Temperature programmed decomposition

The concept of intact emission of adsorbed molecular species for identifying reaction intermediates is also well illustrated in several recent studies. Benninghoven and coworkers (2-4,12) used SIMS to study the reactions of H2 with O2, C2H4 an< 2H2 on P°ly polycrystalline Ni. For the C2H /Ni interaction, for example, direct relationships could be established between characteristic secondary ions and the presence of specific surface complexes (12). In another study, Drechsler et al. (13) used SIMS to identify NH(ads) as the active intermediate during temperature-programmed decomposition of NH3 on Fe(110). 

The surface nethoxyl groups on the modified catalyst were measured by i.r. spectroscopy and their thermal stabilities were studied by Temperature-Programmed Decomposition (TPDE) in Ar. The surface acidity was measured by TPD of irreversibly adsorbed ammonia and by pyridine adsorption by dynamic method and i.r. spectroscopy. 0.10 g pretreated catalyst was used to measure the amount of irreversibly adsorbed pyridine. The irreversibly adsorbed ammonia was... 

Figure 2. Temperature-Programmed Decomposition of surface methoxyl groups in Ar.

Bimetallic catalysts can be prepared by a direct redox method when a cationic complex of a metal of higher electrochemical potential is reduced by another metal of lower electrochemical potential that has been deposited and reduced first187 (see Table 4.10) PdAu/SiO 88 and PdAu/C189 have been made in this way, gold being deposited after the palladium. Small amounts of the metals were found in filtrates, and XRD and temperature-programmed decomposition of palladium hydride indicated a substantial... 

Figure 38. Temperature-programmed decomposition (0.25 K s 1) of oxygen surface functional groups from a graphite powder. The simultaneous mass-spectroscopic analysis reveals the irreversible character of this experiment in which the substrate surface is removed during desorption of the adsorbate.

Temperature-Programmed Decomposition of 2-Propanol on the Zinc-Polar, Nonpolar, and Oxygen-Polar Surfaces of Zinc Oxide... 

The dehydrogenation reaction produces acetone and hydrogen, and is dominant over basic oxides ( ) The dehydration reaction produces propene and water, and is dominant over acidic oxides. It would be interesting to see if the competition between these two pathways depend on the exposed crystal planes of ZnO. We report here the results of such an investigation. 2-Propanol was decomposed on ZnO single crystal surfaces by the temperature programmed decomposition technique. To assist the interpretation of data, the temperature programmed desorption of propene and acetone were also studied. 

The temperature programmed decomposition of the firesh and used Pd/SF-1173 catalyst indicated the presence of two PdO species on the catalyst surface. A single 02-evolution peak with maximum at 903 K took place from the fi-esh catalyst, whereas, on the aged catalyst two 02-evolution peaks with maxims at 948 K and 1053 K were observed. Similar twin 02-evolution peaks are also observed from alinnina supported Pd-catalysts [7]. The 02-evolution peak at lower temperatures is originating from the decottq>osition of crystalline palladium oxide, while the higher teitq)erature peak is due to the decomposition of the amorphous PdO. A comparison of the performances of the knitted silica-fiber catalysts with those over... 

Hexacarbonyl molybdenum Mo(CO)6 was successfully used to prepare intrazeolite molybdenum sulfide clusters in the cavities of NaY (CVD technique) [4,5,7,8]. The decomposition and sulfidation of Mo(CO)e encaged in NaY were extensively studied by Okamoto et al. [7-11] by means of temperature programmed decomposition (TPDE), XPS, and XAFS techniques. It has been claimed that the structure of molybdenum sulfides is described as molybdenum dinuclear sulfide clusters M02S4. de Bont et al. [12] supported the formation of molybdenum sulfide dimer species. The extremely high dispersion of molybdenum sulfide clusters prepared fi"om Mo(CO)6 was also suggested by an NO adsorption capacity much hi er than those of other conventional catalyst systems such as M0S2/AI2O3 [9]. 

The potential of M(T 2-H2) moieties in the heterogeneous hydrogenation of aromatics has been demonstrated for [RuH2(H2)2(PCy3)2], which, in temperature-programmed decomposition under hydrogen, has been found to convert benzene into cyclohexane [57]. 

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