Fourier transform infrared adsorption spectra

Characterization of catalysts The zeolite structure was checked by X-ray diffraction patterns recorded on a CGR Theta 60 instrument using Cu Ka, filtered radiation. The chemical composition of the catalysts was determined by atomic absorption analysis after dissolution of the sample (SCA-CNRS, Solaize, France). Micropore volumes were measured by N2 adsorption at 77 K using a Micromeritics ASAP 2000 apparatus and by adsorption of cyclohexane (at P/Po=0.15) using a microbalance apparatus SET ARAM SF 85. Incorporation of tetrahedral cobalt (II) in the framework of Co-Al-BEA and Co-B-BEA was confirmed by electronic spectroscopy [18] using a Perkin Elmer Lambda 14 UV-visible diffuse reflectance spectrophotometer. Acidity measurements were performed by Fourier transform infrared spectroscopy (FT-IR, Nicolet FTIR 320) after pyridine adsorption. Self-supported wafer of pure zeolite (20 mg/cm ) was outgassed at 673 K for 6 hours at a pressure of lO Pa. After cooling at 423 K, the zeolite was saturated with pyridine vapour (30 kPa) for 5 min, evacuated at this temperature for 30 min and the IR spectrum was recorded. 

Fourier transform infrared spectroscopy (FTIR) is a technique which is used to obtain infrared spectrum of absorption, emission, and photoconductivity of sohd, hquid, and gas. It is used to detect different functional groups in PHB. FTIR spectrum is recorded between 4000 and 400 cm b For FTIR analysis, the polymer was dissolved in chloroform and layered on a NaCl crystal and after evaporation of chloroform, the polymer film was subjected to FTIR. The spectnun of PHB shows peaks at 1724 cm and 1279 cm b which corresponds to specific rotations around carbon atoms. The peak at 1724cm corresponds to C—O stretch of the ester group present in the molecular chain of highly ordered structure and the adsorption band at 1279cm corresponds to ester bonding.Figure 17.5 shows FTIR spectrum of PHB. 

The conventional spectrometer with a dispersive prism or grating has been largely superseded by the Fourier transform infrared (FTIR) technique. This uses a moving mirror in an interferometer to produce an optical transform of the infrared signal. Numerical Fourier analysis gives the relation of intensity and frequency, that is, the IR spectrum. The FTIR technique can be used to analyze gases, liquids, and sohds with minimal preparation in short times. The FTIR technique has been applied to the study of many systems, including adsorption on polymer surfaces, chemical modification, and irradiation of polymers and oxidation of rubbers [66]. The application of infrared spectroscopy to the study of polymers has been reviewed by Bower and Maddams [62]. 

Infrared (IR) spectrum of adsorbed carbon monoxide was recorded with a JASCO FT/IR-3 Fourier-transform IR spectrometer. The construction of the vacuum IR cell used for the measurements was similar to that reported by Peri and Hannan (ref. 3). The sample was pressed into a thin self-supporting wafer and pretreated in the cell. After reduction with hydrogen at 673 K for 2 h, the sample was evacuated at the same temperature for 30 min and the temperature of the sample was lowered to room temperature for adsorption of carbon monoxide. The adsorption was carried out at a constant pressure of 40 Torr for 15 min at room temperature. Carbon monoxide in the gas phase was evacuated at room temperature for 5 min before IR measurement. The spectrum taken before carbon monoxide adsorption was used as the background spectrum. 

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