Reactivity screening of silica

Adsorption Dynamics of Alkanes on Single-Wall Carbon Nanotubes: A Molecular Beam Scattering Study

“…Both features are commonly observed for alkane adsorption. 26,32 In contrast, exposing n-pentane on the silica-supported CNTs leads to the observation of four distinct TDS structures which are labeled as A-D. The D peak is easily identified as a support-independent condensation peak since the leading edges line up.…”

“…The binding energies on interior sites for n-butane are slightly larger than those for isobutane, consistent with their geometrical structure and the physisorption of the alkanes. 26,32 On the bare silica support monolayer, TDS peak temperatures of 115/ 110 K have been determined for n-/isobutane at saturation, corresponding to 29.6/28.3 kJ/mol. 45 (We are not aware of kinetic data for butane on graphite surfaces.)…”

“…For example, TDS studies characterizing the adsorption kinetics of alkanes have been conducted for a large variety of single-crystal surfaces, including graphite, [22][23][24] sapphire, 25 ZnO, 26 Ru, 27 Cu, 28 alloys, 29 and silica. 30 At low exposures, the alkanes form a monolayer, providing information about kinetics parameters (which can reflect specific adsorption sites) 31 and lateral interactions. 32 At large exposures, the multilayer grows with desorption temperatures independent of the surface, allowing for a simple calibration of the temperature reading in TDS.…”

“…30 At low exposures, the alkanes form a monolayer, providing information about kinetics parameters (which can reflect specific adsorption sites) 31 and lateral interactions. 32 At large exposures, the multilayer grows with desorption temperatures independent of the surface, allowing for a simple calibration of the temperature reading in TDS. As a unique feature of CNTs, the adsorption on grooves, external, and internal sites can be distinguished with TDS providing "fingerprint spectra", uniquely indicating high-energy binding sites 6 and gas adsorption on interior sites.…”

“…Furthermore, precursormediated (Kisliuk-like) adsorption dynamics have been observed for the o-CNTs, whereas the as-prepared c-CNTs show more Langmuirian-like (direct) adsorption dynamics. To distinguish possible support and CNT effects, the adsorption of the alkanes has also been studied thoroughly on clean silica supports, 32 and pentane/CNT data are included as a reference system. 33 2.…”