Basicity and catalytic activity studies of hydrotalcite MgAL-CO3 and its mixed oxide by adsorption of phenol and aldolic condensation of furfural on acetone [Etude de la basicité de l'hydrotalcite MgAL-CO3 et de son oxyde mixte par adsorption du phénol et par mesure de l'activité catalytique dans la condensation du furfural avec l'acétone]

Mg-al hydrotalcite-like compounds (with molar ratios ranging from 2 to 3) containing carbonate anions in the interlayer space were synthesized by co-precipitation method. the obtained materials were characterized using various experimental techniques such as x-ray powder diffraction (xrd),infrared spectroscopy (ftir),thermo-gravimetric analysis (tga),n2 adsorption (bet) and elemental analysis. the basicity of mg-al hydrotalcites and mg-al mixed oxides,was evaluated using the adsorption of phenol as a probe molecule and aldol condensation at 90°c without solvent between furfural and acetone as reaction model. this reaction provides the 4- (2-furyl) -3-butene-2-one (fac),a high value added product used as a flavor in the food industry. the kinetic study of the reaction was followed performing sampling at regular intervals; the samples were analyzed by gas chromatography. the adsorbed amounts of phenol have been determined by uv-visible spectrophotometry. the highest conversion (about 99%) and the maximum quantities of phenol adsorbed (qads = 44,23 mg/g cat) were obtained with the mixed oxide from hydrotalcite mgal-co3 having mg/al molar ratio equal to 3. a correlation between the catalytic activity and the measure of the basicity by phenol probe was highlighted.