Study of photocatalytic reaction of methanol with water over Rh-, and Pd-loaded TiO2 catalysts. The role of added alkali metal cations

1986 ◽  
Vol 64 (9) ◽  
pp. 1795-1799 ◽  
Author(s):  
Shuichi Naito

The product selectivity of the photocatalytic reaction of methanol with water is changed drastically by the addition of alkali metal cations to Rh- and Pd-loaded TiO2 catalysts. Over alkali metal cation free catalysts, the main products are 1:1 ratio of H2 and dimethoxymethane, which is replaced with H2, methyl formate, and CO2 over alkali metal cation added catalysts. The role of added alkali metal cations is the stabilization of the reaction intermediate as adsorbed formate instead of adsorbed formaldehyde, which causes the selectivity change from dimethoxymethane to methyl formate.

RSC Advances ◽  
2014 ◽  
Vol 4 (29) ◽  
pp. 15271-15275 ◽  
Author(s):  
Bruno A. F. Previdello ◽  
Eduardo G. Machado ◽  
Hamilton Varela

Non-covalent interactions between hydrated alkali metal cations and oxygenated species on platinum considerably impact the mechanism of formate electro-oxidation.


1997 ◽  
Vol 62 (9) ◽  
pp. 1446-1456 ◽  
Author(s):  
Jörg Hiller ◽  
Vojtech Varga ◽  
Ulf Thewalt ◽  
Karel Mach

Crystal structures of the Ti(III) tweezer complexes [(C5HMe4)2Ti(σ-C≡CSiMe3)2]-[Li(THF)2]+ (2a), [(C5HMe4)2Ti(σ-C≡CSiMe3)2]-Na+ (3) and [(C5HMe4)2Ti(σ-C≡CSiMe3)2]-Cs+ (5) have been determined. In all of them the alkali metal cation is placed away from the Ti-Cα1-Cα2 plane at the distance: Li+ 0.511 Å, Na+ 1.023 Å and Cs+ 0.521 Å. The reason for the deviation of Li+ in 2a is the asymmetrical orientation of the THF ligands in the [Li(THF)2]+ cation with respect to the Ti-Cα1-Cα2 plane, which seems to release the steric congestion between the THF ligands and the trimethylsilyl groups. In 3 and 5, the molecules form polymer chains with a weak intermolecular bonding interaction between the cations and one of the C5HMe4 ligands of the neighbouring molecule in a sandwich manner.


2010 ◽  
Vol 74 (1) ◽  
pp. 95-120 ◽  
Author(s):  
Joaquín Ariño ◽  
José Ramos ◽  
Hana Sychrová

SUMMARY The maintenance of appropriate intracellular concentrations of alkali metal cations, principally K+ and Na+, is of utmost importance for living cells, since they determine cell volume, intracellular pH, and potential across the plasma membrane, among other important cellular parameters. Yeasts have developed a number of strategies to adapt to large variations in the concentrations of these cations in the environment, basically by controlling transport processes. Plasma membrane high-affinity K+ transporters allow intracellular accumulation of this cation even when it is scarce in the environment. Exposure to high concentrations of Na+ can be tolerated due to the existence of an Na+, K+-ATPase and an Na+, K+/H+-antiporter, which contribute to the potassium balance as well. Cations can also be sequestered through various antiporters into intracellular organelles, such as the vacuole. Although some uncertainties still persist, the nature of the major structural components responsible for alkali metal cation fluxes across yeast membranes has been defined within the last 20 years. In contrast, the regulatory components and their interactions are, in many cases, still unclear. Conserved signaling pathways (e.g., calcineurin and HOG) are known to participate in the regulation of influx and efflux processes at the plasma membrane level, even though the molecular details are obscure. Similarly, very little is known about the regulation of organellar transport and homeostasis of alkali metal cations. The aim of this review is to provide a comprehensive and up-to-date vision of the mechanisms responsible for alkali metal cation transport and their regulation in the model yeast Saccharomyces cerevisiae and to establish, when possible, comparisons with other yeasts and higher plants.


RSC Advances ◽  
2014 ◽  
Vol 4 (47) ◽  
pp. 24433-24438 ◽  
Author(s):  
Ying Gao ◽  
Shi-Ling Sun ◽  
Hong-Liang Xu ◽  
Liang Zhao ◽  
Zhong-Min Su

1-Li+, 1-Na+ and 1-K+ complexes formed by N-methylbenzoaza-18-crown-6-ether derivatives with one alkali metal cation were investigated. Their dipole moments and first hyperpolarizabilities take on opposite trends with increasing the atomic number.


2020 ◽  
Vol 12 (30) ◽  
pp. 34402-34412 ◽  
Author(s):  
Siyuan Zhang ◽  
Ming-Chun Tang ◽  
Yuanyuan Fan ◽  
Ruipeng Li ◽  
Nhan V. Nguyen ◽  
...  

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