Hydrogen Activation Catalyst Harnesses Boron and Sodium

Researchers in Japan have developed a transition metal-free catalyst for activating hydrogen.

They are confident that the novel reaction mechanism, which involves main-group-mediated small molecule activation, will have an important impact on both the design of more efficient catalytic processes and the discovery of new catalytic transformations.

The researchers, based at Nagoya Institute of Technology (NITech), started with the concept of frustrated Lewis pairs (FLPs).

FLPs are made of two reactive components that are prevented from reacting with each other due to spatial or electronic hindrance. The resulting “frustration” makes them incredibly reactive and capable of activating bonds in normally stable molecules such as hydrogen, carbon dioxide and ammonia.

Led by Professor Yuji Iwamoto of NITech’s Graduate School of Engineering, the researchers chemically modified polysilazane – a molecule with alternating silicon and nitrogen atoms in its backbone – with boron and sodium. Following exposure to flowing ammonia at 1000°C this became a sodium-doped amorphous silicon boron nitride (Na-doped SiBN), effectively a scaffold with precisely controlled pore sizes that act as what Iwamoto describes as nanoconfined reaction fields.

When hydrogen was introduced at certain temperatures, the resulting FLPs began a dynamic interaction that enabled reversible hydrogen adsorption and desorption. This was confirmed through thermodynamic experiments. The high activation energy for hydrogen release also suggested strong interactions.

In addition, the amorphous Na-SiBN exhibits high thermal stability, making it suitable for catalytic processes under harsh conditions. Both its shape and porosity can be tailored for different reaction conditions.

"This approach holds promise for advancing main-group-mediated solid-gas phase interactions in heterogeneous catalysis, offering valuable insights and promising significant impacts in this domain," explained Iwamoto.

For now, the team is working to improve the properties of the Na-doped SiBN, while investigating other material systems using the principles they now have established.

“I also am interested in carbon dioxide hydrogenation and will start these investigations in my lab,” he said, adding that other applications will be discussed with research colleagues, including Dr Samuel Bernard, director of research at the French National Center for Scientific Research and contributor to a recent article about the work in Angewandte Chemie International Edition.

Iwamoto added that the work already has attracted interest from domestic industrial companies in Japan.