The characterization of anomalous adsorption sites on silica surfaces

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

“…Furthermore, of the various environments in which the silanol function may find itself, it is what is isolated, freely vibrating, and not hydrogen bonded to another silanol or to water, that is the most effective in binding (35)(36)(37). In the present instance, because of the dimension of the adsorbed naphthalene and pyrene, even when the {ehydration of the surface is taken to about -2 silanols/100 A' (21), there must be more than one hydrogen bond per molecule.…”

Effect of catalyst preparation conditions on the performance of eggshell cobalt/SiO2 catalysts for Fischer–Tropsch synthesis

“…For organic compounds (e.g. ethanol), Hair et al [19] as well as Clark-Monks and Ellis [20] claim that the best adsorption sites are the freely vibrating isolated silanol groups and there is little tendency of bonding on the mutually hydrogen bonded adjacent SiOH. Robert [21] finds that ethanol is adsorbed vertically oriented on the hydroxyl group (hydrogen bonded to the OH groups of silanol).…”

Nature and Estimation of Functional Groups on Solid Surfaces

“…These could contain either non-or only very weakly bridging oxygen atoms [48] and should be strongly dipolar. Evidence for the existence of aprotonic sites of this type on the surface of partially dehydroxylated silica surfaces has also come from adsorption studies of a variety of probe molecules [53,[195][196][197][198][199][200][201][202][203][204][205][206], which suggest the importance of such sites for the chemical modification and functionalization of silica surfaces (II.A.1.a.iv.). Morterra [207] reported on the observation of surface AI-O modes near the high-frequency part (1100-1000 cm -1) of the AI-O lattice modes of alumina which are responsible for the so-called cut-off.…”