Recent developments in catalyst design for liquid organic hydrogen carriers: Bridging the gap to affordable hydrogen storage

Addressing the urgent need to reduce global CO₂ emissions, there is a growing emphasis on transitioning from the current fossil fuel-dependent energy system to an environmentally sustainable hydrogen-based economy, devoid of carbon emissions. However, the inherent challenges in the conventional storage and transportation of elemental hydrogen have impeded progress. To overcome this hurdle and achieve a seamless transition to a cost-effective hydrogen storage solution, researchers propose the use of liquid organic hydrogen carriers (LOHCs). These carriers involve chemically binding elemental hydrogen within hydrogen-deficient organic molecules, allowing for efficient storage and retrieval of hydrogen under low pressure conditions. An attractive feature of LOHCs is their compatibility with existing infrastructure such as storage tanks, ships, and fueling stations, facilitating a smoother transition. This contribution delves into the crucial role of various catalyst materials in enhancing the hydrogenation activity of various LOHCs such as benzene, toluene, N-ethylcarbazole (NEC) and dibenzyltoluene (DBT). Through the exploration of catalytic aspects, this review investigates the effect of noble metal, transition metal, and multimetallic catalysts, providing valuable insights into their design and optimization. These efforts aim to achieve efficient and sustainable hydrogen storage within the LOHC framework. The findings presented in this study aim to contribute to the development of economically viable solutions for hydrogen storage and utilization, thereby aiding the seamless transition toward a hydrogen-based energy economy.