A series of MgAl hydrotalcites (HTs) were synthesized by a sol-gel procedure with ethanol, 2-propanol, and 1-butanol as solvents. Particular attention was paid to controlling hydrolysis reactions by means of using a substoichiometric H 2 O/Al molar ratio equal to 1. The sol-gel HTs were characterized by means of thermogravimetry, mass spectrometry (MS) of the decomposition products, X-ray diffraction, diffuse reflectance infrared spectroscopy (DRIFT), electron microscopy, and N 2 adsorption-desorption. Decomposition products of sol-gel HTs were identified by MS and included, among others, C x H y fragments from alkoxy groups, which were partially withdrawn between 250 and 450 °C. Alkoxy groups, from the alcohols employed as solvents, are probably intercalated within the HT layers, as indicated by XRD and DRIFT analyses. C x H y groups in these alkoxy groups were detected by DRIFT at ∼2945 and ∼2831 cm -1 in dried HTs, even after annealing at 500 °C. The HTs obtained by the sol-gel procedure described in this work showed nanocapsular morphology. Transmission electron microscopy and Rietveld refinement techniques evidenced the curvature of the HT layers. In comparison with coprecipitated MgAl-CO 3 HT particles (>10 µm), sol-gel HTs showed very small particle aggregates (ca. 300∼350 nm). Calcined HTs presented specific surface area and pore volume values between 254∼332 m 2 /g and 0.81∼1.39 cm 3 /g, respectively, depending on the alcohol used in the sol-gel procedure.

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MgO prepared with the sol−gel technique had crystalline structure defects, obtained from X-ray powder diffraction and crystalline structure refinement, that correlated with its acidic and basic sites. The acidic sites, measured by adsorbing pyridine and NH3, were found when brucite and MgO coexisted, which only occurred after annealing the sample at 673 K. Two different basic sites, measured by adsorbing CO2, were present in a total concentration of about 1021 sites per gram. These sites correlated to the presence of magnesium vacancies in MgO crystal. Both basic site and magnesium vacancy concentrations diminished when the sample annealing temperature was increased.