Static FTIR

Dehydration kinetics of the four alochols were followed using two distinct types of catalytic reactors a static FTIR spectrometer cell, in which the concentration of alcohol adsorbed by the catalyst was adjusted to be less than or equal to the concentration of the active sites and a flow microreactor, which allowed the escaping products (and reactant) to be identified by gas chromatography. Kinetic measurements conducted with the FTIR cell refer to the... 

A. Kinetic Studies Using a Static FTIR Cell... 

Note that the rate coefficients k determined by our kinetic studies with the static FTIR reactor for all four butyl alcohols are the true rate coefficients for the forward step of stage II of Scheme 1, i. e., k = k+//. But under the steady-state conditions of the flow microreactor, the observed reation rate, Wbuoh, of butyl alcohol dehydration is less than or equal to the product (k+//N) of the rate... 

Note also that the rate coefficients in Scheme 1 (k2 among them) measured in our static FTIR and flow GS kinetic measurements should not necessarily coincide because of the solvation effects that may become important in the latter (but not in the former) case (vide infra). 

TIME-RESOLVED INFRARED AND STATIC FTIR STUDIES OF Qb electron TRANSFER IN RHODOPSEUDOMONAS VIRIDIS REACTION CENTERS... 

FTIR can be used to screen membranes for fouling tendencies prior to the first ultrafiltration experiment. Screening can be done by means of a simple static adsorption test. Membranes showing greater static adsorption are expected to foul more during ultrafiltration and are disfavored. Figure 8 illustrates the FTIR results... 

Figure 8. Example of FTIR analysis of Polysulfone (PS) ultrafilter static adsorption test.

The ability of SFE-FTIR to perform a variety of extraction methods is a definite advantage, especially for the study of complex mixtures containing analytes of varying solubility. For analytes which are readily solubilised in C02, direct dynamic and direct static-dynamic SFE-FTIR methods are quite successful. Elimination of the trapping process reduces both analysis time and potential analyte loss arising from... 

In both cases, either conventional FTIR transmission or diffuse reflection detection may be used. Because TLC and the postspectroscopic evaluation are not linked directly, few compromises have to be made with regard to the choice of the solvent system employed for separation. Chromatographic selectivity and efficiency are not influenced by the needs of the detector. The TLC plate allows the separation to be made in a different site from the laboratory where the separated analytes are evaluated. The fact that the sample is static on the plate, rather than moving with the flow of a mobile phase, also puts less demand on the spectrometer. The popularity of TLC-IR derives in part from its low cost. 

Fig. 5.12 The oxide thickness (broken line) and the free carrier absorption (dotted line, in arbitrary units) determined by FTIR spectroscopy for galvanostatic (top, 58 pA cm-2) and potentio-static (bottom, 7 V) conditions in buffered HF (0.1 M, pH=4.5). Redrawn from [Chi 2].

All experiments utilized a variable wavelength uv detector. Analysis of the hexane fraction was carried out using both the UV detector and an on-line Nicolet 6000 FTIR. The FTIR flow cell interface has been described in detail elsewhere.(9) This same FTIR was also used to gather static spectra on the various fractions, utilizing a liquid cell with KBr windows. 

The problem with sulfide catalysts (hydrotreatment) is to determine the active centres, which represent only part of their total surface area. Chemisorption of O2, CO and NO is used, and some attempts concern NIL, pyridine and thiophene. Static volumetric methods or dynamic methods (pulse or frontal mode) may be used, but the techniques do not seem yet reliable, due to the possible modification (oxidation) of the surface or subsurface regions by O2 or NO probe molecules or the kinetics of adsorption. CO might be more promising. Infrared spectroscopy, especially FTIR seems necessary to characterise co-ordinativcly unsaturated sites, which are essential for catalytic activity. CO and NO can also be used to identify the chemical nature of sites (sulfided, partially reduced or reduced sites). For such... 

The transmission FTIR studies of aqueous protein solutions indicate how structural and conformational differences in a protein can be related to spectral changes, and that spectral features can be used to identify proteins in mixtures. However, these studies involve static systems, and our goal was to study flowing systems and the adsorption of proteins onto various surfaces. 

Figure 1 Block diagram of the key components of the continuous reactor for hydrogenation of organic compounds at Nottingham [31]. SCCO2, H2 and the organic substrate were mixed in a heated mixer. The mixture was then passed through a reactor containing a fixed bed catalyst (usually a supported noble metal). There was optional on-line FTIR monitoring before the product and CO2 were separated by expansion. More recent reactors have used static rather than mechanical premixers.

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