Immobilization of aluminum chloride on MCM-41 as a new catalyst system for liquid-phase isopropylation of naphthalene

A great deal of effort has been made at searching for alternative catalysts to replace conventional Lewis acid catalyst aluminum trichloride (AlCl3). In this paper, immobilization of AlCl3 on mesoporous MCM-41 silica with and without modification was carried out. The catalytic properties of the immobilized catalyst systems for liquid-phase isopropylation of naphthalene were studied and compared with those of H/MCM-41 and H/mordenite. The structures of the surface-immobilized aluminum chloride catalysts were studied and identified by using solid-state magic angle spinning nuclear magnetic resonance (MAS NMR), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption, and X-ray diffraction (XRD) techniques. The catalytic activity of the immobilized catalysts was found to be similar to that of acidic mordenite zeolite. A significant enhancement in the selectivity of 2,6-diisopropylnaphthalene (2,6-DIPN) was observed over the immobilized aluminum chloride catalysts. Immobilization of aluminum chloride on mesoporous silica coupled with surface silylation is a promising way of developing alternative catalyst system for liquid-phase Friedel-Crafts alkylation reactions. (C) 2002 Elsevier Science B.V. All rights reserved.

Nanocrystalline zirconia as catalyst support in methanol synthosis

Nanocrystalline zirconia was synthesized and used as catalyst support for methanol synthesis. The nanocrystallite particles have new physical and textural properties which are critical in determining the catalytic performance. Nanocrystalline zirconia changes the electronic structure and affects the metal and support interactions on the catalyst. leading to facile reduction. intimate interaction between copper and zirconia, more corner defects and oxygen vacancies on the surface of the catalyst. All these changes are beneficial to the reaction of methanol synthesis from hydrogenation of CO2. As a result. higher conversion of CO2 and selectivity of methanol are achieved compared to the catalysts prepared by conventional co-precipitation method. (C) 2004 Elsevier B.V. All rights reserved.