Fig. 4: Catalytic performance of Co1/Nb2O5 in the solvent-free selective hydrogenation of nitrobenzene to azoxybenzene.

Conversion and selectivity of (a) Co1/Nb2O5 and (b) Co NPs/Nb2O5. c The corresponding TOF values of different samples. d Arrhenius plots and Ea values. e Recycling results (Reaction time: 5 min). f The proposed reaction routes. In situ DRIFTS spectra were recorded during the hydrogenation of nitrobenzene over (g) Co1/Nb2O5 and (h) Co NPs/Nb2O5. (NB nitrobenzene; NSB nitrosobenzene; PHA phenylhydroxylamine; AB azobenzene; AOB azoxybenzene; AN aniline).