Synthesis of intermediates for fine chemicals: Alkylation of phenol to p-cresol

M.E. SAD; C.L. PADRÓ; C.R. APESTEGUIA

Seoul, Korea

Congreso; 14th International Congress on Catalysis; 2008

A half page abstract template, 14th ICC, Seoul, Korea, 2008                                             [Scopes #: 5]   Synthesis of intermediates for fine chemicals: Alkylation of phenol to p-cresol    María E. Sad, Cristina L. Padró and  Carlos R. Apesteguía* Catalysis Science and Engineering Research Group (GICIC), Instituto de Investigaciones en Catálisis y Petroquímica -INCAPE-(UNL-CONICET). Santiago del Estero 2654, (3000) Santa Fe, Argentina   *Corresponding author: Fax: 54-342-4531068, Email: capesteg@fiqus.unl.edu.ar   Abstract: The gas-phase methylation of phenol was studied on samples containing only strong Brönsted acid sites (HPA/SiO2), or both Lewis and Brönsted acid sites of either strong (zeolites HZSM5, HBEA and HMCM22) or moderate (SiO2-Al2O3) strength.  Zeolites HBEA, HZSM5 and HMCM22 were more active than SiO2-Al2O3 or HPA/SiO2.  At 50% phenol conversion, the selectivity to cresols was clearly higher on HMCM22 (90%) than on HBEA, or HZSM5; HPA/SiO2 formed predominantly anisole. The distribution of cresol isomers on HBEA, HZSM5, and SiO2-Al2O3 was similar, being o-cresol the predominant product (p:o ratios between 0.7 and 0.8).  In contrast, the p:o ratio increased to 3.4 on HMCM22.  Thus, results show that the primary and secondary reaction pathways leading from phenol to cresols depend on both the pore microstructure and the nature, density, and strength of surface acid sites, but the para-selectivity is only dramatically increased by using zeolite MCM22, because the narrow channels of this zeolite are particularly suitable for improving by shape selectivity the formation of p-cresol. Specifically, the p-cresol yield and the para-/ortho-cresol ratio on HMCM22 for 93% phenol conversion were about 58 % and 3.4, respectively, the highest values reported up to now for the p-cresol formation from methylation of phenol. Keywords: p-Cresol synthesis, Fine chemicals, Phenol methylation.