Articles de revues : « Hydrogénation du CO/CO2 »

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Ahouari, Hania, Ahcène Soualah, Anthony Le Valant, Ludovic Pinard, Patrick Magnoux et Yannick Pouilloux. « Hydrogénation du CO2 en hydrocarbures sur des catalyseurs bifonctionnels CFA-HZSM-5 ». Comptes Rendus Chimie 18, n^o 3 (mars 2015) : 241–49. http://dx.doi.org/10.1016/j.crci.2014.08.001.

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Kim, Jun-Sik, Sang-Bong Lee, Min-Chul Kang, Kyu-Wan Lee, Myoung-Jae Choi et Yong Kang. « Promotion of CO2 hydrogénation to hydrocarbons in three-phase catalytic (Fe-Cu-K-Al) slurry reactors ». Korean Journal of Chemical Engineering 20, n^o 5 (septembre 2003) : 967–72. http://dx.doi.org/10.1007/bf02697307.

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Drouin, Michel, et John F. Harrod. « Insertion and other reactions of some hydridoolefin complexes of iridium(I) ». Canadian Journal of Chemistry 63, n^o 2 (1 février 1985) : 353–60. http://dx.doi.org/10.1139/v85-060.

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A family of complexes IrH(CO)(Ph3P)2(ol), where ol is a monosubstituted ethylene, has been synthesized. Under an inert atmosphere the acrylonitrile complex undergoes clean decomposition to produce C2H5CN, half of the necessary hydrogen for the ligand reduction apparently being furnished by the phosphine ligand. The first step in the hydrogénation is insertion of the unsaturated ligand into the Ir—H bond. The alkyl product is unstable but may be trapped by O2, to give the alkyl dioxygen complex, or by excess acrylonitrile to give the α-cyanoethyl acrylonitrile complex. Other ligands, such as CO and phosphines, displace the olefinic ligand more rapidly than insertion occurs. When ol = sytrene, the complex is very unstable with respect to styrene dissociation and very little insertion is observed. Under O2, the styrene complex gives the first known hydridodioxygen complex IrH(CO)(PPh3)2(O2). The methyl acrylate complex exhibits behavior intermediate between that of the styrene and acrylonitrile analogues.

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Bagheri, Mohammad B., Matthew Wallace, Vello Kuuskraa, Hadi Nourollah, Matthias Raab et Tim Duff. « CO ». APPEA Journal 62, n^o 2 (13 mai 2022) : S372—S377. http://dx.doi.org/10.1071/aj21144.

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This paper discusses the potential for storing CO2 and producing lower carbon intensity oil from onshore oil fields in the Cooper and Surat basins of South Australia and Queensland. A comprehensive database was compiled for the oil fields in the basins above, including the key required data to assess the potential of the basins for CO2 enhanced oil recovery (EOR). The South Australia and Queensland oil field databases contain 140 reservoirs with a combined original oil in-place of 1497 million barrels. These reservoirs have, to date, produced a total of 382 million barrels, with 458 million barrels of expected ultimate recovery (EUR). The database was compiled with support from Santos, Bridgeport, and Beach Energy. These reservoirs were screened further based on their size and pressure. The next step was to model the application of a CO2 flood in each of the shortlisted reservoirs using the CO2 EOR Prophet model developed by Advanced Resources International. The modelling showed that joint implementation of CO2 storage and CO2 EOR would allow the Cooper and Surat basins to store 116–158 million metric tons of CO2 and produce 248–518 million barrels of additional oil. Creating hubs and clustering fields based on their geographical location helps to reduce the cost of infrastructure and CO2 transportation. Therefore, the reservoirs in this study, were grouped and anchored to the most dominant oil reservoir that has the largest CO2 storage and EOR capacity. The results of the clusters are summarised in this paper.

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Srivastava, Sumit, Manvender S. Dagur, Afsar Ali et Rajeev Gupta. « Trinuclear {Co2+–M3+–Co2+} complexes catalyze reduction of nitro compounds ». Dalton Transactions 44, n^o 40 (2015) : 17453–61. http://dx.doi.org/10.1039/c5dt03442f.

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Trinuclear {Co²⁺–Co³⁺–Co²⁺} and {Co²⁺–Fe³⁺–Co²⁺} complexes function as reusable heterogeneous catalysts for the selective reduction of assorted nitro compounds to their corresponding amines. The mechanistic investigations suggest the involvement of a Co(ii)–Co(i) cycle in the catalysis.

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Kovács, István, Ferenc Ungváry et László Markó. « Cleavage of Co-C and Co-Co bonds by hydrogen halides. Reaction of (CH3)2CHC(O)Co(CO)4, Co2(CO)8, Co2(CO)7PPh3 and Co2(CO)6(PBun3)with HX (X = Cl, I) ». Inorganica Chimica Acta 116, n^o 1 (juin 1986) : L15—L16. http://dx.doi.org/10.1016/s0020-1693(00)84604-6.

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Bargrizan, Sima, Tapas K. Biswas, Klaus D. Joehnk et Luke M. Mosley. « Sustained high CO ». Marine and Freshwater Research 73, n^o 4 (8 février 2022) : 540–51. http://dx.doi.org/10.1071/mf21154.

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Many of the world’s rivers have been found to be sources of CO2 to the atmosphere, however, there has been limited assessment in arid regions. This analysis of a long-term (1979–2013) dataset (n = 3496) along Australia’s largest river system (River Murray) showed that there were sustained high pCO2 (carbon dioxide partial pressure) levels, ranging from 1210 ± 107 to 3066 ± 579 µatm along the main river channel, and 5114 ± 1221 µatm on the major tributaries. As a consequence, the River Murray is a significant source of CO2 to the atmosphere, with an estimated average annual (±s.d.) flux of 218 ± 98 g C m−2 year−1 and total emissions of 355 000 ± 29 000 t CO2 year−1 over a total river area of 386 km2 from below Lake Hume to Tailem Bend, although there is some uncertainty with gas transfer coefficients. Supersaturation with CO2 relative to the atmosphere was maintained even under drought conditions with minimal external carbon inputs, suggesting internal carbon cycling and respiration is important in driving net CO2 production. Supersaturation of the river water relative to calcium carbonate minerals was also observed under low flow conditions. Hydro-climatic changes could be having significant impacts on the CO2 system in the River Murray and other arid river systems.

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Xiao, Yurou Celine, Christine M. Gabardo, Shijie Liu, Geonhui Lee, Yong Zhao, Colin P. O'Brien, Rui Kai Miao et al. « Integrated Capture and Electrochemical Conversion of CO₂ into CO ». ECS Meeting Abstracts MA2023-02, n^o 47 (22 décembre 2023) : 2390. http://dx.doi.org/10.1149/ma2023-02472390mtgabs.

