152 Producing Fuels and Fine Chemicals from Biomass Using Nanomaterials
(ii) A second strong component located at 1592 cm
−1
is ascribed to the partner
8a mode of 2,6-DMP H-bonded to surface OH groups.
(iii) A third higher-υ band, present as a weak shoulder at 1606 cm
−1
only in the
case of the USZT_40_1_30 sample, can be ascribed to 2,6-DMP interact-
ing with medium-strong Lewis acid sites [coordinatively unsaturated (cus)
Zr
4+
or Ti
4+
cations]. The presence of this component in one single sample
indicates that only specic synthesis conditions (i.e., using 40% of the US
maximum power, continuous US, and a water/precursors molar ratio equal
to 30) are able to generate at the surface of the material the above men-
tioned sites.
When excess base ...