DRIFTS spectra

Figure 11 DRIFT spectra of Cu-ZSM-5 at 450 K in 5 kPa CO in Ar. Dashed line is a Fourier self-deconvolution spectrum.

When considering libraries of spectra for identification purposes, the effect of sample preparation on spectral characteristics is also important. Two FUR sampling methods have been adopted for IR analysis of TLC eluates in the presence of a stationary phase, namely DRIFTS [741] and PAS [742], of comparable sensitivity. It is to be noted that in situ TLC-PA-FTIR and TLC-DRIFT spectra bear little resemblance to KBr disc or DR spectra [743,744]. This hinders spectral interpretation by fingerprinting. For unambiguous identification, the use of a reference library consisting of TLC-FTIR spectra of adsorbed species is necessary. 

Diffuse reflectance FTIR (DRIFT) spectra were recorded on a Bio-Rad FTIR spectrometer (EXCALIBUR FTS3000). A high-temperature cell was attached to a flow system that allows in-situ sample treatment, adsorption and desorption of probe molecules at different temperatures. 

The apparent acidities of zeolite catalysts are characterized by Av0h values induced by adsorption of hexane (Av0h.C6) under the same conditions than those applied during separate catalytic experiments. The Avoh,c6 values for the different zeolite samples shown in fig. 2 were determined as Figure 1. DRIFT spectra measured in the above for the nitrogen probe molecule. vOH region before (solid lines) and after (dashed lines) contacting the samples with N2 at 298 K and 9 bar equilibrium pressure. 

Figure 2. DRIFT spectra measured in the vOH and v( region in He flow (solid lines) and in 6.1% hexane/He flow (dashed lines) at 553 K, i.e., under reaction conditions.

DRIFTs spectra of the Rh-LDH catalysts showed no change of the structure of the initial LDHs. Additionally, specific bands for the organic part of the complex (1260-1210 and 1450-1430 cm 1 for S=0 and Ar-P vibrations) were observed, providing confirmation of the presence of the exchanged Rh on the surface of the brucite-like layers without affecting the LDH structure. 

Figures 19.6 through 19.11 detail the isotopic exchange rates during water-gas shift for the formate, C02, and Pt-CO bands, in switching from the 12C to 13C label. In all cases, the reactive exchange rates of formate and C02 were virtually identical, implicating the formate species as the likely intermediate to the water-gas shift catalytic mechanism over Pt/Zr02 and PtNa/Zr02 catalysts. The DRIFTS spectra at the top of each figure show the switching of these species from...

DRIFT spectra, acquiring, 24 111. See also Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) Drilling, of hydrothermal wells, 12 525-527 Drilling fluid (drilling mud) companies, 9 2 Drilling fluid materials, 9 2, 9-25. See also Drilling fluids Drilling muds alkalinity control in, 9 19 barite, 9 9-10 calcite, 9 10... 

Figure 8.1 Time-resolved DRIFTS spectra of the reduction of a resin-bound 2-deoxy-2-azidoglucuronic acid derivative to the corresponding amine.12...

Figure 18. DRIFT spectra of (a) HMS-CHjCHjCOjH (b) Co(III)-CMS3 (c) CoaH)-CMS5 (d)...

Figure 23. Temperature dependent DRIFT spectra of pyridine adsorbed on three selected compositions from Cul-xZnxFe204 (x = 0.05, 0.5 and 1) between 100 and 400oC.

Figure 6.13 In situ DRIFTS spectra during crotonaldehyde hydrogenation over (a) Pt/Si02 and (b) PtSn/Si02 as a function of temperature and time on stream. (Reproduced from Reference [95].)...

The fitting of the DRIFTS spectra was accomplished using the Grams software, Galactic Industries Ltd. 

Figure 2 DRIFTS spectra for the unrefined and milled kaolin samples collected at 25 °C. (a) OH stretching region (b) OH bending region...

Figure 8 Comparison of the DRIFTS spectra for unmilled kaolin and unmilled kaolin/ pyridine...

Fig. 8 (a) DRIFTS spectra of catalyst surface in NO flow. Absorbance increases with time, (b) In situ Raman spectra measured while methanol flowing over catalyst. ... 

The commercial Pd/Al203 catalyst used in this pilot scale study was characterized via DRIFT spectroscopy. In situ DRIFT spectra of carbon monoxide, MIBK, acetone... 

Figure 3 DRIFT spectra of carbon monoxide probe molecule pulse adsorbed on...

Left DRIFT spectra of MIBK pulse adsorbed on Pd/ALOs recorded in 10 sec intervals Right DRIFT desorption spectra of MIBK as temperature is increased to 200X. 

The DRIFT spectra of MIBK are illustrated on the left side of Figure 5, as MIBK is pulse adsorbed onto the Pd/ALOs catalyst. The MIBK desorption DRIFT... 

Figure 2. DRIFT spectra of MCM-41 a) calcined, b) outer surface silylated, c) silylated in dichloromethane and d) azo dye grafted.

The DRIFT spectra show the typical broad peaks of an amorphous material up to approximately 1200 °C. Indeed, even at 1400 °C the sharp peaks indicative of a highly ordered, crystalline material are not really evident. These data suggest that the material is not particularly crystalline, possibly even up to 1400 °C. The solid state 29Si MAS NMR data suggest the same thing as shown in Figure 14. 

Figure 9.7 DRIFT spectra of APTS modified silica gel (a) air cured (b) vacuum cured.

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