Shape-selective methylation of 2-methylnaphthalene (2-MN) was carried out over NH 4 F and Pt modified HZSM-5 (SiO 2 /Al 2 O 3 = 83) catalysts in a fixed-bed down-flow reactor using methanol as methylating agent and 1,...Shape-selective methylation of 2-methylnaphthalene (2-MN) was carried out over NH 4 F and Pt modified HZSM-5 (SiO 2 /Al 2 O 3 = 83) catalysts in a fixed-bed down-flow reactor using methanol as methylating agent and 1,3,5-trimethylbenzene (1,3,5-TMB) as a solvent. Pt promoted HZSM-5 catalysts showed low concentration of coke-like polycondensed aromatics, NH 4 F modification decreased non-shape-selective acid sites. After Pt and NH 4 F co-modification, both conversion of 2-MN and selectivity to 2,6-DMN were improved. 6%NH 4 F/0.5%Pt/HZSM-5 catalyst exhibited 13.8% of 2-MN conversion with 6.2% of 2,6-DMN yield after 7 h time on stream (TOS), and 2,6-/2,7-DMN ratio of 1.7 after 10 h of TOS.展开更多
Fluorine doped tin oxide SnO2:F thin films were prepared by the spray pyrolysis(SP) technique on glass substrates by using SnCl2-2H2O as a precursor and NH4F and HF as doping compounds.A comparison between the propert...Fluorine doped tin oxide SnO2:F thin films were prepared by the spray pyrolysis(SP) technique on glass substrates by using SnCl2-2H2O as a precursor and NH4F and HF as doping compounds.A comparison between the properties of the films obtained by using the two doping compounds was performed by using I-V characteristics in the dark at room temperature,AC measurements,and transmittance.It is found that the films prepared by using HF have smaller resistivity,lower impedance and they are less capacitive than films prepared by using NH4F.In addition,these films have higher transmittance,higher optical bandgap energy and narrower Urbach tail width.These results are interesting for the use of SnO2:F as forecontact in CdS/CdTe solar cells.展开更多
北京师范大学无机化学教研室等编写的《无机化学实验》一书的实验二十四,配合物的生成和性质中配位平衡和介质的酸碱性实验中,有如下一段实验内容: “在试管中注入1ml0.5 M FeCl3溶液,再逐滴滴入4 M NH4F至溶液呈无色”。这一实验的原...北京师范大学无机化学教研室等编写的《无机化学实验》一书的实验二十四,配合物的生成和性质中配位平衡和介质的酸碱性实验中,有如下一段实验内容: “在试管中注入1ml0.5 M FeCl3溶液,再逐滴滴入4 M NH4F至溶液呈无色”。这一实验的原理应是:展开更多
基金Supported by the Program for New Century Excellent Talents in University (NCET-04-0268)the Expertise-Introduction Project for Disciplinary Innovation of Universities
文摘Shape-selective methylation of 2-methylnaphthalene (2-MN) was carried out over NH 4 F and Pt modified HZSM-5 (SiO 2 /Al 2 O 3 = 83) catalysts in a fixed-bed down-flow reactor using methanol as methylating agent and 1,3,5-trimethylbenzene (1,3,5-TMB) as a solvent. Pt promoted HZSM-5 catalysts showed low concentration of coke-like polycondensed aromatics, NH 4 F modification decreased non-shape-selective acid sites. After Pt and NH 4 F co-modification, both conversion of 2-MN and selectivity to 2,6-DMN were improved. 6%NH 4 F/0.5%Pt/HZSM-5 catalyst exhibited 13.8% of 2-MN conversion with 6.2% of 2,6-DMN yield after 7 h time on stream (TOS), and 2,6-/2,7-DMN ratio of 1.7 after 10 h of TOS.
文摘Fluorine doped tin oxide SnO2:F thin films were prepared by the spray pyrolysis(SP) technique on glass substrates by using SnCl2-2H2O as a precursor and NH4F and HF as doping compounds.A comparison between the properties of the films obtained by using the two doping compounds was performed by using I-V characteristics in the dark at room temperature,AC measurements,and transmittance.It is found that the films prepared by using HF have smaller resistivity,lower impedance and they are less capacitive than films prepared by using NH4F.In addition,these films have higher transmittance,higher optical bandgap energy and narrower Urbach tail width.These results are interesting for the use of SnO2:F as forecontact in CdS/CdTe solar cells.
