Electron-Deficient Co<sup>δ+</sup> Induced by Synergistic Co–ZnO–ZnAl<sub>2</sub>O<sub>4</sub> Interface Interactions for Enhanced <i>N</i>-Propylcarbazole Hydrogenation
Yinheng Zhao, Ting Zhu, Jiaqi Li, Chenggen Li, Wenxin Lu, Jia Liu, Dazhou Zhang, Yuan Dong, Ming Yang
Abstract
Developing efficient and cost-effective hydrogenation catalysts is essential for advancing liquid organic hydrogen carrier (LOHC) technology. In this study, ZnO-modified Co/Al 2 O 3 catalysts were synthesized via coprecipitation and evaluated for N -propylcarbazole (NPCZ) hydrogenation. Among them, Co 50 Zn 2 Al 8 achieved complete hydrogenation within 60 min under mild conditions (150 °C, 7 MPa), demonstrating outstanding activity. This performance is attributed to the synergistic Co–ZnO–ZnAl 2 O 4 interface, which induces electron transfer from Co to ZnO, generating electron-deficient Co δ+ species. These species enhance hydrogen dissociation and NPCZ adsorption, accelerating the reaction. ZnO also forms a protective layer around Co particles, preventing strong Co–Al 2 O 3 interactions and suppressing inactive CoAl 2 O 4 formation, thereby improving the Co reducibility and dispersion. Advanced characterization and density functional theory calculations provided insights into the electronic and structural effects of ZnO on the catalytic mechanism. Stability tests confirmed that Co 50 Zn 2 Al 8 retained high activity over five cycles without significant deactivation. The synergistic Co–ZnO interaction reduces the activation energy and improves reaction rates, making Co 50 Zn 2 Al 8 a highly efficient and durable catalyst. With its low cost, high activity, and remarkable stability, Co 50 Zn 2 Al 8 shows great potential for LOHC hydrogenation, offering a promising pathway for efficient hydrogen storage and utilization.