Zeolite Catalysts with Various Pore Structures in the Synthesis of Pyridines

Abstract

Development of catalysts based on modified zeolites with a micro- or micro-meso-porous structure and mesoporous metallosilicates is aimed at creating of highly selective methods for producing pyridine and alkylpyridines. A heterogeneous catalytic synthesis of pyridine and methylpyridines was first done via the reaction of ethanol with ammonia and formaldehyde in the presence of the following catalyst systems: microporous zeolites Y, Beta, ZSM-12 and ZSM-5 in the H form, and a granulated Y zeolite with a combined micro-, meso-, and macro-porous structure (HY-MMM). The last is the most effective for the synthesis of picolines: the selectivity toward their formation is 46–63 % at an ethanol conversion of 70–80 %. Among the microporous catalysts, the most active are the highly decationized zeolites H-Y and H-Beta. The main reaction products on the catalysts H-Beta and H-ZSM-5 are pyridine (up to 50 %) and picolines (up to 40 %), while on the catalysts H-Y and H-ZSM-12, the main product are picolines (45–52 %) and lutidines (19–25 %). For zeolite HY-MMM, the influence of reaction conditions on the conversion of ethanol and the composition of pyridines is studied.