SAPO-34 catalyst with plate-like morphology was designed and synthesized for the first time, by the dry gel conversion method using cheap triethylamine as a structure-directing agent assisted with seed suspension cont...SAPO-34 catalyst with plate-like morphology was designed and synthesized for the first time, by the dry gel conversion method using cheap triethylamine as a structure-directing agent assisted with seed suspension containing nanosheet-like SAPO-34 seed. The latter played an important role in formation of SAPO-34 （CHA-type） with plate-like morphology. In addition, the yield of the product in the synthesis system containing seed suspension reached 97%, 15% higher than that obtained in the corre- sponding synthesis system without the seed suspension. Meanwhile, the plate-like SAPO-34 catalysts synthesized by this method exhibited higher selectivity to light olefins and longer lifetime in methanol-to-olefins （MTO） reaction than the traditional cubic SAPO-34 catalyst. This work provides a new technical route for green and efficient synthesis of SAPO-34 catalysts with improved MTO performance.展开更多
Raman spectra and surface-enhanced Raman scattering （SERS） spectra of filter paper and silica gel plate are ob- tained at 785-nm excitation wavelength. The results show that filter paper has thirteen Raman lines in ...Raman spectra and surface-enhanced Raman scattering （SERS） spectra of filter paper and silica gel plate are ob- tained at 785-nm excitation wavelength. The results show that filter paper has thirteen Raman lines in 800 - 1 500 cm 1 and silica gel plate has eight lines in the region of 400 - 1 200 cm-I. The frequencies and Raman active modes are assigned. By comparing their Raman spectra and SERS spectra, we find that the silver colloid could repress the Raman intensities of filter paper and silica gel plate, and reduce their effects on the combination of thin-layer chromatographic （TLC） and SERS. Ac- cording to SERS spectra, the bands at 997 cm 1,1 094 cm I ,1 118 cm-1 ,1 336 cm-1 and 1 378 cm-1 for filter paper and the peak of v l [ SO4] symmetric stretching vibration （--1 017 cm-1 ） for silica gel plate also have high intensities, and those lines should be paid enough attention in TLC-SERS.展开更多
SnO2 nanocrystal and rare-earth Eu^3＋ ion co-doped SiO2 thin films are prepared by sol-gel and spin coating methods. The formation of tetragonal rutile structure SnO2 nanocrystals with a uniform distribution is confi...SnO2 nanocrystal and rare-earth Eu^3＋ ion co-doped SiO2 thin films are prepared by sol-gel and spin coating methods. The formation of tetragonal rutile structure SnO2 nanocrystals with a uniform distribution is confirmed by X-ray diffraction and transmission electron microscopy. Fourier transform infrared spectroscopy is used to investigate the densities of the hydroxyl groups, and it is found that the emission intensity from the 5Do-TF2 transitions of the Eu^3＋ ions is enhanced by two orders of magnitude due to energy transfer from the oxygen-vacancy-related defects of the SnO2 nanocrystals to nearby Eu^3＋ ions. The influences of the amounts of Sn and the post-annealing temperatures are systematically evaluated to further understand the mechanism of energy transfer. The luminescence intensity ratio of Eu^3＋ ions from electric dipole transition and magnetic dipole transition indicate the different probable locations of Eu^3＋ ions in the sol-gel thin film, which are further discussed based on temperature-dependent photoluminescence measurements.展开更多
文摘SAPO-34 catalyst with plate-like morphology was designed and synthesized for the first time, by the dry gel conversion method using cheap triethylamine as a structure-directing agent assisted with seed suspension containing nanosheet-like SAPO-34 seed. The latter played an important role in formation of SAPO-34 （CHA-type） with plate-like morphology. In addition, the yield of the product in the synthesis system containing seed suspension reached 97%, 15% higher than that obtained in the corre- sponding synthesis system without the seed suspension. Meanwhile, the plate-like SAPO-34 catalysts synthesized by this method exhibited higher selectivity to light olefins and longer lifetime in methanol-to-olefins （MTO） reaction than the traditional cubic SAPO-34 catalyst. This work provides a new technical route for green and efficient synthesis of SAPO-34 catalysts with improved MTO performance.
基金Programs for Science and Technology Development of Shandong,China(No.2010GSF10285)
文摘Raman spectra and surface-enhanced Raman scattering （SERS） spectra of filter paper and silica gel plate are ob- tained at 785-nm excitation wavelength. The results show that filter paper has thirteen Raman lines in 800 - 1 500 cm 1 and silica gel plate has eight lines in the region of 400 - 1 200 cm-I. The frequencies and Raman active modes are assigned. By comparing their Raman spectra and SERS spectra, we find that the silver colloid could repress the Raman intensities of filter paper and silica gel plate, and reduce their effects on the combination of thin-layer chromatographic （TLC） and SERS. Ac- cording to SERS spectra, the bands at 997 cm 1,1 094 cm I ,1 118 cm-1 ,1 336 cm-1 and 1 378 cm-1 for filter paper and the peak of v l [ SO4] symmetric stretching vibration （--1 017 cm-1 ） for silica gel plate also have high intensities, and those lines should be paid enough attention in TLC-SERS.
基金Project supported by the National Natural Science Foundation of China(Grant No.61036001)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK2010010)the Fundamental Research Funds for the Central Universities of China(Grant Nos.1112021001 and 1116021003)
文摘SnO2 nanocrystal and rare-earth Eu^3＋ ion co-doped SiO2 thin films are prepared by sol-gel and spin coating methods. The formation of tetragonal rutile structure SnO2 nanocrystals with a uniform distribution is confirmed by X-ray diffraction and transmission electron microscopy. Fourier transform infrared spectroscopy is used to investigate the densities of the hydroxyl groups, and it is found that the emission intensity from the 5Do-TF2 transitions of the Eu^3＋ ions is enhanced by two orders of magnitude due to energy transfer from the oxygen-vacancy-related defects of the SnO2 nanocrystals to nearby Eu^3＋ ions. The influences of the amounts of Sn and the post-annealing temperatures are systematically evaluated to further understand the mechanism of energy transfer. The luminescence intensity ratio of Eu^3＋ ions from electric dipole transition and magnetic dipole transition indicate the different probable locations of Eu^3＋ ions in the sol-gel thin film, which are further discussed based on temperature-dependent photoluminescence measurements.
