Al<sub>2</sub>O<sub>3</sub> Nanorod with Rich Pentacoordinate Al<sup>3+</sup> Sites Stabilizing Co<sup>2+</sup> for Propane Dehydrogenation

oleh: Zhiping Zhao, Zhixia Wang, Yanbing Tong, Jinru Sun, Ming Ke, Weiyu Song

Format: Article
Diterbitkan: MDPI AG 2023-04-01

Deskripsi

The search for inexpensive, environmentally friendly, and highly effective catalysts to activate C-H bonds in propane dehydrogenation (PDH) reactions is still a major challenge. Co-based catalysts have gained significant attention in recent years due to their excellent ability to activate C-H bonds and their high selectivity towards olefins, despite being a non-noble and environmentally unfriendly metal. However, further improvements are necessary for practical utilization, particularly in terms of activity and anti-carbon deposition capacity. In this study, we synthesized Al<sub>2</sub>O<sub>3</sub> nanorods with abundant pentacoordinated Al<sup>3+</sup> (Al<sup>3+</sup><sub>penta</sub>) sites. The supported Co on the Al<sub>2</sub>O<sub>3</sub> nanorod (Co/Al<sub>2</sub>O<sub>3</sub>-NR) exhibited higher selectivity (>96% propylene selectivity) and stability (deactivation rate 0.15 h<sup>−1</sup>) compared to Co supported on an Al<sub>2</sub>O<sub>3</sub> nanosheet with fewer pentacoordinated Al<sup>3+</sup> sites. Various characterizations confirmed that Co(II) mainly exists as CoAl<sub>2</sub>O<sub>4</sub> rather than Co<sub>3</sub>O<sub>4</sub> in the form of Co/Al<sub>2</sub>O<sub>3</sub>-NR, which inhibits the reduction of Co(II) to Co<sup>0</sup> and accordingly improves catalyst stability.