Researchers find a surprise just beneath the surface in carbon dioxide experiment
Caltech, Berkeley Lab teams combines theory, X-ray experiments to explain what’s at work in copper catalyst
In a classic tale of science taking twists and turns before coming to a conclusion, two teams of researchers–one a group of theorists and the other, experimentalists–have worked together to solve a chemical puzzle that may one day lead to cleaner air and renewable fuel. The scientists’ ultimate goal is to convert harmful carbon dioxide (CO2) in the atmosphere into beneficial liquid fuel. Currently, it is possible to make fuels out of CO2–plants do it all the time–but researchers are still trying to crack the problem of artificially producing the fuels at large enough scales to be useful.
In a new study published the week of June 12 in the journal Proceedings of the National Academy of Sciences (PNAS), researchers report the mechanics behind an early key step in artificially activating CO2 so that it can rearrange itself to become the liquid fuel ethanol. Theorists at Caltech used quantum mechanics to predict what was happening at atomic scales, while experimentalists at the Department of Energy’s (DOE’s) Lawrence Berkeley National Lab (Berkeley Lab) used X-ray studies to analyze the steps of the chemical reaction.
The scientists are part of the Joint Center for Artificial Photosynthesis (JCAP), a DOE Energy Innovation Hub, whose goal is to convert CO2 into high-value chemical products like liquid fuels. JCAP is led by Caltech in partnership with Berkeley Lab, the Stanford Linear Accelerator Center (SLAC), and UC campuses at San Diego and Irvine.
“One of our tasks is to determine the exact sequence of steps for breaking apart water and CO2 into atoms and piecing them back together to form ethanol and oxygen,” says William Goddard (PhD ’65), the Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics, who led the Caltech team. “With these new studies, we have better ideas about how to do that.”
The metal copper is at the heart of the reaction for converting CO2 to fuel. Copper is a catalyst–a material used to activate and speed up chemical reactions–and, while it aids in the production of ethanol when exposed to CO2 and water, it is not efficient enough to make large quantities of ethanol. At Berkeley Lab, researchers exposed a thin foil sheet of copper to CO2 gas and water at room temperature. They found that the copper bound CO2 weakly and that adding water activated the CO2 by bending it into the shape needed to ultimately form the ethanol. However, when the theorists at Caltech used quantum mechanics and computer models to predict the atomic-level details of this reaction, they found that pure copper would not bind the CO2 and that water would not activate it.
CREDIT Berkeley Lab
This left both teams scratching their heads until they noticed that the copper in the experiments contained tiny amounts of oxygen beneath its surface. The theorists went back to their quantum mechanics equations, adding in a tiny amount of sub-surface oxygen, and were happy to find their calculations all agreed with the experiments.
“We do our experiments virtually in computers,” says JCAP research scientist Hai Xiao (PhD ’15). “And this allows us to trace how the electrons and atoms rearrange themselves in the reaction, and thus unravel the correlation between the fundamental structure and the activity.”
The theorists also predicted that when too much oxygen was present, the CO2 would not be activated. Indeed, when the experimentalists deliberately added extra oxygen into the mix, this prediction was confirmed.
“This back and forth between theory and experiment is an exciting aspect of modern research and an important part of the JCAP strategy for making fuels from CO2,” says Goddard.
Subsequent X-ray studies helped further narrow down the role of the oxygen in the reaction. “Having oxygen atoms just beneath the surface–a suboxide layer–is a critical aspect to this,” says Ethan Crumlin, a scientist at Berkeley Lab. “The X-ray work brought new clarity to determining the right amount of this subsurface oxygen–and its role in interactions with CO2 gas and water–to improve the reaction.”
The scientists say that the presence of the oxygen in the copper causes some of the copper to become positively charged and this, in turn, stabilizes the CO2 so that it can bind to water and take on the bent configuration essential to eventually making ethanol.
Based on the new findings, the Caltech researchers then used quantum mechanics to predict ways to make the reaction even more efficient. In a second paper published this week in PNAS, they report that a copper surface that is striped with both neutral and positively charged copper will better speed the reaction along. The team is now using this strategy, called a Metal-Embedded-in-Oxygen-Matrix (MEOM), to predict the best oxide material–either copper or something new–to place next to the neutral copper strips to achieve the fastest reaction.
“Quantum mechanics lets us find the best ways to arrange the atoms and takes us closer to the goal of converting carbon dioxide to fuels and other useful materials,” says Goddard.
