- Utilizing terminal oxidants to achieve P450-catalyzed oxidation of methane
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Terminal oxidant-supported P450 reactions alleviate the need for substrate binding to initiate catalysis by chemically generating "compound I." This allows investigation of the innate substrate range of the enzyme active site. Using iodosylbenzene as the oxidant, CYP153A6, a medium-chain terminal alkane hydroxylase, exhibits methanol formation in the presence of methane demonstrating that P450-mediated methane hydroxylation is possible. Copyright
- Chen, Mike M.,Coelho, Pedro S.,Arnold, Frances H.
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- Methane to acetic acid over Cu-exchanged zeolites: Mechanistic insights from a site-specific carbonylation reaction
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The selective low temperature oxidation of methane is an attractive yet challenging pathway to convert abundant natural gas into value added chemicals. Copper-exchanged ZSM-5 and mordenite (MOR) zeolites have received attention due to their ability to oxidize methane into methanol using molecular oxygen. In this work, the conversion of methane into acetic acid is demonstrated using Cu-MOR by coupling oxidation with carbonylation reactions. The carbonylation reaction, known to occur predominantly in the 8-membered ring (8MR) pockets of MOR, is used as a site-specific probe to gain insight into important mechanistic differences existing between Cu-MOR and Cu-ZSM-5 during methane oxidation. For the tandem reaction sequence, Cu-MOR generated drastically higher amounts of acetic acid when compared to Cu-ZSM-5 (22 vs 4 μmol/g). Preferential titration with sodium showed a direct correlation between the number of acid sites in the 8MR pockets in MOR and acetic acid yield, indicating that methoxy species present in the MOR side pockets undergo carbonylation. Coupled spectroscopic and reactivity measurements were used to identify the genesis of the oxidation sites and to validate the migration of methoxy species from the oxidation site to the carbonylation site. Our results indicate that the CuII-O-CuII sites previously associated with methane oxidation in both Cu-MOR and Cu-ZSM-5 are oxidation active but carbonylation inactive. In turn, combined UV-vis and EPR spectroscopic studies showed that a novel Cu2+ site is formed at Cu/Al 0.2 in MOR. These sites oxidize methane and promote the migration of the product to a Bronsted acid site in the 8MR to undergo carbonylation.
- Narsimhan, Karthik,Michaelis, Vladimir K.,Mathies, Guinevere,Gunther, William R.,Griffin, Robert G.,Romn-Leshkov, Yuriy
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- Catalytic Hydrogenation of CO2to Methanol Using Multinuclear Iridium Complexes in a Gas-Solid Phase Reaction
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We report a novel approach toward the catalytic hydrogenation of CO2 to methanol performed in the gas-solid phase using multinuclear iridium complexes at low temperature (30-80 °C). Although homogeneous CO2 hydrogenation in water catalyzed by amide-based iridium catalysts provided only a negligible amount of methanol, the combination of a multinuclear catalyst and gas-solid phase reaction conditions led to the effective production of methanol from CO2. The catalytic activities of the multinuclear catalyst were dependent on the relative configuration of each active species. Conveniently, methanol obtained from the gas phase could be easily isolated from the catalyst without contamination with CO, CH4, or formic acid (FA). The catalyst can be recycled in a batchwise manner via gas release and filling. A final turnover number of 113 was obtained upon reusing the catalyst at 60 °C and 4 MPa of H2/CO2 (3:1). The high reactivity of this system has been attributed to hydride complex formation upon exposure to H2 gas, suppression of the liberation of FA under gas-solid phase reaction conditions, and intramolecular multiple hydride transfer to CO2 by the multinuclear catalyst.
- Kanega, Ryoichi,Onishi, Naoya,Tanaka, Shinji,Kishimoto, Haruo,Himeda, Yuichiro
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- Selective hydroxylation of methane by dioxiranes under mild conditions
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The direct conversion of methane to methanol at low temperatures was achieved selectively using dioxiranes 1a,b either in the isolated form or generated in situ from aqueous potassium caroate and the parent ketone at a pH close to neutrality. Results suggest that the more powerful dioxirane TFDO (1b) should be the oxidant of choice.
- Annese, Cosimo,D'Accolti, Lucia,Fusco, Caterina,Curci, Ruggero
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- A mild synthesis of13C-methanol
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The formation of oxazolidinon-2-ones from amino alcohols and carbon dioxide is well known. Until now it was not possible to reduce the fixed carbon dioxide to any basic chemical like formaldehyde or methanol, only the less interesting N-methyl compounds w
- Fr?hlich, J?rg,Berger, Stefan
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- Aqueous Electrochemical Reduction of Carbon Dioxide and Carbon Monoxide into Methanol with Cobalt Phthalocyanine
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Conversion of CO2 into valuable molecules is a field of intensive investigation with the aim of developing scalable technologies for making fuels using renewable energy sources. While electrochemical reduction into CO and formate are approaching industrial maturity, a current challenge is obtaining more reduced products like methanol. However, literature on the matter is scarce, and even more for the use of molecular catalysts. Here, we demonstrate that cobalt phthalocyanine, a well-known catalyst for the electrochemical conversion of CO2 to CO, can also catalyze the reaction from CO2 or CO to methanol in aqueous electrolytes at ambient conditions of temperature and pressure. The studies identify formaldehyde as a key intermediate and an unexpected pH effect on selectivity. This paves the way for establishing a sequential process where CO2 is first converted to CO which is subsequently used as a reactant to produce methanol. Under ideal conditions, the reaction shows a global Faradaic efficiency of 19.5 % and chemical selectivity of 7.5 %.
