Fourier transform infrared-temperature programmed desorption

6 Fourier Transform Infrared-Temperature Programmed Desorption 

The cell is water cooled and equipped with CaF2 windows. This cell was mounted in the sample section of a Bio-Rad FTS 40A FTIR spectrophotometer. 

Adsorption of benzene, toluene, and ethylbenzene on the three zeolites at 298 K for partial pressures ranging from about IVP0 = 0.01 to 0.8 were first performed [98], and it appears that all the systems approach saturation at P/P0 = 0.1-0.2. Therefore, we decided to carry out the adsorption of the adsorbate molecules at partial pressures of 15-30 Pa. 

The uptake process was followed by purging for 7 min, and subsequently the TPD was carried out. The results were obtained by monitoring the decrease, during desorption, of the absorbance A measured in arbitrary units (au), of a typical IR band of the adsorbate molecules, where A is proportional to N (A = K x N), and where N is the amount of adsorbate in the material and K, a proportionality constant [98,99], For benzene, the region between 1450 and 1550 cm-1 was integrated to obtain a measure of the intensity of the band around 1482 cm-1. For toluene and ethylbenzene, the segment between 1477 and 1517 cm-1 was integrated to obtain an intensity measure for the band around 1497 cm-1 [97,98], 

For the generation of the FTIR-TPD profiles (A vs. T), the decrease in the intensity (absorbance) of one of the selected bands was monitored, during heating at a constant rate [97] 

---

Zhang, W.Z., Burckle, E.C., and Smimiotis, P.G. (1999) Charaderization of the acidity of ultrastable Y, morden-ite, and ZSM-12 via NH3-stepwise temperature programmed desorption and Fourier transform infrared spectroscopy. Micropor. Mesopor. 

Three series of LaCoi. CuxOs, LaMni.xCuxOs, LaFei x(Cu, Pd)x03 perovskites prepared by reactive grinding were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature programmed desorption (TPD) of O2, NO + O2, and CsHg in the absence or presence of H2O, Fourier transform infrared (FTIR) spectroscopy as well as activity evaluations without or with 10% steam in the feed. This research was carried out with the objective to investigate the water vapor effect on the catalytic behavior of the tested perovskites. An attempt to propose a steam deactivation mechanism and to correlate the water resistance of perovskites with their properties has also been done. 

The term 1 or h indicates low or high coverage of adsorbed ethene, as inferred from ethene exposures.h TPD, temperature-programmed desorption LITD, laser-induced thermal desorption 1 FT-MS, Fourier-transform mass spectrometry SIMS, secondary-ion mass spectrometry MS, mass spectrometry T-NEXAFS, transient near-edge X-ray absorption fine structure spectroscopy RAIRS, reflection-absorption infrared spectroscopy. d Data for perdeut-erio species.1 Estimated value. 

Koehler, B.G., Middlebrook, AM., and Tolbert, M.A. (1992) Characterisation of model polar stratospheric cloud forts using Fourier transform infrared spectroscopy and temperature programmed desorption, J. Geophys. Res. 97,8065-8074. 

The experiments were performed in two different ultra high vacuum (UHV) chambers using two different Pt(lll) single crystals. The X-ray photoelectron spectra were obtained in a chamber with a base pressure of lxlO" Torr. The system has been described in detail elsewhere. In brief, the UHV chamber is equipped with low energy electron diffraction (LEED), an X-ray photoelectron spectrometer (XPS), a quadrupole mass spectrometer (QMS) for temperature programmed desorption (TPD), and a Fourier transform infrared spectrometer (FTIR) for reflection absorption infrared spectroscopy (RAIRS). All RAIRS and TPD experiments were performed in a second chamber with a base pressure of 2 X 10 ° Torr. The system has been described in detail elsewhere. In brief, the UHV chamber is equipped for LEED, Auger electron spectroscopy (AES) and TPD experiments with a QMS. The chamber is coupled to a commercial FTIR spectrometer, a Bruker IFS 66v/S. To achieve maximum sensitivity, an... 

