FeCo-Al2O3 catalyst was prepared by an ultrasonic coprecipitation （UC） method for the growth of carbon nanotubes （CNTs） from catalytic decomposition of methane.Its catalytic performance was compared with that of t...FeCo-Al2O3 catalyst was prepared by an ultrasonic coprecipitation （UC） method for the growth of carbon nanotubes （CNTs） from catalytic decomposition of methane.Its catalytic performance was compared with that of the FeCo-Al2O3 catalyst counterparts prepared by stepwise impregnation （I） and conventional coprecipitation （C） methods,respectively.The structure and properties of the catalysts and the CNTs as produced thereon were investigated by means of XRD,XPS,TEM and N2 adsorption techniques.It was found that the catalyst prepared by the ultrasonic coprecipitation method was more active,and the yield and purity of the synthesized CNTs were promoted evidently.The XPS results revealed that there were more active components on the surface of the catalyst prepared by the ultrasonic coprecipitation method.On the other hand,N2 adsorption demonstrated that the catalyst prepared by the ultrasonic coprecipitation method conferred larger specific surface area,which was beneficial to dispersion of active components.TEM images further confirmed its higher dispersion.These factors could be responsible for its higher activity for the growth of CNTs from catalytic decomposition of methane.展开更多
采用超声辅助共沉淀法合成了以Eu^(3+)为激活离子的Ca Mo O_4荧光粉。通过X-射线衍射、扫描电镜(SEM)、荧光分光光度计对样品进行了表征和分析,研究了溶剂浓度、表面活性剂种类、表面活性剂添加量、超声时间等反应参数对Ca Mo O_4∶Eu^(...采用超声辅助共沉淀法合成了以Eu^(3+)为激活离子的Ca Mo O_4荧光粉。通过X-射线衍射、扫描电镜(SEM)、荧光分光光度计对样品进行了表征和分析,研究了溶剂浓度、表面活性剂种类、表面活性剂添加量、超声时间等反应参数对Ca Mo O_4∶Eu^(3+)发光性能的影响。结果表明:制备的样品为球形纯相四方晶系Ca Mo O_4晶体,在Ca Mo O_4∶Eu^(3+)中存在Mo O_4^(2-)到Eu^(3+)的能量传递。以50%丙酮溶液作为溶剂、PEG添加量为9 m L、Eu^(3+)掺杂浓度为10%、超声时间为10 min时,制备的样品在393 nm光激发下,Ca Mo O_4∶Eu^(3+)的最强峰所在位置是616 nm,实现了有效的红光发射,样品在紫外灯下呈现出明亮的红色。展开更多
文摘FeCo-Al2O3 catalyst was prepared by an ultrasonic coprecipitation （UC） method for the growth of carbon nanotubes （CNTs） from catalytic decomposition of methane.Its catalytic performance was compared with that of the FeCo-Al2O3 catalyst counterparts prepared by stepwise impregnation （I） and conventional coprecipitation （C） methods,respectively.The structure and properties of the catalysts and the CNTs as produced thereon were investigated by means of XRD,XPS,TEM and N2 adsorption techniques.It was found that the catalyst prepared by the ultrasonic coprecipitation method was more active,and the yield and purity of the synthesized CNTs were promoted evidently.The XPS results revealed that there were more active components on the surface of the catalyst prepared by the ultrasonic coprecipitation method.On the other hand,N2 adsorption demonstrated that the catalyst prepared by the ultrasonic coprecipitation method conferred larger specific surface area,which was beneficial to dispersion of active components.TEM images further confirmed its higher dispersion.These factors could be responsible for its higher activity for the growth of CNTs from catalytic decomposition of methane.
文摘采用超声辅助共沉淀法合成了以Eu^(3+)为激活离子的Ca Mo O_4荧光粉。通过X-射线衍射、扫描电镜(SEM)、荧光分光光度计对样品进行了表征和分析,研究了溶剂浓度、表面活性剂种类、表面活性剂添加量、超声时间等反应参数对Ca Mo O_4∶Eu^(3+)发光性能的影响。结果表明:制备的样品为球形纯相四方晶系Ca Mo O_4晶体,在Ca Mo O_4∶Eu^(3+)中存在Mo O_4^(2-)到Eu^(3+)的能量传递。以50%丙酮溶液作为溶剂、PEG添加量为9 m L、Eu^(3+)掺杂浓度为10%、超声时间为10 min时,制备的样品在393 nm光激发下,Ca Mo O_4∶Eu^(3+)的最强峰所在位置是616 nm,实现了有效的红光发射,样品在紫外灯下呈现出明亮的红色。
