Quantum chemical analysis of the Eley-Rideal and Langmuir-Hinshelwood mechanisms of the catalytic oxidation of carbon monoxide on the nickel surface

Abstract

The studies concerned with the oxidation of carbon monoxide on the nickel surface are reviewed. The Eley-Rideal (ER) collision and Langmuir-Hinshelwood (LH) The oxidation of carbon monoxide with metal catalysts was studied by many authors [1][2][3][4]. However, there are numerous discrepancies between their results, which concern both the reaction mechanism and basic kinetic characteristics [2, 4]. In [5, 6] it is shown that during the oxidation of CO at low pressures, oxygen is irreversibly adsorbed on Pt or Pd by dissociation, and the gas-phase CO molecules react with the atomic oxygen adsorbed on the surface. This oxidation path is referred to as the Eley-Rideal (ER) collision mechanism [4]. The reality of the collision mechanism has been the subject of debate. This problem is of fundamental importance for explanation and prediction of catalytic effects. Validity of the collision mechanism means that the chemisorbed oxygen is reactive enough to interact with the oxidized substance without catalytic activation. In this case, the role of catalyst is determined only by its effect on oxygen, i.e., by the bond energies and reactivity of oxygen atoms on the surface. Unlikeliness of the collision mechanism of the reaction means that both oxygen and the oxidized substance should be catalyzed. In this case, CO can chemically interact with the catalyst to yield an activated complex involving the catalyst together with chemisorbed O and CO, i.e., the reaction follows the Langmuir-Hinshelwood (LH) adsorption mechanism [4].In [7], it was established that in the oxidation of CO on a polycrystalline plate by the LH adsorption mechanism the activation energy is 92 kJ/mole, and the interaction between oxygen and gas-phase or weakly bound CO by the ER collision mechanism occurs with zero activation energy. The activation effect of palladium catalysts on the oxidation of CO is similar to that of platinum catalysts. In the most comprehensive studies of the oxidation of CO on palladium Kiev Polytechnical Institute.

Competition between Eley–Rideal and Langmuir–Hinshelwood Pathways of CO Oxidation on Cun and CunO (n = 6, 7) Clusters

“…These two mechanisms are competitive depending on the compositions of the catalysts and the activation of adsorbates on them. For example, an oscillatory mechanism of ER and LH was observed on platinum and iridium surfaces, , while the LH mechanism is preferential for the catalytic oxidation of CO on Ni surfaces and Au 55 cluster. , Differently, the ER preference was found on W 10 clusters and W(111) surface …”

“…The CO oxidation follows either an Eley–Rideal (ER) or a Langmuir–Hinshelwood (LH) mechanism on catalyst surfaces. − In the ER case, CO reacts with the chemisorbed O 2 on the surfaces, that is, the role of the catalyst is determined only by its effect on O 2 . On the contrary, in the LH mechanism, the reaction involves a coadsorption of O 2 and CO on the catalyst and yields an intermediate in which both molecules are activated .…”

Atomically dispersed Pd catalysts in graphyne nanopore: formation and reactivity

“…Using CO oxidation as a model reaction, we investigated the reactivity of Pd@graphyne. We considered the Langmuir-Hinshelwood (L-H) mechanism [56][57][58], which involves a peroxo-type COO 2 complex intermediate state (MS). CO oxidation on the catalyst can be divided into two steps.…”

Triazine COF-supported single-atom catalyst (Pd1/trzn-COF) for CO oxidation

“…To explore the catalytic properties of the Pd 1 /trzn-COF, the CO oxidation to CO 2 is studied as a probe reaction. Furthermore, both Langmuir-Hinshelwood (L-H) and tri-molecular mechanisms [57][58][59] for CO oxidation on Pd 1 /trzn-COF SAC are taken into consideration. Based on our theoretical calculations, we demonstrate that the Pd SAs can be stably anchored on the side-wall of trzn-COF through a strong interaction between the conjugated π electrons/lone-pair electrons of trzn-COF and the d orbitals of Pd SAs, and Pd 1 /trzn-COF SAC shows relatively high catalytic activity for CO oxidation.…”