A typical method of hydrogen storage is physically storing hydrogen using compression or liquefaction; these methods require higher energy to increase storage capacity and expensive distributing infrastructure. To overcome these limitations, research efforts to store hydrogen chemically in liquid carriers, such as liquid organic hydrogen carriers (LOHCs) or ammonia, have been conducted. Hydrogen can be safely stored in LOHCs at room temperature and atmospheric pressure before being extracted at locations for use.

Various organic compounds have been suggested for LOHCs. However, there have been few comparative studies on LOHC performance, leading to a lack of scientific consensus in the hydrogen community for downselecting LOHCs and catalysts.

Now, researchers at the Korea Institute of Science and Technology (KIST) have developed a high-throughput benchmarking protocol for the adoption of promising liquid organic hydrogen carriers (LOHCs) and their well-matched catalysts.

Credit: Korea Institute of Science and Technology(KIST)

The KIST LOHC research team in the Hydrogen and Fuel Cell Research Center led by Dr. Yongmin Kim developed a semi-automatic evaluation system for LOHC dehydrogenation (hydrogen extraction from LOHC). This system allows the rapid testing of dehydrogenation in well-defined and standardized reaction conditions and carries out comparative analyses to draw out optimal solutions for the successful commercial deployment of LOHCs.

One LOHC in the analyses is methylcyclohexane (MCH) with high technological readiness. It shows a higher dehydrogenation rate with minimal byproduct formation. Monobenzyltoluene (MBT) is another promising candidate because it has been mass-produced as a safe chemical while extracting hydrogen quickly.

A biphenyl-based eutectic mixture developed by KIST in 2017 shows 20% higher dehydrogenation rate than those of other LOHCs. This biphenyl-based LOHC with a superior hydrogen storage density of 6.85 wt.%-H₂ is applicable for onboard hydrogen storage such as in hydrogen vehicles or trains.

The proposed system for fast screening of LOHCs materials and catalysts will be also helpful for both domestic and international research collaborators in industry and academia.

In addition to ongoing research collaboration with Hyundai Motor Group and Korea Gas Corporation, international collaborative research projects with Germany and Japan are being planned to widely disseminate this generalized benchmarking LOHC study platform for accelerating LOHC deployment in the hydrogen economy.

Resources

• Yeonsu Kwak, Jaewon Kirk, Seongeun Moon, Taeyoon Ohm, Yu-Jin Lee, Munjeong Jang, La-Hee Park, Chang-il Ahn, Hyangsoo Jeong, Hyuntae Sohn, Suk Woo Nam, Chang Won Yoon, Young Suk Jo, Yongmin Kim, (2021)“Hydrogen production from homocyclic liquid organic hydrogen carriers (LOHCs): Benchmarking studies and energy-economic analyses” Energy Conversion and Management doi: 10.1016/j.enconman.2021.114124