IISER researchers make solid material that releases two fuel gases

Scientists at the Indian Institute of Science Education and Research, Thiruvananthapuram, have developed a chemical compound that releases hydrogen and methane when heated moderately. Per the team, the work is a step towards new, better methods to store and transport these fuel gases.

The findings were published in Science Advances on October 7.

Both in India and around the world, hydrogen is emerging as an important new fuel because its combustion does not directly release carbon dioxide. However, because of its very low density, hydrogen is very difficult to store and transport and demands the use of expensive technologies.

Scientists have previously proposed blending hydrogen with methane as an intermediary step: while hydrogen burns faster than methane, methane can reduce the risk of flames travelling back into burners or triggering violent detonations. They have also devised ways to store the two fuels as compressed gases and solid materials that can release one or the other gas.

In the new study, researchers developed a compound of magnesium, zinc, hydrogen, and carbon called magnesium hydridomethylzincate. When the compound was heated in solution to 100° C, it released hydrogen — and when its crystals were heated in the absence of a solvent, at 80-110° C, it released both hydrogen and methane.

“The broader significance of the work is that organometallic compounds could potentially provide molecular platforms for the storage and controlled release of fuel gases,” chemistry professor and study lead Ajay Venugopal told The Hindu.

The team established that methane emerged before hydrogen, indicating the compound was releasing the gases through successive chemical reactions. Further analysis also revealed that each unit of the compound’s paired molecular structure could produce two molecules each of hydrogen and methane.

Since magnesium hydridomethylzincate is a solid at room temperature, it could offer an alternative to transporting methane and hydrogen as compressed gases. This together with the relatively low temperature required to liberate the gases merit more research on the compound, the paper said.

More research attention is warranted considering, as the team has acknowledged, the compound is also highly sensitive to moisture and it is not known whether it can be ‘replenished’ once its gaseous contents have been depleted.

“Although we are yet to demonstrate reversibility in our system, the study provides a starting point for exploring molecular compounds that can reversibly uptake and release fuel gases using main-group elements,” Prof. Venugopal said.

The study’s other authors were Sheetal Kathayat Bisht, Poorna Gomathisankaran, and Alex Andrews.