Fig. 3. Characterization of the accessible acid sites by in situ FTIR.

In situ FTIR spectra at 298 K of CD₃CN (red to gray, probe small doses to up to 10 torr equilibrium pressure) adsorbed on HD-US-UiO-66 (5 nm), the peaks position and peak area are shown in dotted lines and red area, respectively, the small doses and equilibrium indicate the increasing CD₃CN dosing from 0.2 torr to saturated 6.4 torr.