- Boutin, Etienne,Wang, Min,Lin, John C.,Mesnage, Matthieu,Mendoza, Daniela,Lassalle-Kaiser, Benedikt,Hahn, Christopher,Jaramillo, Thomas F.,Robert, Marc
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- Hydrogenation of CO2 to Methanol by Pt Nanoparticles Encapsulated in UiO-67: Deciphering the Role of the Metal-Organic Framework
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Metal-organic frameworks (MOFs) show great prospect as catalysts and catalyst support materials. Yet, studies that address their dynamic, kinetic, and mechanistic role in target reactions are scarce. In this study, an exceptionally stable MOF catalyst consisting of Pt nanoparticles (NPs) embedded in a Zr-based UiO-67 MOF was subject to steady-state and transient kinetic studies involving H/D and 13C/12C exchange, coupled with operando infrared spectroscopy and density functional theory (DFT) modeling, targeting methanol formation from CO2/H2 feeds at 170 °C and 1-8 bar pressure. The study revealed that methanol is formed at the interface between the Pt NPs and defect Zr nodes via formate species attached to the Zr nodes. Methanol formation is mechanistically separated from the formation of coproducts CO and methane, except for hydrogen activation on the Pt NPs. Careful analysis of transient data revealed that the number of intermediates was higher than the number of open Zr sites in the MOF lattice around each Pt NP. Hence, additional Zr sites must be available for formate formation. DFT modeling revealed that Pt NP growth is sufficiently energetically favored to enable displacement of linkers and creation of open Zr sites during pretreatment. However, linker displacement during formate formation is energetically disfavored, in line with the excellent catalyst stability observed experimentally. Overall, the study provides firm evidence that methanol is formed at the interface of Pt NPs and linker-deficient Zr6O8 nodes resting on the Pt NP surface.
- Gutter?d, Emil S.,Lazzarini, Andrea,Fjermestad, Torstein,Kaur, Gurpreet,Manzoli, Maela,Bordiga, Silvia,Svelle, Stian,Lillerud, Karl P.,Skúlason, Egill,?ien-?Degaard, Sigurd,Nova, Ainara,Olsbye, Unni
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- Efficient Hole Trapping in Carbon Dot/Oxygen-Modified Carbon Nitride Heterojunction Photocatalysts for Enhanced Methanol Production from CO2 under Neutral Conditions
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Artificial photosynthesis of alcohols from CO2 is still unsatisfactory owing to the rapid charge relaxation compared to the sluggish photoreactions and the oxidation of alcohol products. Here, we demonstrate that CO2 is reduced to me
- Wang, Yiou,Godin, Robert,Durrant, James R.,Tang, Junwang
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- Tandem amine and ruthenium-catalyzed hydrogenation of CO2to methanol
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This Communication describes the hydrogenation of carbon dioxide to methanol via tandem catalysis with dimethylamine and a homogeneous ruthenium complex. Unlike previous examples with homogeneous catalysts, this CO2-to-CH3OH process proceeds under basic reaction conditions. The dimethylamine is proposed to play a dual role in this system. It reacts directly with CO2 to produce dimethylammonium dimethylcarbamate, and it also intercepts the intermediate formic acid to generate dimethylformamide. With the appropriate selection of catalyst and reaction conditions, >95% conversion of CO2 was achieved to form a mixture of CH3OH and dimethylformamide.
- Rezayee, Nomaan M.,Huff, Chelsea A.,Sanford, Melanie S.
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- Highly Efficient CO2 Electroreduction to Methanol through Atomically Dispersed Sn Coupled with Defective CuO Catalysts
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Using renewable electricity to drive CO2 electroreduction is an attractive way to achieve carbon-neutral energy cycle and produce value-added chemicals and fuels. As an important platform molecule and clean fuel, methanol requires 6-electron transfer in the process of CO2 reduction. Currently, CO2 electroreduction to methanol suffers from poor efficiency and low selectivity. Herein, we report the first work to design atomically dispersed Sn site anchored on defective CuO catalysts for CO2 electroreduction to methanol. It exhibits high methanol Faradaic efficiency (FE) of 88.6 % with a current density of 67.0 mA cm?2 and remarkable stability in a H-cell, which is the highest FE(methanol) with such high current density compared with the results reported to date. The atomic Sn site, adjacent oxygen vacancy and CuO support cooperate very well, leading to higher double-layer capacitance, larger CO2 adsorption capacity and lower interfacial charge transfer resistance. Operando experiments and density functional theory calculations demonstrate that the catalyst is beneficial for CO2 activation via decreasing the energy barrier of *COOH dissociation to form *CO. The obtained key intermediate *CO is then bound to the Cu species for further reduction, leading to high selectivity toward methanol.
- Guo, Weiwei,Liu, Shoujie,Tan, Xingxing,Wu, Ruizhi,Yan, Xupeng,Chen, Chunjun,Zhu, Qinggong,Zheng, Lirong,Ma, Jingyuan,Zhang, Jing,Huang, Yuying,Sun, Xiaofu,Han, Buxing
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- Hierarchical TiO2/Ni(OH)2 composite fibers with enhanced photocatalytic CO2 reduction performance
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In the past few years, Ni(OH)2 has been found to be an effective cocatalyst for photocatalytic hydrogen evolution. Herein, we report that it can also be used to enhance the photoreduction of CO2 into chemical fuels. Vertically aligned Ni(OH)2 nanosheets are deposited onto electrospinning TiO2 nanofibers via simple wet-chemical precipitation to manufacture TiO2/Ni(OH)2 hybrid photocatalysts. The TiO2 nanofibers can direct the ordered growth of Ni(OH)2 nanosheets, which have a thickness of 20 nm and uniformly cover the surface of the TiO2 substrate. The TiO2/Ni(OH)2 hierarchical composite displays remarkably improved photocatalytic CO2 reduction activity compared to that displayed by pristine TiO2 fibers. The bare TiO2 can only produce methane and carbon monoxide (1.13 and 0.76 μmol h-1 g-1, respectively) upon CO2 photoreduction. After loading 0.5 wt% Ni(OH)2, the methane yield increases to 2.20 μmol h-1 g-1, meanwhile the CO yield is unchanged. Interestingly, alcohols (methanol and ethanol) also appear as products, in addition to CH4 and CO, over the TiO2/Ni(OH)2 hybrid, and the maximum yield is reached with 15 wt% Ni(OH)2 loading (0.58 and 0.37 μmol h-1 g-1 for methanol and ethanol, respectively). This can be ascribed to an enhanced charge separation efficiency and higher CO2 capture capacity due to the presence of Ni(OH)2. These results demonstrate that Ni(OH)2 can not only improve the total CO2 conversion efficiency, but can also alter the product selectivity upon photocatalysis. This work opens a new pathway for achieving high-efficiency photocatalytic CO2 reduction with Ni(OH)2 as a cocatalyst.