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The capture and electrochemical conversion of CO2, powered by renewable electricity, is an attractive method of sustainably producing valuable chemicals and fuels (e.g. carbon monoxide (CO)), reducing atmospheric CO2, and storing intermittent renewable energy. Integrated capture and conversion (reactive capture) of CO2 presents a CO2-to-CO electrolysis pathway that eliminates most of the upstream capital and energy costs by releasing CO2 directly inside the electrolyzer using an internal pH-swing. The reactive capture system readily allows for the collection of produced gas products via phase separation, thus minimizing downstream separation costs. Industrial-scale integration of reactive capture systems with upgrading processes require a pure and consistent product stream. Previous studies using bicarbonate electrolytes have demonstrated high selectivity towards CO. However, the limited CO2 capture capacity of bicarbonate electrolytes dilute the cathode product gas stream with excess CO2. This mandates a secondary CO2 capture unit and increases the cost of downstream separation. Other studies using carbonate or carbamate electrolyte as the inlet feed did not simultaneously achieve high CO selectivity and long-term stability. This study sought to improve the Faradaic efficiency (FE) toward CO in our carbonate electrolysis system by engineering a novel membrane electrode assembly structure. We designed a composite CO2 diffusion layer (CDL) between the cathode and the membrane that attains high CO selectivity by simultaneously achieving high alkalinity and sufficient CO2 availability at the cathode. We determined that the thickness, wettability, and permeability of the CDL affected species transport and were important optimization parameters. Applying this strategy, we produced syngas, a mixture of CO and hydrogen (H2), with an industrial H2/CO ratio of 1.16 at 200 mA cm-2. This corresponded to a CO Faradaic efficiency (FE) of 46% and energy intensity of 52 GJ tsyngas-1. The syngas produced in this system was not diluted by CO2 and contained sufficient CO content to meet industrial standards. We further increased the FE towards CO by exploring different capture solutions and designing selective catalysts for energy efficient CO production. System parameters such as temperature and pressure effects were also investigated to improve the CO2 concentration at the cathode. This study illustrated the potential for the industrial implementation of an energy efficient and capital cost effective CO2-to-CO pathway via reactive capture.

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Fišer, Jiří, Tomáš Boublík et Rudolf Polák. « Intermolecular Interactions in the (CO2)2, N2-CO2 and CO-CO2 Complexes ». Collection of Czechoslovak Chemical Communications 69, n^o 1 (2004) : 177–88. http://dx.doi.org/10.1135/cccc20040177.

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Interaction energies of the most stable structures of the title complexes are calculated using the supermolecule CCSD(T) and MP4 methods and aug-cc-pVXZ (X = D, T, Q) basis sets extended by a set of midbond functions centered in the middle of the intermolecular bond. Geometrical parameters for these structures are in very good agreement with experimental data.

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Tsuchiya, Y. « Co/co2 Ratios In Fire ». Fire Safety Science 4 (1994) : 515–26. http://dx.doi.org/10.3801/iafss.fss.4-515.

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Yamamoto, Takashi, Tatsuhiko Mikami, Mai Tomisaki et Yasuaki Einaga. « Electroreduction of CO₂ into CO Using Amine-Modified Diamond Electrode ». ECS Meeting Abstracts MA2023-02, n^o 52 (22 décembre 2023) : 2502. http://dx.doi.org/10.1149/ma2023-02522502mtgabs.

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Electroreduction of CO2 is promising to convert CO2 into value-added compounds since electroreduction does not necessarily require a catalyst because an electrochemical energy itself can activate the reactivity of CO2. Most of the reported studies on CO2 electroreduction use a metal electrode material, and the selectivity of reduction products depends on the metal species. However, as the use of noble or toxic metals should be avoided from the viewpoint of sustainability, a metal-free carbon-based material are desirable. Along these lines, we have focused on boron-doped diamond (BDD) as a carbon-based electrode in CO2 electroreduction. On the other hand, molecular modification of electrode surface is an important technique in various fields. Functional molecules can be covalently immobilized onto carbon electrodes by an electrografting method. Along these lines, we decided to immobilize amine on BDD surface, which integrates CO2 capture and storage technologies and CO2 electroreduction. Here, we prepared amine-modified BDD (NH2-BDD) to elucidate an effect of amine modification on CO2 electroreduction. Prior to the electrolysis experiments, linear sweep voltammetry (LSV) was performed to investigate the electrochemical difference between bare- and NH2-BDD. As an energetically equivalent criterion for the CO2 electroreduction, E red was defined as the potential at which the current density reached -30 µA/cm2; E red (vs. Ag/AgCl) were determined to be -1.56 and -1.16 V for bare-BDD and NH2-BDD, respectively. A positive shift of E red in the NH2-BDD electrode is probably because CO2 molecules form the C-N bond with the amino group on the electrode surface, which results in enhancing the electrophilicity of the carbon atom. Next, we investigated how amine modification affects the product selectivity in CO2 electroreduction. Products were CO, HCOOH, and H2 regardless of the type of electrode and applied potentials. Difference between the Faraday efficiencies (FE) of HCOOH and CO production was dependent on applied potentials in NH2-BDD. Particularly, in the most prominent case, the selectivity of CO production was 8 times higher for NH2-BDD than the case of bare-BDD. Since CO production requires the adsorption of intermediate species, CO2 • -, on the electrode surface, the adsorption of CO2 and CO2 • - would be promoted on NH2-BDD through the formation of C-N bond. In order to obtain the direct evidence for CO2 capturing by NH2-BDD during the electroreduction, in situ ATR-IR measurements were performed. We focused on the C=O (carbonyl) stretching vibration of the carbamate anion, observed in the region of 1700-1500 cm-1. In NH2-BDD, a broad peak attributed to the C=O stretching vibration was observed at around 1640 cm-1, and the peak intensity decreased as the applied potential became negative. This result strongly supports that CO2 was captured by amine at the BDD surface to form the carbamate anion and reduced to CO. The above discussion can be explained by the behavior of LSV of NH2-BDD, in which two drops were observed. The first drop at around -1.20 V (vs. Ag/AgCl) is probably ascribed to the reduction of CO2 captured by amine, and the second drop at around -1.70 V (vs. Ag/AgCl) is ascribed to the reduction of free CO2. Therefore, CO production would be favored at potentials between -1.20 and -1.70 V (vs. Ag/AgCl) and HCOOH production would be favored at potentials more negative than -1.70 V (vs. Ag/AgCl). These threshold potentials are in good agreement with the potentials at which the product selectivity switched. It is noted that, in bare-BDD electrodes showing the different E red, the selectivity of CO production was almost unchanged, which suggests that the potential dependence of product selectivity in CO2 electroreduction cannot be explained only by differences in E red. Therefore, the product selectivity was driven by the interaction between the surface amine groups and CO2, i.e. the reaction via carbamate formation. Figure 1

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Tan, Jeannie Z. Y., Stelios Gavrielides, Hao R. Xu, Warren A. Thompson et M. Mercedes Maroto-Valer. « Alkali modified P25 with enhanced CO2 adsorption for CO2 photoreduction ». RSC Advances 10, n^o 47 (2020) : 27989–94. http://dx.doi.org/10.1039/d0ra05010e.

