Selective Synthesis of p ‐Cresol by Alkylation of Phenol with Methanol over SiO 2 ‐Modified HMCM‐22 Catalyst

Abstract A series of x SiO 2 /HMCM‐22 were prepared by chemical liquid deposition of HMCM‐22 with tetraethyl orthosilicate and evaluated in the catalytic synthesis of p ‐cresol by alkylation of phenol with methanol. Several characterization techniques including N 2 adsorption‐desorption, X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), Pyridine‐IR, temperature‐programmed desorption of NH 3 (NH 3 ‐TPD) as well as the probe reaction of m ‐xylene isomerization and 1,3,5‐triisopropyl benzene (1,3,5‐TIPB) cracking have been used to analyze the physicochemical properties of x SiO 2 /HMCM‐22 catalyst. The conversion of phenol decreased with increasing SiO 2 loading of x SiO 2 /HCM‐22 catalyst; while the selectivity for p ‐cresol maximized at x=1 %. The 1 %SiO 2 /HMCM‐22 catalyst was identified as the most efficient catalyst, showing the highest p ‐cresol selectivity for longer than 15 h under optimized reaction conditions. The high p ‐cresol selectivity of the catalyst is attributed to the fact that SiO 2 covered the acid sites of the external surface of the HMCM‐22 and preserved the acid sites in the micropores of zeolite.