A low-cost catalytic cycle could advance the separation, storage and transportation of hydrogen

Hydrogen (H₂) is an Earth-abundant molecule that is widely used in industrial settings and could soon contribute to the clean generation and storage of electricity. Most notably, it can be used to generate electricity in fuel cells, which could in turn power heavy-duty vehicles or serve as back-up energy systems.

Despite its potential for various real-world applications, hydrogen is often expensive to produce, store and safely transport to desired locations. Moreover, before it can be used, it typically needs to be purified, as hydrogen produced industrially is typically mixed with other gases, such as carbon monoxide (CO), carbon dioxide (CO₂), nitrogen (N₂) and light hydrocarbons.

Researchers at Fudan University and other institutes in China recently devised a new strategy to separate hydrogen from impurities at low temperatures, while also enabling its safe storage and transportation. Their proposed method, outlined in a paper published in Nature Energy, relies on a reversible chemical reaction between two organic compounds that act as hydrogen carriers, enabling the reversible absorption and release of hydrogen.

“One of our key inspirations was a pressing industrial challenge in China, where highly developed process industries generate vast amounts of crude and byproduct hydrogen,” Prof. Yifeng Zhu, senior author of the paper, told Tech Xplore.

“Much of this hydrogen-rich gas, often containing over 50 vol.% impurities such as CO, CO₂, and hydrocarbons, gets burned because conventional recovery technologies like pressure swing adsorption and membranes are prohibitively costly and energy-intensive. At the same time, the deployment of green hydrogen and the necessary supporting infrastructure remains slow worldwide due to technological immaturity and high costs.”

The main objective of this recent study by Prof. Zhu and his colleagues was to devise a scalable approach to facilitate the widespread use of clean hydrogen by simplifying its separation from other gases, as well as its storage and transport. The strategy they proposed relies on a low-cost catalytic cycle, which involves the reversible interconversion of the compounds γ-butyrolactone (GBL) and 1,4-butanediol (BDO).

“Using crude hydrogen feeds with over 50 vol.% impurities, GBL is hydrogenated to BDO at 170 ^oC, achieving >99.2% H₂-to-BDO selectivity while suppressing side reactions,” said Prof. Zhu. “The hydrogen-rich BDO can then be safely stored and transported using existing liquid fuel infrastructure. Upon demand, catalytic dehydrogenation regenerates GBL and releases high-purity hydrogen (>99.998%), free of CO_x impurities.”

Essentially, the researchers used an inexpensive copper-based catalyst to capture hydrogen from impure industrial gas streams and store it in BDO, a cheap and safe oil-like liquid. Notably, this liquid can be transported using the same tanks, pipelines and trucks that are currently used to transport other fuels. When it reaches its destination, the hydrogen stored in the liquid can be easily released with high purity.

“A key advantage of our strategy is that both the catalyst and the liquid organic hydrogen carriers or LOHC (GBL/BDO) are abundant and inexpensive,” explained Prof. Zhu.

“Moreover, hydrogen capture and storage occur in a single step, simplifying the overall system. Our approach is safe and scalable, as the liquid carrier can be handled at ambient conditions using existing fuel infrastructure. The system can operate with gas feeds containing over 50% CO and CO₂ without catalyst deactivation, which is a major hurdle for conventional catalysts (<2 vol. % for state-of-the-art catalysts).”

The new strategy for separating, storing and transporting hydrogen devised by the researchers is both easy to deploy and scalable, as it relies on low-cost products and is compatible with existing infrastructure. In the future, it could aid the production of high-purity hydrogen and contribute to its widespread use within the global energy sector.

“Our cheap catalytic cycle can directly upgrade waste and crude hydrogen resources that are often flared or vented into the valuable, high-purity H₂,” said Prof. Zhu. “Our approach bypasses expensive purification steps and utilizes existing fuel infrastructure, offering a scalable pathway to boost global hydrogen utilization in the near term. Enabled by the precise activation of molecules (H₂ versus CO_x) over the novel inverse Al₂O₃/Cu catalyst, this work also demonstrates how fundamental advances in catalytic science can directly translate into impactful, real-world solutions that drive the clean energy transition.”

The recent work by Prof. Zhu and his colleagues at Fudan University could soon inspire the development of similar catalytic approaches to simplify the production and distribution of high-purity hydrogen. The researchers are currently working with various industrial partners to test and scale up their technology, with a keen focus on validating the long-term stability of the catalyst they employed and optimizing the efficiency of their approach.

“Concurrently, we are also exploring other hydrogen carrier systems and process designs to expand the range of hydrogen sources and end-use scenarios, from industrial waste streams to decentralized hydrogen storage and renewable energy integration,” added Prof. Zhu.

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