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

Abstract

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 lattice and various reaction parameters are discussed. The activity and selectivity were shown to be strongly dependent on the surface acidity of the systems. 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≥0.5) favor the production of 3-picolines and 3,5-lutidine. Pyridine conversion increased with the progressive substitution of Zn2+ ions by Co2+ ions. Cation distribution in the spinel lattice influences their acidic properties. These factors have been adequately considered as helpful to evaluate the activity of the systems.