Methylation of pyridine over zeolites. FT-IR studies for selectivity and acidity correlations

Methylation of pyridine on HY, HZSM-5, Mordenite, MgAlPO-11 and Zeolite Beta under gas phase conditions leads to the formation of 2-, 3-, 4-picolines along with higher alkylpiridines, while SAPO-5 does not exhibit any activity. On a conventional acid catalyst only 3-picoline and the successive higher products can be expected and the formation of 2- and/or 4-substituted products is intriguing. Two different mechanisms for the formation of 2-/4- and 3-substituted pyridines are proposed. FT-IR studies were carried out to understand the correlation between acidity and activity/selectivity for the reaction. © 1995 Akadémiai Kiadó.