- From K-O2 to K-Air Batteries: Realizing Superoxide Batteries on the Basis of Dry Ambient Air
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Although using an air cathode is the goal for superoxide-based potassium-oxygen (K-O2) batteries, prior studies were limited to pure oxygen. Now, the first K-air (dry) battery based on reversible superoxide electrochemistry is presented. Spectroscopic and gas chromatography analyses are applied to evaluate the reactivity of KO2 in ambient air. Although KO2 reacts with water vapor and CO2 to form KHCO3, it is highly stable in dry air. With this knowledge, rechargeable K-air (dry) batteries were successfully demonstrated by employing dry air cathode. The reduced partial pressure of oxygen plays a critical role in boosting battery lifespan. With a more stable environment for the K anode, a K-air (dry) battery delivers over 100 cycles (>500 h) with low round-trip overpotentials and high coulombic efficiencies as opposed to traditional K-O2 battery that fails early. This work sheds light on the benefits and restrictions of employing the air cathode in superoxide-based batteries.
- Chen, Xiaojuan,Qin, Lei,Wu, Yiying,Xiao, Neng,Zhang, Songwei
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- Absorption of carbon dioxide into potassium hydroxide: Preliminary study for its application into liquid scintillation counting procedure
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This preliminary study presents a theoretical and experimental investigation on the absorption of CO2 into KOH solution. The study provides variation of KOH concentrations at 1, 2, 3, 4, and 5 N. The value of pH was observed for each increment of sample volume. The absorbed CO2 was measured by applying titration. The amounts of CO2 resulted from every provided KOH concentration were respectively 0.0075, 0.0075, 0.0232, 0.0305, and 0.0395 mol. The results reveal an increase in absorbed CO2 with each increment of KOH concentration. The absorption efficiency values of each KOH concentration were 0.3750, 0.4000, 0.3861, 0.3813, and 0.3950 mol total CO2/mol KOH, respectively. The difference values of experimental and theoretical absorbed CO2 may be caused by the formation of other compounds.
- Firman, Nur Faiizah Aqiilah,Noor, Alfian,Zakir, Muhammad,Maming,Fathurrahman, Achmad Fuad
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p. 4907 - 4912
(2021/08/31)
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- The Alkali Metal Salts of Methyl Xanthic Acid
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Methyl xanthates of the type M(SSC-OMe) (M = Li–Cs) are readily formed when carbon disulfide is reacted with the corresponding alkali metal hydroxides in methanol exposed to air, or with the alkali metal methoxides in dry methanol or THF under exclusion of air. The reactions are easily monitored by 13C NMR spectroscopy. The Na, K, Rb, and Cs salt could be isolated in high yields, while the Li salt decomposed upon attempted isolation. All compounds are readily complexed by crown ethers and form isolable 1:1 adducts, including the elusive Li salt. All products were studied by NMR (1H, 13C, and alkali metal nuclei) and IR spectroscopy, and most of them where structurally characterized by single-crystal X-ray diffraction. Li(SSC-OMe)(12c4) (12c4 = [12]crown-4) and Cs(SSC-OMe)(18c6) (18c6 = [18]crown-6) represent the first structurally characterized lithium and caesium xanthate complexes, respectively.
- Liebing, Phil,Schmeide, Marten,Kühling, Marcel,Witzorke, Juliane
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p. 2428 - 2434
(2020/06/17)
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- Structural Sensitivities in Bimetallic Catalysts for Electrochemical CO2 Reduction Revealed by Ag-Cu Nanodimers
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Understanding the structural and compositional sensitivities of the electrochemical CO2 reduction reaction (CO2RR) is fundamentally important for developing highly efficient and selective electrocatalysts. Here, we use Ag/Cu nanocrystals to uncover the key role played by the Ag/Cu interface in promoting CO2RR. Nanodimers including the two constituent metals as segregated domains sharing a tunable interface are obtained by developing a seeded growth synthesis, wherein preformed Ag nanoparticles are used as nucleation seeds for the Cu domain. We find that the type of metal precursor and the strength of the reducing agent play a key role in achieving the desired chemical and structural control. We show that tandem catalysis and electronic effects, both enabled by the addition of Ag to Cu in the form of segregated nanodomain within the same catalyst, synergistically account for an enhancement in the Faradaic efficiency for C2H4 by 3.4-fold and in the partial current density for CO2 reduction by 2-fold compared with the pure Cu counterpart. The insights gained from this work may be beneficial for designing efficient multicomponent catalysts for electrochemical CO2 reduction.
- Huang, Jianfeng,Mensi, Mounir,Oveisi, Emad,Mantella, Valeria,Buonsanti, Raffaella
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p. 2490 - 2499
(2019/03/04)
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- A Carbon-Neutral CO2 Capture, Conversion, and Utilization Cycle with Low-Temperature Regeneration of Sodium Hydroxide
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A highly efficient recyclable system for capture and subsequent conversion of CO2 to formate salts is reported that utilizes aqueous inorganic hydroxide solutions for CO2 capture along with homogeneous pincer catalysts for hydrogenation. The produced aqueous solutions of formate salts are directly utilized, without any purification, in a direct formate fuel cell to produce electricity and regenerate the hydroxide base, achieving an overall carbon-neutral cycle. The catalysts and organic solvent are recycled by employing a biphasic solvent system (2-MTHF/H2O) with no significant decrease in turnover frequency (TOF) over five cycles. Among different hydroxides, NaOH and KOH performed best in tandem CO2 capture and conversion due to their rapid rate of capture, high formate conversion yield, and high catalytic TOF to their corresponding formate salts. Among various catalysts, Ru- and Fe-based PNP complexes were the most active for hydrogenation. The extremely low vapor pressure, nontoxic nature, easy regenerability, and high reactivity of NaOH/KOH toward CO2 make them ideal for scrubbing CO2 even from low-concentration sources - such as ambient air - and converting it to value-added products.
