Vapor-phase methylation of pyridine with methanol to 3-picoline over Zn1-xCoxFe2O4 (x=0, 0.2, 0.5, 0.8 and 1.0)-type ternary spinels prepared via a low temperature method

The reaction of pyridine with methanol was carried out over Zn1-xCoxFe2O4 ( x=0, 0.2, 0.5, 0.8 and 1.0)-type systems in a fixed-bed down-flow reactor. The influences of surface acidity, cation distribution in the spinel lattic e and various reaction parameters are discussed. The activity and selectivi ty were shown to be strongly dependent on the surface acidity of the system s. Over all compositions of the systems, 3-picoline was formed as the major product, even though the activity and selectivity show a strong dependence on composition and reaction conditions. Generally, the systems possessing more acidic sites (x greater than or equal to0.5) favor the production of 3 -picolines and 3.5-lutidine. Pyridine conversion increased with the progres sive substitution of Zn2+ ions by Co2+ ions. Cation distribution in the spi nel lattice influences their acidic properties. These factors have been ade quately considered as helpful to evaluate the activity of the systems. (C) 2001 Elsevier Science B.V. All rights reserved.