- Meng, Aiyun,Wu, Shuang,Cheng, Bei,Yu, Jiaguo,Xu, Jingsan
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- Neighboring Zn-Zr Sites in a Metal-Organic Framework for CO2Hydrogenation
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ZrZnOx is active in catalyzing carbon dioxide (CO2) hydrogenation to methanol (MeOH) via a synergy between ZnOx and ZrOx. Here we report the construction of Zn2+-O-Zr4+ sites in a metal-organic framework (MOF) to reveal insights into the structural requirement for MeOH production. The Zn2+-O-Zr4+ sites are obtained by postsynthetic treatment of Zr6(μ3-O)4(μ3-OH)4 nodes of MOF-808 by ZnEt2 and a mild thermal treatment to remove capping ligands and afford exposed metal sites for catalysis. The resultant MOF-808-Zn catalyst exhibits >99% MeOH selectivity in CO2 hydrogenation at 250 °C and a high space-time yield of up to 190.7 mgMeOH gZn-1 h-1. The catalytic activity is stable for at least 100 h. X-ray absorption spectroscopy (XAS) analyses indicate the presence of Zn2+-O-Zr4+ centers instead of ZnmOn clusters. Temperature-programmed desorption (TPD) of hydrogen and H/D exchange tests show the activation of H2 by Zn2+ centers. Open Zr4+ sites are also critical, as Zn2+ centers supported on Zr-based nodes of other MOFs without open Zr4+ sites fail to produce MeOH. TPD of CO2 reveals the importance of bicarbonate decomposition under reaction conditions in generating open Zr4+ sites for CO2 activation. The well-defined local structures of metal-oxo nodes in MOFs provide a unique opportunity to elucidate structural details of bifunctional catalytic centers.
- An, Bing,Cao, Yonghua,Dai, Yiheng,Li, Zhe,Lin, Wenbin,Wang, Cheng,Wang, Wangyang,Zeng, Lingzhen,Zhang, Jingzheng
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- Reduction of CO2 to methanol using aluminum ester FLPs
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Herein we report the synthesis of Al-based esters containing halogenated benzene rings. These Lewis acids were paired with phosphines to form frustrated Lewis pairs (FLPs) which could subsequently bind CO2. While these FLPs were not sufficientl
- Smythe, Nathan C.,Dixon, David A.,Garner, Edward B.,Rickard, Meredith M.,Mendéz, Mariano,Scott, Brian L.,Zelenay, Barbara,Sutton, Andrew D.
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- Photocatalytic CO2 Conversion of M0.33WO3 Directly from the Air with High Selectivity: Insight into Full Spectrum-Induced Reaction Mechanism
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Natural photosynthesis is a solar light-driven process utilized by plants to convert CO2 and water into carbohydrate molecules. The goal of artificial photosynthesis is the reduction of CO2 directly from air into high purity value-added products at atmospheric pressure. However, its realization, combined with deep mechanism investigation, is a huge challenge. Herein, we demonstrate that hexagonal tungsten bronze M0.33WO3 (M = K, Rb, Cs) series with {010} facets, prepared by a peculiar "water-controllable releasing" solvothermal method, showed excellent full spectrum (UV, visible, and NIR lights)-induced photocatalytic CO2 reduction performance directly from the air at ambient pressure. Particularly, after 4 h near-infrared light irradiation, ca. 4.32% CO2 in the air could be converted into CH3OH with 98.35% selectivity for Rb0.33WO3. The experiments and theoretical calculations unveiled that the introduced alkali metal atom occupied the tunnel of hexagonal structure and donated more free electrons to reconstruct the electronic structure of M0.33WO3, which can enhance the polaron transition, modify the energy band structure, selectively adsorb CO2 rather than O2 from the air, decrease the activation energy of CO2 reaction, and finally make the effective CO2 reduction in the air a reality. This work may provide a new possibility for the practical application of artificial photosynthesis.
- Wu, Xiaoyong,Li, Yuan,Zhang, Gaoke,Chen, Hong,Li, Jun,Wang, Kai,Pan, Yang,Zhao, Yan,Sun, Yongfu,Xie, Yi
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- Photochemical reduction of carbon dioxide to methanol and formate in a homogeneous system with pyridinium catalysts
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Photochemical catalytic CO2 reduction to formate and methanol has been demonstrated in an aqueous homogeneous system at pH 5.0 comprising ruthenium(II) trisphenanthroline as the chromophore, pyridine as the CO 2 reduction catalyst, KCl, and ascorbic acid as a sacrificial reductant, using visible light irradiation at 470 ± 20 nm. Isotopic labeling with 13CO2 yields the six-electron-reduced product 13CH3OH. After 1 h photolysis, the two-electron-reduced product formate and the six-electron-reduced product methanol are produced with quantum yields of 0.025 and 1.1 × 10 -4, respectively. This represents 76 and 0.15 turnovers per Ru for formate and methanol, respectively, and 152 and 0.9 turnovers per Ru on an electron basis for formate and methanol, respectively. The system is inactive after 6 h irradiation, which appears largely to be due to chromophore degradation. A partial optimization of the methanol yield showed that high pyridine to Ru ratios are needed (100:1) and that the optimum pH is near 5.0. The presence of potassium salts enhances the yield in formate and methanol by 8- and 2-fold, respectively, compared to electrolyte-free solutions; however, other alkali and alkali earth cations have little effect. The addition of small amounts of solid metal catalysts immobilized on carbon had either no effect (M = Pt or Pd) or deleterious effects (M = Ni or Au) on methanol production. Addition of colloidal Pt resulted in no methanol production at all. This is in notable contrast with the pyridine-based electrocatalysis of CO2 to methanol in which metallic or conductive surfaces such as Pt, Pd, or p-type GaP are necessary for methanol formation.
- Boston, David J.,Xu, Chengdong,Armstrong, Daniel W.,Macdonnell, Frederick M.
