Oxidic supports potential

The data in the Figs. 9.1,9.2 and 9.4 nicely illustrate the complementarity of XPS and SIMS and the possibilities that thin film oxide supports offer for surface investigations. Owing to the conducting properties of the support, charging is virtually absent and typical single crystal techniques such as monochromatic XPS and static SIMS can be applied to their full potential to answer questions on the preparation of supported catalysts. 

Niobia has a PZC of about 2.5. It is desired to use niobia as a catalyst promoter for Pt, by supporting the niobia onto an oxide support. It will then be attempted to impregnate Pt only onto the niobia phase. Which common support and what Pt complex should be used and why A sketch of the surface potential vs. pH for niobia and the support will help. 

Of the alternative Ft formulations, the FtMo system has been the most studied in recent years. Work on bulk FtsMo alloys by Grgur, Markovic, and Ross showed similar CO tolerance to FtRu in the presence of H2. This tolerance was correlated with the ability of FtMo to oxidize CO at potentials as low as 0.05 V. However, unlike Ru but similar to Sn, the Mo appeared to oxidize CO just at neighboring Ft sites, with the majority of CO oxidized af potentials typical of pure Ft. The surface Mo atoms were found to be oxidized even at 0.0 V. Therefore, it was postulated that H2O dissociation to form OH was mediated by a Mo(IV)/(Vl) couple. Carbon-supported FtMo catalysts were reported to have better CO tolerance than FtRu in MEA testing up to CO concentrations of 100 ppm.i39... 

This chapter gives a comprehensive account of the development and progress of SOLnC and SOAnC on oxidic supports and potential appUcations of the respective materials in catalysis. As an introduction, special emphasis is put on the topology and surface morphology/properties of mesoporous siUca supports and commonly... 

This review is a summary of the work done and potential opportunities for inexpensive and easily accessible base catalysts, such as alkaline earth metal oxides and hydroxides, as well as alkali metals and oxides supported on alkaline earth metal oxides. Preparation methods of these materials, as well as characterization of basic sites are reported. An extensive review of their catalytic applications for a variety of organic transformations including isomerization, carbon-carbon and carbon-oxygen bond formation, and hydrogen transfer reactions is presented. 

We report here a study of Zr, Nb, Cr, and Mo hydrocarbyl compounds grafted onto oxide supports as potential olefin polymerization catalysts and oxide-supported Mo and W 7r-allyl derivatives in olefin disproportionation catalyses. The interaction of these compounds with silica and alumina supports has been examined using ESR and IR, analyses to define the catalytic materials that result. Finally, we consider why chemical support of these organometallic compounds confers on them an enhanced catalytic activity. 

If the sample under study is an insulator (e.g., an oxide-supported catalyst), the arrival of positively charged primary ions and the emission of electrons by either potential or kinetic emission leads to positive charging of the sample. This has two negative effects ... 

Summarizing, Raman spectra can be recorded of single crystals, powders, glasses, nanocrystalline, and amorphous materials, and of surface species such as transition metal compounds on high-surface-area oxide supports or surface adsorbates on some metals. Thus, Raman spectroscopy is a potentially valuable tool for the characterization of a broad range of catalytic materials and surfaces. 

In Equation 1, C is the molar MIC in vitro value, and Eh represents the oxidation-reduction potentials of the drugs. The figures in parenthesis are the 95% confidence limits. Equation 1 is statistically significant. Of the variance in the in vitro log l/C values 42% can be explained by a linear regression with E. This supports the hypothesis that the 5-nitro-thiazoles affect an important enzymatic reduction process of the tricho-... 

Ruthenium on a graphite or basic oxide support is also used as a catalyst in industrial synthesis. A Co-Mo-N system has also been investigated as a potential catalytic material, however, it has to be improved to compete with the aheady available catalysts." ... 

The as-received material shows the NMR peak at 1.089 G/kHz that is characteristic of platinum particles exposed to the atmosphere (Fig. 61a) it has been attributed to H2Pt(OH)5 or Pt02. For oxide-supported catalysts, it is removed by thermal treatment under oxygen and hydrogen. The electrocatalysts arc cleaned by electrochemical methods, whereby the sample is used as the working electrode in a three-electrode cell as a reference electrode, 1 M NaCl AgCl j Ag was used. In the first experiments, the as-received material was subjected to extensive potential cycling, but later it... 

As deduced from Tables 4.1 and 4.2, the studies specifically dealing with the other pure higher rare earth oxide supports (praseodymia and terbia) are much scarce. However, a number of recent investigations have shown that the incorporation of praseodymium (69,100,274-278) and terbium (115,187,279-281) ions into the ccria lattice may improve its redox behaviour very significantly, thus becoming materials with potential interest in TWC technology and several other catalytic applications. 

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