Magnesium oxide supported on active carbon (AC), siliceous mesoporous molecular sieve MCM-41, silica (SiO₂) and γ-Al₂O₃, respectively, was prepared by the impregnation method. Their catalytic activities in the Meerwein-Ponndorf-Verley (MPV) reduction of acetophenone with 2-propanol as a reducer were investigated, and campared to that of pure MgO catalyst. At the same time, the catalysts were characterized with XRD, TEM, N₂ adsorption-desorption, XPS and CO₂-TPD methods. Support effect on the activity of catalyst was studied. The results show that the catalytic activity of pure MgO is low, due to the smaller specific surface area resulting in the less basic sites on its surface. In the 10% MgO/AC catalyst, the high surface area of AC and no strong interaction of MgO with AC support favor the high dispersion of MgO on the surface of AC to form very small crystallites leading to a clear increase of basic sites on the surface of catalyst. On the other hand, the concentration of acetophenone near the active sites in the catalyst increases because of the possible π-electron interaction between the benzene ring in the acetophenone and graphite layer of AC support. The effects of above two aspects lead to a significant increase of the catalytic activity of 10% MgO/AC campared to pure MgO. The 10% MgO/MCM-41, 10% MgO/SiO₂, 10% MgO/γ-Al₂O₃ are hardly active due to the strong interaction of MgO with the support materials resulting in the dramatic decrease of number of basic sites on the surface of these catalysts.

Key words: support effect, magnesium oxide, acetophenone, MPV reduction