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- Methanol synthesis: Via CO2 hydrogenation over a Au/ZnO catalyst: An isotope labelling study on the role of CO in the reaction process
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Methanol synthesis for chemical energy storage, via hydrogenation of CO2 with H2 produced by renewable energies, is usually accompanied by the undesired formation of CO via the reverse water-gas shift reaction. Aiming at a better mechanistic understanding of methanol formation from CO2/H2 on highly selective supported Au/ZnO catalysts we have investigated the role of CO in the reaction process using isotope labelling experiments. Using 13C-labelled CO2, we found for reaction at 5 bar and 240 °C that (i) the methanol formation rate is significantly higher in CO2-containing gas mixtures than in a CO2-free mixture and (ii) in mixtures containing both CO2 and CO methanol formation from CO increases with the CO content up to 1% CO, and then remains at 20% of the total methanol formation up to a CO2/CO ratio of 1/1, making CO2 the preferred carbon source in these mixtures. A shift in the preferred carbon source for MeOH from CO2 towards CO is observed with increasing reaction temperatures between 240 °C and 300 °C. At even higher temperatures CO is expected to become the dominant carbon source. The consequences of these findings for the application of Au/ZnO catalysts for chemical storage of renewable energies are discussed. the Owner Societies.
- Hartadi, Yeusy,Widmann, Daniel,Behm, R. Jürgen
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- Condensed-phase low temperature heterogeneous hydrogenation of CO2 to methanol
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A low-temperature CH3OH synthesis was achieved at 120-170 °C using tertiary amine and alcohol in the presence of a Cu/ZnO/Al2O3 catalyst by CO2 hydrogenation. A series of 1°, 2° and 3° amines and alcohols were screened to study their influence on the formation of CH3OH. Particularly, 3° amines such as NEt3 in combination with EtOH formed CH3OH with 100% yield with respect to the amine. Unlike the traditional gas-phase heterogeneous metal catalyzed CO2-to-CH3OH reactions, no CO is used in the feed gas mixture in this method. In addition, the hydrogenation gives good selectivity (>95%) to CH3OH and only trace amounts of CO and CH4 are formed. The presence of CO in the gas mixture was attributed to the decomposition of the CH3OH product, which was confirmed by high-temperature and high-pressure MAS NMR. The reaction was performed in the condensed phase at relatively lower temperatures, thus the RWGS reaction, which typically operates at >250 °C, was significantly reduced at these temperatures (120-170 °C). The first in situ spectroscopic evidence for the condensed phase hydrogenation of alkylcarbonate to CH3OH via ammonium formate and alkylformate intermediates was also presented under the experimental conditions.
- Kothandaraman, Jotheeswari,Dagle, Robert A.,Dagle, Vanessa Labarbier,Davidson, Stephen D.,Walter, Eric D.,Burton, Sarah D.,Hoyt, David W.,Heldebrant, David J.
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- Hybrid technologies for an enhanced carbon recycling based on the enzymatic reduction of CO2 to methanol in water: Chemical and photochemical NADH regeneration
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Rocking chair enzyme: Chemical reducing agents (sodium dithionite) or bioglycerol (as H and e--donor under irradiation in the presence of ZnS-A as photocatalyst) are able to back-convert NADP+ into NADPH, which is used as e--donor in the enzymatic reduction of CO 2 into CH3OH. In doing so, the molar ratio CH 3OH/CO2 has been increased (without recycling of NADP +) using the photocatalyst. Copyright
- Dibenedetto, Angela,Stufano, Paolo,MacYk, Wojciech,Baran, Tomasz,Fragale, Carlo,Costa, Mirco,Aresta, Michele
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- Dinuclear uranium(vi) salen coordination compound: An efficient visible-light-active catalyst for selective reduction of CO2to methanol
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A new dinuclear uranyl salen coordination compound, [(UO2)2(L)2]·2MeCN [L = 6,6′-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl)bis(azaneylylidene))-bis(methaneylylidene))bis(2-methoxyphenol)], was synthesized using a multifunctional salen ligand to harvest visible light for the selective photocatalytic reduction of CO2 to MeOH. The assembling of the two U centers into one coordination moiety via a chelating-bridging doubly deprotonated tetradentate ligand allowed the formation of U centers with distorted pentagonal bipyramid geometry. Such construction of compounds leads to excellent activity for the photocatalytic reduction of CO2, permitting a production rate of 1.29 mmol g-1 h-1 of MeOH with an apparent quantum yield of 18%. Triethanolamine (TEOA) was used as a sacrificial electron donor to carry out the photocatalytic reduction of CO2. The selective methanol formation was purely a photocatalytic phenomenon and confirmed using isotopically labeled 13CO2 and product analysis by 13C-NMR spectroscopy. The spectroscopic studies also confirmed the interaction of CO2 with the molecule of the title complex. The results of these efforts made it possible to understand the reaction mechanism using ESI-mass spectrometry.
- Azam, Mohammad,Kumar, Umesh,Olowoyo, Joshua O.,Al-Resayes, Saud I.,Trzesowska-Kruszynska, Agata,Kruszynski, Rafal,Islam, Mohammad Shahidul,Khan, Mohammad Rizwan,Adil,Siddiqui, Mohammad Rafique,Al-Harthi, Fahad Ahmed,Alinzi, Abdul Karim,Wabaidur, Saikh Mohammad,Siddiqui, Masoom Raza,Shaik, Mohammed Rafi,Jain, Suman L.,Farkhondehfal, M. Amin,Hernàndez, Simelys
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- A bis(thiosemicarbazonato)-copper complex, a new catalyst for electro- A nd photo-reduction of CO2 to methanol
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Diacetyl-2-(4-N-methyl-3-thiosemicarbazone)-3-(4-N-amino-3-thiosemicarbazone) (H2ATSM) reacts with CuCl2 to form a copper complex, Cu-ATSM, a new catalyst for electrochemically and photochemically driven CO2 reduction to methanol. As an electrocatalyst, this copper complex can catalyse methanol generation from a CO2-saturated buffer with a turnover frequency (TOF) of 2844 moles of methanol per mole of catalyst per hour and a faradaic efficiency of 74% during a 6 h electrolysis. Under blue light (λ = 469 nm), combining with Au-CdS nanoclusters (Au-CdS NCs) as a photosensitizer, and ascorbic acid (H2A) as a sacrificial electron donor, this copper complex can catalyse methanol generation with a turnover number (TON) of 4067 moles of methanol per mole of catalyst (mol of cat-1) and a methanol selectivity of 74%. The highest apparent quantum yield (AQY) is 9.0%.
