Catalytic Performance of Al-MCM-48 Molecular Sieves for Isopropylation of Phenol with Isopropyl Acetate

Al-MCM-48 molecular sieves (Si/Al molar ratios = 25, 50, 75, and 100) were synthesized hydrothermally using cetyltrimethylammonium bromide as the structure directing template. The orderly arrangement of mesopores was evident from the low angle X-ray diffraction patterns and transmission electron microscopy images. The catalytic performance of the materials was evaluated in the vapor phase isopropylation of phenol with isopropyl acetate. Phenol conversion decreased with the increase in the Si/Al ratio of the catalysts. The major reaction product was 4-isopropyl phenol with 78% selectivity. The delocalization of phenolic oxygen electron pair over the aromatic ring promoted para-selective alkylation. Such delocalization could be aided by the hydrophilic surface of the molecular sieves. Although an ester was used as the alkylating agent, phenyl isopropyl ether was not formed in the reaction.

MCM-48 possesses three dimensional mesopores high surface area and well dispersed acid sites. It is good for vapour phase alkylation of aromatics and alkyl aromatics. In addition it possesses high coke resistant characteristic by such features it could a versatile catalyst for vapour phase alkylation. Isopropylation of phenol by using novel isopropyl acetate proved such features.Figure optionsDownload as PowerPoint slide