Fumiaki Hori

The effects of water coadsorption on the adsorption of oxygen over metal oxides: I. Temperature-programmed desorption study of Co3O4

Adsorption of oxygen and water and the effects of coadsorption of water on oxygen adsorption over Co3O4 were studied by means of temperature-programmed desorption (TPD). There were at least three kinds of adsorbed oxygen on the Co3O4 samples calcined at 823–973 K, which desorbed at 300–400, 450–600, and >600 K (denoted α, β, and γ oxygen, respectively). γ Oxygen inhibited the adsorption of α and β oxygen in the same degree. N2O reacted with evacuated surface to evolve almost equimolar N2 at room temperature. TPD chromatograms of oxygen from the sample with oxygen adsorbate derived from N2O decomposition well agreed with those from the sample with a corresponding amount of oxygen adsorbate formed from oxygen preadsorption in regard to peak shape and peak maximum temperature. The TPD experiments using 18O2 revealed that oxygen exchange between oxygen adsorbates and oxide ions of the Co3O4 sample took place above 323 K, and the equilibration of isotopes among oxygen adsorbates was observed even below 323 K. Dissociative adsorption of oxygen appears to be compatible with the experimental results. TPD of water from Co3O4 preadsorbed with varied amount of water disclosed the presence of four kinds of adsorbed water which desorbed at 300–450, 450–550, 550–700, and >700 K. Preadsorption of water at 473 K brought about the slight decrease of γ oxygen and the rearrangement of α and β oxygen to e oxygen (350–450 K) without change of the total amount of oxygen desorbed.

RECOVERY OF LITHIUM FROM GEOTHERMAL WATER BY SOLVENT EXTRACTION TECHNIQUE

ABSTRACT The solvent extraction of alkali and alkaline earth metals (Li, Na, K, Mg, Ca) was studied using organophosphorus compounds like di-2-ethylhexylphosphoric acid(D2EHPA) or 2-ethylhexyl-phosphonic acid 2-ethylhexyl ester (MEHPA) as extractants. Extraction equilibrium constants and composition of each metal complex in organic phase were determined. Synergistic effect of tri-n-butylphosphate (TBP) was observed for lithium and sodium. This effect was presumed to be due to the replacement of solvated extractant(D2EHPA or MEHPA) by TBP. Finally, lithium was recovered by the above solvent extraction system from hot spring water in Oita, Japan.

Oxidation of ketones over metal oxide catalysts: I. Catalytic synthesis of biacetyl from methyl ethyl ketone

Abstract The gas-phase oxidation of methyl ethyl ketone was studied on metal oxide catalysts in the presence of water vapor. Two types of competitive partial oxidations, i.e., biacetyl formation and oxidative scission reaction leading to acetaldehyde and acetic acid, took place on every oxide studied at 400–500 K. An approximate linear relationship was observed between the selectivity of each reaction and the acid-base property of the oxides; the former reaction was accelerated on the basic oxides such as Co 3 O 4 , while the latter reaction became predominant on the acidic oxides. As Co 3 O 4 was the most effective biacetyl former of single-component oxides, modification of Co 3 O 4 was examined to develop more effective catalysts for biacetyl synthesis. Scission reaction took the place of biacetyl formation over a catalyst where Co 2+ ions were located in Y zeolite by an ion-exchanged method. Scission reaction was suppressed when Co oxide was supported on basic oxides such as MgO or CaO; however, the selectivity to biacetyl was slightly decreased due to the occurrence of a new reaction, acetone formation. The addition of Na 2 O or Li 2 O to Co 3 O 4 was found to improve the selectivity to biacetyl without loss of catalytic activity. The maximum efficiency (13%) in biacetyl formation was attained at a Li content of ca. 7 at.%.

Electroreductive dimerization of acetyl compounds in dimethylformamide

Abstract Seven acetyl compounds were cathodically electrolyzed in dimethylformamide containing TBAI and LiI to give corresponding hydrodimers in good yields respectively. On the basis of the rate constant of dimerization determined by use of digital simulation, it was found that the dimerization proceeded through anion radical (R − )/ion-pair (R − Li + ) coupling in all the cases that a linear relationship existed between the logarithm of the rate constant and electron spin density at the carbonyl carbon.

Application of Liquid Membrane Technique to the Recovery if Fermented Organic Acids

ABSTRACT To establish a new recovery process of organic acids from the fermented broth, the liquid surfactant membrane technique was applied to separate some organic acids. Extraction equilibria of lactic acid with various extractants, that is, tri-n-octylphosphineoxide(TOPO), tri-n-butylphosphate, tri-n-octylamine and dioctylamine, were studied. Diluent effect on the extraction equilibrium of lactic acid was discussed. The separation and enrichment of various organic acids which could be produced by fermentation was conducted with liquid surfactant membrane containing TOPO as a mobile carrier and polyamine as an emulsifier.

Separation and Enrichment of Amino Acids with Liquid Surfactant Membrane

ABSTRACT The separation and enrichment of amino acids were carried out with liquid surfactant membrane(LSM) containing tri-n-octylmethylammonium chloride(TOMAC) as a mobile carrier and polyamine as an emulsifier. To clarify the extraction mechanism, the extraction equilibrium and kinetics were investigated. The extraction equilibrium constants(KA) for various amino acids differed considerably, and could be correlated well with hydrophobicity scale of each amino acid. The permeation kinetics of amino acids through LSM was studied in a stirred transfer-cell. Mass transfer coefficients were determined based on the double-film model with an instantaneous reaction. The initial permeation rate was controlled by the mass transfer processes across the interface between the aqueous and emulsion phases.

The Effects of W/O Emulsion Properties in Electrostatic Demulsification Kinetics

The contribution of water- and oil-phase properties in the electrostatic demulsification was investigated in batch and continuous demulsifiers by using W/O emulsions prepared with various aqueous and organic solutions. The demulsification rates changed with the surfactant and diluents in addition to the drop size and hold-up of the water phase. When the same surfactant was used, the rates decreased in proportion to the 3.2 power of the viscosity of the oil phase. The distinct correlations between the rates and other physical properties like density, electric conductivity, dielectric constant and interfacial tension were not observed. The contribution of the water-phase properties could be represented well by the ionic strength. The demulsification kinetics obtained in a batch operation was found to be valid in a continuous operation. Stirring the emulsion during the operation was effective for the demulsification.