The nature of support and type of active metal affect catalytic performance. In this work, the effect of using La203 as promoter and support for Ni/γ-A1203 catalysts in dry reforming of methane was investigated. The ...The nature of support and type of active metal affect catalytic performance. In this work, the effect of using La203 as promoter and support for Ni/γ-A1203 catalysts in dry reforming of methane was investigated. The reforming reactions were carried out at atmosphenc pressure in the temperature range of 500-2700℃. The activity and stability of the catalyst, carbon formation, and syngas (H2/CO) ratio were determined. Various techniques were applied for characterization of both fresh and used catalysts. Addition of La2O3 to the catalyst matrix improved the dispersion of Ni and adsorption of CO2, thus its activity and stability enhanced.展开更多
A warm-white emitting persistent luminescence phosphor Lu3Al2Ga3O12:Pr^3+ was synthesized by solid state method at 1600 °C in air. The refined crystal structure of Lu3Al2Ga3O12 host was solved by X-ray diffract...A warm-white emitting persistent luminescence phosphor Lu3Al2Ga3O12:Pr^3+ was synthesized by solid state method at 1600 °C in air. The refined crystal structure of Lu3Al2Ga3O12 host was solved by X-ray diffraction(XRD). The photoluminescence spectra, decay curve and thermoluminescence were investigated. It was revealed that the persistent luminescence originated from the f-f transitions of Pr^3+ emitters at Lu^3+ sites in LuO8 polyhedrons, and it showed white color due to the ^3P0→^3H4, ^3P1→^3H5, ^3P0→^3H5, ^3P0→^3H6, ^3P0→^3F2, ^3P0→^3F3 and ^3P0→^3F4 transitions of Pr^3+ emitters in a wide range. The persistent luminescence of Pr^3+ in this host could be promoted by f-d transition(278 nm) but f-f transitions, due to the different thermal activation energy. The persistent luminescence of the optimal sample could be actually recorded for 3 h by the definition of 0.32 mcd/m^2 and was visible for more than 7 h by dark-adapted vision in darkness. The initial depth of the dominant shallow traps was calculated to be about 0.56 eV, which is suitable for persistent luminescence. The different roles of the shallow and deep traps on the persistent decay process were investigated. Accordingly, the persistent luminescence processes and mechanism of the as-synthesized Lu3Al2Ga3O12:Pr^3+ phosphors were proposed.展开更多
基金the Deanship of Scientific Research at KSU for funding the work through the research group Project # RGP-VPP119
摘要The nature of support and type of active metal affect catalytic performance. In this work, the effect of using La203 as promoter and support for Ni/γ-A1203 catalysts in dry reforming of methane was investigated. The reforming reactions were carried out at atmosphenc pressure in the temperature range of 500-2700℃. The activity and stability of the catalyst, carbon formation, and syngas (H2/CO) ratio were determined. Various techniques were applied for characterization of both fresh and used catalysts. Addition of La2O3 to the catalyst matrix improved the dispersion of Ni and adsorption of CO2, thus its activity and stability enhanced.
基金Project supported by the National Natural Science Foundation of China(10904057)the Fundamental Research Funds for Central Universities(Lzjbky-2015-112,Lzjbky-2015-113)the National Science Foundation for Fostering Talents in Basic Research of the National Natural Science Foundation of China(041105,041106)
摘要A warm-white emitting persistent luminescence phosphor Lu3Al2Ga3O12:Pr^3+ was synthesized by solid state method at 1600 °C in air. The refined crystal structure of Lu3Al2Ga3O12 host was solved by X-ray diffraction(XRD). The photoluminescence spectra, decay curve and thermoluminescence were investigated. It was revealed that the persistent luminescence originated from the f-f transitions of Pr^3+ emitters at Lu^3+ sites in LuO8 polyhedrons, and it showed white color due to the ^3P0→^3H4, ^3P1→^3H5, ^3P0→^3H5, ^3P0→^3H6, ^3P0→^3F2, ^3P0→^3F3 and ^3P0→^3F4 transitions of Pr^3+ emitters in a wide range. The persistent luminescence of Pr^3+ in this host could be promoted by f-d transition(278 nm) but f-f transitions, due to the different thermal activation energy. The persistent luminescence of the optimal sample could be actually recorded for 3 h by the definition of 0.32 mcd/m^2 and was visible for more than 7 h by dark-adapted vision in darkness. The initial depth of the dominant shallow traps was calculated to be about 0.56 eV, which is suitable for persistent luminescence. The different roles of the shallow and deep traps on the persistent decay process were investigated. Accordingly, the persistent luminescence processes and mechanism of the as-synthesized Lu3Al2Ga3O12:Pr^3+ phosphors were proposed.