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Wolf, Stephanie E., Lucy Dittrich, Markus Nohl, Tobias Duyster, Izaak C. Vinke, Rüdiger-A. Eichel et L. G. J. (Bert) de Haart. « Boundary Investigation of High-Temperature Co-Electrolysis Towards Direct CO₂ Electrolysis ». Journal of The Electrochemical Society 169, n^o 3 (1 mars 2022) : 034531. http://dx.doi.org/10.1149/1945-7111/ac5e45.

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In the temperature range of high temperature co-electrolysis of both steam and carbon dioxide, the reverse water-gas shift reaction (RWGS) takes place. Prior studies were conducted with a narrow gas composition range to investigate the role of RWGS during co-electrolysis. The results for steam electrolysis, CO2 electrolysis, and co-electrolysis caused different conclusions regarding the role of electrochemical CO2 and H2O conversion compared to RWGS during co-electrolysis. This work aims to resolve the role of CO2 conversion as part of RWGS in co-electrolysis. The boundary is characterized by AC and DC measurements over a broad gas composition range from CO2 electrolysis towards co-electrolysis with nearly 50%eq H2O. Especially, the electrochemical CO2 reduction and CO2 conversion in the RWGS are compared to clarify their role during co-electrolysis. The results revealed that gas composition determined the predominant reaction (H2O or CO2 reduction). The cell performance of co-electrolysis in the boundary region up to 5%eq H2O was similar to the performance of CO2 electrolysis. Up to 30%eq H2O, the performance increases with H2O concentration. Here, both CO2 and H2O electrolysis occur. Above 30%eq H2O, steam electrolysis and the RWGS reaction both dominate the co-electrolysis process.

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Park, Chae-Young, Bong-Jun Chang, Jeong-Hoon Kim et Young Moo Lee. « UV-crosslinked poly(PEGMA-co-MMA-co-BPMA) membranes : Synthesis, characterization, and CO2/N2 and CO2/CO separation ». Journal of Membrane Science 587 (octobre 2019) : 117167. http://dx.doi.org/10.1016/j.memsci.2019.06.007.

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Ungváry, Ferenc, Jabir Shanshool et László Markó. « Kinetics and equilibrium of Co2(CO)6(η4-norbornadiene) formation from Co2(CO)8 and norbornadiene under CO ». Journal of Organometallic Chemistry 296, n^o 1-2 (novembre 1985) : 155–59. http://dx.doi.org/10.1016/0022-328x(85)80346-6.

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Fan, Yan, Jianqiang Feng, Miao Yang, Xin Tan, Hongjun Fan, Meijin Guo, Binju Wang et Song Xue. « CO2(aq) concentration–dependent CO2 fixation via carboxylation by decarboxylase ». Green Chemistry 23, n^o 12 (2021) : 4403–9. http://dx.doi.org/10.1039/d1gc00825k.

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Liu, Yan, Yawei Li, Yuanzhen Chen, Ting Qu, Chengyong Shu, Xiaodong Yang, Haiyan Zhu et al. « A CO2/H2 fuel cell : reducing CO2 while generating electricity ». Journal of Materials Chemistry A 8, n^o 17 (2020) : 8329–36. http://dx.doi.org/10.1039/d0ta02855j.

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Gómez-Ortiz, Carlos, Guillaume Monteil, Sourish Basu et Marko Scholze. « A CO₂–Δ¹⁴CO₂ inversion setup for estimating European fossil CO₂ emissions ». Atmospheric Chemistry and Physics 25, n^o 1 (13 janvier 2025) : 397–424. https://doi.org/10.5194/acp-25-397-2025.

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Abstract. Independent estimation and verification of fossil CO2 emissions on a regional and national scale are crucial for evaluating the fossil CO2 emissions and reductions reported by countries as part of their nationally determined contributions (NDCs). Top-down methods, such as the assimilation of in situ and satellite observations of different tracers (e.g., CO2, CO, Δ14CO2, XCO2), have been increasingly used for this purpose. In this paper, we use the Lund University Modular Inversion Algorithm (LUMIA) to estimate fossil CO2 emissions and natural fluxes by simultaneously inverting in situ synthetic observations of CO2 and Δ14CO2 over Europe. We evaluate the inversion system by conducting a series of observing system simulation experiments (OSSEs). We find that in regions with a dense sampling network, such as western/central Europe, adding Δ14CO2 observations in an experiment where the prior fossil CO2 and biosphere fluxes are set to zero allows LUMIA to recover the time series of both categories. This reduces the prior-to-truth root mean square error (RMSE) from 1.26 to 0.12 TgC d−1 in fossil CO2 and from 0.97 to 0.17 TgC d−1 in biosphere fluxes, reflecting the true total CO2 budget by 91 %. In a second set of experiments using realistic prior fluxes, we find that in addition to retrieving the time series of the optimized fluxes, we are able to recover the true regional fossil CO2 budget in western/central Europe by 95 % and in Germany by 97 %. In all experiments, regions with low sampling coverage, such as southern Europe and the British Isles, show poorly resolved posterior fossil CO2 emissions. Although the posterior biosphere fluxes in these regions follow the seasonal patterns of the true fluxes, a significant bias remains, making it impossible to close the total CO2 budget. We find that the prior uncertainty of fossil CO2 emissions does not significantly impact the posterior estimates, showing similar results in regions with good sampling coverage like western/central Europe and northern Europe. Finally, having a good prior estimate of the terrestrial isotopic disequilibrium is important to avoid introducing additional noise into the posterior fossil CO2 fluxes.

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Scarpelli, Tia R., Paul I. Palmer, Mark Lunt, Ingrid Super et Arjan Droste. « Verifying national inventory-based combustion emissions of CO₂ across the UK and mainland Europe using satellite observations of atmospheric CO and CO₂ ». Atmospheric Chemistry and Physics 24, n^o 18 (26 septembre 2024) : 10773–91. http://dx.doi.org/10.5194/acp-24-10773-2024.