- Jiang, Wen-Xing,Liu, Wei-Xia,Wang, Chun-Li,Zhan, Shu-Zhong,Wu, Song-Ping
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- Tricycloquinazoline-Based 2D Conductive Metal–Organic Frameworks as Promising Electrocatalysts for CO2 Reduction
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2D conductive metal–organic frameworks (2D c-MOFs) are promising candidates for efficient electrocatalysts for the CO2 reduction reaction (CO2RR). A nitrogen-rich tricycloquinazoline (TQ) based multitopic catechol ligand was used to
- Liu, Jingjuan,Yang, Dan,Zhou, Yi,Zhang, Guang,Xing, Guolong,Liu, Yunpeng,Ma, Yanhang,Terasaki, Osamu,Yang, Shubin,Chen, Long
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- NMR VISUALIZATION OF FREE ASPARAGINE IN POTATO TISSUE USING ADDUCT FORMATION WITH FORMALDEHYDE
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The free asparagine in potato (Solanum tuberosum) tuber tissue has been observed by 13C NMR, using labelled formaldehyde as a marker; formaldehyde-asparagine adduct formation is specific and leads to characteristic 13C resonances.In addition, metabolism of formaldehyde to methanol and formate by potato tissue has been observed by 13C and deuterium NMR.Metabolism of formaldehyde-d2 leads to 3 : 1 mixture of CD3OH and CD2HOH.
- Mason, Ralph P.,Sanders, Jeremy K. M.,Gidley, Michael J.
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- Artificial Photosynthesis of Methanol by Mn:CdS and CdSeTe Quantum Dot Cosensitized Titania Photocathode in Imine-Based Ionic Liquid Aqueous Solution
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The artificial photosynthesis (APS) of carbon-based chemicals from CO2 and water is a promising strategy for solar energy conversion and storage. A new Mn-doped CdS and CdSeTe quantum dot cosensitized TiO2 photocathode was fabricated and applied to CO2 reduction in an APS cell with modified BiVO4 as the counter electrode. The 3 D structure of the photocathode constructed by Mn:CdS and CdSeTe quantum dots showed a high efficiency for light harvesting and electron transfer in this system to yield methanol at a rate of 90 μm h?1 cm?2 at ?0.9 V versus the saturated calomel electrode under 200 mW cm?2 irradiation. Methanol could also be produced by a two-electrode system under the same conditions. 13CO2-labeling experiments were performed to show that the carbon-based products are derived from CO2. A mechanism for CO2 reduction in this new APS cell was proposed based on the experimental results. In addition, headspace GC was used to quantify the products by an external standard method.
- Nie, Rong,Ma, Wenjie,Dong, Yapeng,Xu, Yanjie,Wang, Jinyuan,Wang, Jianguo,Jing, Huanwang
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- Time-resolved infrared-spectroscopic observation of relaxation and reaction processes during and after infrared-multiphoton excitation of 12CF3I and 13CF3I with shaped nanosecond pulses
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We have produced shaped infrared laser pulses of several kinds ranging from about 2-100 ns duration using a line tuned CO2 laser combined with intracavity absorbers and CdTe electro-optical switch.The time-dependent infrared absorption of 12CF3I and 13CF3I during and after infrared-multiphoton excitation with these pulses was followed by means of a line tuned continuous wave-CO2 laser and a fast HgCdTe infrared detector (time resolution about 1 ns).The effective time-dependent absorption cross section shows fluence-dependent decay at large fluence with an effective exponential decay constant k1,? ca. 1.12 cm2J-1.This can be interpreted by first generation and then decay by further radiative pumping of highly excited levels of CF3I.The results have been analyzed by master equation modeling using a nonlinear case B/C master equation for multiphoton excitation and very simple models for the absorption properties of highly excited molecules.After nanosecond excitation to very high levels, one finds unimolecular decay CF3I --> CF3 + I with distinct rate constants (2+/-1) * 108 and (5+/-4) * 106 s-1, which corresponds to ensembles of molecules differing by one CO2-laser quantum of energy, in agreement with unimolecular rate theory and master equation models.The most striking observation is a slow, collision-free intramolecular rovibrational redistribution process observed by real time spectroscopy on the nanosecond time scale for molecules excited by modest fluence corresponding to typical average energies of five CO2 laser quanta and somewhat more.
- Quack, Martin,Schwarz, Rene,Seyfang, Georg
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- Mechanistic Study of Carbon Dioxide Hydrogenation over Pd/ZnO-Based Catalysts: The Role of Palladium–Zinc Alloy in Selective Methanol Synthesis
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Pd/ZnO catalysts show good activity and high selectivity to methanol during catalytic CO2 hydrogenation. The Pd-Zn alloy phase has usually been considered as the active phase, though mechanistic studies under operando conditions have not been c
- Krumeich, Frank,Nachtegaal, Maarten,Newton, Mark A.,Sushkevich, Vitaly L.,Zabilskiy, Maxim,van Bokhoven, Jeroen A.
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- Highly Efficient Electroreduction of CO2 to Methanol on Palladium–Copper Bimetallic Aerogels
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Electrochemical reduction of CO2 to CH3OH is of great interest. Aerogels have fine inorganic superstructure with high porosity and are known to be exceptional materials. Now a Pd?Cu bimetallic aerogel electrocatalyst has been develop
- Lu, Lu,Sun, Xiaofu,Ma, Jun,Yang, Dexin,Wu, Haihong,Zhang, Bingxing,Zhang, Jianling,Han, Buxing
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- Structure-Tailored Surface Oxide on Cu–Ga Intermetallics Enhances CO2 Reduction Selectivity to Methanol at Ultralow Potential
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Electrochemical CO2 reduction reaction (eCO2RR) is performed on two intermetallic compounds formed by copper and gallium metals (CuGa2 and Cu9Ga4). Among them, CuGa2 selectively converts CO
- Bagchi, Debabrata,Cherevotan, Arjun,Manoj, Kaja Sai,Peter, Sebastian C.,Raj, Jithu,Roy, Soumyabrata,Singh, Ashutosh Kumar,Vinod, C. P.
