Energy
Nanotechnology, Energy

Molecular-based technology directly using crude hydrogen
Center for Future Innovation, Graduate School of Engineering
Associate Professor (Outstanding young researcher) Yoichi Hoshimoto
https://researchmap.jp/YHoshimoto/?lang=en

Abstract
Molecular hydrogen (H2) is one of the most important energy carriers. In the mid-term future, a huge amount of H2 will be produced
from a variety of hydrocarbon sources through the in-depth purification of a gaseous mixture of H2, CO, CO2, and other components.
However, bypassing these purification processes is desirable,
given their energy consumption and environmental impact, which
ultimately increases the cost of H2. Here, we demonstrate a strategy to separate H2 from a gaseous mixture of H2/CO/CO2/CH4 andsimultaneously store it in N-heterocyclic compounds that act asliquid organic hydrogen carriers (LOHCs), which can be applied toproduce H2 by subsequent dehydrogenation (Figure). Our results
demonstrate that LOHCs can potentially be used for H2 purificationin addition to their well-established use in H2 storage.

Energy▍ Background & Results
Hydrogen is essential to the modern economy, and expanding
its utility in a more sustainable society is a major global priority.
A major obstacle to this goal is how we currently produce hydrogen. There are many methods for producing hydrogen—such as
by reacting high-temperature steam with natural gas—but theseapproaches result in the production of crude hydrogen, which contains contaminant gases that are difficult to remove, decreasing
the value of the resulting hydrogen. For the commercial use of hydrogen, all contaminants must be rigorously removed by multistep,energy-intensive processes that are independently optimized foreach contaminant, making it difficult to extract the hydrogen fromthe crude mixture containing the by-products. The difficulty of extracting hydrogen from common contaminant gases has restricted

the utility of liquid organic hydrogen carriers, the state-of-the-art
for hydrogen storage. In these systems, many researchers havestruggled for decades to overcome the challenge of inducing thecarriers to uptake—i.e., store—hydrogen in the presence of contaminant gases.
To overcome these challenges, we have synthesized shelf-stable
triarylboranes that took up hydrogen even in the presence of common contaminant gases, achieving the following ground-breaking
results: hydrogen storage (with up to >99% efficiency) and subsequent hydrogen release at a purity of up to 99.999%.

▍ Significance of the research and Future perspective
This work demonstrated a proof-of-concept for a novel hydrogenproduction method that eliminates the need for separate purification stages prior to storage, and it thus demonstrates the potential
to increase the economic sustainability of hydrogen as an energy
carrier.

P a t e n t Japanese Patent No. 7079696, Japanese Patent Application No. 2023-95773, No. 2023-185532
Hoshimoto, Yoichi et al. Main group catalysis for H2 purification based on liquid organic hydrogen carriers. Sci. Adv. 2022, 8, eade0189.
Tr e a t i s edoi: 10.1126/sciadv.ade0189
https://www.azom.com/news.aspx?newsID=60330
UR
L https://newenergyandfuel.com/http:/newenergyandfuel/com/2022/12/01/proof-of-concept-for-new-hydrogen-production-and-storage/
https://cosmosmagazine.com/science/hydrogen-storage-borane/
K e y w o r d hydrogen, crude hydrogen, hydrogen storage, hydrogen purification, catalysts