Comparison of mesoporous Al-MCM-41 molecular sieves in the production of p-cymene for isopropylation of toluene

Mesoporous aluminosilicate Al-MCM-41 with Si/Al = 93 and 104 were synthesized using cetyltrimethylammonium bromide as the structuring agent and the materials were characterized using several techniques. The mesoporous structure was confirmed by X-ray diffraction (XRD) technique. The surface area, pore size and wall thickness was calculated by BET equation and BJH method using nitrogen sorption technique. Fourier transform-infrared (FF-IR) spectroscopy was used in order to obtain information on incorporated aluminum atoms in the mesoporous structure of Al-MCM-41. Thermogravimetric-differential thermal analyzer (TG-DTA) was used to determine the thermal stability of the materials. The effect of reaction temperature, WHSV and isopropanol: toluene ratios on the selectivity of p-cymene were studied. The Al-MCM-41 (93) catalyst exhibited excellent selectivity in the production of p-cymene by the isopropylation of toluene using isopropanol as the propylating agent. (C) 2002 Elsevier Science B.V. All rights reserved.