Acid–base interaction of probes at silica surface. Microcalorimetry and adsorption

Adsorption of organic probes on silica through Lewis interactions: A comparison of experimental results and quantum chemical calculations

“…The absorbance was measured at 259.0 nm for benzyl alcohol and phenyl acetic acid, at 260.0 nm for benzyl amine and phenyl acetone, at 263.0 nm for (2,2,2-trichlor ethyl) benzene and at 260.5 nm for ethyl benzene. The experimental setup is more thoroughly explained in our previous work [8].…”

“…The isotherms can be expressed by equations containing an equilibrium constant K i (i = L or H). The adsorption isotherms are usually presented as the surface excess of probe molecule (Γ ) plotted against the equilibrium concentration of the probe molecule (C eq ) [8].…”

“…[8]. Here we have only used the initial part of the isotherms since they are best compared with a quantum chemical analysis.…”

“…These are the Lewis active sites. The density and amount of these can be adjusted by treating the silica sample thermally [3][4][5][6][7][8]. We have experimentally characterized these sites with a method previously used for Lewis acid-base characterization of road stone aggregates [9], silicon nitride powder [10] and metallocene catalyst support [7].…”

“…To verify and explain these results, quantum chemical calculations were performed on the same systems. Since the systems are water free and since the non-polar solvent cyclohexane is used in the experiments, the previous work [8]. The BET surface area of 424 m 2 g −1 was determined with N 2 physisorption (ASAP 2010, Micromeritics).…”