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- Methane-to-Methanol on Mononuclear Copper(II) Sites Supported on Al2O3: Structure of Active Sites from Electron Paramagnetic Resonance**
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The selective conversion of methane to methanol remains one of the holy grails of chemistry, where Cu-exchanged zeolites have been shown promote this reaction under stepwise conditions. Over the years, several active sites have been proposed, ranging from mono-, di- to trimeric CuII. Herein, we report the formation of well-dispersed monomeric CuII species supported on alumina using surface organometallic chemistry and their reactivity towards the selective and stepwise conversion of methane to methanol. Extensive studies using various transition alumina supports combined with spectroscopic characterization, in particular electron paramagnetic resonance (EPR), show that the active sites are associated with specific facets, which are typically found in γ- and η-alumina phase, and that their EPR signature can be attributed to species having a tri-coordinated [(Al2O)CuIIO(OH)]? T-shape geometry. Overall, the selective conversion of methane to methanol, a two-electron process, involves two monomeric CuII sites that play in concert.
- Ashuiev, Anton,Copéret, Christophe,Horton, Andrew D.,Jeschke, Gunnar,Klose, Daniel,Meyet, Jordan,Newton, Mark A.,Noh, Gina,Searles, Keith,van Bavel, Alexander P.,van Bokhoven, Jeroen A.
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supporting information
p. 16200 - 16207
(2021/06/18)
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- MAGNESIUM NANOPARTICLES TO CAPTURE AND CONVERT CO2 TO METHANE, METHANOL OR FORMIC ACID OR OTHER FUELS OR CHEMICALS
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This invention discloses a process of conversion of Carbon Dioxide (CO2) into methane, methanol, formic acids or other fuels or chemicals, characterized by the use of Magnesium (Mg) nanoparticles (NPs) or bulk Mg for the conversion process, wherein Magnesium (Mg) chemisorbs and then activates the Carbon Dioxide (CO2) molecules by electron transfer to facilitate the reduction, using water as a hydrogen source. This conversion of Carbon Dioxide (CO2) is carried out at atmospheric pressure and at room temperature, and without any external energy source, such as thermal, light or electric energy source, or any sacrificial reagent or any co-catalysts. The reaction also facilitates in the production of high yield of Hydrogen.
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Page/Page column 7
(2021/11/26)
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- Alcohol promoted N -methylation of anilines with CO2/H2over a cobalt catalyst under mild conditions
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N-Methylation of amines with CO2/H2 to N-methylamines over non-noble metal catalysts is very interesting but remains challenging. Herein, we present an alcohol (e.g., ethanol) promoted strategy for the N-methylation of anilines with CO2/H2 with high efficiency under mild conditions (e.g., 125 °C), which is achieved over a cobalt catalytic system composed of Co(OAc)2·4H2O, triphos and Sn(OTf)2. This catalytic system has a broad substrate scope and is tolerant toward a wide range of anilines and N-methyl anilines, and a series of N,N-dimethyl anilines were obtained in high yields. Mechanism investigation indicates that the alcohol solvent shifts the equilibrium of CO2 hydrogenation by forming an alkyl formate, which further reacts with the amine to produce N-formamide, and Sn(OTf)2 promotes the deoxygenative hydrogenation of N-formamides to afford N-methylamines. This is the first example of the N-methylation of amines with CO2/H2 over a cobalt catalytic system, which shows comparable performance to the reported Ru catalysts and may have promising applications.
- Han, Buxing,Ke, Zhengang,Li, Ruipeng,Liu, Zhimin,Tang, Minhao,Wang, Huan,Zeng, Wei,Zhao, Yanfei
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supporting information
p. 9147 - 9153
(2021/11/30)
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- Engineering the Cu/Mo2CTx (MXene) interface to drive CO2 hydrogenation to methanol
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Development of efficient catalysts for the direct hydrogenation of CO2 to methanol is essential for the valorization of this abundant feedstock. Here we show that a silica-supported Cu/Mo2CTx (MXene) catalyst achieves a higher intrinsic methanol formation rate per mass Cu than the reference Cu/SiO2 catalyst with a similar Cu loading. The Cu/Mo2CTx interface can be engineered due to the higher affinity of Cu for the partially reduced MXene surface (in preference to the SiO2 surface) and the mobility of Cu under H2 at 500 °C. With increasing reduction time, the Cu/Mo2CTx interface becomes more Lewis acidic due to the higher amount of Cu+ sites dispersed onto the reduced Mo2CTx and this correlates with an increased rate of CO2 hydrogenation to methanol. The critical role of the interface between Cu and Mo2CTx is further highlighted by density functional theory calculations that identify formate and methoxy species as stable reaction intermediates. [Figure not available: see fulltext.]
- Abdala, Paula M.,Chen, Zixuan,Comas-Vives, Aleix,Copéret, Christophe,Donat, Felix,Fedorov, Alexey,Kierzkowska, Agnieszka,Kuznetsov, Denis A.,López, Anna Vidal,López, Estefanía Díaz,Lam, Erwin,Müller, Christoph R.,Mance, Deni,Tsoukalou, Athanasia,Willinger, Elena,Zhou, Hui
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p. 860 - 871
(2021/10/27)
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- Highly selective aerobic oxidation of methane to methanol over gold decorated zinc oxide: Via photocatalysis
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Photodriven CH4 conversion has been regarded as a promising green strategy for fabrication of value-added commodity chemicals, in particular methanol. However, due to the incomplete transformation of intermediates or the overoxidation of products, a good selectivity of methanol is hard to achieve. Here, we present a highly selective transformation of methane to methanol using gold modified zinc oxide as a photocatalyst under full light spectrum irradiation at atmospheric temperature. The selectivity of methanol can reach 99.1percent with a productivity of 1371 μmol g-1. Fine tuning the loading amount of gold nanoparticles (0.75 wtpercent) and inputting an appropriate light energy are the pivotal factors for selectivity improvement. Besides, in contrast to the reported photocatalytic aerobic CH4 oxidation on gold modified zinc oxide, we find that both oxygen and water, rather than only molecular oxygen, provide the O-source for methanol formation. This result is verified through 18O-isotope tests (18O2 and H218O), leading to a disparate mechanism.
