<div>
<p>Zr-MOFs are characterized by their high thermal and
chemical stability which may facilitate their application in heterogeneous
catalysis. However, these well-known microporous materials could see restricted
their applications in heterogeneous catalysis if large reactants exceed their
pore sizes leading to unavailable surface areas. In this work, we studied the
effect of acetic acid concentration, used as the modulator, on the formation of
micro/mesoporous materials. This inclusion of a modulator during synthesis and
its removal by activation process generate materials with missing linker
defects. We showed that an increase in the concentration of modulator leads to
an improvement of calculated apparent surface area and a modification of
MOF-808 pore structure by producing mesopores at the expense of micropores.
Furthermore, we performed a post-synthetic modification of the MOF-808. We
observed the expected sulfation of the zirconium oxo-cluster but also the
sulfonation of the organic ligand. Also,
we found that only the families of mesopores and the larger micropores are
interconnected within the material, and the ultramicropores seems to be
isolated from the porous structure. The PSM process led to the addition of Lewis and Brønsted acid sites to the MOF-808.
Experimental results were complemented by theoretical calculations using
Density Functional Theory (DFT) and Ab Initio Molecular Dynamics (AIMD)
simulations. The rationalization of the synthesis conditions effect and the post-synthetic
sulfation process on final properties presented in this paper can serve as a
basis for engineering of defects towards the synthesis of solid acid catalysts
from MOF 808.</p>
</div>
<br>