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Umsa Jameel,Mingqiao Zhu,Xin-Zhi Chen,Hengquan Chen,Nousheen Iqbal,Zhangfa Tong,Satmon John Timayo 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.6
Selective oxidation of olefins using molecular oxygen is a great challenge. This study reports two types of novel eco-friendly heterogeneous hybrid catalysts. One comprises of a lacunary Keggin-type polyoxometalate (POM) GaW11 linked to nano-sized silica using (3-aminopropyl) triethoxysilane (APTES) to form GaW11-APTES@SiO2 . Another catalyst is Au/GaW11-APTES@SiO2 prepared by wet deposition of nano-gold on the former one. The catalysts were characterized and used for the solvent-free oxidation of cyclohexene with molecular oxygen under mild reaction conditions. Both the catalysts showed good conversion and significant selectivity towards oxidized products for cyclohexene. GaW11-APTES@SiO2 showed a high conversion of up to 62.02% with a selectivity of 59.13% towards epoxide at a mild temperature of 50°C. Au/GaW11-APTES@SiO2 showed a conversion of 69.32% with 57.34% selectivity to 2-cyclohexene-1-ol at a temperature of 80°C. The heterogeneous catalysts were reused several times with no significant loss in conversion or selectivity towards the oxidized products.
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Yangfan Su,Mengjuan Li,Mingqiao Ge 한국섬유공학회 2019 Fibers and polymers Vol.20 No.9
FexMnyCuzOw/γ-Al2O3 nanoparticles were prepared by a wet impregnation -calcination method and characterizedby means of XRD, BET, SEM-EDS. Box-Behnken design was used to investigate the degradation of PVA in aqueoussolution. Besides, the effect of different calcination temperature, FexMnyCuzOw/γ-Al2O3 dosage, H2O2 dosage, initial PVAconcentration and initial solution pH on the removal of PVA were also studied. Results showed that PVA can be efficientlyremoved and oxidized by the heterogeneous Fenton-like process with appropriate amount of FexMnyCuzOw/γ-Al2O3 andH2O2. In this paper, the efficiency of PVA was above 90 % by FexMnyCuzOw/γ-Al2O3 nanoparticles at an initial PVAconcentration below 25 g/l, temperature at 60 oC, initial pH from 1.0 to 6.0, H2O2 and catalyst dose of 60 ml/l and 0.5 g/l,respectively. In addition, chromatography (GPC) was applied to further analyze the degradation of PVA under differentexperimental conditions, which revealed that the backbone chain of PVA could be effectively broken and oxidized. Severalunsaturated degradation products, including butanones, benzaldehydes, hexanals and acetic acids were also detected andidentified by gas chromatography-mass spectrometry (GC-MS). Besides, the nano catalyst maintained favorable catalyticability during the five-times utilization, which means it could be recycled by filtration and calcination.
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Working Conditions on the Afterglow Characteristics of Rare-earth Luminous Fibers
Xuefeng Guo,Keqin Zhang,Hongwei Zhang,Mingqiao Ge 한국섬유공학회 2018 Fibers and polymers Vol.19 No.3
To test and clarify the stability of afterglow performance of luminescent fibers can accelerate the step of the commercialized application on luminescent textiles. This work investigated the possible effects of a number of working conditions on the afterglow characteristics of luminous fibers. The fibers in our studies did not show any significant change in their afterglow brightness and duration after storage for 12 months under conditions of constant temperature and humidity, after 5 hours of light exposure, or soaking in water for 4 hours. The insignificant decay appears to follow the same mechanism. Thermal perturbation seemed to cause some changes to the initial brightness and decay time with the best performance being observed at about 80 oC. Moreover, contact with acid or base for 5 minutes only resulted in slight reduction of the afterglow brightness. Our studies thus indicate a high degree of stability of the afterglow performance of the luminous fibers used.
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