Nanostructured Ceria–Niobia Catalyst for Selective Synthesis of <i>N</i>‐Benzylideneanilines

Abstract 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 CeO 2 –Nb 2 O 5 catalysts: (i) one‐pot hydrothermal synthesis of CeO 2 –Nb 2 O 5 (CeNb 2 O 5 ‐HTS, HTS stands for hydrothermal synthesis) and (ii) CeO 2 impregnation on hydrothermally synthesized Nb 2 O 5 nanorods (CeNb 2 O 5 ‐WI, WI stands for wet‐impregnation) to elucidate the role of particle shape and CeO 2 addition in the structure–activity efficacy of Nb 2 O 5 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 Nb 2 O 5 and high dispersion of CeO 2 on Nb 2 O 5 nanorods in the CeNb 2 O 5 ‐WI catalyst with strong acidic sites and more oxygen vacancies. Consequently, a significantly enhanced catalytic activity was achieved with CeNb 2 O 5 ‐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 Nb 2 O 5 nanorods. In contrast, the CeNb 2 O 5 ‐HTS catalyst gave 37% conversion of aniline only. The versatile efficiency of the CeNb 2 O 5 ‐WI nanocatalyst is showcased by synthesizing various functional NBA products. The CeNb 2 O 5 ‐WI catalyst can be recycled 4 times without much variation in NBA selectivity by achieving reasonably good conversion of aniline.