N-Butyl Acetate Synthesis in the Presence of Pyridinium-Based Acidic Ionic Liquids: Influence of the Anion Nature

Abstract

The catalytic behavior of three Bronsted acidic ionic liquids: pyridinium hydrogen sulfate ([H–Pyr]+[HSO4]−), pyridinium dihydrogen phosphate ([H–Pyr]+[H2PO4]−) and pyridinium nitrate ([H–Pyr]+[NO3]−) in the esterification of acetic acid with n-butanol was compared in the current paper. The alteration in the values of acetic acid conversion and esterification rate were investigated as a function of the process parameters: catalyst nature, catalyst loading, initial molar ratio n-butanol:acetic acid and reaction temperature. The anion variety modified the acidity of the obtained samples and effected their catalytic activity as follows: [H–Pyr]+[NO3]− < [H–Pyr]+[H2PO4]− < [H–Pyr]+[HSO4]−. The increasing of both catalyst loading and reaction temperature led to higher values of acetic acid conversion and esterification rate. The existence of a positive linear relationship between the esterification rate and acetic acid concentration was observed. The increasing of the n-butanol concentration negatively affected the rate of esterification. The acetic acid conversion was improved as the initial molar ratio n-butanol-to-acetic acid was raised.