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Abstract. Under the Paris Agreement, countries report their anthropogenic greenhouse gas emissions in national inventories, which are used to track progress towards mitigation goals, but they must be independently verified. Atmospheric observations of CO2, interpreted using inverse methods, can potentially provide that verification. Conventional CO2 inverse methods infer natural CO2 fluxes by subtracting a priori estimates of fuel combustion from the a posteriori net CO2 fluxes, assuming that a priori knowledge for combustion emissions is better than for natural fluxes. We describe an inverse method that uses measurements of CO2 and carbon monoxide (CO), a trace gas that is co-emitted with CO2 during combustion, to report self-consistent combustion emissions and natural fluxes of CO2. We use an ensemble Kalman filter and the GEOS-Chem atmospheric transport model to explore how satellite observations of CO and CO2 collected by the TROPOspheric Monitoring Instrument (TROPOMI) and Orbiting Carbon Observatory-2 (OCO-2), respectively, can improve understanding of combustion emissions and natural CO2 fluxes across the UK and mainland Europe in 2018–2021. We assess the value of using satellite observations of CO2, with and without CO, above what is already available from the in situ network. Using CO2 satellite observations leads to small corrections to a priori emissions that are inconsistent with in situ observations, due partly to the insensitivity of the atmospheric CO2 column to CO2 emission changes. When we introduce satellite CO observations, we find better agreement with our in situ inversion and a better model fit to atmospheric CO2 observations. Our regional mean a posteriori combustion CO2 emission ranges from 4.6–5.0 Gt a−1 (1.5 %–2.4 % relative standard deviation), with all inversions reporting an overestimate for Germany's wintertime emissions. Our national a posteriori CO2 combustion emissions are highly dependent on the assumed relationship between CO2 and CO uncertainties, as expected. Generally, we find better results when we use grid-scale-based a priori CO2:CO uncertainty estimates rather than a fixed relationship between the two species.

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Frogneux, Xavier, Olivier Jacquet et Thibault Cantat. « Iron-catalyzed hydrosilylation of CO2 : CO2 conversion to formamides and methylamines ». Catal. Sci. Technol. 4, n^o 6 (2014) : 1529–33. http://dx.doi.org/10.1039/c4cy00130c.

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Catalytic hydrosilylation of CO₂ is an efficient and selective approach to form chemicals. Herein, we describe the first iron catalysts able to promote the reductive functionalization of CO₂ using hydrosilanes as reductants. Iron(ii) salts supported by phosphine donors enable the conversion of CO₂ to formamide and methylamine derivatives under mild reaction conditions.

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Zhao, Kechao, Zhenhua Li et Li Bian. « CO2 methanation and co-methanation of CO and CO2 over Mn-promoted Ni/Al2O3 catalysts ». Frontiers of Chemical Science and Engineering 10, n^o 2 (14 mars 2016) : 273–80. http://dx.doi.org/10.1007/s11705-016-1563-5.

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Frerichs, M., F. X. Schweiger, F. Voigts, S. Rudenkiy, W. Maus-Friedrichs et V. Kempter. « Interaction of O2, CO and CO2 with Co films ». Surface and Interface Analysis 37, n^o 7 (2005) : 633–40. http://dx.doi.org/10.1002/sia.2060.

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Moskovich, Shahar, Dana Reuvenov et Richard H. Schultz. « Microsecond UV flash photolysis of Co2(CO)8 in solution : Wavelength dependence of the Co(CO)4/Co2(CO)7 branching ratio ». Chemical Physics Letters 431, n^o 1-3 (novembre 2006) : 62–66. http://dx.doi.org/10.1016/j.cplett.2006.09.012.

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Wang, Ruiqin, Mengxin Zhang, Ying Guan, Mao Chen et Yongjun Zhang. « A CO2-responsive hydrogel film for optical sensing of dissolved CO2 ». Soft Matter 15, n^o 30 (2019) : 6107–15. http://dx.doi.org/10.1039/c9sm00958b.

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Lončarević, D., et Ž. Čupić. « Characterization and Catalytic Activity of Poly(4-Vinylpyridine-Co-Divinylbenzene)-Co²⁺ Complex ». Materials Science Forum 494 (septembre 2005) : 363–68. http://dx.doi.org/10.4028/www.scientific.net/msf.494.363.

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Poly(4-vinylpyridine-co-divinylbenzene)-Co2+ was characterized using infrared spectroscopy (IR), thermogravimetric analysis (TG-DTA), N2-physisorption and polarography. Thermal analysis suggests sufficient thermal stability of the polymer support, under reaction conditions. From polarography measurements, the Co2+ content on polymer-supported catalysts is estimated and it was proved that no significant leaching occurred during the activity tests. At the molecular level, FTIR of P4VP-DVB-Co2+ reveals that the pyridine nitrogen lone pair coordinates to the metal center in the polymeric complex. The obtained P4VP-DVB-Co2+ catalysts performed interesting catalytic activity in reaction of the cyclohexane oxidation with air, indicating that increasing Co2+ content lowers the initiation temperature and raises the decomposition of cyclohexylhydroperoxide.

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Vardag, S. N., C. Gerbig, G. Janssens-Maenhout et I. Levin. « Estimation of continuous anthropogenic CO2 ; using CO2, CO, δ13C(CO2) and Δ14C(CO2) ». Atmospheric Chemistry and Physics Discussions 15, n^o 14 (24 juillet 2015) : 20181–243. http://dx.doi.org/10.5194/acpd-15-20181-2015.

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Abstract. We investigate different methods for estimating anthropogenic CO2 using modelled continuous atmospheric concentrations of CO2 alone, as well as CO2 in combination with the surrogate tracers CO, δ13C(CO2) and Δ14C(CO2). These methods are applied at three hypothetical stations representing rural, urban and polluted conditions. We find that independent of the tracer used, an observation-based estimate of continuous anthropogenic CO2 is not feasible at rural measurement sites due to the low signal to noise ratio of anthropogenic CO2 estimates at such settings. At urban and polluted sites, potential future continuous Δ14C(CO2) measurements with a precision of 5 ‰ or better are most promising for anthropogenic CO2 determination (precision ca. 10–20%), but the insensitivity against CO2 contributions from biofuel emissions may reduce its accuracy in the future. Other tracers, such as δ13C(CO2) and CO could provide an accurate and already available alternative if all CO2 sources in the catchment area are well characterized with respect to their isotopic signature and CO to anthropogenic CO2 ratio. We suggest a strategy for calibrating these source characteristics on an annual basis using precise Δ14C(CO2) measurements on grab samples. The precision of anthropogenic CO2 determination using δ13C(CO2) is largely determined by the measurement precision of δ13C(CO2) and CO2. The precision when using the CO-method is mainly limited by the variation of natural CO sources and CO sinks. At present, continuous anthropogenic CO2 could be determined using the tracers δ13C(CO2) and/or CO with a precision of about 30 %, a mean bias of about 10 % and without significant diurnal discrepancies. This allows significant improvement, validation and bias reduction of highly resolved emission inventories using atmospheric observation and regional modelling.

