3390/molecules26123705.
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The xanthine-derivatives 1,3,7-trimethylxanthine, 1,3-dimethyl-7-benzylxanthine and 1,3-dimethyl-7-(4-chlorobenzyl)xanthine are readily ethylated at N9 using the cheap alkylating agents ethyl tosylate or diethyl sulfate. The resulting xanthinium tosylate or ethyl sulfate salts can be converted into the corresponding PF6- and chloride salts. The reaction of these xanthinium salts with silver(I) oxide results in the formation of different silver(I) carbene-complexes. In the presence of ammonia, ammine complexes [Ag(NHC)(NH3)]PF6 are formed, whilst with Et2NH, the bis(carbene) salts [Ag(NHC)2]PF6 were isolated. Using the xanthinium chloride salts neutral silver(I) carbenes [Ag(NHC)Cl] were prepared. These silver complexes were used in a variety of transmetallation reactions to give the corresponding gold(I), ruthenium(II) as well as rhodium(I) and rhodium(III) complexes. The compounds were characterized by various spectroscopic methods as well as X-ray diffraction.
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Longevial, Jean-François, Mamadou Lo, Aurélien Lebrun, Danielle Laurencin, Sébastien Clément, and Sébastien Richeter. "Molecular complexes and main-chain organometallic polymers based on Janus bis(carbenes) fused to metalloporphyrins." Dalton Transactions 49, no. 21 (2020): 7005–14. http://dx.doi.org/10.1039/d0dt00594k.
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Janus bis(N-heterocyclic carbenes) composed of a porphyrin core with two N-heterocyclic carbene (NHC) heads fused to opposite pyrroles were used as bridging ligands for the preparation of metal complexes.
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Jutand, Anny, Julien Pytkowicz, Sylvain Roland, and Pierre Mangeney. "Mechanism of the oxidative addition of aryl halides to bis-carbene palladium(0) complexes." Pure and Applied Chemistry 82, no. 7 (2010): 1393–402. http://dx.doi.org/10.1351/pac-con-09-09-22.
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Bis-N-heterocyclic carbenes Pd0 complexes, Pd0(NHC)2, are efficient catalysts in Heck reactions performed with aryl bromides or chlorides. The Pd0(NHC)2 that are not stable are generated in situ from PdII precursors PdY2(NHC)2 (Y = halides) after a chemical reduction. The latter procedure can be mimicked by an electrochemical reduction. The transient Pd0(NHCBn)2 is generated by electrochemical reduction of PdY2(NHCBn)2, and its reactivity in oxidative addition to aryl bromides and chlorides is characterized by the same electrochemical technique with the determination of the rate constants. Pd0(NHCBn)2 is found to be more reactive than the mixed complex Pd0(NHCBn)(PPh3). Both are the reactive species in an associative mechanism. Comparison with the isolated Pd0(NHCtBu)2 reveals that Pd0(NHCBn)2 is more reactive than Pd0(NHCtBu)2 even if the latter reacts via the mono-carbene Pd0(NHCtBu) in a dissociative mechanism. This suggests that the formation of mono-carbene Pd0(NHC) is not a guarantee for a fast oxidative addition because it is always generated at low concentration in its equilibrium with the related nonreactive bis-carbene Pd0(NHC)2.
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Elvan, Üstün, and Şahin Neslihan. "Molecular docking analysis of N-heterocyclic carbene and silver N-heterocyclic carbene complexes with thioredoxin reductas." Journal of Indian Chemical Society Vol. 97, No. 10c, Oct 2020 (2020): 2013–16. https://doi.org/10.5281/zenodo.5970121.
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Department of Chemistry, Faculty of Art and Science, Ordu University, 52200 Ordu, Turkey Department of Basic Education, Faculty of Education, Cumhuriyet University, 58140 Sivas, Turkey <em>E-mail</em>: elvanustun@odu.edu.tr <em>Manuscript received online 20 October 2020, revised and accepted 31 October 2020</em> Molecular docking is a frequently used method in computer-supported drug design studies. It is possible to obtain useful information about the magnitude and character of the interaction between known targets and bioactive molecules thanks to docking methods. Besides the well-known antibacterial activity of NHC molecules and their Ag-complexes, anti-cancer, and anti-proliferative activity of them have been studied frequently. In anti-cancer studies, the inhibition effects of drug candidate molecules on the growth and proliferation of cancer cell are generally examined. In this study, thioredoxin reductase was selected as a cancer target molecule and interaction of 1-allyl-3-benzylbenzimidazolium, 1-allyl-3-(naphthylmethyl)benzimidazolium, 1-allyl-3-(anthracen-9-yl-methyl)benzimidazolium, Cl[1-allyl-3-benzylbenzimidazolium-2-ylidene]Ag(I), Cl[1-allyl-3- (naphthylmethyl)benzimidazolium-2-ylidene]Ag(I), Cl[1-allyl-3-(anthracen-9-yl-methyl)benzimidazolium-2-ylidene]Ag(I) with thioredoxin reductase were analyzed by molecular docking methods.
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Nonnenmacher, Michael, Dominik M. Buck, and Doris Kunz. "Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes." Beilstein Journal of Organic Chemistry 12 (August 23, 2016): 1884–96. http://dx.doi.org/10.3762/bjoc.12.178.
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Rh(CO)2Cl(NHC) complexes of dipyrido-annelated N-heterocyclic carbenes were prepared. From the C–H coupling constant of the respective imidazolium salts and the N–C–N angle of the N-heterocyclic carbene (NHC), a weaker σ-donor character than that of typical unsaturated NHCs is expected. However, the IR stretching frequencies of their Rh(CO)2Cl complexes suggest an electron-donor character even stronger than that of saturated NHCs. We ascribe this to the extremely weak π-acceptor character of the dipyrido-annelated NHCs caused by the conjugated 14 πe− system that thus allows for an enhanced Rh–CO backbonding. This extremely low π-acceptor ability is also corroborated by the 77Se NMR chemical shift of −55.8 ppm for the respective selenourea, the lowest value ever measured for imidazole derived selenoureas. DFT-calculations of the free carbene confirm the low σ-donor character by the fact that the σ-orbital of the carbene is the HOMO−1 that lies 0.58 eV below the HOMO which is located at the π-system. Natural population analysis reveals the lowest occupation of the pπ-orbital for the saturated carbene carbon atom and the highest for the pyrido-annelated carbene. Going from the free carbene to the Rh(CO)2Cl(NHC) complexes, the increase in occupancy of the complete π-system of the carbene ligand upon coordination is lowest for the pyrido-annelated carbene and highest for the saturated carbene.
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Qie, Boyu, Ziyi Wang, Jingwei Jiang, et al. "Synthesis and characterization of low-dimensional N-heterocyclic carbene lattices." Science 384, no. 6698 (2024): 895–901. http://dx.doi.org/10.1126/science.adm9814.
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The covalent interaction of N-heterocyclic carbenes (NHCs) with transition metal atoms gives rise to distinctive frontier molecular orbitals (FMOs). These emergent electronic states have spurred the widespread adoption of NHC ligands in chemical catalysis and functional materials. Although formation of carbene-metal complexes in self-assembled monolayers on surfaces has been explored, design and electronic structure characterization of extended low-dimensional NHC-metal lattices remains elusive. Here we demonstrate a modular approach to engineering one-dimensional (1D) metal-organic chains and two-dimensional (2D) Kagome lattices using the FMOs of NHC–Au–NHC junctions to create low-dimensional molecular networks exhibiting intrinsic metallicity. Scanning tunneling spectroscopy and first-principles density functional theory reveal the contribution of C–Au–C π-bonding states to dispersive bands that imbue 1D- and 2D-NHC lattices with exceptionally small work functions.
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Ojha, Minita, Shweta Choudhary, and Raj K. Bansal. "3-Benzylbenzothiazolylidene Carbene Catalyzed Isomerization of Dimethyl Maleate to Dimethyl Fumarate: Experimental and Theoretical Results." Current Organocatalysis 7, no. 2 (2020): 108–17. http://dx.doi.org/10.2174/2213337206666191018111354.
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Background: N-Heterocyclic Carbenes (NHCs) have emerged as ubiquitous species having applications in a broad range of fields, including organocatalysis and organometallic chemistry. Since Arduengo and co-workers first isolated a bottlable NHC, namely imidazol-2-ylidene derivative, these nucleophilic species have attained a prominent place in synthetic organic chemistry. The NHC-induced non-asymmetric catalysis has turned out to be a really fruitful area of research in recent years. Methods and Results: The quantitative aspects of the experimental and theoretical investigation of isomerization of dimethyl maleate to dimethyl fumarate catalyzed by an N-heterocyclic carbene (NHC), namely 3-benzylbenzothiazolylidene are being reported for the first time. Dimethyl maleate on treating with 3-benzylbenzothiazolylidene carbene (10 mol%), generated in situ from the reaction of 3- benzylbenzothiazolium bromide with triethylamine in diethyl ether at room temperature under nitrogen atmosphere isomerizes quantitatively to dimethyl fumarate. Theoretical investigation of a model reaction scheme at the wB97XD/6-31+G(d) level reveals that initial attack of the carbene, which is the ratedetermining step, is followed by rotation about the C-C bond in preference to a higher activation free energy path involving proton abstraction. The species so formed splits off the carbene to yield dimethyl fumarate. Eyring equation has been used to rationalize the effect of temperature on the isomerization rate. Conclusions and Perspective: 3-Benzylbenzothiazolylidene carbene catalyzes the isomerization of dimethyl maleate to its trans-isomer. This carbene can be used in other catalytic reactions, such as acyloin condensation and Stetter reaction.
