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Kinetics of solid acids catalysed nitration of toluene: Change in selectivity by triphase (liquid–liquid–solid) catalysis
Author(s) -
Jeeru Lakshmana Rao,
R. V. Saikumar Reddy,
Pradhan Sayantan,
Kundu Gautam,
Pradhan Narayan C.
Publication year - 2017
Publication title -
asia‐pacific journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.348
H-Index - 35
eISSN - 1932-2143
pISSN - 1932-2135
DOI - 10.1002/apj.2158
Subject(s) - nitration , chemistry , catalysis , toluene , nitric acid , mordenite , amberlite , inorganic chemistry , selectivity , sulfuric acid , nuclear chemistry , organic chemistry , zeolite , adsorption
Nitrotoluenes are precursors to a variety of commercially important products such as dyes, pharmaceuticals, and plastics. The protonated form of Y, ZSM‐5, and mordenite zeolites as well as strongly acidic cation exchange resin (Amberlite IR‐120) were examined as triphase catalyst (liquid–liquid–solid) for the nitration of toluene to produce mainly mononitrotoluenes. Among the solid acid catalysts tested, zeolites were found to be more active than cation exchange resin with highest activity for H‐mordenite followed by HZSM‐5 and HY zeolites. The reaction was found to be free from external diffusional resistance. The effects of other parameters (temperature, catalyst loading, and nitric acid concentration) on the rate of toluene nitration over H‐mordenite catalyst were also investigated. The selectivity for p ‐nitrotoluene increases with temperature but decreases with increase in nitric acid concentration. The acidity level of the catalyst determines the product distribution; the stronger the acidity, the lower the ortho/para ratio is in the product mixture. The triphasic nitration reaction is kinetically controlled with an activation energy of 24.24 kJ/mol. The catalyst could be reused for several cycles with negligible loss in activity.