Preparation and characterisation of mesoporous silica–alumina and silica–titania with a narrow pore size distribution

Abstract

Amorphous mesoporous materials with a different degree of order in the arrangement of pores are outlined. Particularly, the synthesis of a class of mesoporous silica–alumina (MSA) materials with narrow pore size distribution and a disordered arrangement of pores is reported and discussed. Likewise, the preparation of titanium-containing ordered mesoporous silicates (Ti-MCM-41) and disordered mesoporous silica–titania (MST) are also described in detail. The structural properties of the solids are compared by means of X-ray diffraction and UV-Vis diffuse reflectance spectroscopy. The nitrogen adsorption–desorption measurements were performed and the textural properties are evaluated by the BET, DFT, BJH and t-plot methods. The high specific surface area and pore volume, as well as the acidity, make MSA solids interesting catalysts in several petrochemical transformations, i.e. oligomerisation, alkylation, hydroisomerisation, rearrangement reactions. Besides, thanks to the width of the mesopores of such solids, the catalytic activity of titanium-containing silicates may have a potential application in the epoxidation of bulky unsaturated fine chemical substrates.