Dissociative adsorption of hydrogen molecules

Thus, the adsorption of CO on active ZrOa catalysts led to the formation of various types of adsorption species of CO having different reactivities toward Ha, and these species were found to play a significant role in the hydrogenation of CO. Moreover, it is likely that CO is adsorbed on the active surface sites of low coordination and that an electron transfer from the other surface sites to this CO species leads to the formation of the dimeric adsorbed species (CO)a. These dimeric species react, step by step, with CO molecules from the gas phase to from a relatively stable cyclic polymer species of (CO)s and then (CO) ", Such adsorbed CO species easily react with hydrogen and are also activated through the dissociative adsorption of hydrogen on surface sites of low coordination or the coordina-tively unsaturated surface sites on the catalyst. 

In the account of this chemisorption work, hydrogen chemisorption was also described. Hydrogen chemisorption was consistently less than the CO (after correction for substrate contribution) and it is suggested that this difference is owing to the need for nickel crystallites large enough to provide adjacent sites for dissociative adsorption of hydrogen atoms, whereas the CO can adsorb as an undissociated molecule on individual surface nickel atoms. 

Some key adsorbates and reaction intermediates relevant to fuel-cell anodes are H2 as the fuel, CO and CO2 as poisons in hydrogen reformate feeds, and water as a co-adsorbate and potential oxidant. In the case of the cathode, oxygen is clearly the most important reactant. In the case of a number of these molecules, such as H2, O2, and H2O, not only is the molecular adsorption important on platinum (or promoted platinum catalysts), but the dissociative adsorption of the molecules is important as well. With this in mind, some details concerning the dynamics of adsorption of these molecules, the associated dissociation barriers, molecular degrees of freedom, and energy partition are important to the overall catalytic processes. In addition to the... 

Our paper (5), presented in the section entitled "Energetics and Kinetics of Adsorption" emphasized the thesis that high-temperature para-H2 conversion on metals is caused by dissociative adsorption of hydrogen while the formation of para-H on charcoal at low temperatures involved adsorbed molecules. 

Subsequently, I wrote a paper entitled "The Activation of Hydrogen in Catalytic Reactions of Hydrocarbons" ( ) for presentation at the 1939 Faraday Society Discussion on hydrocarbon chemistry. This article proposed that dissociative adsorption of hydrogen and of hydrocarbon molecules on metal catalysts can explain a wide variety of reactions in... 

As another example, consider the dissociative adsorption of hydrogen chloride on titanium oxide. The gas molecule undergoes a heterolytic rupture to provide a chloride ion that is placed in the interstitial position and a hydrogen ion that is... 

Yildirim, T., J. Iniguez, S. Ciraci, Molecular and dissociative adsorption of multiple hydrogen molecules on transition metal decorated C60. Phys. Rev. B Condens. Matter Mater. Phys. 72(15), 153403 (4 pages), 2005. 

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