The synthesis of pyridine and 3-picoline from gas-phase acrolein diethyl acetal with ammonia over ZnO/HZSM-5.

A novel pathway for the synthesis of pyridine and 3-picoline was developed in this work. The method involved the condensation of gas-phase acrolein diethyl acetal and ammonia over the ZnO/HZSM-5 catalyst in a fixed-bed reactor. The problem of polymerization in existing process was effectively solved. The ZnO/HZSM-5 catalyst was proved to be the most promising catalyst relative to the ZnO/Al 2 O 3 and ZnO/HY ones. The reaction conditions and preparation conditions of the ZnO/HZSM-5 catalyst had great influences on the total yield of pyridine and 3-picoline. Characterization of ZnO/HZSM-5 had been done using X-ray diffraction (XRD), N 2 adsorption–desorption isotherms, ammonia temperature programmed desorption (NH 3 -TPD) and X-ray photoelectron spectroscopy (XPS) techniques. The characterized results revealed change of the pore structure and acidity of the catalyst upon ZnO introduction. The superior specific activity of ZnO/HZSM-5 was attributed to enhancing the various processes such as dehydrogenation in the addressed reaction. The raw materials from biological sources are possible for the synthesis of pyridine and 3-picoline in industry. [ABSTRACT FROM AUTHOR]