Reaction kinetics and mechanism of adiponitrile preparation by adipic acid ammoniation

Adiponitrile (ADN), a key precursor for the production of nylon 66, can be synthesized via adipic acid (ADA) ammoniation. The decrease in ADA cost has made this route an alternative route to prepare ADN recently. However, studies on the reaction kinetics and mechanism of this method were scarce, which limits the development of ammoniation reactors. In this study, reaction kinetics and mechanism of ADN preparation by ADA ammoniation were carried out. First, the operating conditions including reaction temperature, phosphoric acid (H3PO4) dosage, ammonia (NH3) volume content and stirring speed were optimized. Then Gas ChromatographyMass Spectrometer (GC-MS) and Density Functional Theory (DFT) were adopted to study the intermediates and mechanism. The Monomolecular Mechanism of a two-step dehydration process was proposed. Finally, the reaction rate constant equation of ADA ammoniation was first established. The result showed pre-exponential factor for the reaction was 387.41 L/(mol & sdot;s), and the activation energy was 3.44 x 104 J/mol.