Oxides, chemisorption

Freund s group at the Fritz Flaber Institute have put much emphasis on linking surface science studies with applied catalysts through replicating the latter with model systems without having to resort to the complexity of the real system. A system they have studied in detail is that of nitric oxide chemisorption at a palladium-alumina model catalyst, where they isolated different... 

This oxidative chemisorption reaction also occurs on Ir and Au since, in addition to evidence described below, it was found that I (Q-Qb) red, 103-I is equal to I (Q-Qb)ox, 11 ... 

The most natural explanation of this is that doubly bonded >CHOH on the surface of the platinum particles is oxidised to formic acid given that subsequent to this process, CO bonded at step sites is observed to form, this suggests that the >CHOH species are actually formed at the steps at low potentials indeed, it would appear likely that the step sites may well facilitate the oxidative chemisorption of methanol, and the doubly bonded >CHOH species are then intermediates in the overall chemisorption to adsorbed CO. The removal of these species from the step sites by oxidation leads to migration of CO from the terraces to the steps, and the reduction in CO coverage on the terraces then leads to conversion of some of the linearly bonded CO to multiply bonded forms. 

TABLE XI. Carbon Monoxide, Di-Nitrogen and Nitric Oxide Chemisorption on Metals... 

An observed rest-potential shift in the negative direction upon chemisorption of H2Q provides evidence for an oxidative-chemisorption reaction. The H2Q(aq)-to-Pd-p Q(ads) chemisorption process has also been reported for Pt. ... 

Surface Complex Formation on Carbonates. There are various possibilities for functional groups on the surface of carbonates, sulfides, phosphates, and similar compounds. By using a very simple approach similar to the one used for hydrous oxides (chemisorption of H20), one could postulate surface groups for carbonates (e.g., FeC03) as shown in List III. 

Of the many isothermal kinetics observed on real surfaces for different processes like oxidation, chemisorption and desorption, only one has deserved a special attention — the time-logarithm law... 

Iron Ammonia synthesis Hydrogenation Oxidation Chemisorption Chemisorption Chemisorption O2, H2O, CO, S. C2H2 Bi, Se, Te, P, H2O VSO4, Bi... 

For all catalysts the reaction is first order with respect to NO. Oxygen strongly inhibits the decomposition reaction. The inhibition by oxygen is ascribed to the chemisorption of oxygen on sites on which nitric oxide chemisorption takes place. 

It is suggested that the formation of strongly chemisorbed species is connected with oxidative transformations and the apparent potential dependence of the adsorption may be explained in terms of oxidative chemisorption and reductive desorption processes. 

Total smface areas were measured by nitrogen adsorption at -196 C, using an automated instrument (Omnisorp lOOCX, Coulter Electronics Limited). The cross sectional area of the nitrogen molecule was assumed to be 16.2 x 10 m. Pore type and volume data were also obtained by this method, using t-plot analysis. Metal areas were measured by selective chemisorption of hydrogen at 30 °C in the same instrument. Copper surface areas were measured in a flow system by nitrous oxide chemisorption at 60 C. 

Except for binary oxides, chemisorption-type conductometric sensors employ complex oxides such as Cdlnp, NiTa Og, CoTa O, CuTOjO, BaSnOj, LnFeOj, CdFe O, Bi Sn O, YBa CUjO, Bi Mo O, ... 

Reduction of metal oxide, chemisorption of H2, and surface oxidation ... 

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