The effective diffusivities of glucose and its linear analog
glucitol were measured by a liquid
chromatographic technique at 30 °C within water-filled silica and
aluminosilicate catalysts of
mean pore size ranging from 7.4 to 116 Å. For glucose, the
effective diffusivity decreased from
1.08 × 10-6 to 1.77 × 10-9
cm2/s as the mean pore size decreased from 116 to 7.4 Å.
All values
were significantly lower than the molecular diffusivity of 7.02 ×
10-6 cm2/s. The effective
diffusivities for glucitol were three times lower than those for
glucose over the same pore size
range due to differences in solute size, structure, and
solute−adsorbent interactions. The 8.6 Å
glucose molecule was able to diffuse into the 7.4 Å Y-zeolite pore,
possibly as its acyclic form.
However, the 9.7 Å glucitol molecule could not diffuse into the
Y-zeolite pore. The reduced
diffusivity was correlated to the reduced pore diameter using the
Ternan model.