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Zhu, Tingshun, Ke Xu, and Ziyuan Wang. "N-Heterocyclic Carbene-Organocatalyzed Arene Formation: Application in Atroposelective Synthesis of Polysubstituted Benzenes." Synlett 31, no. 10 (2020): 925–32. http://dx.doi.org/10.1055/s-0039-1690814.
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In recent decades, organocatalysis by N-heterocyclic carbenes (NHCs) has emerged as a versatile and powerful method in organic synthesis. As a result of the power of NHC organocatalysis to produce cyclic compounds, polysubstituted benzenes, which are among the most important cyclic compounds in organic chemistry, can be synthesized efficiently and selectively. This article briefly summarizes the history of NHC organocatalysis, including recent developments in benzene-formation methods, and highlights our recent work in atroposelective arene formation by carbene-catalyzed formal [4+2] cycloadditions. We expect that more NHC-catalyzed methods for the synthesis of asymmetric arenes will be developed in the near future, providing shortcuts to syntheses of sophisticated chiral functional molecules with polysubstituted benzene nuclei.
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Rey, Yannick P., and Ryan Gilmour. "Modulating NHC catalysis with fluorine." Beilstein Journal of Organic Chemistry 9 (December 6, 2013): 2812–20. http://dx.doi.org/10.3762/bjoc.9.316.
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Fluorination often confers a range of advantages in modulating the conformation and reactivity of small molecule organocatalysts. By strategically introducing fluorine substituents, as part of a β-fluoroamine motif, in a triazolium pre-catalyst, it was possible to modulate the behaviour of the corresponding N-heterocyclic carbene (NHC) with minimal steric alterations to the catalyst core. In this study, the effect of hydrogen to fluorine substitution was evaluated as part of a molecular editing study. X-ray crystallographic analyses of a number of derivatives are presented and the conformations are discussed. Upon deprotonation, the fluorinated triazolium salts generate catalytically active N-heterocyclic carbenes, which can then participate in the enantioselective Steglich rearrangement of oxazolyl carbonates to C-carboxyazlactones (e.r. up to 87.0:13.0).
Dissertations / Theses on the topic "Carbène NHC"
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Haumesser, Julien. "Synthèse et caractérisation d'assemblages multi-porphyriniques à espaceurs NHC." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-01017421.
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L'objectif de cette thèse a été de mettre au point l'introduction d'azoles en meso d'une porphyrine par couplage d'Ullmann; Divers azoles ont pu être introduit par cette méthode avec de bons rendements, par formation d'une liaison carbone-azote. il a même été possible avec certains azotes de réaliser des doubles couplages d'Ullmann, conduisant ainsi à des 5.15-diazolyle-porphyrines. De plus, ces même conditions réactionnelles ont été utilisées pour introduire un ou deux dérivés donneurs d'électrons (carbazole, phénoxazine, phénothiazine). L'introduction d'imidazole, de triazole et de benzimidazole en meso a permis, après alkylation, d'obtenir des précurseurs de carbènes N-hétérocycles (NHC). La coordination de deux équivalents de NHC sur un sel de palladium conduit à un dimère de porphyrines via coordination exocyclique. La géométrie de coordination trans-anti autour du palladium a été confirmée par l'obtention de la structure radiocristallographique de deux complexes. Les études par électrochimie de ces complexes ont révélé une communication interporphyrinique à l'état fondamental, mise en évidence par une succession de quatre vagues monoélectroniques en oxydation.
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Fernandez, de Larrinoa Patricia. "Synthèse et formulation de complexes NHC-platine ciblant la mitochondrie pour combattre le glioblastome." Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAF037.
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Le glioblastome est la tumeur cérébrale la plus agressive avec un pronostic fatal, principalement à cause des cellules souches cancéreuses. Les médicaments à base de platine, utilisés pour traiter d’autres types de cancers, sont limités par l’apparition d’effets secondaires et le développement de résistances.Les complexes de platine à base de carbène N-hétérocyclique (NHC-Pt) ont été récemment identifiés comme des options thérapeutiques potentielles pour le traitement du glioblastome. Leur efficacité a été démontrée in vitro et in vivo pour éradiquer les cellules souches de glioblastome en ciblant les mitochondries.Dans cette contribution, de nouveaux complexes NHC-Pt ont été synthétisés pour éradiquer à la fois les cellules différenciées et souches de glioblastome. La nanoencapsulation des meilleurs composés a été réalisée pour faire face à leur faible solubilité dans l’eau sans perdre l’activité cytotoxique. Enfin, ces nanovecteurs ont été intégrés dans des hydrogels injectables pour permettre une libération localisée et contrôlée des complexes NHC-Pt<br>Glioblastoma is the most aggressive brain tumor with a fatal prognosis mainly due to cancer stem cells. Platinum-based drugs, used to treat other types of cancer, are limited by the emergence of side effects and the development of resistance.N-heterocyclic carbene platinum (NHC-Pt) complexes have been recently identified as potential therapeutic options for glioblastoma treatment. It has been demonstrated in vitro and in vivo efficacy in eradicating glioblastoma stem cells by targeting mitochondria.In this work, novel NHC-Pt complexes were synthetized to eradicate both glioblastoma differentiated and stem cells. Nanoencapsulation of the best compounds was performed to address poor water solubility without losing the cytotoxic activity. Finally, these nanovectors were integrated into injectable hydrogels to allow a localized and controlled release of the NHC-Pt complexes
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Kong, Lingyu. "De ligands NHCs prochiraux à des complexes métal-NHC énantiopurs : nouvelles perspectives pour la catalyse asymétrique." Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0502.
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Les carbènes N-hétérocycliques (NHC) sont connus pour être de bons ligands des métaux de transition (TM). Dans ce manuscrit, le premier chapitre est consacré une présentation non exhaustive des différentes approches qui ont été utilisées dans la littérature pour le design de NHCs chiraux efficaces en catalyse enantiosélective. Au début du deuxième chapitre, le nouveau concept est présenté. Celui-ci repose sur la formation d’un axe de chiralité qui est créé lors de la coordination du ligand NHC à un métal de transition. Ce chapitre est consacré à la synthèse de complexes possédant une symétrie C1. Différents sels d’imidazolium, précurseurs des NHCs, ont été synthétisés et utilisé pour former des complexes palladium. Ils ont été sous forme énantiopure par HPLC chirale à l’échelle préparative. Ces complexes ont fait l’objet d’études concernant leurs propriétés chiroptiques et leurs barrières de rotation avant d’être testé en catalyse. Le concept a été ensuite étendu pour la synthèse de complexes d’or et de cuivre. Ces derniers se sont avérés être intéressants car non seulement ils ont permis d’obtenir de bons excès énantiomériques en catalyse mais leurs utilisations comme agent de transfert de ligands NHC a permis de proposer un mécanisme pour le procédé de transmétallation. Le troisième chapitre fait état des travaux qui ont été réalisés sur la préparation de complexes chiraux NHC-TM possédant une symétrie C2. Différents sels d’imidazolium symétriques ont été synthétisés et utilisés pour former des complexes de palladium. Les versions homochirales de ces complexes se sont avérées être d’excellents catalyseurs chiraux pour la réaction l’α-arylation d’amides (jusqu’à 98% ee)<br>N-heterocyclic carbenes (NHC) are recognized to be excellent ligands towards transition metals ™. In this manuscript, the first chapter is dedicated to a non-exhaustive presentation of the various approaches of the literature which have been used to design chiral NHCs efficient in enantioselective catalysis. As a prelude of the second chapter, the new concept lies on the formation of an axis of chirality during the coordination between the NHC ligand and the transition metal. This chapter is dedicated to the synthesis of complexes with a C1 symmetry. Various imidazolium salts, have been synthesized and then used to generate palladium complexes. These complexes have been obtained in a enantiopurically form thanks to a chiral HLPC resolution at a preparative scale. These homochiral complexes were firstly subjected to studies aiming the investigation of their chiroptic properties and the determination of their rotation barriers values. The concept was then successfully extended to the synthesis of gold- and copper-based complexes. Homochiral copper-NHC complexes were found of particular importance since their applications in catalysis allowed to reach good enantioinductions and as NHC transfer reagents brought some experimental proofs on the transmetalation process. The third chapter disclosed the works that have been done on the preparation of heterochiral NHC-TM complexes possessing a C2 symmetry. Various symmetric imidazolium salts have been synthesized and then used to form the corresponding palladium-based complexes. Homochiral complexes were found displaying good activities for α-arylation of amides and excellent enantioselectivities (up to 98% ee)
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Passays, Johan. "Nouveaux ligands mixtes de type phosphore / carbène N-hétérocyclique : synthèse et applications en catalyse asymétrique." Thesis, Rouen, INSA, 2011. http://www.theses.fr/2011ISAM0008.
