Preparation, characterization and use of K2O, Al2O3 and SiO2 modified iron oxide as catalyst for the vapor phase synthesis of 2,3,6-trimethyiphenol from m-cresol and methanol

摘要

Vapor phase ortho-selective methylation of m-cresol with methanol has been carried out over the catalyst of Fe, Si, Al and K oxides in a fixed-bed, down-flow reactor at 573-673 K. Catalyst characterization has been carried out by XRD, BET and SEM. 2,3,6-Trimethylphenol was found to be the major product derived with very little 2,3-xylenol and 2,5-xylenol. The effect of the K2O content of the catalyst, reaction temperature, reactant molar ratio and LHSV on the methylation of m-cresol with methanol was investigated. When the formation of the catalyst was fixed at Fe2O3:SiO2:Al2O3:K2O = 100:5:2:0.9, under a reaction condition of 653 K reaction temperature, 7:1 methanol to m-cresol molar ratio and 1.3 h~(-1) LHSV, the maximum yield of 97.2 % was obtained for 2,3,6-trimethylphenol, and the yield kept around 97 % even after the reaction time of 100 h.