Characterization of surface functional groups by FT-near infrared spectroscopy

Research Project

Project/Area Number	09490019
Research Category	Grant-in-Aid for Scientific Research (B).
Allocation Type	Single-year Grants
Section	一般
Research Field	広領域
Research Institution	Toyohashi University of Technology
Principal Investigator	KAKUTA Noriyoshi Toyohashi University of Technology, 工学部, 助教授 (30201411)
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)
Project Period (FY)	1997 – 2000
Project Status	Completed (Fiscal Year 2000)
Budget Amount *help	¥3,200,000 (Direct Cost: ¥3,200,000) Fiscal Year 2000: ¥1,200,000 (Direct Cost: ¥1,200,000) Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000) Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Keywords	Near infrared spectroscopy / OH groups / acid strength / 固体酸 / ゼオライト / シリカアルミナ / 赤外分光法 / 酸強度
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.