Efficient hydrogenation of Nitrocyclohexane to cyclohexanone oxime over CuFeAl-Layered Double Hydroxide: The promoting role of FeO.

Nitrocyclohexane (NCH) hydrogenation to cyclohexanone oxime (CHO) is of great significance in the production of caprolactam. In this work, CuFeAl-Layered Double Hydroxide (CuFeAl-LDH) catalysts with lamellar structure were prepared by co-precipitation method and applied for NCH hydrogenation, and the promoting role of FeO was discussed. It was found that FeO species promote the reduction of Cu and control the ratio of Cu to Cu. In situ DRIFT and density-functional theory (DFT) calculation results confirm that the presence of FeO species can act as lewis base site to reduce the acid sites and facilitate the isomerization of nitrosocyclohexane to CHO, and promotes the adsorption of NCH and the desorption of the formed CHO to prevent its further reaction to form byproducts. CuFeAl shows the best catalytic performance of 100 % NCH conversion and 93.35 % selectivity to CHO under mild conditions. This work provides a new idea for the design of non-noble metal-based catalysts with high activity for the selective hydrogenation of nitro compounds.