2000 Fiscal Year Final Research Report Summary
Characterization of surface functional groups by FT-near infrared spectroscopy
| Project/Area Number |
09490019
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
広領域
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| Research Institution | Toyohashi University of Technology |
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Principal Investigator |
KAKUTA Noriyoshi Toyohashi University of Technology, 工学部, 助教授 (30201411)
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| Co-Investigator(Kenkyū-buntansha) |
OHKITA Hironobu Toyohashi University of Technology, 工学部, 教務職員 (20262967)
MIZUSHIMA Takanori Toyohashi University of Technology, 工学部, 講師 (60239233)
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| Project Period (FY) |
1997 – 2000
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| Keywords | Near infrared spectroscopy / OH groups / acid strength |
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| Research Abstract |
Fourier Transform Near Infrared Spectroscopy (FT-NIR) is a powerful analytical method but is not familiar except for in agricultural fields. The NIR region(4000cm^<-1>〜10000cm^<-1>) covers the overtones and combination of stretching and bending vibrations of O-H bonds. The aim of study is to identify O-H vibrations originated from the acid property, especially on solid acid oxides. As there are a few results on NIR studies, standard samples for the assignment of peaks have been employed using diluents such as CCl_4, C_6H_6 and CHCl_3. The acid strength in the liquid sample is associated to the vibration frequencies of the corresponding OH groups as follows : 1) When the acid strength(pKa) is about 4.5, the vibration frequency of OH groups is observed around 6890Cm^<-1> in CDCl_3 solution. 2) When the acid strength becomes ca. 3, the frequency is shifted to 6850cm^<-1>. 3) When the acid strength is between 4.5 and 3, the absorption peaks appear between 6890Cm^<-1> and 6850cm^<-1> in CDCl_3 solution.
In solid samples, zeolites, where the structures and Si/Al ratios are identified already, show the characteristic peak shoulders at 6500-7000cm^<-1> and 5000cm^<-1>. The positions of peak shoulders are closely correlated with changes in the Si/Al ratio, suggesting that the peak shoulders might be attributed to the OH groups derived from the acid strength. Since the zeolites observed were exposed to air, the peaks from adsorbed H_2O also were detected. In order to identify clearly the peak corresponding to the acid strength, the in-situ and diffuse reflectance techniques are prerequisite. The study is under way.
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