Infrared Study of the Adsorption of Methanol and Ethanol on Aluminum Oxide

Abstract

The adsorbed surface species which result when aluminum oxide is exposed to methanol or ethanol vapor have been studied. Three different surface species have been identified for both methanol and ethanol. At 35°C a weakly bound layer of liquid alcohol is observed, which is removed by evacuation. Another species which persists after prolonged evacuation is identified as a surface methoxide in the case of methanol and an ethoxide in the case of ethanol. When the alumina sample is heated to 170°C in alcohol vapor a formate-like surface compound is formed from methanol and an acetate-like compound from ethanol. This interpretation of the surface structure has been checked by using deuterated methanols and C13-enriched methanol.

Preparation and Characterization of Two Distinct Ethylene Glycol Derivatives of Kaolinite

“…While the surface silicate sheet of kaolinite is not particularly amenable to covalent bond attachment, the relatively reactive aluminol surface has the potential to be functionalized via A1-O-R bonds. It is known for example, that alcohols may condense with the aluminol groups on the surface of alumina to give surface ethers (A1-O-R) (Greenler 1962;Boreskov et al 1964) and there are several examples of functionalized aluminas being used in chromatography and catalysis (Tundo et al 1982). These materials are the products of the condensation reactions between reactant molecules and the surface aluminol groups.…”

Modification of ceramic membranes by alcohol adsorption

“…1, alcohol can chemisorb by reaction of its hydroxyl group with surface hydroxyl groups of the alumina, thus forming a stable alkoxide and releasing water. This mechanism has been proven for different normal and secondary alcohol [12,[17][18][19][20][21][22].…”

“…However, the presence of adsorbed water on the alumina could also be enough for preventing the alcohol from reacting with the surface hydroxyl groups. Therefore, a second modification procedure, Procedure #2, was checked using vacuum in the permeate side as the activation of alumina is preferentially carried out under vacuum or using an inert gas carrier [17,20,22,24]. This procedure aimed at a double objective.…”

Search for chemisorbed HCO: The interaction of formaldehyde, glyoxal, and atomic hydrogen + CO with Rh

“…These species are present on the crystalline Rh sites described previously (14,18 Simultaneously, distinct features appear at lower wavenumber which. ;--..-indicate the presence of molecularly adsorbed H 2 CO (see Table III Greenler (17) has attributed these modes to formate (HCOO) formation from CH 3 0H decomposition on A1 2 0 3 . Evacuation of the sample further reduces the intensity above 1700cmn( and below 1350cm .…”