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The first PNAS paper, titled “Subsurface oxide plays a critical role in CO2 activation by Cu(111) surfaces to form chemisorbed CO2, the first step in reduction of CO2,” is authored by Crumlin, Marco Favaro, and Junko Yano of Berkeley Lab; and Xiao, Goddard, and Tao Cheng of Caltech.
The second PNAS paper, titled “The Cu Metal Embedded in Oxidized Matrix Catalyst to Promote CO2 Activation and CO Dimerization for Efficient and Selective Electrochemical Reduction of CO2,” was authored by Xiao, Goddard, Cheng, and Yuanyue Liu, a Resnick Sustainability Institute Postdoctoral Scholar at Caltech.
This research was supported by the DOE Office of Basic Energy Science and by JCAP.
The problem, as I see it, is that ethanol is a long-lived, highly toxic green house gas, that combines readily with water
There is no free lunch in energy, energy out is always less than energy in.
For perspective on computational materials engineering state-of-the-art circa 2007:
Computational Materials Engineering
An Introduction to Microstructure Evolution
Author(s): Koenraad G.F. Janssens, Dierk Raabe, Ernst Kozeschnik, Mark A. Miodownik and Britta Nestler
ISBN: 978-0-12-369468-3
Copyright © 2007 Elsevier Inc. All rights reserved
“Computational Materials Engineering is an advanced introduction to the computer-aided modeling of essential material properties and behavior, including the physical, thermal and chemical parameters, as well as the mathematical tools used to perform simulations. Its emphasis will be on crystalline materials, which includes all metals. The basis of Computational Materials Engineering allows scientists and engineers to create virtual simulations of material behavior and properties, to better understand how a particular material works and performs and then use that knowledge to design improvements for particular material applications. The text displays knowledge of software designers, materials scientists and engineers, and those involved in materials applications like mechanical engineers, civil engineers, electrical engineers, and chemical engineers. Readers from students to practicing engineers to materials research scientists will find in this book a single source of the major elements that make up contemporary computer modeling of materials characteristics and behavior. The reader will gain an understanding of the underlying statistical and analytical tools that are the basis for modeling complex material interactions, including an understanding of computational thermodynamics and molecular kinetics; as well as various modeling systems. Finally, the book will offer the reader a variety of algorithms to use in solving typical modeling problems so that the theory presented herein can be put to real-world use. Balanced coverage of fundamentals of materials modeling, as well as more advanced aspects of modeling, such as modeling at all scales from the atomic to the molecular to the macro-material. Concise, yet rigorous mathematical coverage of such analytical tools as the Potts type Monte Carlo method, cellular automata, phase field, dislocation dynamics and Finite Element Analysis in statistical and analytical modeling. Companion web site will offer ample workable programs, along with suggested projects, resources for further reading, and useful classroom exercises.”
“…harmful carbon dioxide (CO2) in the atmosphere…”
Harmful only if you don’t want any plant life on earth.
What’s up with this?
Every Air Bar will want one.
I am reminded of the desperation behind creating oxygen generators on the dead sea bottoms of Barsoom.
The only copper you need to make ethanol is that in a still.
The sugar to ferment into alcohol comes from CO2 and water in the first place.
Gabro,
Which implies that a low-tech, but probably more practical, approach would be to grow sugar beets or sugar cane in green houses in proximity to fossil fuel power generating plants. The increased growth rate created by the elevated CO2 and higher temperatures would produce more sugar than if the same plants were grown in the open.
Yes. The startup costs of the greenhouses wouldn’t be a pimple on the posterior of the costs for these researchers’ catalytic process, interesting though it might be scientifically.
And the captive oxygen released by those sugar-producing plant plants would also be valuable.
2 (H2O + 2 (CO2) -> 2 HOOCH. + O2
Makes sense to me
Makes dollars and cents as well.
But I’m partial to ethanol.
The substance, not the subsidies to make it to add to gasoline. If you want ethanol in gasoline, you can make it in the petroleum cracking process.
Really? What does formic acid have to do with this?
Ethanol is C2H5OH.
Formic acid is more related to methanol (wood alcohol) than ethanol.
The formic acid and formaldehyde produced as metabolites of methanol are responsible for the optic nerve damage leading to blindness from methanol poisoning, as from drinking Sterno (canned heat),
The catalytic hydrogenation of CO2 to formic acid can be conducted homogeneously.
Formic acid is the original “ant-acid”.
The Ant
The ant has made himself illustrious,
through constant industry, industrious.
So what? Would you be calm and placid,
if you were full of formic acid?
– Ogden Nash
Reading some of the stupid anti global warming comments here, just convinces me more and more that stupid people shouldn’t read scientific news, as they are too stupid to grasp even very basic concepts.
