Catalytic characterization of bi-functional catalysts derived from Pd-Mg-Al layered double hydroxides

ydrotalcite like precursors containing Pd-II-Mg-II-Al-III with varying molar ratios, (Pd + Mg)/Al = 3 and Mg/Pd = 750 to 35, were prepared by coprecipitation of metal nitrates at constant pH. Characterization of samples as synthesized and their calcined products by elemental analyses, powder XRD, TG-DTA, FT-IR spectroscopy, TPR and N-2 physisorption indicated a well crystalline hydrotalcite like structure with incorporation of Pd2+ in the brucite layers. Thermal decomposition of hydrotalcite precursors at intermediate temperatures led to amorphous mixed oxides, Pd/MgAl(O), which on reduction yielded bi-functional catalyst, Pddegrees/MgAl(O). The resultant catalysts with acid, base and hydrogenating sites, were highly active and selective for one-step synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen. The results showed an optimal balance between acid-base and metallic sites were required to increase the selectivity of MIBK and stability of the catalysts.