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Une méthode simple et efficace a été développée pour la préparation de ligands bifonctionnels associant les motifs phosphine ou phosphite d'une part, et carbène Nhétérocyclique(NHC) ou imidazolium d'autre part. Dans un premier temps, une série de ligands diphénylphosphine-carbène chiraux portant un centre stéréogène en a de la phosphinea été développée à partir b-hydroxyesters. Une famille de ligands a ainsi été développée afin d'évaluer l'influence de l'encombrement stérique de différents groupements alkyles en a de la phosphine et de la nature des groupements aromatiques portés sur l'imidazole sur leur activité catalytique. L’étude s’est ensuite étendue à la synthèse de ligands de type dialkylphosphine carbène et phosphite-carbène. Ces différents ligands ont été complexés avec des métaux tels que l’iridium ou le rhodium de manière à en étudier l’activité en hydrogénation asymétrique<br>A straightforward method for the preparation of new bidentate ligands containing aphosphine or a phosphite and a carbene function was developed. Different phosphorus-imidazolium compounds were prepared according to this method. First, diphenylphosphine-NHC ligands featuring a stereogenic center a to the phosphine were synthesized from b-hydroxyesters. This strategy was then extended to the preparation of phosphite-imidazoliumand dialkylphosphine-imidazolium compounds. Complexation of these phosphorus-NHCligands with different metals like Ir or Rh was performed in order to study there catalytic properties in asymmetric hydrogenation
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Tang, Shun. "Cycloisomérisations catalysées par les sels du gallium et les complexes NHC-Gallium(III)." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112271.
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Afin de développer des méthodes alternatives à l'activation de systèmes Pi en catalyse homogène par des métaux nobles coûteux et toxiques, nous nous sommes focalisés sur des complexes métalliques et plus particulièrement ceux de la colonne du group XIII. Cette thèse approche une contribution à ce champ d'études, et nous nous sommes particulièrement concentrés sur la chimie de gallium.Trois principaux aspects ont été étudiés dans ce manuscrit: la réactivité des halogénures de gallium(III), des complexes bien définis de gallium (III) portant carbènes N- hétérocycliques (NHCs), et leur activation de systèmes en catalyse.La thèse est divisée en trois chapitres. Le premier chapitre donne un aperçu des travaux effectués dans le domaine de la synthèse organique faisant intervenir des composés de gallium (III) , en se concentrant sur leur utilisation en tant qu’ acides de Lewis et .Dans le deuxième chapitre, nous avons tenté d'exploiter le potentiel catalytique de GaCl3 dans une nouvelle réaction de cycloisomérisation/Friedel-Crafts en tandem. Une section dédiée à l'étude sur l’hydratation d’alcyne catalysée par GaCl3 est également fournie.Le troisième chapitre commence par une description de la synthèse d'une série de complexes de gallium (III) portant diverses NHCs comme ligands pour surmonter les limites des halogénures de gallium(III) en catalyse. Ensuite, des études de méthodologie sur le processus de tandem impliquant arenynes-1,6 avec les gallium(III) complexes neutres et cationiques ont été décrits. Une évaluation cinétique pour des catalyseurs, des divers substrats et l'influence de contreanions sont discutés. En outre, les efforts dans la version asymétrique de cette tandem transformation et des autres cyclisations sont également présentés.Le dernier chapitre reprend les résultats les plus importants obtenus dans la thèse. Et les orientations futures de la recherche sur l'utilisation des complexes NHC- gallium (III) sont discutées<br>Recently, in order to develop alternative activation methods for Pi-systems in homogeneous catalysis instead of employing expensive and toxic noble metal catalysts, first row transition metals and main group metal complexes have attracted great attention. This thesis is a contribution to it, and we focus on gallium chemistry. There are three main aspects dominating this thesis: gallium(III) halides, well-defined gallium(III) complexes bearing N-heterocyclic carbenes (NHCs), and -systems activation in catalysis.The thesis is divided into three chapters. Chapter I provides an overview of the field of organic synthesis involving gallium(III) compounds, focusing on their use as - or -Lewis acids.In Chapter II, we expose our attempts to exploit the catalytic potential of gallium(III) chloride in a novel tandem cycloisomerization/Friedel-Crafts reaction. A section dedicated to the study on GaCl3-catalyzed alkyne hydration is also provided.Chapter III begins with a description of the synthesis of a series of gallium(III) complexes bearing various NHCs as ligands in order to overcome the limitations of gallium(III) halides in catalysis. Next, methodology studies on the tandem process involving 1,6-arenynes with the neutral and cationic gallium(III) complexes are described. The evaluation of scission kinetics for catalysts, substrates variation and influence of counteranions are discussed. In addition, efforts towards the asymmetric version of this tandem transformation and some other cyclizations are also presented.The concluding chapter reiterates the most important results obtained in the body chapters of the thesis. To conclude, the future directions for the research on the use of the NHC-gallium(III) complexes are discussed
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Gojon, Sophie. "Carbènes N-hétérocycliques : nouvelle méthode de synthèse et activité catalytique pour la réticulation de silicone." Toulouse 3, 2011. http://www.theses.fr/2011TOU30321.
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Ce travail concerne l'étude de carbènes de type N-hétérocyclique (NHCs) sous deux aspects : synthèse et réactivité<br>The main objective of this thesis is to study the synthesis of N-heterocyclic (NHCs) and their catalytic activity toward silicone elastomer formation
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Darari, Mohamed. "Synthèse et caractérisation de nouveaux complexes Fe-NHC applicables en cellule solaire DSSC." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0318.
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Ces travaux de thèse se situent dans un domaine au cœur des préoccupations actuelles qui est le développement de nouveaux complexes photoactifs utilisant des métaux abondants pour remplacer les métaux nobles dans les dispositifs à énergie renouvelable. De nouvelles familles de complexes précurseurs ou sensibilisateurs potentiels pour les cellules DSSC (Dye-sensitized solar cells) à base de fer et de ligands tridentates pyridyl-carbènes (FeNHC) ont été préparées et caractérisées. L’objectif, à côté de l’aspect applicatif pour l’énergie, est d’accroître les connaissances dans l’étude des relations structure-propriétés dans les complexes homoleptiques Fe-NHC portant des ligands pyridyl-bisimidazolylidènes par modification du noyau central, du groupe de greffage et de la géométrie de coordination. Après mise au point de la synthèse, les complexes ont fait l’objet de différentes caractérisations photophysiques, électrochimiques et théoriques. Un nouveau record de durée de vie des états excités MLCT a été obtenu avec des complexes à noyau pyrazine (32 ps). L’optimisation géométrique, c’est-à-dire le design de ligands permettant d’obtenir une géométrie de coordination octaédrique idéale pour induire un champ de ligand fort a été étudiée. Nous avons obtenu les complexes recherchés (structure attestée par diffraction RX) en accroissant la distance entre le cœur pyridine et les carbènes latéraux. Cette modification induit un décalage bathochrome, mais la conjugaison électronique ainsi que la rigidité du complexe restent à optimiser. Nous avons aussi développé une nouvelle voie de synthèse permettant d’introduire des groupes d’accroche Π-étendus dans le but de limiter la recombinaison de charge après injection dans le semi-conducteur TiO2. Enfin, Le rendement des cellules DSSC a été optimisé par l’incorporation d’un nouvel additif MgI2 dans la composition de l’électrolyte permettant d’atteindre une efficacité de 0.5% inédite pour un complexe de fer. Au final ces travaux de thèse mettent à la disposition de la communauté des outils synthétiques pour la conception de complexes FeII-NHC à durée de vie prolongée à l'état excité, et représentent une étape supplémentaire dans la compréhension des processus photophysiques opérés au sein de ces complexes<br>This thesis is part of a current concern and high interest research field, which is the development of new photoactive complexes using abundant metals to replace noble metals in renewable energy devices. Novel families of potential sensitizers for DSSC (Dye-sensitized solar cells) based on iron and tridentate pyridyl-carbene ligands (FeNHC) have been prepared and characterized. The aim, besides the application aspect for energy, is to increase the understanding of the structure-property relationships in Fe-NHC homoleptic complexes carrying pyridyl-bisimidazolylidene ligands by modification of the central core, anchoring group and coordination geometry. Once synthesized, the complexes were submitted to various photophysical, electrochemical and theoretical characterizations. A new MLCT excited state lifetime record was obtained with a pyrazine-based complexes (32 ps). The geometric optimization, which means the design of ligands to obtain an ideal octahedral coordination geometry to induce a strong ligand field was studied. X-ray diffraction measurements attested that the desired complexes were obtained by increasing the distance between the pyridine core and the lateral carbenes. This modification induces a bathochromic shift, but the electronic conjugation as well as the rigidity of the complexes remain to be optimized further. We have also developed a novel synthetic route for introducing Π-extended anchoring groups in order to limit the charge recombination after the injection into the TiO2 semiconductor. The efficiency of the DSSC cells was optimized by the incorporation of a new MgI2 additive in the electrolyte composition which led to an unprecedented efficiency of 0.5% for an iron complex. Finally, this thesis offers new synthetic tools for the design of FeII-NHC complexes with extended excited state lifetimes and represents a further step in the understanding of the photophysical processes operated within this type of iron complexes
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Savchuk, Mariia. "Complexes atropisomériques d'or-NHC : design, synthèse et applications dans des réactions de cycloisomérisation asymétriques." Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0571.
