A novel route to produce thymol by vapor phase reaction of m-cresol with isopropyl acetate over Al-MCM-41 molecular sieves

Mesoporous Al-MCM-41 (Si/Al = 55 and 104) and Al,Zn-MCM-41 (Si/(Al+Zn)=52) molecular sieves were synthesized hydrothermally. The materials were characterized by XRD, TGA, TPD (pyridine), ICP-AES, nitrogen sorption, and FT-IR techniques. The catalytic performance of these materials was examined in the vapor phase alkylation of m-cresol with isopropyl acetate. The products obtained were thymol, isothymol, 2-isopropyl-5-methylphenyl acetate (2-I-5-MPA), and isopropyl-3-methylphenyl ether (I-3-MPE). The time-on-stream study was carried out over Al-MCM-41(55) at 300 °C and WHSV 1.52 h−1 wherein optimum conversion of m-cresol and selectivity to thymol were obtained. The dependence of activity and selectivity on the acid sites and hydrophobic and hydrophilic properties of the catalysts is discussed.