A Northwestern University research team has designed and synthesized a new material with ultrahigh porosity and surface area for the storage of hydrogen and methane for fuel cell-powered vehicles. These gases are attractive clean energy alternatives to carbon dioxide-producing fossil fuels.

Highly porous programmable sponge for clean energy storage. Image Credit: Northwestern University. Click image for the largest view.

The material is a type of a metal-organic framework (MOF) that can store significantly more hydrogen and methane than conventional adsorbent materials at much safer pressures and at much lower costs. A one-gram (0.0353 ounce) sample of the material (with a volume of six M&M candies, 3.816 cubic centimeters, or 0.233 cubic inches) has a surface area that would cover 1.3 football fields.

Omar K. Farha, who led the research said, “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.” Farha is an associate professor of chemistry in the Weinberg College of Arts and Sciences. He also is a member of Northwestern’s International Institute for Nanotechnology.

Adsorbents are porous solids which bind liquid or gaseous molecules to their surface. Thanks to its nanoscopic pores, the one-gram sample of the Northwestern material has a surface area that would cover 1.3 football fields or 74,880 square feet (6957 square meters).

The new material 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 study, combining experiment and molecular simulation has been published by the journal Science.

The ultraporous MOFs, named NU-1501, are built from organic molecules and metal ions or clusters which self-assemble to form multidimensional, highly crystalline, porous frameworks. To picture the structure of a MOF, Farha said, envision a set of Tinkertoys in which the metal ions or clusters are the circular or square nodes and the organic molecules are the rods holding the nodes together.

Hydrogen- and methane-powered vehicles’ fuel tanks currently require high-pressure compression to operate. The pressure of a hydrogen tank is 300 times greater than the pressure in car tires. Because of hydrogen’s low density, it is expensive to accomplish this pressure, and it also can be unsafe because the gas is highly flammable.

Developing new adsorbent materials that can store hydrogen and methane gas onboard vehicles at much lower pressures can help scientists and engineers reach U.S. Department of Energy targets for developing the next generation of clean energy automobiles.

To meet these goals, both the size and weight of the onboard fuel tank need to be optimized. The highly porous materials in this study balance both the volumetric (size) and gravimetric (mass) deliverable capacities of hydrogen and methane, bringing researchers one step closer to attaining these targets.

Farha said, “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.”

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.

Farha is the lead and corresponding author. Zhijie Chen, a postdoctoral fellow in Farha’s group, is co-first author. Penghao Li, a postdoctoral fellow in the lab of Sir Fraser Stoddart, Board of Trustees Professor of Chemistry at Northwestern, also is a co-first author. Stoddart is an author on the paper.

Freshly designed makes for quite an exciting breakthrough. Lower pressure and “huge” volumes of gas make for milestone being reached. Yet the abstract shows working pressures up to 100 bar or 1450 psi. This is not the kind of pressure that will function in today’s amazing polymer fuel tanks convoluted to fit maximum capacity into small spaces.

Still, this technology helps immensely as today hydrogen storage solutions can run up to as much as 700 bar or 10,150 psi.

But before one gets real excited, be sure to consider the information here, and read the whole thing. https://en.wikipedia.org/wiki/Hydrogen_safety .

Yes, the Northwestern team does have a breakthrough, but it is not a solution for making a hydrogen economy. The disappointment is mentioning the application to methane (natural gas), but not providing those details.


Comments

4 Comments so far

  1. Matt Musson on May 6, 2020 8:43 AM

    Why do I get the feeling that this is another breakthrough material that is synthesized one gram at a time, orders of magnitude more expensive than gold or platinum.

  2. Brian Westenhaus on May 8, 2020 9:03 AM

    Good intuition there, Matt! It helps get a hydrogen economy closer, but that is still – very far away, indeed.

  3. Jagdish on May 7, 2020 1:20 PM

    Methane is a fuel found in ground and its management at lower pressure may be helpful. However hydrogen is a synthetic fuel and is not a commercially suited product. We should best go for smokeless liquid fuels like ethanol and methanol which are better handled as fuel for fuel cells.

  4. Brian Westenhaus on May 8, 2020 9:06 AM

    If thought about with a sense of what reality allows, you’re right. Hydrogen is great when its atoms are connected to some carbon in a molecule.

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