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Le premier chapitre de ce manuscrit est consacré à l’étude des différents designs de NHCs chiraux décrits dans la littérature et leurs applications en tant que ligand dans les transformations énantiosélectives catalysées par l’or. Un nouveau concept de complexes atroipsomériques métal de transition-NHC a été conçu et développé dans notre groupe. Son application pour préparer des complexes de métaux de transition chiraux portant un ligand NHC de symétrie C1 contenant un NHC saturé a été étudiée au cours de mes travaux de doctorat et sera présentée dans le deuxième chapitre. Divers complexes chiraux ont été obtenus, séparés par HPLC chirale à l’échelle préparative et leurs stabilités configurationnelles ont été étudiées en profondeur. Le complexe contenant de l’or(I) a été testé pour la cycloisomérisation d’1,6-énynes, donnant une énantiosélectivité prometteuse (70% ee). Dans le troisième chapitre de ce manuscrit, le concept de complexes atroipsomériques métal de transition-NHC a été étendu à des ligands NHCs de symétrie C2 et appliqué des transformations asymétriques catalysées par de l’or(I). Les 1,6-énynes possédant un lien malonate de diisopropyle se sont avérés être d’excellents substrats pour des réactions de cycloisomérisation et les produits d’alcoxycyclisation qui en ont résultées ont été isolés avec d’excellentes énantiopuretés (7 exemples avec des rendements de 51 à 92% et des excès énantiomériques compris entre 56 et 99%). La cycloisomérisation lorsqu’elle est réalisée sans nucléophile externe a également conduit à d’excellents résultats (6 exemples avec des rendements allant de 72 à 99%, et des excès énantiomériques dans la gamme 86-93% ee)<br>The first chapter of this manuscript is dedicated to survey the design of chiral NHC and their applications as ligand in gold-catalyzed enantioselective transformations. This presentation clearly showed the importance of new ligand designs, because only poor enantioselectivities have been reached up to date. A new concept of atroipsomeric transition metal-NHC complexes has been devised and developed in our group. Its application to prepare chiral transition metal complexes bearing C1-symmetric NHC ligand containing a satured backbone was investigated during my Ph.D. work and will be presented in the second chapter. Various chiral complexes were obtained, separated by chiral HPLC at preparative scale and their configurational stabilities were investigated in depth. The gold (I) containing complex was tried in the 1,6-enyne cycloisomerization, giving a promissing enantioselectivity (70% ee). In the third chapter of this manuscript, the concept of atroipsomeric transition metal-NHC complexes was extended to C2-symmetric NHC ligands and applied to the asymmetric Au(I)-catalyzed transformations. Diisopropyl malonate-tethered 1,6-enynes were identified as excellent substrates for cycloisomerization reactions and resulting alkoxycyclization products were isolated with excellent enantiopurities (7 examples with 51-92% yield, 56-99% ee). The cyclization without external nucleophiles led also to excellent results a (6 examples with 72-99% yield, 86-93% ee)
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Hussein, Hiba. "Synthèses de nouveaux ligands carbènes à structures N-hétérocycliques et macro-N-Bis-hétérocycliques symétriques et dissymétriques. Études de leurs propriétés photophysiques, biologiques et de coordination." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0014.
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L'objectif de ce travail de thèse consiste à préparer de nouvelles molécules photosensibles de type carbènes N-hétérocycliques, ligands ou complexes, dessinées pour répondre aux critères des photosensibilisateurs (PS) (molécules pures, hydrosolubles, biocompatibles, non toxiques, d'efficacité d'absorbance maximale, possédant de bonnes propriétés photophysiques) applicables dans le domaine des matériaux ou/et dans le domaine biomédical tel qu'en photothérapie. L'ambition étant d'optimiser les propriétés spectroscopiques des photosensibilisateurs et d'obtenir une bonne photoactivité. Ce travail de thèse décrit dans un premier chapitre un état de l'art non exhaustif concernant les macrocycles hétérocycliques, les carbènes N-hétérocycliques (NHC) et les macrocycles de type NHC ainsi qu'un rappel des propriétés attendues des molécules photosensibles. Dans un deuxième chapitre, il détaille les synthèses de ligands originaux N-hétérocycliques et N-bis-hétérocycliques bis-imidazolium de structures ouvertes ou macrocycliques fermées ainsi que leurs caractérisations physico-chimiques (infrarouge, RMN, spectroscopie de masse). Des structures cristallographiques de certains de ces macrocycles ont été obtenues par diffraction des rayons X. Dans un troisième et dernier chapitre, sont détaillés les différents essais de formation des carbènes et l'étude de leurs propriétés de complexation vis-à-vis des métaux de transition. Des calculs théoriques Gaussian viennent en appui de celle-ci. Une étude par fluorescence et par production d'oxygène singulet ainsi qu'une évaluation des propriétés biologiques des macrocycles et ligands flexibles présentés précédemment, montrent des propriétés photophysiques et biologiques prometteuses. De plus, une étude préliminaire intéressante de l'échange proton/deutérium des protons carbèniques des macrocycles bis-imidazolium est décrite<br>The objective of this thesis is to prepare new photosensitive molecules of N-heterocyclic carbenes, ligands or complexes, designed to meet the criteria of photosensitizers (PS) (pure, water-soluble, biocompatible, non-toxic molecules, with maximum absorbance efficiency, possessing good photophysical properties) applicable in the field of materials and/or in the biomedical field such as phototherapy. The ambition is to optimise the spectroscopic properties of the photosensitisers and to obtain a good photoactivity. This thesis describes in a first chapter a non-exhaustive state of the art concerning heterocyclic macrocycles, N-heterocyclic carbenes (NHC) and NHC macrocycles as well as a reminder of the expected properties of photosensitive molecules. In a second chapter, it details the syntheses of original N-heterocyclic and N-bis-heterocyclic bis-imidazolium ligands of open or closed macrocyclic structures as well as their physicochemical characterizations (infrared, NMR, mass spectroscopy). Crystallographic structures of some of these macrocycles were obtained by X-ray diffraction. In a third and final chapter, the various tests for the formation of carbenes and the study of their complexation properties towards transition metals are detailed. Theoretical Gaussian calculations are used to support this study. A fluorescence and singlet oxygen production study as well as an evaluation of the biological properties of the previously presented flexible macrocycles and ligands show promising photophysical and biological properties. In addition, an interesting preliminary study of the proton/deuterium exchange of carbon protons of bis-imidazolium macrocycles is described.Keywords: NHC, macrocyclic ligands, bipyridine, bithiazole, imidazolium, photosensitiser, photoactivity, anti-bacterial properties
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Schnee, Gilles. "Synthèse et réactivité de nouveaux complexes des métaux du groupe 13 portés par des ligands carbènes N-hétérocycliques." Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAF053/document.
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Au début de ces travaux, peu d’études avaient été faites sur la complexation des carbènes N-hétérocycliques avec des métaux oxophiles, électropositifs et à hauts degrés d’oxydation tel que les métaux du groupe 13. L’optimisation de voies de synthèse a permis d’étendre le nombre de complexes de types NHC-MIII (M = aluminium, gallium et indium), ainsi qu’à des complexes cationiques. L’association de ces précurseurs avec des NHCs plus encombrés a permis l’observation de réactivités sans précédent (complexes anormaux, paires de Lewis frustrées, dicarbènes N-hétérocycliques). Dans un second temps, la réactivité inhabituelle des ligands NHCs a permis l’isolation d’analogue au réactif de Tebbe, très actifs en méthylénation de dérivés carbonyles<br>At the beginning of this work, few studies had been performed on the complexation of N-heterocyclic carbenes with oxophilic metals, in high oxidation states such as group 13 metals. The synthetic routes optimization has extended the number of complexes-type NHC-MIII (M = aluminum, gallium and indium), and the corresponding cationic complexes. The combination of these precursors with sterically congested NHCs allowed the observation of unprecedented reactivities (abnormal complexes, Frustrated Lewis Pairs, N-heterocyclic dicarbenes). In a second step, the unusual reactivity of NHC ligands has allowed the isolation of analogues of the Tebbe’s reagent, formed to be very active in the methylenation of carbonyl compounds
Books on the topic "Carbène NHC"
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Estates, NHS, ed. Carbon/energy management in healthcare: Best practice advice for the NHS in England on meeting the mandatory carbon/energy targets, March 2000-March 2010. Stationery Office, 2004.
