Pd-Ag bimetallic alloy nanoparticles were synthesized by the reverse microemulsion method,and then deposited on Al2O3 to form the supported catalyst.The nanoparticles of Pd-Ag and Pd-Ag/Al2O3 samples were characterize...Pd-Ag bimetallic alloy nanoparticles were synthesized by the reverse microemulsion method,and then deposited on Al2O3 to form the supported catalyst.The nanoparticles of Pd-Ag and Pd-Ag/Al2O3 samples were characterized by UV/Vis,HRTEM,EDX,XRD,and XPS.The test results indicated that Pd-Ag bimetallic alloy nanoparticles with a size of about 2 nm and a face-centered cubic(fcc) structure were formed in the measured area of microemulsion.The growth of nanoparticles was effectively limited within the droplet of micoremulsion.TEM image exhibited that the Pd-Ag alloy nanoparticles were well-dispersed on the Al2O3 support.The catalytic performance of various catalysts for selective hydrogenation of acetylene showed that a higher acetylene conversion and selectivity to ethylene upon acetylene hydrogenation was achieved on a nano-sized Pd-Ag bimetallic catalyst with a Pd/Ag alloy supported molar ratio of 1:1.5.展开更多
La or Ce-containing mordenite samples were synthesized from an amine-free fluorine-containing system with a quite broad range of raw materials compositions.When cerous nitrate was used in place of lanthanum nitrate as...La or Ce-containing mordenite samples were synthesized from an amine-free fluorine-containing system with a quite broad range of raw materials compositions.When cerous nitrate was used in place of lanthanum nitrate as the starting material for synthesis of the zeolite,the formation of quartz could be inhibited.Aluminum is the necessary starting material for synthesis of the rare earth-containing modernite,which features good activity for catalyzing phenol hydroxylation reaction with a less tar formation and a higher ratio of ortho-hydroxyphenol/para-hydroxyphenol.The activity of Ce-containing modernite is apparently higher than that of La-containing mordenite.The mordenite sample with high cerium content can give a higher phenol conversion coupled with a 200% increase in hydroquinone selectivity,resulting in an apparent reduction in para-benzoquinone selectivity.The phenol conversion increases in big chunks with an increasing reaction temperature,leading to an obvious reduction in para-benzoquinone selectivity along with an increasing decline ratio of ortho/para-positioned hydroxyphenol products.The appropriate hydroxylation reaction time is in the range of 4-6 hours.展开更多
A nano-crystal N–Zn/TiO 2 anode film was prepared using a combined technology. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry characterizations showed tha...A nano-crystal N–Zn/TiO 2 anode film was prepared using a combined technology. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry characterizations showed that the two elements N and Zn were doped into nano-crystal TiO 2 successfully. This resulted in a strong redshift in the UV-Visible spectrum. UV-Visible measurements showed that the light absorption of N719 and P3OT were complementary and covered the entire visible region. This led to a high utilization of visible light. Solar cells based on the N–Zn/TiO 2 anode film were co-sensitized using P3OT and N719. The cells have a short-circuit current density of 7.91 mA/cm 2 , an open-circuit photovoltage of 0.659 V, and a photoelectric conversion efficiency of 2.64%. Also, the relationship among the N–Zn/TiO 2 -film anode’s electric structure, the dye’s LUMO, electrochemical impedance, and photoelectric conversion efficiency are discussed in the paper.展开更多
Vanadium oxide nanotubes (VOx-NTs) have been synthesized by using n-butylamine as structuredirecting template and V2O5 as precursor under hydrothermal conditions. XRD, FTIR, SEM, TEM, BET and TG-DTA characterizations ...Vanadium oxide nanotubes (VOx-NTs) have been synthesized by using n-butylamine as structuredirecting template and V2O5 as precursor under hydrothermal conditions. XRD, FTIR, SEM, TEM, BET and TG-DTA characterizations have been performed to both optimize the synthetic conditions and understand the growth mechanism of VOx-NTs. The results showed that open-ended VOx-NTs were obtained under the optimized conditions (hydrothermal temperature: 150―160°C, hydrothermal time: 5―7 d, the molar ratio of V2O5 to n-butylamine is 1:1) with diameters ranging from about 30 to 100 nm and several micrometers in length. The BET surface area and the desorption cumulative pore volume of pores of the as-synthesized sample were about 27.4609 m2/g and 0.191087 cm3/g, respectively. The result presents that the synthesis of VOx-NTs is controlled by the "rolling" mechanism and temperature is primary driving force for rolling.展开更多
Silver behenate nanocrystals were first prepared by chemical precipitation in a water tert-butyl alcohol mixed solvent. The influence of main factors on the silver behenate crystal size was studied. The morphology, cr...Silver behenate nanocrystals were first prepared by chemical precipitation in a water tert-butyl alcohol mixed solvent. The influence of main factors on the silver behenate crystal size was studied. The morphology, crystal structure and ther- mal behavior of silver behenate nanocrystals were investigated using SEM, TEM, XRD, IR and TG-DTA. These results showed that the preparation method, reaction temperature and excessive silver ion con- centration in reaction solution played important roles in determining the size of silver behenate nanocrys- tals. The prepared silver behenates were scaly crys- tals with a mean diameter of about 70 nm. The silver behenate nanocrystals possessed layer structure. A series of structural changes of silver behenate nanocrystals were observed at different temperatures. The silver behenate nanocrystals had excellent thermal stability below 120℃. At high temperature there were two distinct transitions resulting in dra- matic structural changes. In the first transition at 138℃, the alkyl chains of silver behenate were trans- formed from an ordered into a disordered state. In the second transition at 230℃, a completely irreversible structural change took place due to the decomposi- tion of silver behenate nanocrystals.展开更多
文摘Pd-Ag bimetallic alloy nanoparticles were synthesized by the reverse microemulsion method,and then deposited on Al2O3 to form the supported catalyst.The nanoparticles of Pd-Ag and Pd-Ag/Al2O3 samples were characterized by UV/Vis,HRTEM,EDX,XRD,and XPS.The test results indicated that Pd-Ag bimetallic alloy nanoparticles with a size of about 2 nm and a face-centered cubic(fcc) structure were formed in the measured area of microemulsion.The growth of nanoparticles was effectively limited within the droplet of micoremulsion.TEM image exhibited that the Pd-Ag alloy nanoparticles were well-dispersed on the Al2O3 support.The catalytic performance of various catalysts for selective hydrogenation of acetylene showed that a higher acetylene conversion and selectivity to ethylene upon acetylene hydrogenation was achieved on a nano-sized Pd-Ag bimetallic catalyst with a Pd/Ag alloy supported molar ratio of 1:1.5.
