Process Development and DFT‐Assisted Mechanism of the Vapour Phase Ammoxidation of 2,6‐Dichlorotoluene to 2,6‐Dichlorobenzonitrile over the V₂O₅/γ‐Al₂O₃ Catalyst

Abstract

Ammoxidation of 2,6‐dichlorotoluene (2,6‐DCLT) to 2,6‐dichlorobenzonitrile (2,6‐DCLBN) over V2O5/γ‐Al2O3 catalyst has been carried out in a fixed bed reactor. A maximum conversion of 96% of (2,6‐DCLT) and 79% yield to 2,6‐dichlorobenzonitrile have been obtained at a temperature of 425 °C, Air : 2,6‐DCLT mole ratio of 22 : 1 and NH3 : 2,6‐DCLT mole ratio of 11 : 1. A DFT theory computations have been performed with the objective of finding a mechanism of the reaction, activation energy and transition state for different reactions. Abstraction of C−H bond with an activation energy of 64.60 kcal mol−1 was found to be rate determining step. A new approach has been suggested for the reoxidation of the catalyst which supports reoxidation of every step associated with dehydration of species during the reaction. This finding is a contrary of the previous studies which assume reoxidation of the catalyst at the end of all reactions. Rapid reoxidation of the catalyst surface to release water is found to be the driving force for all reactions involving the cleavage of C−H or N−H bonds.