Partial oxidation of cyclohexane into cyclohexanone and cyclohexanol (KA-oil) is an industrially significant reaction for producing precursors for the synthesis of ε-caprolactam and adipic acid, which are the building blocks of nylon. However, to date, the cyclohexane conversion ratio has usually been limited to less than 6% to prevent further oxidation of the cyclohexanol and cyclohexanone targets. In this study, we report that Pt/CeO 2 -ZrO 2 -SnO 2 /SiO 2 , in which CeO 2 -ZrO 2 -SnO 2 provide reactive oxygen molecules from inside the bulk, can act as efficient catalysts. Optimization of the catalyst composition and reaction conditions provided a cyclohexane conversion ratio of 24.1% and a total selectivity for cyclohexanol and cyclohexanone of 83.4% at 130 ℃ in 0.5 MPa (4.9 atm) air for 7 h over a 5wt%Pt/16wt%Ce 0.68 Zr 0.17 Sn 0.15 O 2.0 /SiO 2 catalyst. This catalyst has significant advantages over conventional catalysts because the reaction proceeds at a lower pressure, and there is no need for toxic radical initiators or free-radical scavengers.
Green-emitting phosphors based on lanthanum-gadolinium oxybromide were synthesized in a single phase form by the conventional solid state reaction method, and photoluminescence properties of them were characterized. The excitation peak wavelength of (La1-xGdx)OBr:Tb3+ shifted to the shorter wavelength side with the increase in the crystal field around the Tb3+ ions by doping Gd3+ ions into the La3+ site, and, as a result, the green emission intensity was successfully enhanced. The maximum emission intensity was obtained for (La0.95Gd0.05)OBr:5%Tb3+, where the relative emission intensity was 45% of that of a commercial green-emitting LaPO4:Ce3+,Tb3+ phosphor.
Red-emitting phosphors, (La1−xCax)OCl:y%Eu3+ (0 ≤ x ≤ 0.17, 1 ≤ y ≤ 5), were synthesized in a single-phase form by a liquid-phase method and photoluminescence properties were characterized. The excitation peak intensity of the phosphor was increased with Ca2+ doping into the LaOCl lattice, corresponding to the successful enhancement of the emission intensity. The maximum emission intensity was obtained for (La1−xCax)OCl:y%Eu3+, where it was 63% of that of a commercial Y2O3:Eu3+ phosphor.
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