- Fan, Yingying,Han, Dongxue,Jiang, Yuheng,Niu, Li,Qiu, Xueying,Tang, Zhiyong,Wei, Shilei,Zhou, Wencai
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p. 13277 - 13284
(2020/07/16)
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- Monomeric Copper(II) Sites Supported on Alumina Selectively Convert Methane to Methanol
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Monomeric CuII sites supported on alumina, prepared using surface organometallic chemistry, convert CH4 to CH3OH selectively. This reaction takes place by formation of CH3O surface species with the concomitant reduction of two monomeric CuII sites to CuI, according to mass balance analysis, infrared, solid-state nuclear magnetic resonance, X-ray absorption, and electron paramagnetic resonance spectroscopy studies. This material contains a significant fraction of Cu active sites (22 %) and displays a selectivity for CH3OH exceeding 83 %, based on the number of electrons involved in the transformation. These alumina-supported CuII sites reveal that C?H bond activation, along with the formation of CH3O- surface species, can occur on pairs of proximal monomeric CuII sites in a short reaction time.
- Meyet, Jordan,Searles, Keith,Newton, Mark A.,W?rle, Michael,van Bavel, Alexander P.,Horton, Andrew D.,van Bokhoven, Jeroen A.,Copéret, Christophe
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supporting information
p. 9841 - 9845
(2019/06/21)
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- Formation of Glyoxylic Acid in Interstellar Ices: A Key Entry Point for Prebiotic Chemistry
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With nearly 200 molecules detected in interstellar and circumstellar environments, the identification of the biologically relevant α-keto carboxylic acid, glyoxylic acid (HCOCOOH), is still elusive. Herein, the formation of glyoxylic acid via cosmic-ray driven, non-equilibrium chemistry in polar interstellar ices of carbon monoxide (CO) and water (H2O) at 5 K via barrierless recombination of formyl (HCO) and hydroxycarbonyl radicals (HOCO) is reported. In temperature-programmed desorption experiments, the subliming neutral molecules were selectively photoionized and identified based on the ionization energy and distinct mass-to-charge ratios in combination with isotopically labeled experiments exploiting reflectron time-of-flight mass spectrometry. These studies unravel a key reaction path to glyoxylic acid, an organic molecule formed in interstellar ices before subliming in star-forming regions like SgrB2(N), thus providing a critical entry point to prebiotic organic synthesis.
- Eckhardt, André K.,Bergantini, Alexandre,Singh, Santosh K.,Schreiner, Peter R.,Kaiser, Ralf I.
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supporting information
p. 5663 - 5667
(2019/03/29)
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- Artificial photosynthesis of methanol from carbon dioxide and water via a Nile red-embedded TiO2 photocathode
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The conversion of carbon dioxide into useful chemicals is a prospective strategy for alleviating the greenhouse effect and the depletion of energy. Herein, we report an artificial photosynthetic system composed of a photoanode and a photocathode comprised of NRx@TiO2 functionalized with Nile red via covalent linkage or Pd/NRx@TiO2 with additional palladium nanoparticles. The new Nile red derivatives and organic-inorganic composite electrodes were steadily prepared and well characterized using NMR, HRMS, UV-vis, FTIR, TEM, XPS, XRD and SEM. Methanol and oxygen were the products that could be detected in the liquid and gas phase. The main active species in this artificial photosynthesis system were proven using EPR spectroscopy to be hydroxy radicals releasing O2 gas via H2O2. Moreover, the carbon source of methanol was validated using a 13CO2 labeling experiment; 18O2 was determined to come from H2O using GC-MS. The optimal photoelectrocatalytic CO2 reduction was carried out using Pd/NR2@TiO2 as the working electrode yielding methanol at a rate of 106 μM h?1 cm?2 with high light quantum efficiency (Φcell = 0.95).
- Jia, Yongjian,Xu, Yanjie,Nie, Rong,Chen, Fengjuan,Zhu, Zhenping,Wang, Jianguo,Jing, Huanwang
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supporting information
p. 5495 - 5501
(2017/03/22)
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- METHOD FOR PRODUCING METHANOL FROM CARBON DIOXIDE AND HYDROGEN GAS IN HOMOGENEOUSLY CATALYZED REACTIONS AND IN AN AQUEOUS MEDIUM
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The invention relates to a method for producing methanol from hydrogen and carbon dioxide gas in homogeneously catalyzed reactions, composed of the carbon dioxide hydrogenation reaction to formic acid and the formic acid disproportionation reaction into methanol, both being conducted in aqueous media at mild conditions (temperature in the range from 20 to 100 °C, total hydrogen and carbon dioxide gas pressure up to 100 bar).
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Page/Page column 18
(2017/07/12)
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- Carbon Dioxide to Methanol: The Aqueous Catalytic Way at Room Temperature
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Carbon dioxide may constitute a source of chemicals and fuels if efficient and renewable processes are developed that directly utilize it as feedstock. Two of its reduction products are formic acid and methanol, which have also been proposed as liquid organic chemical carriers in sustainable hydrogen storage. Here we report that both the hydrogenation of carbon dioxide to formic acid and the disproportionation of formic acid into methanol can be realized at ambient temperature and in aqueous, acidic solution, with an iridium catalyst. The formic acid yield is maximized in water without additives, while acidification results in complete (98 %) and selective (96 %) formic acid disproportionation into methanol. These promising features in combination with the low reaction temperatures and the absence of organic solvents and additives are relevant for a sustainable hydrogen/methanol economy.
- Sordakis, Katerina,Tsurusaki, Akihiro,Iguchi, Masayuki,Kawanami, Hajime,Himeda, Yuichiro,Laurenczy, Gábor
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supporting information
p. 15605 - 15608
(2016/10/25)
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- Efficient disproportionation of formic acid to methanol using molecular ruthenium catalysts
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The disproportionation of formic acid to methanol was unveiled in 2013 using iridium catalysts. Although attractive, this transformation suffers from very low yields; methanol was produced in less than 2 % yield, because the competitive dehydrogenation of formic acid (to CO2 and H2) is favored. We report herein the efficient and selective conversion of HCOOH to methanol in 50 % yield, utilizing ruthenium(II) phosphine complexes under mild conditions. Experimental and theoretical (DFT) results show that different convergent pathways are involved in the production of methanol, depending on the nature of the catalyst. Reaction intermediates have been isolated and fully characterized and the reaction chemistry of the resulting ruthenium complexes has been studied. The search for selectivity: Methanol is efficiently produced in >50 % yield by the disproportionation of formic acid using molecular ruthenium catalysts. Mechanistic experimental and DFT investigations have unveiled different pathways involving transient ruthenium hydride species.
