Continuous-flow hydrogenation of nitrocyclohexane toward value-added products with CuZnAl hydrotalcite derived materials

Herein, catalytic performance of two CuZnAl hydrotalcite derived materials with different Cu content was investigated in continuous hydrogenation of nitrocyclohexane in liquid phase. We have shown that catalytic behavior of these materials depends strongly on Cu content. Activation of the catalyst with lower Cu loading by calcination at 773 K and reduction in 10 %H₂/Ar at 673 K led to formation of mainly CuZn alloys surrounded by ZnO phase - highly selective for cyclohexanone (crucial for nylon production). On the other hand, activation of hydrotalcite based material with higher Cu content led to formation of Cu-ZnO core-shell structure with larger Cu nanoparticles - efficient in production of cyclohexylamine – an essential building block in pharmaceutical manufacturing. The proper interpretation of the catalytic results was supported by CuZnAl physicochemical characterization using physisorption analysis, TGA, ICP OES, TPR, H₂-TPD, NH₃-TPD, CO₂-TPD, XRD, including in-situ XPS and TEM measurements.