Heterocyclic LOHCs: Advantages and Challenges in Hydrogen Storage

Heterocycles containing nitrogen or oxygen atoms exhibit superior thermodynamic properties for dehydrogenation reactions compared to their carbocyclic counterparts. This makes them attractive candidates for use as liquid organic hydrogen carriers (LOHCs). Extensive research has focused on developing heterogeneous catalysts to exploit these advantages in practical applications. A groundbreaking discovery by Pez and colleagues introduced an LOHC system based on N-ethylcarbazole (NEC), boasting a hydrogen storage capacity of 5.8 wt%. Despite demonstrating efficient dehydrogenation and hydrogenation processes, the NEC/H12-NEC system encounters obstacles in commercial viability. These challenges primarily stem from the solid state of N-ethylcarbazole and the formation of undesirable byproducts during dehydrogenation.