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United States. National Aeronautics and Space Administration., ed. Analysis of minerals containing dissolved taraces of the fluid phase components "water" and "carbon dioxide": Final report submitted to the NASA Ames Research Center for NASA cooperative agreement NCC 2-446. SETI Institute, 1991.
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Mozambique - Strengthening NDC Ambitions through Blue Carbon Frontiers. Washington, DC: World Bank, 2024. http://dx.doi.org/10.1596/42281.
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Jaramillo, Marcela, and Valentina Saavedra. NDC Invest: Supporting Transformational Climate Policy and Finance. Inter-American Development Bank, 2021. http://dx.doi.org/10.18235/0003340.
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The Inter-governmental Panel on Climate Change (IPCC) indicates that meeting the Paris Agreement's goal of limiting the global temperature rise from pre-industrial levels to between 1.5 and 2 degrees Celsius requires reaching net-zero emissions of carbon dioxide (CO2) between 2050 and 2070, as well as deep reductions in the emissions of other greenhouse gases by around mid-century (GHGs) (IPCC, 2018). At the same time countries need to build resilience to face the changes that cannot be avoided. NDC Invest was created as the one-stop-shop of the IDB Group providing technical and financial support for countries in Latin American and Caribbean (LAC) in their efforts to achieve the climate objectives under the Paris Agreement, seeking to transition to a net zero, resilient and sustainable development pathways that improve quality of life and prosperity in LAC. Through our research and experience supporting countries and piloting solutions we have developed a toolbox for support. This paper describes three NDC Invest products to support Governments to tackle challenges and scale up action towards a climate aligned and sustainable development path: i) the design of Long-Term Strategies (LTS) for net-zero emissions and resilience; ii) design of ambitious Nationally Determined Contributions (NDCs), aligned to LTS; and iii) design of investment plans and finance strategies. Our three products are not a fix recipe, but rather a toolbox to provide flexible and relevant solutions tailored to country needs and context, and different stages of design and implementation of their climate targets.
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Great Britain: Department of Health: Estates and Facilities Division. Statistics on energy performance and carbon and CO2 Emissions: NHS England, 1999/00 to 2004/05. Stationery Office, The, 2006.
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Strand, Jon. Climate Finance, Carbon Market Mechanisms and Finance “Blending” as Instruments to Support NDC Achievement under the Paris Agreement. World Bank, Washington, DC, 2019. http://dx.doi.org/10.1596/1813-9450-8914.
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Eland, John H. D., and Raimund Feifel. Molecules with four, five or seven atoms. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198788980.003.0005.
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Double photoionisation spectra of NH3, C2H2, HCHO, C2N2, PCl3, CH4, the methyl halides CH3F, CH3Cl, CH3I, the methylene halides CH2Cl2, CH2Br2, CH2I2, the carbon tetrahalides CF4, CCl4, CBr4, germanium tetrahalides GeCl4, GeBr4, and SF6 are presented with analysis to identify the electronic states of the doubly charged ions. The effects of indirect double ionisation pathways are discussed. There are relatively few important molecules with just four atoms, but most of the ones included here are present and sometimes abundant in planetary and astrophysical environments. The range of five-atom molecules includes methane and all its simple derivatives. Where possible closely related molecules are grouped together in this chapter, as much of the discussion of their electronic structure is the same for all members of a group. This chapter also includes SF6 as a closely related molecule, even though its atom count goes beyond those of some molecules in later chapters.
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Marques, Marcia, ed. Estudos Avançados em Engenharia Civil. Bookerfield Editora, 2022. http://dx.doi.org/10.53268/bkf21111100.
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No Brasil a Engenharia Civil se utiliza de ciência aplicada na execução de ações indispensáveis prestadas à sociedade. Além da grande área das Engenharias, sua abrangência multidisciplinar frequentemente colabora com as demais áreas do conhecimento com soluções em benefício da sociedade. Este livro reúne capítulos que trazem importantes avanços relacionados a estruturas, construção civil, eletrotécnica, hidráulica ambiental e geotecnia. Visando uma melhor organização, os capítulos estão agrupados nas seções: Ciência Onshore e Ciência Offshore. A seção de Ciência Onshore é composta por cinco capítulos. Pelo primeiro capítulo é avaliada a resistência e a rigidez de diafragmas horizontais, construídos em Sistemas Leves de Madeira. Foram ensaiados protótipos em escala real com diferentes arranjos construtivos concluindo-se que o emprego de dispositivos enrijecedores permite o aumento da resistência e rigidez dos diafragmas. O segundo capítulo aborda construções em madeira sob a ótica de sistemas com estruturas leves, apresentando análise computacional através de modelagem pelo método de elementos finitos. As análises demonstraram que a flecha real e a calculada para as vigas individuais, que compõem o diafragma de piso, apresentam reduções que variam de 18 a 30% quando comparadas com valores calculados para vigas isoladas. No contexto dos sistemas construtivo e estrutural da Construção Civil, observa-se uma inevitável e progressiva tendência de substituição dos sistemas convencionais por sistemas industrializados. Por meio do terceiro capítulo é apresentada uma revisão bibliográfica sobre conceitos de construção industrializada, abordando o atual cenário técnico no Brasil, e confrontando algumas das principais tecnologias industrializadas presentes hoje no segmento da Construção Civil. O quarto capítulo trata da engenharia aplicada ao ambiente offshore e apresenta uma análise de fadiga estrutural de conexões entre um reforçador longitudinal do costado e uma antepara transversal de uma unidade flutuante de produção, armazenamento e transferência (FPSO) convertida a partir de um navio petroleiro, sendo possível estimar a vida remanescente do FPSO. Por meio do capítulo cinco são apresentados detalhes de um reforço estrutural utilizando polímero reforçado com fibra de carbono (PRFC) em uma plataforma offshore de concreto armado. Apesar de adotada uma técnica consolidada, pouco se sabe sobre o desempenho do reforço ao longo do tempo quando exposto ao ambiente marinho. Pelo capítulo é apresentado um panorama geral da estrutura após 17 anos da execução do reforço que comprovou o bom desempenho da técnica empregada. A seção de Ciência Offshore é composta por quatro capítulos. Pelo capítulo seis é abordada a utilização de sistemas solares fotovoltaicos conectados à rede (SFVCR), enquanto apresenta uma proposta de metodologia para avaliar o potencial fotovoltaico para a Região Metropolitana de Curitiba. Foi realizado ainda, um levantamento do montante de gases de efeito estufa que são deixados de emitir. O capítulo contribui para a implantação de políticas públicas de incentivo para esta fonte energética. Geopolímeros são materiais alternativos ao cimento Portland, apresentando alta resistência mecânica e durabilidade química e térmica. Pelo capítulo sete são avaliadas as propriedades mecânicas de argamassas geopoliméricas contendo adição de Nanotubos de Carbono (NTC) assim como o método de incorporação do nanocompósito a argamassa. Os resultados mostram que os NTC quando bem distribuídos na matriz promovem um aumento de resistência à compressão e flexão das amostras. O capítulo oito trata do fetch, importante elemento na quantificação de fenômenos gerados pelo vento em reservatórios de Usinas Hidrelétricas. A abordagem apresentada amplia a compreensão do fetch através de um conceito bidimensional via processamento computacional, permitindo a geração de mapas e a determinação segura dos valores máximos para cada direção e a localização dos maiores comprimentos para o reservatório de Tucuruí, este importante reservatório no Brasil. Na quantificação dos fenômenos hidrodinâmicos em lagos e reservatórios é frequente a necessidade de conhecer o alcance das perturbações alcançadas pelas ondas ao se propagarem. Este fenômeno está relacionado à ressuspensão de sedimentos, desestratificação térmica, e erosão das margens, afetando o ecossistema aquático, as cadeias produtivas aquícolas e a vida útil de componentes mecânicos das UHE’s. Por meio do capítulo nono é apresentado o conceito de profundidade de mistura aplicado ao reservatório da hidrelétrica de Lajeado, Tocantins. É realizado o mapeamento das profundidades máximas perturbadas pelas ondas de vento ao se propagarem, contribuindo para uma melhor compreensão da estratificação térmica e da ressuspensão de sedimentos no reservatório desta importante usina hidrelétrica.
Book chapters on the topic "Carbène NHC"
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Louie, Janis. "Ni-NHC Mediated Catalysis." In N-Heterocyclic Carbenes in Synthesis. Wiley-VCH Verlag GmbH & Co. KGaA, 2006. http://dx.doi.org/10.1002/9783527609451.ch7.
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Lazreg, Faïma, and Catherine S. J. Cazin. "NHC-Copper Complexes and their Applications." In N-Heterocyclic Carbenes. Wiley-VCH Verlag GmbH & Co. KGaA, 2014. http://dx.doi.org/10.1002/9783527671229.ch08.
