Nanostructured Ceria‐Niobia Catalyst for Selective Synthesis of N‐benzylideneanilines

The shape and structure engineering of metal oxide nanomaterials are the potential strategies to optimize surface‐active sites with tunable selectivity for heterogeneous catalysis. This work reports the synthesis of two types of nanostructured CeO2‐Nb2O5 catalysts: (i) one‐pot hydrothermal synthesis of CeO2‐Nb2O5 (CeNb2O5‐HTS) and (ii) CeO2 impregnation on hydrothermally synthesized Nb2O5 nanorods (CeNb2O5‐WI) to elucidate the role of particle shape and CeO2 addition in the structure‐activity efficacy of Nb2O5 nanocatalyst for the selective oxidative C‐N coupling of benzyl alcohol with aniline to produce N‐benzylideneaniline (NBA). The characterization studies showed nanorod morphology of Nb2O5 and high dispersion of CeO2 on Nb2O5 nanorods in the CeNb2O5‐WI catalyst with strong acidic sites and more oxygen vacancies. Consequently, a significantly enhanced catalytic activity was achieved with CeNb2O5‐WI nanocatalyst in the coupling of benzyl alcohol and aniline with 96% yield to NBA, whereas 62% conversion of aniline with 92% selectivity to NBA was obtained with pure Nb2O5 nanorods. In contrast, the CeNb2O5‐HTS catalyst gave 37% conversion of aniline only. The versatile efficiency of the CeNb2O5‐WI nanocatalyst is showcased by synthesizing various functional NBA products. The CeNb2O5‐WI catalyst can be recycled 5 times without much variation in NBA selectivity by achieving reasonably good conversion of aniline.