Herein, the alcoholysis of furfuryl alcohol in a series
of SBA-15-pr-SO3H catalysts with different pore sizes is
reported. Elemental
analysis and NMR relaxation/diffusion methods show that changes in
pore size have a significant effect on catalyst activity and durability.
In particular, the decrease in catalyst activity after catalyst reuse
is mainly due to carbonaceous deposition, whereas leaching of sulfonic
acid groups is not significant. This effect is more pronounced in
the largest-pore-size catalystC3, which rapidly deactivates
after one reaction cycle, whereas catalysts with a relatively medium
and small average pore size (named, respectively,C2andC1) deactivate after two reaction cycles and to a lesser extent.
CHNS elemental analysis showed thatC1andC3experience a similar amount of carbonaceous deposition, suggesting
that the increased reusability of the small-pore-size catalyst can
be attributed to the presence of SO3H groups mostly present
on the external surface, as corroborated by results on pore clogging
obtained by NMR relaxation measurements. The increased reusability
of theC2catalyst is attributed to a lower amount of
humin being formed and, at the same time, reduced pore clogging, which
helps to maintain accessible the internal pore space.