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Chauhan, Pankaj, Suruchi Mahajan, Xiang-Yu Chen, and Dieter Enders. "Domino Processes in NHC Catalysis." In N-Heterocyclic Carbenes in Organocatalysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2019. http://dx.doi.org/10.1002/9783527809042.ch5.
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Jin, Zhichao, Xingkuan Chen, and Yonggui R. Chi. "Recent Activation Modes in NHC Organocatalysis." In N-Heterocyclic Carbenes in Organocatalysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2019. http://dx.doi.org/10.1002/9783527809042.ch7.
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Nagao, Kazunori, and Hirohisa Ohmiya. "N‑Heterocyclic Carbene (NHC)/Metal Cooperative Catalysis." In Asymmetric Organocatalysis Combined with Metal Catalysis. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43851-7_4.
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Chen, Xiangyu. "NHC-Catalyzed Annulations of Nitroalkenes." In New Strategies for N-Heterocyclic Carbenes Catalyzed Annulations. Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-2899-1_2.
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Lazreg, Faïma, and Catherine S. J. Cazin. "Medical Applications of NHC-Gold and -Copper Complexes." In N-Heterocyclic Carbenes. Wiley-VCH Verlag GmbH & Co. KGaA, 2014. http://dx.doi.org/10.1002/9783527671229.ch07.
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Wurm, Thomas, Abdullah Mohamed Asiri, and A. Stephen K. Hashmi. "NHC-Au(I) Complexes: Synthesis, Activation, and Application." In N-Heterocyclic Carbenes. Wiley-VCH Verlag GmbH & Co. KGaA, 2014. http://dx.doi.org/10.1002/9783527671229.ch09.
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Díez-González, Silvia, and Steven P. Nolan. "Palladium-catalyzed Reactions Using NHC Ligands." In N-Heterocyclic Carbenes in Transition Metal Catalysis. Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/978-3-540-36930-1_3.
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Chen, Xiangyu. "NHC-Catalyzed Enantioselective Annulations of Enals." In New Strategies for N-Heterocyclic Carbenes Catalyzed Annulations. Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-2899-1_3.
Full textConference papers on the topic "Carbène NHC"
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Kmetz, J. H., and D. J. Truax. "Carbonate Stress Corrosion Cracking of Carbon Steel in Refinery FCC Main Fractionator Overhead Systems." In CORROSION 1990. NACE International, 1990. https://doi.org/10.5006/c1990-90206.
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Abstract Intergranular cracking and failure of carbon steel piping and vessels of FCC Main Fractionator overhead systems in NH3-H2S-CO2-containing environments is attributed to carbonate stress corrosion cracking. From a plant water sampling program, cracking is correlated with water chemistry, open circuit potential, and pH.
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Opeka, Mark, and Ben Kowalski. "ZrC-NbC-TaC Solid Solutions for Carbon-Carbon Heat Exchange Tubes for Nuclear Thermal Propulsion Fuel Elements." In Nuclear and Emerging Technologies for Space (NETS 2025). American Nuclear Society, 2025. https://doi.org/10.13182/xyz-47529.
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Fortunato, Jo�o, Pedro M. Castro, Diogo A. C. Narciso, and Henrique A. Matos. "Towards the Decarbonization of a Conventional Ammonia Plant by the Gradual Incorporation of Green Hydrogen." In The 35th European Symposium on Computer Aided Process Engineering. PSE Press, 2025. https://doi.org/10.69997/sct.104649.
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As initiatives to decarbonize societies increase, industry is also being considered for policies to encourage its sustainability. Ammonia (NH3) industry relies entirely on Haber-Bosch (HB) process, consuming fossil fuels for hydrogen production and energy purposes, accounting for more than 1 % of anthropogenic carbon dioxide (CO2) emissions. Emerging technologies such as the electrochemical synthesis of NH3 promise sustainable production from water, air, and renewable energies, but low TRLs are still reported. The electrification of the HB process opens a more viable path for sustainable NH3 production in the near future, where hydrogen (H2) is produced by electrolysis of water, powered from renewable energy sources. Many studies have focused on the production of 100 % green NH3 using only electric HB. In this work, a different approach is presented, which consists of studying the gradual incorporation of green H2 into a conventional NH3 plant. An Aspen Plus� V14 model of the methane-fed HB process was developed, and the limitations of the process were identified by sequentially incorporating 0 to 10 % green H2. To avoid overheating the equipment in the natural gas reforming stage, a new configuration is suggested for this step. With this modification, the study is extended to incorporating higher percentages of green H2, up to a limit of around 61 %. Finally, the impact of the reforming temperature tolerance on the green H2 incorporation limits for the suggested configuration was studied.
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Ng, Hon C., Victor Gutiérrez, Diogmary Arreaza, Fernando De Abreu, and Erick Hernández. "Naphthenic Acid Corrosion on a Extra-Heavy Crude Oil Upgrader Medium Vacuum Gasoil Side Cut Piping." In CORROSION 2013. NACE International, 2013. https://doi.org/10.5006/c2013-02185.
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Abstract After 5 years of operation, at an average temperature, sulfur content and neutralization number of 200°C (392°F), 3.3%wt and 4.3 mg KOH/gram, respectively; clean, streamlined through-wall pits, grooves and rivulets have caused leaks in the lower portion of horizontal and inclined pipes of the side cut carbon steel piping that draws medium vacuum gasoil (MVGO) from the vacuum distillation tower (VDT). The average corrosion rate estimated from through-wall pits is 4.7 mm/year (187 mils per year). Comparable corrosion morphologies were observed in carbon steel pump cases and VDT shell. The literature has reported similar damage caused by condensing naphthenic acid, one of the most severe types of naphthenic acid corrosion (NAC); however, cases such as these occurring at 193°- 221°C (380°-430°F) are considered being on the low side for typical NAC and a deeper investigation is needed to reveal the actual mechanisms. Since no damage was detected in the UNS(1) S31703 VDT internals, the side cut piping was partially upgraded to this material. Because the naphthenic acid condensation process can be exacerbated when the MVGO tray level is emptied, it was recommended to maintain a high tray level until its temperature decreases below 150°C (300°F) during VDT planned outages. Typical velocity assisted NAC pits were detected with ultrasonic corrosion mapping at the pump’s outlet piping; they will be monitored and the results will determine the future need of chemical inhibition and/or metallurgy upgrading to UNS S31703.
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Kessing, Jonas, Alexander Nadermann, Brandon Shaver, Justin Milner, and Steven Zinkle. "Grain Growth and Hardness of ZrC, NbC, and TaC Tri-Carbide Surrogate Fuels for Nuclear Thermal Propulsion." In Nuclear and Emerging Technologies for Space (NETS 2024). American Nuclear Society, 2024. http://dx.doi.org/10.13182/nets24-43787.
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Srinivasan, Sridhar, Kwei Meng Yap, Richard J. Horvath, and Russell D. Kane. "Prediction and Assessment of Ammonium Bisulfide Corrosion under Refinery Sour Water Service Conditions – Part 3." In CORROSION 2017. NACE International, 2017. https://doi.org/10.5006/c2017-08929.
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Abstract This paper summarizes results from Phase III of the joint industry program (JIP) on refinery alkaline sour water (ammonium bisulfide) corrosion. Phase III included a comprehensive engineering analysis of data from all three phases of the Sour Water JIP and the development of “H2S tie-in plots” based on a single parameter (H2S partial pressure), replacing the isocorrosion diagrams based on NH3 partial pressure developed in Phase II, and linking with the H2S isocorrosion diagrams based on H2S partial pressure developed in Phase I. These H2S tie-in plots enabled corrosion rate data for carbon steel and five commonly used corrosion resistant alloys to be contiguously modeled across the entire range of conditions tested ― six orders of magnitude of H2S partial pressure, from approximately 0.00004 to 150 psia (0.0003 to 1,000 kPa absolute) ― to fully characterize effects of H2S-dominated, NH3-dominated and intermediate sour water conditions. The results clearly demonstrated that NH4HS concentration, flow velocity (wall shear stress), H2S partial pressure, and free cyanide concentration in the NH4HS solution are the key parameters driving severity of refinery sour water corrosion. The effect of temperature was also clarified. Substantial differences in corrosion behavior of carbon steel from the corrosion resistant alloys were observed in low NH4HS concentrations at intermediate H2S partial pressures, where corrosion rates of carbon steel and all the alloys exhibited surprisingly significant dips and peaks on the H2S tie-in plots. The results and analyses of data were synthesized into an enhanced software tool to predict corrosion rates for the six materials (carbon steel, stainless steels, and nickel-based alloys) evaluated in the program, addressing a broad range of environmental conditions encompassed by all three phases of the Sour Water JIP.
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Almarzooq, Yousef M., Matthew Hay, Olivier Mathieu, Waruna D. Kulatilaka, and Eric L. Petersen. "The Effect of Mixture Variation and Initial Temperature on the NH2* Thickness of Spherically Propagating Laminar Ammonia Flames." In ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-129437.