- Kar, Sayan,Goeppert, Alain,Galvan, Vicente,Chowdhury, Ryan,Olah, Justin,Prakash, G. K. Surya
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supporting information
p. 16873 - 16876
(2018/11/06)
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- Carbon dioxide as a pH-switch anti-solvent for biomass fractionation and pre-treatment with aqueous hydroxide solutions
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Rice husks (or rice hulls) pre-treated with aqueous potassium hydroxide solutions showed excellent glucose yields during enzymatic saccharification. CO2 addition to the hydroxide solutions precipitated the dissolved rice husk silica as a nanoporous powder, while Ca(OH)2 addition regenerated the hydroxide solution and precipitated the dissolved lignin. Fractionation of the biomass was thus achieved using CO2 addition as a reversible pH-switch, and the hydroxide could be repeatedly recycled while maintaining biomass pre-treatment and fractionation efficacy.
- To, Trang Quynh,Kenny, Ceire,Cheong, Soshan,Aldous, Leigh
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supporting information
p. 2129 - 2134
(2017/07/18)
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- Process for the preparation of dimethyl ether
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Process for the preparation of dimethyl ether product by catalytic conversion of synthesis gas to dimethyl ether comprising contacting a stream of synthesis gas comprising carbon dioxide with one or more catalysts active in the formation of methanol and the dehydration of methanol to dimethyl ether to form a product mixture comprising the components dimethyl ether, methanol, carbon dioxide and unconverted synthesis gas, washing the product mixture comprising carbon dioxide and unconverted synthesis gas in a scrubbing zone with a liquid solvent being rich in potassium carbonate or amine and thereby selectively absorbing carbon dioxide in the liquid solvent, subjecting the thus treated product mixture to a distillation step to separate methanol and water from dimethyl ether and unconverted synthesis gas stream with a reduced content of carbon dioxide and separating the unconverted synthesis gas from the dimethyl ether product.
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Page/Page column 3-5
(2009/04/23)
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- PROCESS FOR THE PREPARATION OF DIMETHYL ETHER
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Process for the preparation of dimethyl ether product by catalytic conversion of synthesis gas to dimethyl ether comprising contacting a stream of synthesis gas comprising carbon dioxide with one or more catalysts active in the formation of methanol and the dehydration of methanol to dimethyl ether to form a product mixture comprising the components dimethyl ether, methanol, carbon dioxide and unconverted synthesis gas, washing the product mixture comprising carbon dioxide and unconverted synthesis gas in a scrubbing zone with a liquid solvent being rich in potassium carbonate or amine and thereby selectively absorbing carbon dioxide in the liquid solvent, subjecting the thus treated product mixture to a distillation step to separate methanol and water from dimethyl ether and unconverted synthesis gas stream with a reduced content of carbon dioxide and separating the unconverted synthesis gas from the dimethyl ether product.
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Page/Page column 2
(2009/04/24)
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- Process for the production of alkylene glycols using homogeneous catalysts
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A process for the manufacture of alkylene glycol by the hydration of alkylene oxide using a soluble catalyst that permits the separation of the reaction product into an alkylene glycol product stream and a recycle stream without the significant precipitation of the soluble catalyst from the recycle stream.
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- Condensed N-aclyindoles as antitumor agents
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The invention provides compounds of general formula (I), wherein: X is halogen or OSO2R, where R represents H or is unsubstituted or hydroxy-or amino-substituted lower alkyl; Y is a nitro or amine group or a substituted derivative thereof; W is selected from the structures of formulae (Ia, Ib or Ic), where E is -N= or -CH=, G is O, S, or NH, and Q is either up to three of R, OR, NRR, NO2, CONHR, NHCOR or NHCONHR, or is an additional group of formulae (Ia, Ib or Ic) and HET represents a 5- or 6-membered carbocycle or heterocycle; and A and B collectively represent a fused benzene or 2-CO2R pyrrole ring. In one embodiment, the group Y is an amine derivative substituted by a group which is a substrate for a nitroreductase or carboxypeptidase enzyme such that one of said enzymes is able to bring about removal of that group.
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- Novel Synthesis of Oxalate from Carbon Dioxide and Carbon Monoxide in the Presence of Caesium Carbonate
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In the presence of caesium carbonate 1, the direct reaction of CO2 (110 atm) with CO (20 atm) results in reductive capture of CO2 to give caesium oxalate 2 in good yield at elevated temperature (380 deg C).
- Kudo, Kiyoshi,Ikoma, Futoshi,Mori, Sadayuki,Komatsu, Koichi,Sugita, Nobuyuki
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p. 633 - 634
(2007/10/02)
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