THE REACTION OF AMMONIA AND ETHANOL OR RELATED-COMPOUNDS TOWARDS PYRIDINES OVER HIGH-SILICA ZEOLITES WITH MEDIUM PORE-SIZE

Pyridine bases were formed by the reaction of ethanol and ammonia over zeolite Nu-10 in the presence of oxygen, which was shown to play an e ssential role. The use of different proton-introduction procedures res ulted in different activities and selectivities of the catalyst. H-Nu- 10 and H-ZSM-5 showed substantially higher pyridine selectivity than H -mordenite. In order to clarify the reaction mechanism of the title re action, several other small amines and oxygenates were tested in the p resence/absence of oxygen with respect to their selectivity towards py ridines. Zeolitic acid sites were shown to catalyse the dehydrogenatio n of ethanol, together with condensation, cyclization and aromatizatio n, while structural defects probably produced oxidation products such as acetaldehyde and formaldehyde which an thought to play an important role in the reaction. The use of methylamine instead of ammonia great ly enhanced the pyridine selectivity.