The red phosphor materials CaS∶Cu+,Eu 2+ were firstly synthesized in a microwave field, and characterized by XRD、SEM、fluorescent spectroscopy. The experimental results of XRD and SEM show that the phosphors of CaS...The red phosphor materials CaS∶Cu+,Eu 2+ were firstly synthesized in a microwave field, and characterized by XRD、SEM、fluorescent spectroscopy. The experimental results of XRD and SEM show that the phosphors of CaS∶Cu+,Eu 2+ possess a spherical crystallite structure, in the submicrometer(250～500 nm) size range. Compared to the conventional high temperature solid state reaction this new synthetic technique exhibits interesting features, such as rapid reactions without other protective atmosphere,phosphors with high purity, smaller particles,and higher efficient luminescence.展开更多
Submicrometer-sized tin-containing MCM-41 particles with a size of several hundred nanometers（Sn-MCM-41/SMPs） were rapidly prepared with tin chloride as tin source and tetraethyl orthosilicate as silicon source via ...Submicrometer-sized tin-containing MCM-41 particles with a size of several hundred nanometers（Sn-MCM-41/SMPs） were rapidly prepared with tin chloride as tin source and tetraethyl orthosilicate as silicon source via a dilute solution route in sodium hydroxide medium at room temperature. The characterization results show the highly ordered hexagonal mesopores and tetrahedral Sn species in Sn-MCM-41/SMPs. The material proved to be active and selective for Baeyer-Villiger oxidation of adamantanone with aqueous H2O2. Notably, Sn-MCM-41/ SMPs displayed a higher initial reaction rate and turnover number（TON） than common micrometer-sized Sn-MCM-41 large particles（Sn-MCM-41/LPs）, mainly attributed to the accelerated diffusion of the reactants and enhanced accessibility to the catalytic Sn species via shorter mesopore channels in Sn-MCM-41/SMPs. Furthermore, Sn-MCM-41/SMPs could be reused without the loss of activity after five runs, indicating that Sn active sites in the submicrometer-sized particles are remarkably stable. The study shows that decreasing particle size of Sn-MCM-41 in submicrometer scale is an effective way to achieve catalysts for Baeyer-Villiger oxidations with improved catalytic performance.展开更多
文摘The red phosphor materials CaS∶Cu+,Eu 2+ were firstly synthesized in a microwave field, and characterized by XRD、SEM、fluorescent spectroscopy. The experimental results of XRD and SEM show that the phosphors of CaS∶Cu+,Eu 2+ possess a spherical crystallite structure, in the submicrometer(250～500 nm) size range. Compared to the conventional high temperature solid state reaction this new synthetic technique exhibits interesting features, such as rapid reactions without other protective atmosphere,phosphors with high purity, smaller particles,and higher efficient luminescence.
基金Supported by the National Natural Science Foundation of China（No.21303031）, the Natural Science Foundation of Heilongjiang Province of China（No.B201010）, the Open Project of State Key Laboratory of Urban Water Resource and Environment of HIT, China（No.QA201021）, the Fundamental Research Funds for the Central Universities, China（No.HIT. NSRIF. 2013058）, the Talent Program for Innovation of Science and Technology of Harbin City, China（No.2013RFQXJ004） and the China Postdoctoral Science Foundation（Nos.2012T50334, 20100480991）.
文摘Submicrometer-sized tin-containing MCM-41 particles with a size of several hundred nanometers（Sn-MCM-41/SMPs） were rapidly prepared with tin chloride as tin source and tetraethyl orthosilicate as silicon source via a dilute solution route in sodium hydroxide medium at room temperature. The characterization results show the highly ordered hexagonal mesopores and tetrahedral Sn species in Sn-MCM-41/SMPs. The material proved to be active and selective for Baeyer-Villiger oxidation of adamantanone with aqueous H2O2. Notably, Sn-MCM-41/ SMPs displayed a higher initial reaction rate and turnover number（TON） than common micrometer-sized Sn-MCM-41 large particles（Sn-MCM-41/LPs）, mainly attributed to the accelerated diffusion of the reactants and enhanced accessibility to the catalytic Sn species via shorter mesopore channels in Sn-MCM-41/SMPs. Furthermore, Sn-MCM-41/SMPs could be reused without the loss of activity after five runs, indicating that Sn active sites in the submicrometer-sized particles are remarkably stable. The study shows that decreasing particle size of Sn-MCM-41 in submicrometer scale is an effective way to achieve catalysts for Baeyer-Villiger oxidations with improved catalytic performance.