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Abstract Interest in ammonia (NH3) in combustion has increased in recent years as a carbon-free fuel alternative. Therefore, understanding its combustion characteristics is crucial. One way to increase the knowledge of ammonia combustion is by investigating the flame zone of a laminar flame. Using a high-spatial-resolution flame zone measurement technique developed by the current research group, the flame zone of different NH3-containing mixtures was measured experimentally. Those measurements were achieved by investigating spherically propagating flames using a chemiluminescence imaging diagnostic with the focus on NH2* profiles. The effect of the fuel mixture on the profile shape was investigated by examining two different mixtures. The first was an oxy-ammonia mixture consisting of NH3 + oxygen-enriched oxidizer where the oxygen (O2) concentration was varied from 25% to 40%. The second was a blend of NH3-H2 where the NH3 concentration (XNH3) was varied from 0.5 to 0.8. Additionally, the effect of the initial temperature was investigated by varying it from 293 to 373 K for three different mixtures, namely NH3 + (35% O2 + 65% N2), (0.7 NH3 + 0.3 H2) / air, and (0.45 H2 + 0.4 NH3 + 0.15 N2) / air. In all investigated mixtures, the initial pressure was fixed at 1 atm and the equivalence ratio was fixed at Φ = 1.0. The study revealed that increasing the O2 concentration in the oxy-ammonia mixture produced thinner flames. On the contrary, increasing the XNH3 in the NH3-H2 blend produced slightly thicker flames. Varying the initial temperature has two different responses for the three designated mixtures. In the oxy-ammonia mixture and the NH3-H2 blend, increasing the initial temperature resulted in the flame being thinner. On the other hand, increasing the initial temperature produced a slightly thicker flame for the H2-NH3-N2 blend. The predicted NH2* profile thicknesses from chemical kinetics agree with the measurements except for the H2-NH3-N2 blend, where the kinetics model underpredicted the thickness by a significant difference.
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Ou, Juan, Ruomiao Yang, Yuchao Yan, Zhentao Liu, and Jinlong Liu. "Investigation of the Effect of Ammonia Addition on the Two-Stage Ignition Process of Dimethyl Ether Based on Chemical Kinetic Analysis." In ASME 2023 ICE Forward Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/icef2023-110108.
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Abstract Ammonia (NH3) has garnered considerable attention in recent years as a promising carbon-free hydrogen carrier fuel for internal combustion engines. However, directly using pure ammonia in compression-ignition engines poses challenges. To facilitate NH3 ignition, high-activity fuels are often employed to ignite the premixed NH3/air mixture and initiate combustion. This study specifically focuses on the ignition process of binary mixtures of NH3 and dimethyl ether (DME), considering that DME is a carbon-neutral high-activity fuel. By conducting zero-dimensional reaction kinetics analysis, we compare the ignition processes of DME and NH3/DME mixtures. The results reveal that the addition of NH3 has minimal impact on the control mechanism of DME’s two-stage ignition process. DME still heavily relies on the proliferation of OH radicals in the low-temperature oxidation pathway, releasing heat during the reaction progression. As the temperature increases, the low-temperature oxidation branching pathways are gradually replaced by chain propagation pathways, resulting in a decrease in overall reaction activity. The reactivity and temperature rise rate of the reaction system is then controlled by the H2O2 loop mechanism prior to the thermal ignition. However, the presence of ammonia noticeably extends the ignition delay period of DME. Ammonia competes with OH radicals, essential for DME oxidation, thereby inhibiting DME ignition. Additionally, as the ignition reaction advances, the involvement of NH3 kinetics increases. For instance, nitrogen-containing species generated from NH3 oxidation, such as NO, NO2, and NH2, react with CH3OCH2 to form CH3OCHO, reducing the flux through the low-temperature oxidation pathway of DME. While ammonia reaction pathways also generate OH radicals, this comes at the expense of HO2 radicals and H radicals, ultimately leading to H2O2 production. Overall, these findings clearly demonstrate the substantial impact of ammonia addition on the ignition process of DME, emphasizing the necessity for further fundamental research to enhance our understanding of NH3/DME binary fuel ignition. Such insights are pivotal for improving the design and operation strategies of NH3/DME dual-fuel engines, thereby improving engine efficiency and reliability.
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Su, Tong, Boyan Xu, Rob Bastiaans, and Nicholas A. Worth. "Lean Blow-Off Behaviour of Premixed Bluff-Body Stabilized Hydrocarbon-Air Flames and Ammonia/Hydrogen/Nitrogen-Air Flames." In ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-124613.
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Abstract Ammonia blends have great potential to be utilized in gas turbine combustors as carbon-free fuels. This paper investigates and compares the lean blow-off behavior of premixed bluff-body stabilized hydrocarbon flames and ammonia/hydrogen/nitrogen flames both experimentally and numerically. Simultaneous high-speed PIV and OH-PLIF are employed to resolve temporal flame and flow field information, allowing the curvature and hydrodynamic strain rates along the flame surfaces to be calculated. OH* and NH2*, chemiluminescence images are also used to examine flame structures at the same bulk flow velocity but at four equivalence ratios which span a range of flame stability behaviour from far away from to near lean blow-off. The NH3/H2/N2 flames blow off at leaner conditions as the hydrogen volume fractions increase. A NH3/H2/N2 (70%/22.5%/7.5%) flame is slightly more resilient to lean blow-off compared with methane and propane flames at a velocity of 20 m/s despite having a significantly lower laminar flame speed. The flame structure for all fuel blends change from a ‘V-shape’ to ‘M-shape’ when approaching lean blow-off, as observed in the Abel deconvoluted OH* fields for methane and propane flames and NH2* fields for ammonia fuel blends, which can result in incomplete reactions and finally trigger the lean blow-off. However, the strong OH* intensity in the shear layer near flame root for the NH3/H2/N2 flames indicate that a robust reaction is maintained in this region for this fuel blend, increasing flame stability. The flame and recirculation zone lengths both decrease with equivalence ratio. Widely-distributed positive curvature along the flame surface of the ammonia fuel blend flames which have a Lewis number less than unity, may also enhance combustion for these flames. As blow-off is approached hydro-carbon flame fronts undergo increasing strain rates along their flame fronts, which may be due to their migration towards the inner shear layer region of the flow. In comparison the strain rates along NH3/H2/N2 flames fronts do not change significantly as blow-off is approached due to less dramatic changes to the flame shape. The faster consumption rates of hydrogen than ammonia near the flame root for the ammonia blend flames, and the lower temperature loss compared with the adiabatic temperature may also contribute to the stabilization of ammonia blends near lean blow-off.
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Pugh, D., A. Valera-Medina, P. Bowen, et al. "Emissions Performance of Staged Premixed and Diffusion Combustor Concepts for an NH3/Air Flame With and Without Reactant Humidification." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14953.
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Abstract Renewably generated ammonia offers a form of carbon-free chemical energy storage to meet the differences between uncertain renewable supply and fluctuating demand, and has the potential to support future energy requirements as a power-to-X concept. The storage and transportation characteristics of NH3 are favorable compared with H2, however there are significant combustion research challenges to enhance fuel reactivity whilst reducing harmful emissions production. The purpose of the presented work was to evaluate different fuel delivery concepts for a representative GT combustor. An experimental and numerical comparison was made between swirl-stabilized premixed and diffusion NH3-air flames at elevated inlet temperature (473 K). The exhaust NOx and unburned NH3 emissions generated from each concept were quantified to optimize operational combustor performance. High-speed OH* and NH2* chemiluminescence was employed to characterize the change in flame topology with variation in fuel-air equivalence ratio, and the resultant influence on measured emission concentrations. Chemiluminescence intensities were shown to elucidate changes in sampled exhaust emissions, enabling detailed analysis of intermediate chemistry. A comparison was made between experimental data and chemical kinetic simulations with a reactor network model, demonstrating the sensitivity of NOx emissions to premixed fuel-air equivalence ratio. A comparison was also made between exclusive primary airflow, and the staged introduction of secondary air, to quantify the change in NOx production between each configuration and improve fuel burnout. Secondary air loadings were incrementally increased through the combustor, and the change in exhaust emissions mapped. In addition, reactant humidification was employed as a secondary process for NOx reduction, having shown favorable performance with NH3/H2 mixtures to limit thermochemical NO production. The efficacy of humidification was compared for both premixed and diffusion configurations.
Reports on the topic "Carbène NHC"
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Fazekas, Andreas, and Scarleth Nuñez Castillo. NDC Invest Annual Overview 2020. Inter-American Development Bank, 2021. http://dx.doi.org/10.18235/0003430.
