The diffusivity of phenol, catechol and hydroquinone was determined using zero-length column chromatography, with water or methanol as a solvent (table 47). With methanol as a solvent, the diffusivity of phenol in TS-1 was larger than that of catechol or hydroquinone; which were approximately identical. When using water, the diffusivity of phenol in TS-1 was lower than that of catechol, which was lower than that of hydroquinone. The diffusivity of the various compounds could be correlated with the strength of adsorption. That is, the higher the strength of adsorption, the lower the diffusivity. An anomaly in the order of diffusivity of the hydroxybenzenes in TS-1 in water was attributed to polarization of the aromatic ring, in conjunction with strong preferential adsorption of the hydroxybenzenes.

Intracrystalline Diffusivity of Hydroxybenzenes in TS-1 and Al-Free Ti-Beta. U.Wilkenhöner, W.L.Duncan, K.P.Möller, E.Van Steen: Microporous and Mesoporous Materials, 2004, 69[3], 181–6

Table 47

Diffusion in TS-1 Zeolite at 303K