Hydrotalcite-Derived CuMgAl Catalyst for Highly Effective and Stable Hydrogenation of Dimethyl Adipate to 1,6-Hexanediol

Highly effective and stable hydrogenation of dimethyl adipate (DMA) to 1,6-hexanediol (1,6-HDO) over nonnoble metal-based catalysts under relatively mild reaction conditions was quite attractive, yet challenging. Herein, a series of Cu-based catalysts with tunable acid–base sites were developed for the hydrogenation of DMA to 1,6-HDO. Among them, the CuMgAl hydrotalcite-derived Cu–35Mg45AlO catalyst was proven to be the most effective catalyst. Under relatively mild reaction conditions (190 °C and 5 MPa), DMA conversion of 99.0% with 1,6-HDO selectivity of 97.6% was achieved. Moreover, negligible deactivation was observed over a long-term (432 h) stability test. Characterization results revealed that the spatial segregation of the hydrotalcite structure and the interaction between Cu species and MgAl 2 O 4 spinel are responsible for the highly dispersed and stable Cu species. The synergistic mechanism of Cu 0, Cu +, and weak acidic sites was proposed to play a crucial role in DMA hydrogenation, and the promotional role of acid and base sites was also disclosed.