Of course talking about this research being used in scrubbers to remove CO2 from out of the atmosphere is just stupid… And I quote “The scientists’ ultimate goal is to convert harmful carbon dioxide (CO2) in the atmosphere into beneficial liquid fuel.”. I doubt that is their ultimate goal. Gee, why not use it on the tail pipe of a friggen coal plant, where the CO2 is way more concentrated and is already hot (some of the energy comes from using thermal piles, some comes from the hot gas itself)? This is obviously what this type of research is meant to ultimately be used for.
To the idiot who likened recycling CO2 into ethanol research as perpetual motion…. You first need to think of fossil fuels as energy storage. Petroleum based fuels (like ethanol) are popular because of their high energy density. Ethanol can also be made from CO2 & H20, but currently the amount of energy needed is way too high for it to be worthwhile, hence the catalytic materials research this article is about. Now if you can take “some” of that CO2 being emitted using a minimal amount of energy (nobody said anything about it being above unity), and turn it into a more portable type of energy (like ethanol) that can be used in [let’s say] cars and trucks, you are able to get a second shot of energy from that same amount of CO2. This doesn’t stop or reverse CO2 emissions, but if done on a large scale, it would have the net effect of reducing emissions, because it lets you “burn” some of the carbon twice.
But why do you want to reduce emissions of the plant food which is fertilizing the world?
If we weren’t producing CO2 through industrial, heating and transport processes, it would behoove us to do so simply to increase vegetation on our planet, and allow it to spread into desert areas.
Four hundred ppm is way better than 200 ppm, but 800 ppm would be even better and 1200 ppm best of all, ie the level maintained in commercial greenhouses. If that also slightly warmed the globe, that too would be welcome, but there is no evidence that 1200 ppm would actually have a measurable effect on average temperature.
“John Smith” wrote, “Gee, why not use it on the tail pipe of a friggen coal plant… This is obviously what this type of research is meant to ultimately be used for.”
The energy density of ethanol (C2H6O) is about 26 MJ/kg. It is (2*12)/(2*12+6*1+1*16) = 52.2% carbon.
The energy density of coal is about 30 MJ/kg, and high-quality coal is more than 80% carbon.
So, assuming 100% efficiency at every step (haha!):
1. Burning 1 kg of coal will produce 30 MJ of energy.
2. Converting the CO2 which that process emits into 0.80/0.522 = 1.53 kg of ethanol will require 40 MJ of energy.
So even if every process step is 100% efficient, and even if you use all the energy from burning the coal to make ethanol, you still can convert only 3/4 of the CO2 emitted into ethanol.
Alternately, if you “capture” all the CO2 this way, your “power plant” must necessarily be a net consumer of power.
.
Mr. Smith continued, “To the idiot who likened recycling CO2 into ethanol research as perpetual motion…”
“You Idiot!” says the pot to the kettle.
.
Mr. Smith continued, “if you can take “some” of that CO2 being emitted using a minimal amount of energy (nobody said anything about it being above unity), and turn it into a more portable type of energy (like ethanol) that can be used in [let’s say] cars and trucks, you are able to get a second shot of energy from that same amount of CO2. This doesn’t stop or reverse CO2 emissions, but if done on a large scale, it would have the net effect of reducing emissions, because it lets you “burn” some of the carbon twice.”
Which makes exactly as much (non)sense as piping the ethanol back to the coal plant’s combustion chamber, to burn along with the coal, so that you can “burn some of the carbon twice.”
Mr. “Smith,” is your real name Paul McDonald?
I think you called me an idiot. Very naughty.
But the technically literate will recognize your entire second paragraph to be technical gibberish – burning carbon twice, please. I’d suggest you spend some time with an undergraduate thermo text and try to grasp the basic concepts.
ps. it is, in fact, a perpetual motion machine.
Catalyst? Please.
It is interesting how often researchers insert some subjective, inherently political, comment (e.g. harmful carbon dioxide) in their work to presumably justify their work. I don’t know if it is just unthinking blathering or a purposeful attempt to make their work more grant-worthy. In any event, it is a practice to be frowned upon because it is not germane to the actual results that they are presenting. Further, the consensus opinion may change later, making their work appear antiquated and of questionable objectivity. This appears to be another example of how Big Science grant-funding is corrupting science. It is akin to the use of pejorative descriptors such as “ocean acidification.”
Energy is required to make this reaction work. Plants use solar energy to do that. This process might have potential for storing energy produced by intermittent sources if the technology can provide a reasonable, unsubsidized return on investment. However it can not produce additional energy by itself. That would be perpetual motion, which is idiotic.
