Unravelling the role of Ag[sbnd]Cr interfacial synergistic effect in Ag/Cr₂O₃ nanostructured catalyst for the ammoxidation of toluene via low temperature activation of C_sp³-H bond

An environmentally benign and cost-effective synthesis of benzonitrile is reported by direct oxidative cyanation of aromatic Csp³-H bonds of toluene over Ag(I)/Cr₂O₃ nanostructured catalyst. The catalyst was prepared by a hydrothermal route using cationic surfactant cetyltrimethylammonium bromide and was characterized by powder XRD, XPS, SEM, TEM, TGA, TPD, TPR, UV-visible, FTIR, XANES, and ICP-AES methods. Conjugal effect of Lewis plus Brønsted acidity coupled with Ag[sbnd]Cr interfacial synergistic interaction appears as detrimental for its high catalytic activity and selectivity (98.4%) for benzonitrile. In situ DRIFTS analysis suggested that the catalytic system proceeded via a reaction pathway explained by Mars-van Krevelen mechanism.