An investigation into factors which influence the formation of p-cresol in the methanol alkylation of phenol over MCM-22 and ZSM-5

In the methanol alkylation of phenol, the primary products are anisole and cresol. Secondary reactions mainly result from further reactions of anisole. In the present study, it was observed that p-cresol formed preferentially, i.e. greater than the thermodynamically expected amount, over H-MCM-22, especially in the case of catalysts where the crystallite sizes were greater than approximately 1 μm. It is thus proposed that in the case of MCM-22 the 10MR pores in the layers allow easy diffusion of p-cresol and that the effect of this phenomenon is enhanced when the crystallite sizes are relatively large. Many similar observations have been made in the case of the methylation of toluene. Steaming of H-MCM-22 also produces the enhanced diffusional resistance due to the presence of the extra-framework Al species. Further investigations in which the internal acid sites were inertized supported the above observations.