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Ahmad Syuhada, M.I. Maulana et R. Sary. « The Ability of Selected Plants to Absorbing CO₂, CO and HC from Gasoline Engine Exhaust ». International Journal of Automotive and Mechanical Engineering 19, n^o 4 (28 décembre 2022) : 10094–102. http://dx.doi.org/10.15282/ijame.19.4.2022.06.0780.

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Global warming is the unusually rapid increase in the earth’s average surface temperature, which has an impact on climate change. The cause of global warming is the inhibition of heat transfer from the earth’s surface to space, which is analogous to the greenhouse effect. The occurrence of the greenhouse effect is due to the large amount of carbon dioxide (CO2) produced by the complete combustion of fuel in vehicles and industrial processes. The rising use of fossil fuels and the ongoing reduction in forest plants’ ability to absorb CO2 is to blame for the rise in CO2 levels in the atmosphere. To reduce the increase in CO2 gas, one effort that can be made is to increase CO2-absorbing plants. In this regard, plants are able to absorb CO2 and convert it into oxygen and glucose by utilizing solar heat. The purpose of this study is to determine the ability to absorb CO2 from several types of plants. The test was carried out using two closed test rooms with dimensions of 100×50×50 cm, where room 1 (first) was used to store 0.5% of CO2 emissions, while room 2 (second) was used for the plants being tested. Gas is flowed into room 2 using a fan for 300 minutes, and data collection is carried out every 60 minutes. Based on results obtained in this line of research, the best plant ability to absorb CO2 can be ordered as follows 0.25 mg/m2.hour for squirrel tail, 0.243 mg/m2.hour for trembesi, 0.2 mg/m2.hour for mahogany, 0.177 mg/m2.hour for kaffir lime, 0.166 mg/m2.hour for mango, and 0.166 mg/m2.hour for cape.

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Vardag, S. N., C. Gerbig, G. Janssens-Maenhout et I. Levin. « Estimation of continuous anthropogenic CO2 ; : model-based evaluation of CO2, CO, δ13C(CO2) and Δ14C(CO2) tracer methods ». Atmospheric Chemistry and Physics 15, n^o 22 (16 novembre 2015) : 12705–29. http://dx.doi.org/10.5194/acp-15-12705-2015.

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Abstract. We investigate different methods for estimating anthropogenic CO2 using modeled continuous atmospheric concentrations of CO2 alone, as well as CO2 in combination with the surrogate tracers CO, δ13C(CO2) and Δ14C(CO2). These methods are applied at three hypothetical stations representing rural, urban and polluted conditions. We find that, independent of the tracer used, an observation-based estimate of continuous anthropogenic CO2 is not yet feasible at rural measurement sites due to the low signal-to-noise ratio of anthropogenic CO2 estimates at such settings. The tracers δ13C(CO2) and CO provide an accurate possibility to determine anthropogenic CO2 continuously, only if all CO2 sources in the catchment area are well characterized or calibrated with respect to their isotopic signature and CO to anthropogenic CO2 ratio. We test different calibration strategies for the mean isotopic signature and CO to CO2 ratio using precise Δ14C(CO2) measurements on monthly integrated as well as on grab samples. For δ13C(CO2), a calibration with annually averaged 14C(CO2) grab samples is most promising, since integrated sampling introduces large biases into anthropogenic CO2 estimates. For CO, these biases are smaller. The precision of continuous anthropogenic CO2 determination using δ13C(CO2) depends on measurement precision of δ13C(CO2) and CO2, while the CO method is mainly limited by the variation in natural CO sources and sinks. At present, continuous anthropogenic CO2 could be determined using the tracers δ13C(CO2) and/or CO with a precision of about 30 %, a mean bias of about 10 % and without significant diurnal discrepancies. Hypothetical future measurements of continuous Δ14C(CO2) with a precision of 5 ‰ are promising for anthropogenic CO2 determination (precision ca. 10–20 %) but are not yet available. The investigated tracer-based approaches open the door to improving, validating and reducing biases of highly resolved emission inventories using atmospheric observation and regional modeling.

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Ping, Chao, Bao-Qi Feng, Yun-Lei Teng, Han-Qing Chen, Si-Li Liu, Yun-Long Tai, Hao-Nan Liu et Bao-Xia Dong. « Acquiring an effective CaO-based CO2 sorbent and achieving selective methanation of CO2 ». RSC Advances 10, n^o 36 (2020) : 21509–16. http://dx.doi.org/10.1039/d0ra02495c.

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Tian, Jing, Qing Zhang, Wei Feng Li, Yue Meng, Tong Yan, Hong Kai Wang, You Fang Li, Ming Su Liu et Hui Fen Guo. « Influence of Co(ii) Ionic Liquids Catalytic System for Polycarbonate (CHO/CO₂) Synthesis ». Advanced Materials Research 1095 (mars 2015) : 345–48. http://dx.doi.org/10.4028/www.scientific.net/amr.1095.345.

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In the report, Co (ii) ionic liquids catalytic system was synthesized and used in the polycarbonate (CHO/CO2) synthesis. The Co (ii) ionic liquids catalytic system was characterized by infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The influences of different factors, including reaction time, reaction temperature, and pressure of CO2 on the synthesis of polycarbonate (CHO/CO2) were described. The results show that Co (ii) ionic liquids catalytic system could be successfully applied in the copolymerization of carbon oxide (CO2) and cyclohexene oxide (CHO). The optimum synthetic conditions of the polycarbonate, including reaction temperature of 90 °C, reaction time of 8 hours , and CO2 pressure of 25 bar.

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Anila, Sebastian, et Cherumuttathu H. Suresh. « Guanidine as a strong CO2 adsorbent : a DFT study on cooperative CO2 adsorption ». Physical Chemistry Chemical Physics 23, n^o 24 (2021) : 13662–71. http://dx.doi.org/10.1039/d1cp00754h.

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Transformation of the non-covalent G⋯CO₂ complex into a G–CO₂ covalent complex in (G–CO₂)_n clusters with a fivefold increase in ΔE_/CO2 is reported.

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Melnikova, Irina, Philippe Ciais, Katsumasa Tanaka, Hideo Shiogama, Kaoru Tachiiri, Tokuta Yokohata et Olivier Boucher. « Carbon cycle and climate feedbacks under CO₂ and non-CO₂ overshoot pathways ». Earth System Dynamics 16, n^o 1 (6 février 2025) : 257–73. https://doi.org/10.5194/esd-16-257-2025.

