Infrared study of methanol adsorption on Aerosil. I. Chemisorption at room temperature

Abstract

An investigation has been made of Aerosil surface, determining hydroxyl concentration and surface area for various activation temperatures. Strong adsorption of methanol on Aerosil occurs through the formation of two species. The first one is methanol linked by more than one hydrogen bond. The second one originates from the reopening of some siloxane bridges on the surface and is predominant on samples activated at high temperatures.

Surface photochemistry: the effect of surface modification on the photophysics of naphthalene and pyrene adsorbed on silica gel

“…As in the case of water, it has been shown, by infrared studies (22) of methanol adsorption on silica gel activated by heating between 200-950°C, that the formation of two species occurs on the surface. The first is methanol, hydrogen bonded to isolated silanol groups (physical adsorption), and the other involves the formation of Si-0-CH3 bonds (chemisorbed methanol).…”

“…The terminal oxygen functions -the silanols -have been shown by infrared studies to be geminal, vicinal, or isolated (15)(16)(17)(18)(19)(20)(21)(22)(23). These functions, in an amorphous framework, serve to render the silica gel surface inhomogeneous.…”

“…Heat treatment of silica gel first induces loss of the physically adsorbed water molecules and, subsequently, dehydroxylation of the silanol groups. The number of hydroxyl groups on the silica gel surface depends strongly on the temperature of pretreatment of the samples studied (15)(16)(17)(18)(19)(20)(21)(22)(23)(24). Measurements performed by Fripiat and Uytterhoeven (21), amongst others, indicate that the amount of free water rapidly decreases with increasing temperature and, for temperatures higher than about 250°C, it is ' Publication 315 from the Photochemistry Unit.…”

Infrared study of the adsorption, desorption, and degassing processes of trimethyl-borate on a porous high-silica glass system

“…This discrepancy is probably accounted far by the difference in the degassing treatment. The surface -OH can be considered as neighboring but still isolated from each other, and in a continuum of energy states, making the tail of 3750 cm-I as denoted by Borello et al (1). For convenience, we named them the neighboring-OH in reaction [2].…”

Surface electrical resistivity and wettability study of fused silica

“…Silica has been tested in many different forms, including natural transparent (quartz) crystals cut into plates 7 dried gels and powders, 8,9 all of which have been processed using different mechanical, chemical and thermal procedures 10 and different surface preparation techniques. 1,11 Samples may vary widely in surface morphology, water content, defect density, alkali ion content, thermal conductivity and other physical and chemical properties. 1,12 The structure of silica is also known to be dependent on the thermal and chemical history of the sample.…”