The SO42-/WO3-TiO2 solid superacid samples have been prepared by ageing at low temperature. The acidity of samples were determined with flowing indicator method, and the characterization of the samples were performed ...The SO42-/WO3-TiO2 solid superacid samples have been prepared by ageing at low temperature. The acidity of samples were determined with flowing indicator method, and the characterization of the samples were performed by IR, XPS and XRD. The samples were used in the esterification of acetic acid and glycerol. The results show that the sample aged at low temperature have better performance comparing with other samples aged at normal temperature, the flexible vibration peak of S=O bond has been strengthened remarkably in IR spectra. The peak position of W4f have a higher chemical shift in XPS patterns. The diffraction peaks of tetragonal and orthographic phase of WO3 are stronger in XRD patterns. The process of ageing at low temperature is responsible for the stronger acidity and higher activity of SWT samples.展开更多
化石通常赋存在年代久远的地层中,其形成所需的时间是一个尚不清楚的问题.对浙江省朱家尖岛发现的"石化木"———一种形似珊瑚的铁、锰质岩石,进行了元素地球化学、微生物矿物学等的研究,发现它们是在微生物成矿作用下,经Fe,M...化石通常赋存在年代久远的地层中,其形成所需的时间是一个尚不清楚的问题.对浙江省朱家尖岛发现的"石化木"———一种形似珊瑚的铁、锰质岩石,进行了元素地球化学、微生物矿物学等的研究,发现它们是在微生物成矿作用下,经Fe,Mn分异和矿化过程形成的."石化木"炭芯年龄为5 600 cal yr B P,这表明,该石化木正在进行化石化的过程,可能是迄今为止发现的最年轻的石化木.该发现对于解释这种自然现象并说明地球历史时期的化石及其形成过程和外生铁、锰矿床的成因有重要意义.展开更多
文摘本文报道采用反复退火法从 Ba-Yb-Cu-O 体系中制备尺寸约为1×0.5×0.2mm^3的黑色Ba_xYb_(2-x)Cu_2O_(5-δ)小单晶,从魏森堡照相求得其正交晶胞参数为a=3.434(?),b=10.712(?),c=12.338(?)。通过这些数据,成功指标化了该体系多晶 X 射线粉末衍射图。
文摘The SO42-/WO3-TiO2 solid superacid samples have been prepared by ageing at low temperature. The acidity of samples were determined with flowing indicator method, and the characterization of the samples were performed by IR, XPS and XRD. The samples were used in the esterification of acetic acid and glycerol. The results show that the sample aged at low temperature have better performance comparing with other samples aged at normal temperature, the flexible vibration peak of S=O bond has been strengthened remarkably in IR spectra. The peak position of W4f have a higher chemical shift in XPS patterns. The diffraction peaks of tetragonal and orthographic phase of WO3 are stronger in XRD patterns. The process of ageing at low temperature is responsible for the stronger acidity and higher activity of SWT samples.
基金This project has been subsidized by Laboratory of Internal Friction & Defects in Solid, of Institute of Solid State Physics and the University of Science & Technology of China, Academia Sinica, Hefei, China.
文摘化石通常赋存在年代久远的地层中,其形成所需的时间是一个尚不清楚的问题.对浙江省朱家尖岛发现的"石化木"———一种形似珊瑚的铁、锰质岩石,进行了元素地球化学、微生物矿物学等的研究,发现它们是在微生物成矿作用下,经Fe,Mn分异和矿化过程形成的."石化木"炭芯年龄为5 600 cal yr B P,这表明,该石化木正在进行化石化的过程,可能是迄今为止发现的最年轻的石化木.该发现对于解释这种自然现象并说明地球历史时期的化石及其形成过程和外生铁、锰矿床的成因有重要意义.