文摘La or Ce-containing mordenite samples were synthesized from an amine-free fluorine-containing system with a quite broad range of raw materials compositions.When cerous nitrate was used in place of lanthanum nitrate as the starting material for synthesis of the zeolite,the formation of quartz could be inhibited.Aluminum is the necessary starting material for synthesis of the rare earth-containing modernite,which features good activity for catalyzing phenol hydroxylation reaction with a less tar formation and a higher ratio of ortho-hydroxyphenol/para-hydroxyphenol.The activity of Ce-containing modernite is apparently higher than that of La-containing mordenite.The mordenite sample with high cerium content can give a higher phenol conversion coupled with a 200% increase in hydroquinone selectivity,resulting in an apparent reduction in para-benzoquinone selectivity.The phenol conversion increases in big chunks with an increasing reaction temperature,leading to an obvious reduction in para-benzoquinone selectivity along with an increasing decline ratio of ortho/para-positioned hydroxyphenol products.The appropriate hydroxylation reaction time is in the range of 4-6 hours.
基金supported by the National High Technology Research and Development Program of China (2006AA03z412)the Department of Education Research Project of Hainan (Hj2010-52)+2 种基金the Scientific Research Foundation of the Graduate School of Beijing University of Chemical and Technology (09Si005)the Key Science Planning Program of Hainan (ZDXM20100062)the National High Technology Research and Development Program of Hainan (509013)
文摘A nano-crystal N–Zn/TiO 2 anode film was prepared using a combined technology. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry characterizations showed that the two elements N and Zn were doped into nano-crystal TiO 2 successfully. This resulted in a strong redshift in the UV-Visible spectrum. UV-Visible measurements showed that the light absorption of N719 and P3OT were complementary and covered the entire visible region. This led to a high utilization of visible light. Solar cells based on the N–Zn/TiO 2 anode film were co-sensitized using P3OT and N719. The cells have a short-circuit current density of 7.91 mA/cm 2 , an open-circuit photovoltage of 0.659 V, and a photoelectric conversion efficiency of 2.64%. Also, the relationship among the N–Zn/TiO 2 -film anode’s electric structure, the dye’s LUMO, electrochemical impedance, and photoelectric conversion efficiency are discussed in the paper.
基金Research Fund for the Doctoral Program of Higher Education (Grant No. 20050010014)
文摘Vanadium oxide nanotubes (VOx-NTs) have been synthesized by using n-butylamine as structuredirecting template and V2O5 as precursor under hydrothermal conditions. XRD, FTIR, SEM, TEM, BET and TG-DTA characterizations have been performed to both optimize the synthetic conditions and understand the growth mechanism of VOx-NTs. The results showed that open-ended VOx-NTs were obtained under the optimized conditions (hydrothermal temperature: 150―160°C, hydrothermal time: 5―7 d, the molar ratio of V2O5 to n-butylamine is 1:1) with diameters ranging from about 30 to 100 nm and several micrometers in length. The BET surface area and the desorption cumulative pore volume of pores of the as-synthesized sample were about 27.4609 m2/g and 0.191087 cm3/g, respectively. The result presents that the synthesis of VOx-NTs is controlled by the "rolling" mechanism and temperature is primary driving force for rolling.
文摘Silver behenate nanocrystals were first prepared by chemical precipitation in a water tert-butyl alcohol mixed solvent. The influence of main factors on the silver behenate crystal size was studied. The morphology, crystal structure and ther- mal behavior of silver behenate nanocrystals were investigated using SEM, TEM, XRD, IR and TG-DTA. These results showed that the preparation method, reaction temperature and excessive silver ion con- centration in reaction solution played important roles in determining the size of silver behenate nanocrys- tals. The prepared silver behenates were scaly crys- tals with a mean diameter of about 70 nm. The silver behenate nanocrystals possessed layer structure. A series of structural changes of silver behenate nanocrystals were observed at different temperatures. The silver behenate nanocrystals had excellent thermal stability below 120℃. At high temperature there were two distinct transitions resulting in dra- matic structural changes. In the first transition at 138℃, the alkyl chains of silver behenate were trans- formed from an ordered into a disordered state. In the second transition at 230℃, a completely irreversible structural change took place due to the decomposi- tion of silver behenate nanocrystals.