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NDC INVEST is an IDB Group platform offering financial solutions and technical support to help build national goals and transform them into attainable plans that generate prosperous, resilient, and carbon neutral economies. Throughout the years closely supporting LAC countries, NDC INVEST has gained valuable experience and knowledge in designing and implementing concrete actions that lead to long-term climate resilience and net-zero emissions by 2050. In 2020, NDC INVEST confirmed its key role in successfully translating national climate commitments into physical and beneficial economic plans and transformational development projects. 331 initiatives have been supported in IDB Group regional member states through the IDB sovereign window, IDB Invest and IDB Lab. This publication highlights the successful work of NDC Invest in i.) developing relevant knowledge and building national capacities for long-term strategies (LTS), ii.) supporting countries in creating ambitious climate goals and NDCs, and iii.) implementing LTS and NDCs through financial strategies and investment plans.
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Bruce, Fraser. Green Ward Toolkit Project. University of Dundee, 2024. https://doi.org/10.20933/100001403.
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The climate emergency is a health emergency. The British Medical Journal (2021) indicated that “if healthcare was a single country, it would be the world’s fifth largest emitter, accounting for 4.6% of greenhouse gas emissions”. This is resonant in the UK, where the National Health Service (NHS) is a cornerstone of society, deeply connected to the lives and wellbeing of its people. Design HOPES (Healthy Organisations in Place-based Eco-systems Scotland) is a two-year transdisciplinary research project that exploits the potential of design-led thinking to innovate and tackle multifaceted health delivery challenges to meet urgent environmental goals for a sustainable health and social care system. Recognising that health professionals are not only the stewards of the NHS resource but also have a pivotal role in helping NHS Scotland achieve Net Zero carbon emissions by 2040, this poster presents one project within the larger Design HOPES remit – The Green Ward Toolkit. The project aims to develop a design-led toolkit to guide healthcare staff, providing them with essential knowledge, tools, and resources for implementing new sustainable practices. Ultimately, inspiring change by challenging norms, embracing circular economy principles, and raising awareness among staff about innovative possibilities in ward settings resulting in a more sustainable system.
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Chepeliev, Maksym. Development of the Air Pollution Database for the GTAP 10A Data Base. GTAP Research Memoranda, 2020. http://dx.doi.org/10.21642/gtap.rm33.
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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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Schur, Michael, and Aisha Reynolds. National Climate Finance Vehicles: Best Practice Insights from International Case Studies. Asian Development Bank, 2024. http://dx.doi.org/10.22617/wps240495-2.
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This working paper—developed under ADB’s NDC Advance technical assistance platform—sets out the important role that national climate finance vehicles can play in stimulating investment in low-carbon and climate-resilient development. It presents a model design framework and readiness criteria for clarifying the key factors supporting effective operation and achieving prioritized climate outcomes and sustainable development. The paper presents three case studies of national financing vehicles from Australia, Indonesia, and Thailand, identifying success factors and lessons learned. The paper concludes with key recommendations for developing member countries to inform the approach to designing and operationalizing a climate finance vehicle.
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Gasim, Anwar, Lester C. Hunt, and Jeyhun Mikayilov. Baseline Forecasts of Carbon Dioxide Emissions for Saudi Arabia Using the Structural Time Series Model and Autometrics. King Abdullah Petroleum Studies and Research Center, 2023. http://dx.doi.org/10.30573/ks--2022-dp19.
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To tackle the threat of climate change, countries worldwide have signed the Paris Agreement. This agreement aims to limit the global average temperature increase to below 2 degrees Celsius and potentially below 1.5 degrees Celsius above pre-industrial levels (UNFCCC 2015). Parties to the Paris Agreement are required to submit domestic climate plans detailing their mitigation measures, known as nationally determined contributions (NDCs). These plans detail countries’ ambitions and efforts to combat and respond to climate change. NDCs are communicated at five-year intervals, and each successive NDC must represent an increase in ambition over the previous one.
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Chepeliev, Maksym, Israel Osorio Rodarte, and Dominique van der Mensbrugghe. Distributional Impacts of Carbon Pricing Policies under Paris Agreement: Inter and Intra-Regional Perspectives. GTAP Working Paper, 2021. http://dx.doi.org/10.21642/gtap.wp88.
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While bringing multiple benefits for the environment, achievement of the stringent global greenhouse gas emissions reduction target, like the one outlined in the Paris Climate Agreement, is associated with significant implementation costs and could impact different dimensions of human well-being, including welfare, poverty and distributional aspects. In this paper, we analyze the poverty and distributional impacts of different carbon pricing mechanisms consistent with reaching the Paris Agreement targets. We link a global recursive dynamic computable general equilibrium model ENVISAGE with the GIDD microsimulation model and explore three levels of mitigation effort and five carbon pricing options (trade coalitions). Results suggest that while there is a higher incidence of poverty in all scenarios, mainly driven by lower economic growth, Nationally Determined Contribution (NDC) policies result in progressive income distribution at the global level. Such progressivity is caused not only by lower relative prices of food versus non-food commodities, but also by a general decline in skill wage premia.
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Blair, Neal. A benthic carbon budget for the Continental Slope off Cape Hatteras, NC. Office of Scientific and Technical Information (OSTI), 1999. http://dx.doi.org/10.2172/765626.
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Kalman, Joseph, and Maryam Haddad. Wastewater-derived Ammonia for a Green Transportation Fuel. Mineta Transportation Institute, 2022. http://dx.doi.org/10.31979/mti.2021.2041.
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The energy-water nexus (i.e., availability of potable water and clean energy) is among the most important problems currently facing society. Ammonia is a carbon-free fuel that has the potential to reduce the carbon footprint in combustion related vehicles. However, ammonia production processes typically have their own carbon footprint and do not necessarily come from sustainable sources. This research examines wastewater filtration processes to harvest ammonia for transportation processes. The research team studied mock wastewater solutions and was able to achieve ammonia concentrations above 80%(nanofiltration) and 90% (reverse osmosis). The research team also investigated the influence of transmembrane pressure and flow rates. No degradation to the membrane integrity was observed during the process. This research used constant pressure combustion simulations to calculate the ignition delay times for NH3-air flames with expected impurities from the wastewater treatment processes. The influence of impurities, such as H2O, CO, CO2, and HCl, were studied under a range of thermodynamic conditions expected in compression ignition engines. The team observed carbon monoxide and water vapor to slightly decrease (at most 5%) ignition delay time, whereas HCl, in general, increased the ignition delay. The changes to the combustion chemistry and its influence of the reaction mechanism on the results are discussed. The experimental wastewater treatment study determined that reverse osmosis produced higher purity ammonia. The findings of the combustion work suggest that ignition delays will be similar to pure ammonia if HCl is filtered from the final product.
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Kalman, Joseph, and Maryam Haddad. Wastewater-derived Ammonia for a Green Transportation Fuel. Mineta Transportation Institute, 2022. http://dx.doi.org/10.31979/mti.2022.2041.
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The energy-water nexus (i.e., availability of potable water and clean energy) is among the most important problems currently facing society. Ammonia is a carbon-free fuel that has the potential to reduce the carbon footprint in combustion related vehicles. However, ammonia production processes typically have their own carbon footprint and do not necessarily come from sustainable sources. This research examines wastewater filtration processes to harvest ammonia for transportation processes. The research team studied mock wastewater solutions and was able to achieve ammonia concentrations above 80%(nanofiltration) and 90% (reverse osmosis). The research team also investigated the influence of transmembrane pressure and flow rates. No degradation to the membrane integrity was observed during the process. This research used constant pressure combustion simulations to calculate the ignition delay times for NH3-air flames with expected impurities from the wastewater treatment processes. The influence of impurities, such as H2O, CO, CO2, and HCl, were studied under a range of thermodynamic conditions expected in compression ignition engines. The team observed carbon monoxide and water vapor to slightly decrease (at most 5%) ignition delay time, whereas HCl, in general, increased the ignition delay. The changes to the combustion chemistry and its influence of the reaction mechanism on the results are discussed. The experimental wastewater treatment study determined that reverse osmosis produced higher purity ammonia. The findings of the combustion work suggest that ignition delays will be similar to pure ammonia if HCl is filtered from the final product.
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Luomi, Mari, and Hind Aldhuwaihi. Saudi Arabia and the Circular Carbon Economy: From Vision to Implementation. King Abdullah Petroleum Studies and Research Center, 2024. http://dx.doi.org/10.30573/ks--2024-dp36.
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This case study shows how the Circular Carbon Economy (CCE) Index can be used to analyze a country’s CCE performance and enablers in a holistic manner and in a comparative context, relative to other countries. Saudi Arabia is an extremely relevant country to examine in this context given the centrality of the CCE concept in its climate change and energy transition policy. The paper aims to do two things: first, it provides an analysis of Saudi Arabia’s current CCE performance and its enabling environments for the CCE transition, relative to other countries. Second, it places this in the context of the Kingdom’s current policy targets and measures to understand its direction. By doing so, the analysis seeks to help inform the Saudi Government as it prepares its second Paris Agreement nationally determined contribution (NDC) ahead of the 2025 deadline. Overall, Saudi Arabia has already come a long way on its net-zero journey by developing and setting the CCE concept as the framework for the major transition ahead. The 2023 CCE Index paints a picture of a country that is already among the leading countries in the CCE in its region, with high ambition and significant potential to do even more.