Northwestern-led team develops new MOFs with ultrahigh porosity for storage of hydrogen or methane for vehicles
A research team led by Northwestern University has designed and synthesized new metal-organic framework (MOF) materials with ultrahigh porosity and surface area for the storage of hydrogen and methane for fuel cell-powered vehicles. The designer materials can store significantly more hydrogen and methane than conventional adsorbent materials at much safer pressures and at much lower costs. A paper on their work is published in Science.
The ultraporous MOFs are based on metal trinuclear clusters, namely, NU-1501-M (M = Al or Fe). Relative to other ultraporous MOFs, NU-1501-Al exhibits concurrently a high gravimetric Brunauer−Emmett−Teller (BET) area of 7310 m2 g−1 and a volumetric BET area of 2060 m2 cm−3 while satisfying the four BET consistency criteria.
NU-1501-M. Credit: Northwestern University
The high porosity and surface area of this MOF yielded impressive gravimetric and volumetric storage performances for hydrogen and methane: NU-1501-Al surpasses the gravimetric methane storage US Department of Energy target (0.5 g g−1) with an uptake of 0.66 g g−1 [262 cm3 (standard temperature and pressure, STP) cm−3] at 100 bar/270 K and a 5- to 100-bar working capacity of 0.60 g g−1 [238 cm3 (STP) cm−3] at 270 K; it also shows one of the best deliverable hydrogen capacities (14.0 weight %, 46.2 g liter−1) under a combined temperature and pressure swing (77 K/100 bar → 160 K/5 bar).
We’ve developed a better onboard storage method for hydrogen and methane gas for next-generation clean energy vehicles. To do this, we used chemical principles to design porous materials with precise atomic arrangement, thereby achieving ultrahigh porosity.—Omar K. Farha, corresponding author
Adsorbents are porous solids which bind liquid or gaseous molecules to their surface. With its nanoscopic pores, a one-gram sample of the Northwestern material (with a volume of six M&Ms) has a surface area that would cover 1.3 football fields.
The new materials also could be a breakthrough for the gas storage industry at large, Farha said, because many industries and applications require the use of compressed gases such as oxygen, hydrogen, methane and others.
The ultraporous MOFs are built from organic molecules and metal ions or clusters which self-assemble to form multidimensional, highly crystalline, porous frameworks.
We can store tremendous amounts of hydrogen and methane within the pores of the MOFs and deliver them to the engine of the vehicle at lower pressures than needed for current fuel cell vehicles.—Omar Farha
The Northwestern researchers conceived the idea of their MOFs and, in collaboration with computational modelers at the Colorado School of Mines, confirmed that this class of materials is very intriguing. Farha and his team then designed, synthesized and characterized the materials. They also collaborated with scientists at the National Institute for Standards and Technology (NIST) to conduct high-pressure gas sorption experiments.
Zhijie Chen, Penghao Li, Ryther Anderson, Xingjie Wang, Xuan Zhang, Lee Robison, Louis R. Redfern, Shinya Moribe, Timur Islamoglu, Diego A. Gómez-Gualdrón, Taner Yildirim, J. Fraser Stoddart, Omar K. Farha (2020) “Balancing volumetric and gravimetric uptake in highly porous materials for clean energy” Science doi: 10.1126/science.aaz8881