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Chemisorption

About: Chemisorption is a research topic. Over the lifetime, 16298 publications have been published within this topic receiving 554989 citations.


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Journal ArticleDOI
TL;DR: Low energy electron diffraction oxygen adsorption kinetics on planes of tungsten at coverages below monolayer and work function measurements were studied in this paper, where the work function was defined as

115 citations

Journal ArticleDOI
TL;DR: In this paper, the location of binding sites and changes in relative binding energies and net charges with the identity of the adsorbed species are explored with an extended carbon (0001) surface, simulated by an 18-carbon lattice with appropriate boundary connections.
Abstract: The calculation of the chemisorption behavior of atomic H, C, N, O, and F on a graphite basal (0001) surface is examined with the CNDO (complete neglect of differential overlap) molecular-orbital scheme. This approach is a semiempirical approximation to the Hartree-Fock self-consistent field procedure, in which the Hamiltonian explicitly depends upon both atomic and orbital charge distribution. The location of binding sites and changes in relative binding energies and net charges with the identity of the adsorbed species are explored with an extended carbon (0001) surface, simulated by an 18-carbon lattice with appropriate boundary connections. The strength of binding to the simulated graphite substrate increases in the order H, F, O, N, and C. The atoms C and N are most stable when positioned above the center of a hexagonal sixcarbon ring, whereas H, F, and O are most stable above the center of a bond connecting nearest-neighbor carbons. Calculated charge distributions are used to predict a work-function decrease with the adsorption of atomic H or N on graphite, but an increase with the adsorption of C, O, or F. The commonly used electronegativity reasoning is shown to be inadequate for the prediction of adsorbate-charge transfer.

115 citations

Journal ArticleDOI
TL;DR: In this paper, the chemisorption of O2 and NO was investigated at −78 °C and at room temperature using pulse-flow and volumetric techniques. But the results were not consistent with the anion vacancy concentration, and the results could be rationalized by assuming that these chemisors took place on Mo2+ centers (two anion vacancies on the same Mo).

115 citations

Journal ArticleDOI
TL;DR: In this paper, an isotope effect exists with kCH4/kCD4 ratio of 1.05-1.97, depending on reaction temperature and catalyst applied, and the attainment of stable performance over Ni/La2O3 catalyst is found to be related to the strong chemisorption of CO2, weak chemi cation of CH4 and slow rate of CHx formation, and fast rate for CHx removal by oxidation.
Abstract: A study of the kinetic isotope effect (CH4/CO2→ CD4/CO2) for carbon dioxide reforming of methane to synthesis gas shows that an isotope effect exists with kCH 4/kCD 4 ratio of 1.05–1.97, depending on reaction temperature and catalyst applied. The attainment of stable performance over Ni/La2O3 catalyst is found to be related to the strong chemisorption of CO2, weak chemisorption of CH4 and slow rate of CHx formation, and fast rate for CHx removal by oxidation.

115 citations

Journal ArticleDOI
TL;DR: In this paper, the application of hydrogen chemisorption to the measurement of metal surface areas is discussed and the results are interpreted in terms of reversibility of adsorption and interactions of hydrogen with metal oxides present on or near metal crystallites.
Abstract: This paper emphasizes concepts and fundamentals relating to the kinetics, energetics, and stoichiometries of adsorption of hydrogen on supported cobalt, iron and nickel, with emphasis on nickel. Relationships between catalyst and adsorption properties and the application of hydrogen chemisorption to the measurement of metal surface areas are discussed. Evidence is presented for nonstoichiometric adsorption of hydrogen on supported metals and the results are interpreted in terms (i) reversibility of adsorption and (ii) interactions of hydrogen with metal oxides present on or near metal crystallites. Contamination of the metal surface by support moieties can cause (i) the appearance of new adsorption states of hydrogen at higher binding energies and (ii) an increase in the adsorption activation energy for hydrogen which can lead to severe kinetic limitations in the adsorption process. Precalcination treatments and promoters such as potassium also cause the appearance of new high temperature adsorption states and significantly increase the adsorption activation energy for hydrogen.

115 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023567
20221,044
2021538
2020424
2019458
2018350