Influence of acid-base sites on ZnO-ZnCr2O4 catalyst during dehydrocyclization of aqueous glycerol and ethylenediamine for the synthesis of 2-methylpyrazine: Kinetic and mechanism studies

• Published in: Applied catalysis. A, General Vol. 469; pp. 398 - 409
• Main Authors: VENUGOPAL, Akula, SARKARI, Reema, ANJANEYULU, Chatla, KRISHNA, Vankudoth, MANDARI KOTESH KUMAR, NARENDER, Nama, AYTAM HARI PADMASRI
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier 2014
• Subjects: Basicity; Catalysis; Chemistry; Ethylenediamine; Exact sciences and technology; General and physical chemistry; Glycerols; Poisoning; Pyridines; Spectroscopy; Surface physical chemistry; Synthesis; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Zinc; Pyridne-2,6-dimethylpyridine FTIR; Chemisorption; Binary compound; Acidic site; Pulse; Glycerol; TPD; CO; Base; Mechanism; O; Dehydrocyclization; Infrared spectrometry; Ammonia; Heterogeneous catalysis; Synthesis; ZnO―ZnCr; 2-Methylpyrazine; NH; Kinetics; Catalyst; pulse chemisorption
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2013.10.023

The physicochemical characteristics of ZnO-ZnCr2O4 (Zn-Cr-O) mixed oxides were determined by adsorption and spectroscopic methods. The catalytic activities of Zn-Cr-O was investigated for dehydrocyclization of ethylenediamine and aqueous glycerol to synthesize 2-methylpyrazine (2MP). Reductive pre-treatment was required for better 2MP yields and rate of 2MP was dependent upon strong basicity of Zn-Cr-O. Product distribution revealed that cyclocondensation of glycerol and ethylenediamine followed by homo-coupling of 2-pyrazinylmethanol occurred on moderate acid and strong base sites. On the contrary weak to moderate acidic and base sites were inefficient for homo-coupling of 2-pyrazinylmethanol. Role of acid-base properties was examined by pyridine and 2,6-dimethylpyridine poisoning studies.