Rice researchers develop catalyst that could render SMR for hydrogen production emissions-free; plasmonic photocatalysis
12 November 2024
Rice University researchers have developed a catalyst that could render steam methane reforming (SMR) entirely emissions-free by using light rather than heat to drive the reaction. SMR is currently responsible for more than half of global hydrogen production and is emissions-intensive.
The new copper-rhodium photocatalyst sports an antenna-reactor design that, when exposed to a specific wavelength of light, breaks down methane and water vapor without external heating into hydrogen and carbon monoxide.
The research could prove instrumental for extending catalyst lifetimes in general, improving efficiencies and reducing costs for a number of industrial processes plagued by coking, a form of carbon buildup that can deactivate catalysts. A paper on the discovery is published in Nature Catalysis.
This is one of our most impactful findings so far, because it offers an improved alternative to what is arguably the most important chemical reaction for modern society. We developed a completely new, much more sustainable way of doing SMR.
—Peter Nordlander, Rice’s Wiess Chair and Professor of Physics and Astronomy and professor of electrical and computer engineering and materials science and nanoengineering
Nordlander and Naomi Halas, Rice University Professor and the Stanley C. Moore Professor of Electrical and Computer Engineering, are the corresponding authors on the study.
The new SMR reaction pathway leverages the 2011 discovery from the Halas and Nordlander labs at Rice that plasmons—collective oscillations of electrons that occur when metal nanoparticles are exposed to light—can emit “hot carriers” or high-energy electrons and holes that can be used to drive chemical reactions.
Yuan et al.
We do plasmonic photochemistry—the plasmon is really our key here—because plasmons are really efficient light absorbers, and they can generate very energetic carriers that can do the chemistry we need them to much more efficiently than conventional thermocatalysis.
—Yigao Yuan, first author
The new catalyst system uses copper nanoparticles as its energy-harvesting antennae. However, since the copper nanoparticles’ plasmonic surface does not bond well with methane, rhodium atoms and clusters were sprinkled in as reactor sites. The rhodium specks bind water and methane molecules to the plasmonic surface, tapping the energy of hot carriers to fuel the SMR reaction.
The research also shows that the antenna-reactor technology can overcome catalyst deactivation due to oxidation and coking by employing hot carriers to remove oxygen species and carbon deposits, effectively regenerating the catalyst with light. Nordlander said the key to this “remarkable effect was the clever placement of the rhodium,” which is spread sparingly and unevenly across the surface of the nanoparticles.
For the most part, hydrogen is currently produced in large, centralized facilities, requiring the gas to be transported to its point of use. In contrast, light-driven SMR allows for on-demand hydrogen generation, a key benefit for use in mobility-related applications such as hydrogen fueling stations or even vehicles.
The research was supported by the Robert A. Welch Foundation (C-1220, C-1222) and the Air Force Office of Scientific Research (FA9550-15-1-0022). The Shared Equipment Authority at Rice provided valuable insights and data analysis support.
Resources
Yuan, Y., Zhou, J., Bayles, A. et al. Steam methane reforming using a regenerable antenna–reactor plasmonic photocatalyst. Nat Catal (2024). doi: 10.1038/s41929-024-01248-8
Looks good. Rhodium is very expensive ($153 / gm) so let's hope it is not consumed or lost in the process.
Also, they don't say what wavelength of light they are using.
I hope their IP is solid.
- JM
Posted by: mahonj | 12 November 2024 at 04:53 AM
How is steam methane reformation emissions free? Their illustration shows carbon monoxide being generated. All they are doing is substituting light energy for heat energy. I would write this off as just another university research project that will at best produce some research knowledge and educated students.
I first thought that SMR stood for Small Modular (nuclear) Reactor which is a possible path for emission free hydrogen generation.
Posted by: sd | 12 November 2024 at 07:30 AM
Halas and Nordlander are co-founders at Syzygy Plasmonics (https://plasmonics.tech/, a company commercializing multiple reactions based on their research.
Photocatalytic ammonia cracking for low-carbon hydrogen from clean ammonia is one. Greenhouse gas reforming for syngas/fuels is another. The photocatalytic SMR eliminates combustion and uses 40% less methane than the old way. If you capture the CO2 you could think of it as blue+ hydrogen.
Posted by: elf | 12 November 2024 at 09:22 AM
@sd
Their rationale is that carbon monoxide can be used to produce useful chemicals, and products.
They also reckon that using light rather than heat is way more energy efficient.
Posted by: Davemart | 13 November 2024 at 04:38 AM
Problem is if they're getting their light source from solar it's only 6 hours a day. They could do SMR using an electric heat source if the electric is from wind and solar with storage, that could help.
Posted by: SJC | 13 November 2024 at 11:56 AM
The paper does not explicitly say where the light comes from but it does mention the use of a specific wavelength of light so I would assume that it is laser light. How can this be more efficient than just using heat? The one advantage they might have is extending catalyst lifetimes and reducing costs for industrial processes plagued by coking, a form of carbon buildup that can deactivate catalysts when using high temperature heat. Anyway, I doubt that this will lead to low cost, low emission hydrogen. If I was going to use methane to generate hydrogen, I would try to use methane pyrolysis which converts the methane to hydrogen and solid carbon. The problem is someone would probably want to use the carbon as a clean burning fuel.
Anyway, I would still argue that the best way to make clean hydrogen is high temperature electrolysis using neclear power.
Posted by: sd | 13 November 2024 at 07:39 PM