Temperature-programmed reaction study

Sequences such as the above allow the formulation of rate laws but do not reveal molecular details such as the nature of the transition states involved. Molecular orbital analyses can help, as in Ref. 270 it is expected, for example, that increased strength of the metal—CO bond means decreased C=0 bond strength, which should facilitate process XVIII-55. The complexity of the situation is indicated in Fig. XVIII-24, however, which shows catalytic activity to go through a maximum with increasing heat of chemisorption of CO. Temperature-programmed reaction studies show the presence of more than one kind of site [99,1(K),283], and ESDIAD data show both the location and the orientation of adsorbed CO (on Pt) to vary with coverage [284]. 

E.M. Stuve, and R.J. Madix, Bonding and dehydrogenation of ethylene on palladium metal. Vibrational spectra and temperature-programmed reaction studies on Pd(100), J. Phys. Chem. 89, 105-112 (1985). 

Catalytic Reduction of SO3 Stored in SOx Transfer Catalysts -A Temperature-Programmed Reaction Study... 

The evolution of methylchlorosilanes between 450 and 600 K is consistent with the 550 - 600 K typical for the catalytic Rochow Process [3]. It is also reasonably consistent with the evolution of methylchlorosilanes at 500 - 750 K reported by Frank and Falconer for a temperature programmed reaction study of the monolayer remaining on a CuaSi surface after catalytic formation of methylchlorosilanes from CHaCl at higher pressures [5]. Both of these observations suggest that the monolayer formed by methyl and chlorine adsorption on pure CuaSi is similar to that present on active catalysts. For reference, methylchlorosilanes bond quite weakly to tiie surface and desorb at 180 - 220 K. It can thus be concluded that the rate-determining step in the evolution of methylchlorosilanes at 450 - 600 K is a surface reaction rather an product desorption. 

Eliason, S.A., and Bartholomew, C.H. 1997. Temperature-programmed reaction study of carbon transformations on iron Fischer-Tropsch catalysts during steady-state synthesis. Stud. Surf. Sci. Catal. 111 517-26. 

Temperature-programmed reaction (TPR) studies of partial oxidation of propylene was carried out by flowing CsHe (Praxair), O2 (Praxair), H2 (Praxair) and Ar (Praxair) through DRIFTS and stainless steel tubular reactor (3/8 OD) loaded with catalyst. Feed gas at 40 mFmin and 1 atm consists of C3H6 (10%), O2 (10%), H2 (10%) and Ar (70%) for temperature program reaction studies. Prior to each experiment, the catalyst was pretreated in H2 (10 vol%) and O2 (10 vol%) simultaneously at 250°C. Temperature was monitored with a K type thermocouple connected to an omega temperature controller. 

Transient Temperature Programmed Reaction Studies Reveal that C-H Bond Breaking of CH3Oadt Is Rate Determining Step... 

XRD experiments can be carried out to characterize gas-solid reactions and, with some limitations, fluid-solid reactions more generally, as long as the fluid contributes little to the pathway of sight for the X-rays. Areas of recent investigation are catalytic gas-solid reactions, electrochemical processes, synthesis procedures involving precipitation and dissolution of solids, temperature-programmed reaction studies of crystallization, and oxidation and reduction of solids. This enumeration covers essentially all phases of the life of a catalyst. 

After characterizing this type of nanocatalyst consisting of metal atoms trapped on oxygen vacancies, simple reactions like acetylene polymerization or CO oxidation can be studied by means of temperature programmed reaction studies and infrared spectroscopy. 

Temperature-Programmed Reaction Study of Carbon Transformations on Iron Fischer-Tropsch Catalysts During Steady-State Synthesis... 

Interaction and reaction of adsorbed NO and CO on Rh and Ce-Rh catalysts have been studied by combined in situ infrared spectroscopy and temperature-programmed reaction at 298-673 K. At 298 K, adsorption of NO as NO causes the desorption of preadsorbed linear and bridged CO from reduced Rh sites. NO adsorption competes over CO adsorption on the reduced Rh while NO does not adsorb on oxidized Rh catalyst which chemisorbs CO as gem-dicarbonyl. Temperature-programmed reaction study reveals that the type of adsorbate and the surface state of the catalyst change with temperature. At 453 - 543 K, NO adsorbs as low wavenumber NO at 1689-1696 cm which may be involved in NO dissociation and CO adsorbs as gem-dicarbonyl which may be a spectator species for this reaction. 

Lietti, L., Botta, D., Forzatti, R, Mantica, E., Tronconi, E., and Pasquon, I. Synthesis of alcohols from carbon oxides and hydrogen. 8. A temperature-programmed reaction study of -butanol on a Zn-Cr-O catalyst. J. Catal 1988, 111, 360-373. 

Why Chloromethane 205 The Surface Acidity of T -Alumina 206 Three Types of Surface Site Become Four 208 Interaction of Methanol with the TJ-Alumina Surface 211 The Interaction of Anhydrous HCI with T -Alumina 211 Temperature-Programmed Reaction Studies 213 Summary and Future Outlook 213... 

Temperature-programmed reactions between small amounts of adsorbed species are an excellent way to study the intrinsic reactivity of catalytic surfaces. Such experiments on rhodium (100) and (111) surfaces covered by small amounts of CO and... 

The reactions of ethylene, water, and methanol with coadsorbed oxygen on Pdf 100) were studied with temperature programmed reaction spectroscopy (TPRS) and high resolution electron energy loss spectroscopy (EELS). 

The title Spectroscopy in Catalysis is attractively compact but not quite precise. The book also introduces microscopy, diffraction and temperature programmed reaction methods, as these are important tools in the characterization of catalysts. As to applications, I have limited myself to supported metals, oxides, sulfides and metal single crystals. Zeolites, as well as techniques such as nuclear magnetic resonance and electron spin resonance have been left out, mainly because the author has little personal experience with these subjects. Catalysis in the year 2000 would not be what it is without surface science. Hence, techniques that are applicable to study the surfaces of single crystals or metal foils used to model catalytic surfaces, have been included. 

Temperature programmed reaction (TPR) studies involve the adsorption of a substance on the catalyst at relatively low temperatures. After evacuating the vessel, the catalyst is gradually heated and the appearance of gas phase products is monitored. Apart from the desorption of the starting substance, its reaction products also appear thus the method gives information on the... 

Temperature Programmed Reaction. Examination of another redox system, propylene oxidation on M0O3, provides further insight. It is well accepted that propylene oxidation on molybdenum-based catalysts proceeds through formation of allylic intermediates. From isotopic studies it has been demonstrated that formation of the allylic intermediate is rate-determining (H/D effect), and that a symmetric allylic species is formed ( C labelling). 

Robinson, G. N Q. Dai, and A. Freedman, Reactions of Halomethanes with y-Alumina Surfaces. 2. X-ray Photoelectron and Temperature-Programmed Reaction Spectroscopic Studies, J. Phys. Chem. B, 101, 4947-4953 (1997). 

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