Tin oxide surfaces. Part 3.—Infrared study of the adsorption of some small organic molecules on tin(IV) oxide

Abstract

The tin@) oxide surface is strongly oxidising towards smaI1, reactive organic molecules. Methanol is chemisorbed to give methoxy groups but these are readily oxidised to a surface formate at temperatures >320 K. Acetone and acetaldehyde are adsorbed predominantly as acetates but some evidence is found for an en01 form which may be responsible for the rapid deuterium exchange between hexadeuteroacetone and surface hydroxyl groups. The spectra of the formate and acetate structures are confirmed by adsorption of formic and acetic acids, where evidence is also found for undissociated acid molecules bonded to the surface. As expected the acetate is thermally more stable than

Nature and Estimation of Functional Groups on Solid Surfaces

“…Condensation reactions of acetone are catalyzed by acids as well as by bases. Acetate has also been observed after adsorption of acetone or acetaldehyde on Sn0 2 [731]. The authors ascribed this to oxidation of the reagents by the oxide; however, it seems very likely that the reaction was analogous to that observed on alumina with acetone, and that acetaldehyde underwent a Cannizzaro disproportionation, a typical reaction of aldehydes in alkaline media.…”

“…The carboxylate ions are easily recognized by the strong infrared absorption for symmetric and asymmetric stretching vibrations [8,9,14,15]. CarhL>xylate ions which have been first observed on alumina were found also on Sn0 2 [731] and on Fe 2 0 3 [745][746][747].…”

“…Methoxyl groiIps on Sn0 2 , formed by reaction with methanol, are easily oxidized to formate above 320 K, this oxidation is complete at 463 K [731]. Surface esters have also been prepared by reaction of chlorinated alumina surfaces with solutions of sodium alcoholates [717].…”

Adsorption of Acetone onto MgO: Experimental and Theoretical Evidence for the Presence of a Surface Enolate

“…The vesicle fraction fluoresced at 515 nm when irradiated at 370 nm. [10] Although the catalytic activity of MgO is lower than other more basic solids, such as heavier alkaline earth oxides [1] or aluminum phosphorous oxinitrides catalysts, [2] its well-known structure makes it suitable for mechanistic studies. [3] In fact, the acetone ± MgO system has been the subject of several infrared and temperature-programmed desorption studies, H exchange experiments have also been reported.…”

Structure and H2 Sensing Property of TiO2 Sputtered Films Deposited under Various Discharge Gas Pressures

“…It is reported that the adsorption of water on the oxide surface results in the formation of molecular water at low temperature and hydroxyl groups at high temperature. (36,37) Therefore, the decrease in resistance of all films with decreasing temperature below 100°C can be ascribed to the adsorption of molecular water. Figure 7 shows the temperature dependence of the sensitivity of TiO 2 films deposited under three different pressures.…”