Interaction of CO2 with Magnesium Oxide Surfaces: a TPD, FTIR, and Cluster-Model Calculation Study

Abstract

An FTIR spectroscopic study of the adsorption of natural and lSO-enriched CO:! gases on MgO powders was performed and was compared with temperature-programmed desorption analysis. Two types of COS species (a and b) were found after Cl60z adsorption at room temperature: they have characteristic wavenumbers 1659, 1329, and 1024 cm-' (type a) and 1626, 1273, and 947 cm-l (type b), respectively. Ab initio molecular orbital calculations gave theoretical wave numbers. According to comparison of these numbers, type b is a monodentate model. Type a could not be reproduced in the present limited cluster model. It is inferred that it also comes from a monodentate model with partly bidentate and "tridentate" characters.

Diglyceride-rich oils from glycerolysis of edible vegetable oils

“…A N b value of 656 μmol/g was calculated by integration of the TPD curve. This value reasonably agrees with those of other MgO samples we used in the past [30] to promote different base-catalyzed reactions, as well as with those of MgO catalysts reported in the literature and prepared by different techniques [31,32]. The broad temperature range for CO 2 desorption indicates that MgO contains basic sites that bind CO 2 with different strength.…”

CO2 Sorption on MgO and CaO Surfaces: A Comparative Quantum Chemical Cluster Study

“…The carbonate ion is almost planar, as borne out by the fact that all the OdCdO angles are ∼119°. It is not possible to assign any of the experimentally observed bands to tridentate CO 2 at corner sites, but Yanagisawa et al 15 observed the appearance of a new band after successive evacuation of CO 2 on MgO at elevated temperatures; at room temperature, they observed two distinct sets of bands at 1659, 1329, and 1024 cm -1 and 1626, 1273, and 947 cm -1 , i.e., in the same regions as Fukuda and Tanabe 14 ( Figure 10), but upon evacuation at temperatures between 473 and 673 K, the latter bands disappeared and a weak band at 1439 cm -1 emerged. Finally, after evacuation at 823 K, all bands disappeared.…”

Kinetics and Mechanisms of CO Oxidation on Nd1-xSrxCoO3-y Catalysts with Static and Flow Methods

“…20,22,23 In the initial reaction stage, the partial orders with respect to CO on the various catalysts are in the range of 0.8-0.9 as shown in Table 1. These results make it possible to consider that the reaction obeys a mechanism involving the inhibition process by CO 2 formed during the reaction of CO and O 2 on the catalyst.…”