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Abstract. Reducing emissions of non-carbon dioxide (CO2) greenhouse gases (GHGs), such as methane (CH4) and nitrous oxide (N2O), complements CO2 mitigation in limiting global warming. However, estimating carbon–climate feedback for these gases remains fraught with uncertainties, especially under overshoot scenarios. This study investigates the impact of CO2 and non-CO2 gases with nearly equal levels of effective radiative forcing on the climate and carbon cycle, using the Earth system model (ESM) IPSL-CM6A-LR. We first present a method to recalibrate methane and nitrous oxide concentrations to align with published radiative forcings, ensuring accurate model performance. Next, we carry out a series of idealised ramp-up and ramp-down concentration-driven experiments and show that, while the impacts of increasing and decreasing CO2 and non-CO2 gases on the surface climate are nearly equivalent (when their radiative forcing magnitudes are set to be the same), regional differences emerge. We further explore the carbon cycle feedbacks and demonstrate that they differ under CO2 and non-CO2 forcing. CO2 forcing leads to both carbon–climate and carbon–concentration feedbacks, whereas non-CO2 gases give rise to the carbon–climate feedback only. We introduce a framework, building on previous studies that addressed CO2 forcing, to separate the carbon–climate feedback into a temperature term and a temperature–CO2 cross-term. Our findings reveal that these feedback terms are comparable in magnitude for the global ocean. This underscores the importance of considering both terms in carbon cycle feedback framework and climate change mitigation strategies.

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Dwivedi, Tatsat, Ayan Ghosh, M. B. Sai Prasad et Padma Nilaya Jonnalagadda. « Experimental estimation of CO concentration in LN₂ cooled CW CO laser operating with CO₂ laser gas mixture ». Laser Physics Letters 19, n^o 9 (13 juillet 2022) : 095001. http://dx.doi.org/10.1088/1612-202x/ac7ecc.

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Abstract The lasing medium of cryo-cooled CW-CO laser operated with CO2 laser gain medium (CO2–N2–He mixture) resulting in 5 µm emission is formed in-situ in the discharge and its composition, that is sensitively dependent on the discharge temperature, is not known a priori. The composition of the CO lasing gas mixture here was successfully arrived at by way of sampling the gas mixture at the exhaust and measuring the wavelength dependent absorbance by a Fourier Transform Infrared Spectrophotometer. This enabled us to determine the CO and CO2 concentrations in the lasing mixture accurately while the other major constituents were estimated from the initial partial pressures. The composition of the lasing gas mixture was studied for various discharge wall temperatures starting from no cooling condition (∼351 K) to LN2 cooled conditions (79 K). While the concentrations of both, CO2 and CO were found to decrease for temperatures below the freezing point of CO2 at the operating pressure of 11 mbar, the relative concentration of CO with respect to CO2 also increased with reducing temperature accompanied by a steady increase in the CO laser power output. The onset of lasing in 5 µm region was found to occur at a discharge wall temperature of 212 K.

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Jessen, Cecilie Høgfeldt, Jesper Bendix, Theis Brock Nannestad, Heloisa Bordallo, Martin Jæger Pedersen, Christian Marcus Pedersen et Mikael Bols. « CO₂ complexation with cyclodextrins ». Beilstein Journal of Organic Chemistry 19 (17 juillet 2023) : 1021–27. http://dx.doi.org/10.3762/bjoc.19.78.

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Carbon dioxide (CO2) emissions from industrial processes, power generation, and transportation contribute significantly to global warming and climate change. Carbon capture and storage (CCS) technologies are essential to reduce these emissions and mitigate the effects of climate change. Cyclodextrins (CDs), cyclic oligosaccharides, are studied as potential CO2 capture agents due to their unique molecular structures and high selectivity towards CO2. In this paper we have investigated binding efficiency of a number of cyclodextrins towards CO2. It is found that the crystal structure of α-cyclodextrin with CO2 has a 1:1 stoichioimetry and that a number of simple and modified cyclodextrins bind CO2 in water with a Kg of 0.18–1.2 bar−1 (7–35 M−1) with per-O-methyl α-cyclodextrin having the highest CO2 affinity.

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Lee, Jae Won, et Hyunjoo Lee. « Biohybrid CO₂ Electrolysis for the Direct Synthesis of Biomass from CO₂ ». ECS Meeting Abstracts MA2024-02, n^o 28 (22 novembre 2024) : 2179. https://doi.org/10.1149/ma2024-02282179mtgabs.

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Converting anthropogenic CO2 into value-added products using renewable energy has garnered significant attention in pursuit of a sustainable carbon cycle. While CO2 electrolysis has been extensively explored, the resulting products have typically been limited to simple C1-3 compounds like CO, formate, ethylene, and small alcohols. Despite their simplicity, these products can serve as feedstocks for fermenters to produce more complex chemicals. Combining electrochemical CO2 reduction with microbial fermentation has been an active area of research, albeit often hindered by low production rates. In our study, we integrated CO2 electrolysis with microbial fermentation to directly produce biomass from gaseous CO2. Firstly, we established a biohybrid system where the electrolyte solution containing formate was continuously circulated through both the CO2 electrolyzer and fermenter. This approach facilitated efficient accumulation of poly-3-hydroxybutyrate in Cupriavidus necator cells, achieving a PHB content of 83% of dry cell weight and producing 1.38 g PHB. The biohybrid system involved the electrochemical conversion of CO2 to formate on Sn catalysts deposited on a gas diffusion electrode, with careful optimization of the electrolyzer and electrolyte solution. Subsequently, we modified the system to enable continuous PHB production at a steady state by introducing fresh cells and removing PHB. Secondly, we developed electrochemical biohybrid system with metabolically engineered Escherichia coli (E. coli) capable of producing lactic acid solely from CO2 and formic acid. By constructing a biohybrid system comprising a CO2 electrolyzer that generates formic acid from CO2 and a fermenter housing the engineered E. coli, we achieved direct electrochemical production of lactic acid from gaseous CO2. The catholyte was optimized to support the engineered E. coli within the biohybrid system, and the formic acid production rate was controlled to ensure stable lactic acid production. These strategies employed in developing our biohybrid system hold promise for establishing other electrochemical biohybrid systems capable of producing chemicals and materials directly from gaseous CO2.

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Liu, Hanbin, Shaojian Lin, Yujun Feng et Patrick Theato. « CO2-Responsive polymer materials ». Polymer Chemistry 8, n^o 1 (2017) : 12–23. http://dx.doi.org/10.1039/c6py01101b.

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Simon, Alexia, Karin I. Öberg, Mahesh Rajappan et Pavlo Maksiutenko. « Entrapment of CO in CO2 Ice ». Astrophysical Journal 883, n^o 1 (17 septembre 2019) : 21. http://dx.doi.org/10.3847/1538-4357/ab32e5.

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Ishchenko, Olena V., Alla G. Dyachenko, Andrii V. Yatsymyrskiy, Tetiana M. Zakharova, Snizhana V. Gaidai, Vladyslav V. Lisnyak et Ruslan Mariychuk. « CO2 methanation over Co–Ni catalysts ». E3S Web of Conferences 154 (2020) : 02001. http://dx.doi.org/10.1051/e3sconf/202015402001.

