Al2O3 Nanorod with Rich Pentacoordinate Al3+ Sites Stabilizing Co2+ for Propane Dehydrogenation

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 Al2O3nanorods with abundant pentacoordinated Al3+(Al3+penta) sites. The supported Co on the Al2O3nanorod (Co/Al2O3-NR) exhibited higher selectivity (>96% propylene selectivity) and stability (deactivation rate 0.15 h−1) compared to Co supported on an Al2O3nanosheet with fewer pentacoordinated Al3+sites. Various characterizations confirmed that Co(II) mainly exists as CoAl2O4rather than Co3O4in the form of Co/Al2O3-NR, which inhibits the reduction of Co(II) to Co0and accordingly improves catalyst stability.Keywords:propane dehydrogenation;metal oxide;alumina;spinel