I am pleased to reveal that I have found a way to use CO2 as a catalyst to fuel better health.
Breath slowly in for a count of twenty seconds, concentrating on expanding your diaphragm to the max. Hold just a second or so, then exhale slowly for a count of twenty seconds, concentrating on purging all air from your lungs. On the inhale, gather your arms inward towards your solar plexus, extending them, in a continuous fashion through the central axis of your body, all the way over head, then allowing them to fan out to the side and descend slowly and smoothly on the exhale. At the end of each cycle, if you do it with utmost focus, you will feel a delightful sensation of a deep, complete, fulfilling breath (like when yawning), and you can duplicate this quality of focused breathing with practice, for numerous, successive cycles.
This is how I catalyze “harmful CO2” into “pie-in-the-sky” metabolic fuel .
Thanks for tuning in.
The actual PNAS articles do not refer to “bad or harmful” CO2. The “harmful” CO2 silliness was either added by the Cal Tech PR group or the author of this article.
The energy usage quoted was in the 5 – 10 mA/cm**2 and -0.4 – -0.6 V range.
No officer, I wasn’t drinking, I just popped this copper catalyst into my mouth.
Now seriously, catalysts don’t change thermodynamics, they just lower the barriers of chemical pathways to speed reactions. Converting CO2 to EtOH still requires the input of energy.
Now if only that principle could be applied with the climate models and reality.
““We do our experiments virtually in computers,” says JCAP research scientist Hai Xiao (PhD ’15).”
Sheesh! A 2yr old PhD? That is not an experiment! It is a simulation. I do all my base application/OSD testing, virtually, with virtual machines because I can take a snapshot, make a change, and revert back to that snapshot if it fails. I then conduct a test in the real world.
This sounds very interesting. Lets hope they can figure out a way to do it on a large enough scale to make it economical. At the same time I think we need to remember there is an overall benefit to let the CO2 continue to increase for the benefit of plants/agriculture. May need to study the pros and cons of that benefit.
It is illogical. CO2 is produced by extracting energy from a fuel. To turn that CO2 back into a fuel you would need to put the same amount of energy back in. There are only two ways to do that. One is to get it from burning more fossil fuel, which is obviously self defeating. The other is to use energy from the sun and the wind, wind turbines and solar panels. The problem is that these two are woefully inadequate. They can’t even keep up with the increase in global energy demand, let alone have spare capacity to manufacture fuel.
My PhD research was in part about hydrogenation of CO2 on a supported copper catalyst (yes, I always knew it requires energy input), and 10-15 years ago the specialized literature was filled with furious discussions regarding the exact mechanism of CO and CO2 reactions on copper catalyst – which have wider use in the industry than hydrogenation of CO2 (ie. removal of CO from the hydrogen stream in ammonia plants).
This work by Caltech and Berkeley could finally resolve the mechanism of reactions on copper. Also, it is perfectly normal for researchers into the depths of solid state physics and surface reactions to ignore issues like energy balances. That is a matter for the chemists preparing catalysts based on the fundamental discoveries, and for the engineers using them in chemicals plants, to solve.
Of course the press release has to touch the hot topics. That’s a scourge of modern times.
Extracting CO2 from 400 ppm air is like gold mining from ores with gold concentrations less than 1 microgram per ton.
I wonder if they have tried using magnesium instead of copper in their theoretical model. Mg is central to the chlorophyll molecule used by plants to get energy from photons, combining H2O and CO2 to form sugars. “Go to the ‘plant’ thou sluggard; consider her ways and be wise!”
Chlorophyll does indeed include Mg however it is used to break up water to form electrons, H+ and O2 as a result of absorption of light. It is not involved in the reduction of CO2. The copper catalyst binds the CO2 as a substrate so it catalyses a different reaction.
So much energy expended on nonsense. Firstly CO2 is not a pollutant, it is feed-stock for plants, without which we all perish. Secondly, if you believe in AGW nonsense, then by reducing the CO2 content, you kill the plant life, and bring the globe into a new frozen state, in which we all die.
Tree rings are the myth busters that climate change money spinners don’t want anyone to know about. This perfect evidence shows climate changed warm to cold to hot again over hundreds of years without any naughty mankind, or any CO2 produced by anyone.
Everyone realizes this is technically a literal perpetual motion machine. Right?
Financially it is graft.
The key here is excess CO2 and what to do with it. For sometime others have known how to convert CO2 into usable products like formic acid and syngas efficiently. Example: MVTG. So far governments, industry and progressive investors have not seen the vision of CCU vs CCC. Perhaps you here can help them along.