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One of the major goals when creating new energy systems is to provide clean and affordable energy. Currently, there is an excessive increase in the cost of fossil fuels and natural gas because of increased energy consumption and the inability to meet demand. That is why it is necessary to find reliable renewable energy sources and processes that will produce energy materials without toxic by-products in order to preserve the environment and to ensuring sustainable development and a strong economy. From environmental safety reasons, this need has led to the development of the catalytic synthesis of energetic materials from greenhouse gases; in particular, this paper proposes an efficient approach to producing methane by hydrogenation of carbon dioxide over Co–Ni catalysts.

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Bähr, Cornelia. « Rohstoffbasis : CO und CO2 biotechnisch verwerten ». Nachrichten aus der Chemie 65, n^o 1 (janvier 2017) : 35–37. http://dx.doi.org/10.1002/nadc.20174057460.

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Kwon, Min Jung, Ashley Ballantyne, Philippe Ciais, Ana Bastos, Frédéric Chevallier, Zhihua Liu, Julia K. Green, Chunjing Qiu et John S. Kimball. « Siberian 2020 heatwave increased spring CO₂ uptake but not annual CO₂ uptake ». Environmental Research Letters 16, n^o 12 (25 novembre 2021) : 124030. http://dx.doi.org/10.1088/1748-9326/ac358b.

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Abstract Siberia experienced an unprecedented strong and persistent heatwave in winter to spring of 2020. Using bottom–up and top–down approaches, we evaluated seasonal and annual CO2 fluxes of 2020 in the northern hemisphere (north of 30 °N), focusing on Siberia where the pronounced heatwave occurred. We found that, over Siberia, CO2 respiration loss in response to the pronounced positive winter temperature anomaly was greater than in previous years. However, continued warming in the spring enhanced photosynthetic CO2 uptake, resulting in the largest seasonal transition in net ecosystem CO2 exchange; that is, the largest magnitude of the switch from the net CO2 loss in winter to net CO2 uptake in spring until June. However, this exceptional transition was followed by the largest reduction in CO2 uptake in late summer due to multiple environmental constraints, including a soil moisture deficit. Despite a substantial increase of CO2 uptake by 22 ± 9 gC m−2 in the spring in response to the heatwave, the mean annual CO2 uptake over Siberia was slightly lower (3 ± 13 gC m−2yr−1) than the average of the previous five years. These results highlight the highly dynamic response of seasonal carbon fluxes to extreme temperature anomalies at high latitudes, indicating a seasonal compensation between abnormal uptake and release of CO2 in response to extreme warmth that may limit carbon sink capacity in high northern latitudes.

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Garcia, Thelma Y., James C. Fettinger, Marilyn M. Olmstead et Alan L. Balch. « Splendid symmetry : crystallization of an unbridged isomer of Co2(CO)8 in Co2(CO)8·C60 ». Chemical Communications, n^o 46 (2009) : 7143. http://dx.doi.org/10.1039/b915083h.

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Osella, Domenico, Luciano Milone, Carlo Nervi et Mauro Ravera. « Electronic Communication in [Co2(CO)6]2-Diyne and [Co2(CO)4(dppm)]2-Diyne Complexes ». European Journal of Inorganic Chemistry 1998, n^o 10 (octobre 1998) : 1473–77. http://dx.doi.org/10.1002/(sici)1099-0682(199810)1998:10<1473 ::aid-ejic1473>3.0.co;2-t.

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Kobychev, V. B., N. M. Vitkovskaya et F. K. Shmidt. « Nonempirical study of the interaction of CO and Co, Co+, and Co2+ ». Journal of Structural Chemistry 28, n^o 5 (1988) : 766–67. http://dx.doi.org/10.1007/bf00752061.

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Jiménez, Vicente, Paula Sánchez, Paraskevi Panagiotopoulou, José Luís Valverde et Amaya Romero. « Methanation of CO, CO2 and selective methanation of CO, in mixtures of CO and CO2, over ruthenium carbon nanofibers catalysts ». Applied Catalysis A : General 390, n^o 1-2 (20 décembre 2010) : 35–44. http://dx.doi.org/10.1016/j.apcata.2010.09.026.

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Vesztergom, Soma, Alessandro Senocrate, Ying Kong, Viliam Kolivoška, Francesco Bernasconi, Robert Zboray, Corsin Battaglia et Peter Broekmann. « Eliminating Flooding-related Issues in Electrochemical CO₂-to-CO Converters : Two Lines of Defense ». CHIMIA 77, n^o 3 (29 mars 2023) : 104. http://dx.doi.org/10.2533/chimia.2023.104.

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By using silver (Ag) in nanostructured (nanowire, nanosphere, etc.) or thin-layer form as a catalyst for electrochemical CO2 reduction, very high CO-forming selectivity of almost 100% can be achieved. Supported by gas diffusion layers (GDLs), the reactant CO2 in the gas phase can approach and potentially access active Ag sites, which allows current densities in the range of a few hundred mA cm–2 to be reached. Yet, the stability of gas diffusion electrode (GDE) based electrochemical CO2-to-CO converters is far from perfect, and the activity of GDE cathodes, especially when operated at high current densities, often significantly decays during electrolyses after no more than a few hours. The primary reason of stability losses in GDE-based CO2-to-CO electrolysers is flooding: that is, the excess wetting of the GDE that prevents CO2 from reaching Ag catalytic sites. In the past years, the authors of this paper at Empa and at the University of Bern, cooperating with other partners of the National Competence Center for Research (NCCR) on Catalysis, took different approaches to overcome flooding. While opinions differ with regard to where the first line of defense in protecting GDEs from flooding should lie, a comparison of the recent results of the two groups gives unique insight into the nature of processes occurring in GDE cathodes used for CO2 electrolysis.

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Cao, Shuang Cindy, Jong Won Jung et Jong Wan Hu. « CO₂-Brine Displacement in Geological CO₂ Sequestration : Microfluidic Flow Model Study ». Applied Mechanics and Materials 752-753 (avril 2015) : 1210–13. http://dx.doi.org/10.4028/www.scientific.net/amm.752-753.1210.

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Geological CO2 sequestration is a promising method to reduce atmospheric CO2. Deep saline aquifers are one of the most important sites due to their capacity for CO2 storage. Thus, a better understanding of immiscible brine-CO2 mobility and their saturations including invading patterns in deep saline aquifers as CO2 storage sites is required. Microfluidic model provides the opportunity to discover unrecognized processes and to explore existing theories in fluid flow through porous media. In this study, the microfluidic model is used to explore the effects of both the supercritical carbon dioxide (scCO2) injecting velocity and ionic strength in saline aquifers on scCO2 invading patterns in geological CO2 sequestration. The results show that scCO2-brine displacement ratio increases with (1) increased scCO2 injecting velocity up to 40 μL/min, and (2) decreased ionic strength in the range of 1M~5M NaCl.