There are several experimental techniques available to study the chemical properties of clusters on surfaces and when used in combination, a detailed picture can be obtained. A classical approach is the use of temperature programmed desorption (TPD) and temperature programmed reaction (TPR) spectroscopy [39, 239,240] in combination with temperature-dependent and eventually time-dependent Fourier transformed infrared spectroscopy (FTIR) [39,192,241-244]. This combination allows for obtaining information on estimates of binding energies of reactant molecules (TPD), for characterizing... 

The catalysts were characterized by N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), temperature-programmed desorption of ammonia (NH3-TPD), X-ray diffraction (XRD), Raman spectroscopy, in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and X-ray photoelectron spectroscopy (XPS). The procedures and experimental conditions have been detailed elsewhere [9]. 

The following techniques for the characterization of supported vanadia catalysts and vanadia will briefly reviewed temperature programmed reduction (TPR) [26, 30], oxidation (TPO) [30] and desorption (TPD) [33, 36, 41, 44] laser Raman spectroscopy (LSR) [5, 25, 35, 36, 39, 44] Fourier-transform infrared spectroscopy... 

A Cu0/Ti02 catalysts was characterized by NH3 temperature programmed desorption (TPD) and Fourier transform infrared (FT-IR) spectroscopy and tested for NH3 oxidation. TPD measurements showed two forms of adsorbed NH3, one of which could be removed by treatment with water vapour. FT-IR spectra showed NH3 coordinated to Lewis acid sites, which gave rise, after treatment at 150°C, to adsorbed hydrazine and nitrxyl species. In NH3 oxidation tests conversions up to 90% were observed. N2 was the main product, N2O and NO being formed to lower extents. The addition of water vapour in the feed influenced the product distribution. A reaction mechanism was proposed, involving adsorbed hydrazine, nitroxyl and amido species as intermediates for N2, N2O and NO production, respectively. 

The adsorption of furan, 2,5-dihydrofuran and tetrahydrofuran on sodium-ion exchanged faujasites with different Si/Al ratios was studied by combining temperature-programmed desorption (TPD), inelastic neutron scattering (INS), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), quantum mechanical computations and Monte-Carlo simulations. 

The acidity of sites in the walls for surfactant templated aluminosilicates, or silicates doped with other transition metals prepared via surfactant templating can be characterised using a range of techniques including temperature-programmed desorption (TPD) of ammonia, ° solid-state NMR with probe molecules such as trimethylphosphine which bind to acid sites or Fourier transform infrared and diffuse reflectance UV-Vis with ammonia or CO probes.These techniques show that... 

Freriks, I. L. C., van Wechem, H. M. H., Stuiver, J. C. M., Bouwman, R. (1981). Potassium-catalysed gasification of carbon with steam a temperature-programmed desorption and fourier transform infrared study. Fuel, 60, 463—470. 

Temperature-programmed desorption (TPD) and Fourier transform infrared spectroscopy (FTIR) have been used to investigate the structure and environment... 

Ceckiewicz, in Fourier transform infrared spectroscopy (FTIR) studies of methanol sorption on zeolite at 25 50°C, observed the propylene band pattern but failed to detect ethylene [96]. Upon temperature-programmed desorption, however, C -C olefins were identified. In the suggested MTO scheme (Fig. 16), the propylene was nominated as a primary product (ie, obtained directly from MeOH or DME), and the formation of the other products occurs via two parallel routes. 

Further on, different ILs with various structures were confined into the supercage of silica gel and extensively characterized by Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FT-IR), temperature-programmed desorption (TPD), differential scanning calorimetry (DSC), and inverse gas chromatography (ICC) [67]. Compared to the bulk IL and silica gel-supported IL film, the silica gel-confined IL displayed remarkably low specific heat capacities, disordered vibrational conformations, stronger interactions with hydrocarbon solutes, and greatly enhanced fluorescence emission. Furthermore, it could be applied in the separation of CO2 from CO2/N2 mixtures and thiophene from thiophene/octane mixtures. 

---