- Savourey, Solène,Lefèvre, Guillaume,Berthet, Jean-Claude,Thuéry, Pierre,Genre, Caroline,Cantat, Thibault
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supporting information
p. 10466 - 10470
(2016/02/18)
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- CO2 reduction catalyzed by mercaptopteridine on glassy carbon
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The catalytic reduction of CO2 is of great current interest because of its role in climate change and the energy cycle. We report a pterin electrocatalyst, 6,7-dimethyl-4-hydroxy-2-mercaptopteridine (PTE), that catalyzes the reduction of CO2 and formic acid on a glassy carbon electrode. Pterins are natural cofactors for a wide range of enzymes, functioning as redox mediators and C1 carriers, but they have not been exploited as electrocatalysts. Bulk electrolysis of a saturated CO2 solution in the presence of the PTE catalyst produces methanol, as confirmed by gas chromatography and 13C NMR spectroscopy, with a Faradaic efficiency of 10-23%. FTIR spectroelectrochemistry detected a progression of two-electron reduction products during bulk electrolysis, including formate, aqueous formaldehyde, and methanol. A transient intermediate was also detected by FTIR and tentatively assigned as a PTE carbamate. The results demonstrate that PTE catalyzes the reduction of CO2 at low overpotential and without the involvement of any metal.
- Xiang, Dongmei,Magana, Donny,Dyer, R. Brian
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p. 14007 - 14010
(2015/01/09)
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- Cascade catalysis for the homogeneous hydrogenation of CO2 to methanol
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This communication demonstrates the homogeneous hydrogenation of CO 2 to CH3OH via cascade catalysis. Three different homogeneous catalysts, (PMe3)4Ru(Cl)(OAc), Sc(OTf) 3, and (PNN)Ru(CO)(H), operate in sequence to promote this transformation.
- Huff, Chelsea A.,Sanford, Melanie S.
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supporting information; experimental part
p. 18122 - 18125
(2012/01/04)
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- Room temperature reduction of CO2 to methanol by Al-based frustrated Lewis pairs and ammonia borane
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(Formula Presented) AlX3 (X = Cl or Br) and PMes3 (Mes = 2,4,6-C6H2Me3) react to form weak Lewis adducts but also react with CO2 to give Mes3P(CO 2)(AlX3)s
- Menard, Gabriel,Stephan, Douglas W.
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scheme or table
p. 1796 - 1797
(2010/04/25)
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- An efficient nickel catalyst for the reduction of carbon dioxide with a borane
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Nickel hydride with a diphosphinite-based ligand catalyzes the highly efficient reduction of CO2 with catecholborane, and the hydrolysis of the resulting methoxyboryl species produces CH3OH in good yield. The mechanism involves a nickel formate, formaldehyde, and a nickel methoxide as different reduced stages for CO2. The reaction may also be catalyzed by an air-stable nickel formate.
- Chakraborty, Sumit,Zhang, Jie,Krause, Jeanette A.,Guan, Hairong
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supporting information; experimental part
p. 8872 - 8873
(2010/08/21)
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- The mechanism of decomposition of N-methyl-N-nitrosourea (MNU) in water and a study of its reactions with 2'-deoxyguanosine, 2'-deoxyguanosine 5'-monophosphate and d(GTGCAC)
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The carcinogenicity of N-methyl-N-nitrosourea (MNU) arises, from its ability to methylate DNA, This occurs in an aqueous environment and therefore an appreciation of the mode of decomposition of MNU in water is essential to understanding the mechanism of DNA methylation and its base sequence dependence. The kinetics of MNU hydrolyses are shown to be first order in MNU with a steep rise in rate above pH 8. Using NMR for in situ monitoring of reaction intermediates and products from hydrolyses of [13CO]MNU, [15NH2]MNU and [13CH3]MNU, it is proved that base-induced hydrolysis of MNU is initiated by deprotonation at the carbamoyl group. The critical reactive species are shown to be the methyldiazonium ion (Me-N2+) and cyanate (NCO-). Investigations of reactions of [13CH3]MNU with 2'-deoxyguanosine (dGuo) and 2-deoxyguanosine 5'-monophosphate (dGuo-5P) showed that: a) the site of methylation of dGuo is highly pH-dependent (relatively more N-1 and O6-methylation compared to N-7 occurs at higher pH; b) the principal site of methylation of dGuo-5P by MNU is at phosphate; c) incorporation of deuterium into methyl groups occurs in D2O at higher pH. Methylation of the oligonucleotide d(GT[15N]GCAC) by MNU in D2O showed partial deuteriation of the N7-methyl groups of the guanines, whilst methylation by MNU in water indicated no significant preference for either guanine with respect to N7-methylation.
- Golding, Bernard T.,Bleasdale, Christine,McGinnis, Joseph,Mueller, Susanna,Rees, Hue Thu,Rees, Nicholas H.,Farmer, Peter B.,Watson, William P.
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p. 4063 - 4082
(2007/10/03)
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- Reduction of a coordinated carbon monoxide to an oxymethyl-bridging group: Synthesis and X-ray characterization of the dianion [Re3(μ-H)3(μ3-η2-CH 2O)(CO)9]2-
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The reaction of [Re3(μ-H)4(CO)10]- with Li[BH(s-Bu)3] gives in high yields the novel anion [Re3(μ-H)3(CH2O)(CO)9] 2-, which contains a μ3-η2-oxymethyl ligand, representing a type of intermediate of CO hydrogenation never previously fully characterized. Protonation at -80°C leads to an unstable hydroxymethyl derivative, characterized by NMR, which under CO, at room temperature, converts in fair yields to [Re3(μ-H)2(CO)12]- and methanol.
- Beringhelli,D'Alfonso,Ciani,Molinari
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p. 194 - 196
(2008/10/08)
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