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Wang, H., D. J. Jacob, M. Kopacz, D. B. A. Jones, P. Suntharalingam, J. A. Fisher, R. Nassar, S. Pawson et J. E. Nielsen. « Error correlation between CO2 ; and CO as constraint for CO2 ; flux inversions using satellite data ». Atmospheric Chemistry and Physics Discussions 9, n^o 3 (12 mai 2009) : 11783–810. http://dx.doi.org/10.5194/acpd-9-11783-2009.

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Abstract. Inverse modeling of CO2 satellite observations to better quantify carbon surface fluxes requires a forward model such as a chemical transport model (CTM) to relate the fluxes to the observed column concentrations. Model transport error is an important source of observational error. We investigate the potential of using CO satellite observations as additional constraints in a joint CO2–CO inversion to improve CO2 flux estimates, by exploiting the CTM transport error correlations between CO2 and CO. We estimate the error correlation globally and for different seasons by a paired-model method (comparing CTM simulations of CO2 and CO columns using different assimilated meteorological data sets for the same meteorological year) and a paired-forecast method (comparing 48- vs. 24-h CTM forecasts of CO2 and CO columns for the same forecast time). We find strong positive and negative error correlations (r2>0.5) between CO2 and CO columns over much of the world throughout the year, and strong consistency between different methods to estimate the error correlation. Application of the averaging kernels used in the retrieval for thermal IR CO measurements weakens the correlation coefficients by 15% on average (mostly due to variability in the averaging kernels) but preserves the large-scale correlation structure. Results from a testbed inverse modeling application show that CO2–CO error correlations can indeed significantly reduce uncertainty on surface carbon fluxes in a joint CO2–CO inversion vs. a CO2–only inversion.

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M. Yusof, S., et L. P. Teh. « Bifunctional Materials for CO₂ Adsorption : Short Review ». Journal of Chemical Engineering and Industrial Biotechnology 7, n^o 2 (21 novembre 2021) : 15–19. http://dx.doi.org/10.15282/jceib.v7i2.7021.

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In recent years, there has been growing interest in adsorbents with high surface area, high porosity, high stability and high selectivity for CO2 adsorption. By the incorporation of the additive on the supports such as zeolite, silica, and carbon, the physicochemical properties of the adsorbent and CO2 adsorption performance can be enhanced. In this review, we focus on the overview of bifunctional materials (BFMs) for CO2 adsorption. The findings of this study suggests that the high surface area and high porosity of the support provide a good medium for high dispersion and accessibility of additives (amine or metal oxide), enhancing the CO2 adsorption efficiency. The excessive additive however may lead to a decrease of CO2 adsorption performance due to pore blockage and the decrease of active sites for CO2 interactions. The synergistic relationship of the supporting material and additive is significant towards the enhancement of CO2 adsorption.

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Cartwright, Richard J., Bryan J. Holler, William M. Grundy, Stephen C. Tegler, Marc Neveu, Ujjwal Raut, Christopher R. Glein et al. « JWST Reveals CO Ice, Concentrated CO₂ Deposits, and Evidence for Carbonates Potentially Sourced from Ariel’s Interior ». Astrophysical Journal Letters 970, n^o 2 (24 juillet 2024) : L29. http://dx.doi.org/10.3847/2041-8213/ad566a.

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Abstract The Uranian moon Ariel exhibits a diversity of geologically young landforms, with a surface composition rich in CO2 ice. The origin of CO2 and other species, however, remains uncertain. We report observations of Ariel’s leading and trailing hemispheres, collected with NIRSpec (2.87–5.10 μm) on the James Webb Space Telescope. These data shed new light on Ariel's spectral properties, revealing a double-lobed CO2 ice scattering peak centered near 4.20 and 4.25 μm, with the 4.25 μm lobe possibly representing the largest CO2 Fresnel peak yet observed in the solar system. A prominent 4.38 μm 13CO2 ice feature is also present, as is a 4.90 μm band that results from 12CO2 ice. The spectra reveal a 4.67 μm 12CO ice band and a broad 4.02 μm band that might result from carbonate minerals. The data confirm that features associated with CO2 and CO are notably stronger on Ariel’s trailing hemisphere compared to its leading hemisphere. We compared the detected CO2 features to synthetic spectra of CO2 ice and mixtures of CO2 with CO, H2O, and amorphous carbon, finding that CO2 could be concentrated in deposits thicker than ∼10 mm on Ariel’s trailing hemisphere. Comparison to laboratory data indicates that CO is likely mixed with CO2. The evidence for thick CO2 ice deposits and the possible presence of carbonates on both hemispheres suggests that some carbon oxides could be sourced from Ariel’s interior, with their surface distributions modified by charged particle bombardment, sublimation, and seasonal migration of CO and CO2 from high to low latitudes.

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Wang, H., D. J. Jacob, M. Kopacz, D. B. A. Jones, P. Suntharalingam, J. A. Fisher, R. Nassar, S. Pawson et J. E. Nielsen. « Error correlation between CO2 ; and CO as constraint for CO2 ; flux inversions using satellite data ». Atmospheric Chemistry and Physics 9, n^o 19 (2 octobre 2009) : 7313–23. http://dx.doi.org/10.5194/acp-9-7313-2009.

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Abstract. Inverse modeling of CO2 satellite observations to better quantify carbon surface fluxes requires a chemical transport model (CTM) to relate the fluxes to the observed column concentrations. CTM transport error is a major source of uncertainty. We show that its effect can be reduced by using CO satellite observations as additional constraint in a joint CO2-CO inversion. CO is measured from space with high precision, is strongly correlated with CO2, and is more sensitive than CO2 to CTM transport errors on synoptic and smaller scales. Exploiting this constraint requires statistics for the CTM transport error correlation between CO2 and CO, which is significantly different from the correlation between the concentrations themselves. We estimate the error correlation globally and for different seasons by a paired-model method (comparing GEOS-Chem CTM simulations of CO2 and CO columns using different assimilated meteorological data sets for the same meteorological year) and a paired-forecast method (comparing 48- vs. 24-h GEOS-5 CTM forecasts of CO2 and CO columns for the same forecast time). We find strong error correlations (r2>0.5) between CO2 and CO columns over much of the extra-tropical Northern Hemisphere throughout the year, and strong consistency between different methods to estimate the error correlation. Application of the averaging kernels used in the retrieval for thermal IR CO measurements weakens the correlation coefficients by 15% on average (mostly due to variability in the averaging kernels) but preserves the large-scale correlation structure. We present a simple inverse modeling application to demonstrate that CO2-CO error correlations can indeed significantly reduce uncertainty on surface carbon fluxes in a joint CO2-CO inversion vs. a CO2-only inversion.

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