UD catalyst can convert CO2 to CO with 92 percent efficiency
A team of researchers at the University of Delaware has developed a highly selective catalyst capable of electrochemically converting carbon dioxide — a greenhouse gas — to carbon monoxide with 92 percent efficiency. The carbon monoxide then can be used to develop useful chemicals.
The researchers recently reported their findings in Nature Communications.
“Converting carbon dioxide to useful chemicals in a selective and efficient way remains a major challenge in renewable and sustainable energy research,” according to Feng Jiao, assistant professor of chemical and biomolecular engineering and the project’s lead researcher.
Co-authors on the paper include Qi Lu, a postdoctoral fellow, and Jonathan Rosen, a graduate student, working with Jiao.
The researchers found that when they used a nano-porous silver electrocatalyst, it was 3,000 times more active than polycrystalline silver, a catalyst commonly used in converting carbon dioxide to useful chemicals.
Silver is considered a promising material for a carbon dioxide reduction catalyst because of it offers high selectivity — approximately 81 percent — and because it costs much less than other precious metal catalysts. Additionally, because it is inorganic, silver remains more stable under harsh catalytic environments.
The exceptionally high activity, Jiao said, is likely due to the UD-developed electrocatalyst’s extremely large and highly curved internal surface, which is approximately 150 times larger and 20 times intrinsically more active than polycrystalline silver.
Jiao explained that the active sites on the curved internal surface required a much smaller than expected voltage to overcome the activation energy barrier needed drive the reaction.
The resulting carbon monoxide, he continued, can be used as an industry feedstock for producing synthetic fuels, while reducing industrial carbon dioxide emissions by as much as 40 percent.
To validate whether their findings were unique, the researchers compared the UD-developed nano-porous silver catalyst with other potential carbon dioxide electrocatalysts including polycrystalline silver and other silver nanostructures such as nanoparticles and nanowires.
Testing under identical conditions confirmed the non-porous silver catalyst’s significant advantages over other silver catalysts in water environments.
Reducing greenhouse carbon dioxide emissions from fossil fuel use is considered critical for human society. Over the last 20 years, electrocatalytic carbon dioxide reduction has attracted attention because of the ability to use electricity from renewable energy sources such as wind, solar and wave.
Ideally, Jiao said, one would like to convert carbon dioxide produced in power plants, refineries and petrochemical plants to fuels or other chemicals through renewable energy use.
A 2007 Intergovernmental Panel on Climate Change report stated that 19 percent of greenhouse gas emissions resulted from industry in 2004, according to the Environmental Protection Agency’s website.
“Selective conversion of carbon dioxide to carbon monoxide is a promising route for clean energy but it is a technically difficult process to accomplish,” said Jiao. “We’re hopeful that the catalyst we’ve developed can pave the way toward future advances in this area.”
The research team’s work is supported through funding from the American Chemical Society Petroleum Research Fund and University of Delaware Research Foundation. Jiao has patented the novel application technique in collaboration with UD’s Office of Economic Innovation and Partnerships.
Catcracking:
Thanks for your reply at February 2, 2014 at 1:29 pm.
I don’t know what you mean by “high pressures”. The process operates at ~2 atm.
The temperature is limited to ~980°C because higher temperature causes slagging in the fluidised bed and highest temperature is desired. The plant design does use mostly refractory linings for pipework, etc. but – as I said – expansion lengths and sensor covers are intended to operate at gas temperature.
Gasometers have their name because they telescope and their height is a direct indication of their contents. That is why they have numbers on their sides. The exposed numbers provide a direct indication of how much gas is in the gasometers. A really clever piece of Victorian technology.
I, too, have doubts about the reported catalyst and I said that above here. However, as I also said, if an efficient method for the conversion could be achieved then it would enable immense benefits.
Incidentally, I lived on an ocean-going power cruiser for nearly five years to do a project and I returned to land-living about a decade ago. Sacrificial anodes need replacement annually and are expensive.
Richard
Richard,
Except for vacuum pipestills, 2 atmospheres would be the starting point for most Refining processes and pressures can run up to thousands of psi for hydrotreating and desulfurization processes.
I did a lot of engineering for petroleum coke, fluid bed gasifiers as part of a FLEXICOKING Unit process which use air compressors and operated at circa 1800 F . A low BTU gas is produced that was burned in furnaces in the refinery. Slag can also an issue with these gasifiers when vanadium is present in the feed.
Hmm This seems to have vanished. I will try again.
Catcracking:
Thanks for the interesting conversation and information. I have filed your technical info. for future reference.
I hope I have answered your questions. I don’t think I can add much more. I may have already said more than I should.
So, unless you have further specific queries, I am signing off from this with sincere thanks.
Richard
Richardscourtney:
In response to your Feb 2, 2014 @ur momisugly 12:48 comments I offer the following:
First please keep in mind that I make a very good living creating utility generation/chemical process strategies to meet emission goals, develop policy recommendations, financing research, plan capacity expansions, recommend plant closures, and formulate comment on proposed regulations. I’ve been doing this for over thirty years… so, I’m no novice. This not intended to be an appeal to authority. Nor am I trying to puff myself up… lord knows I don’t know everything. But it helps provides context for what I’m about to say. And I’m open to dissenting views.
With regard cost of air and hydro pumped storage. Your correct that both technologies are good for peak power; however, I think your underestimating value of these assets at minimum load. Specifically that both systems save as much money at the minimum daily load as they do a the daily peak (if not more). Specifically, that at minimum load these assets minimize the need to shut -down units thus avoid the maintenance and fuel cost of start-up that may be required 2-3 hours later in the daily cycle.
In my view, in today’s market, a typical regional utility (serving several million people) will benefit if it has roughly 1,000-1,500 Mw of dispatch-able storage capacity. However, to be economically viable, each dispatch-able unit needs to be capable of 200-400 Mw per unit to capture the economics-of-scale. Further, each unit must be able to dispatch within 15 minutes – both in terms of storing and discharging power. And, ideally, all of the storage units must be available to accept power from the utilities entire fleet of generating units and the storage units must be able to discharge power to the grid in a manner that allows transmition to all parts of the grid.
The short version is, to make energy storage economical, you need a good deal of “system” storage capacity with individual unit capacities large enough to readily dispatch in on short notice
With regard to Compressed Air Energy Storage (CAES). Your comments regarding safety appear to related to small-scale above ground air storage. I was referring to large-scale underground air storage in the 200-250 Mw range. Several commercial units have been constructed since the late 1970’s; so, this is a fairly mature technology. Safety wise I’m fairly confident there will not be any “towns falling down” on you :).
With regard to your comment that hydro pumped storage is “expensive” . All energy options are “expensive”. The appropriate metric is wither they make economic sense. Until recently pumped hydro was the least expensive option for utility scale energy storage followed by CAES. Recent developments suggest CAES may be the lease expensive option.
Regarding your statement that pumped storage “lacks appropriate sites”. The same could be said of CAES which requires the presence of suitable caverns. However, because a typical utilities storage needs are regional in nature (see above) you really don’t need that many sites. In this context there are a more suitable sites than one might think. If you’re in a prairie state build a CAES. In a mountain state build a pumped storage unit or modify an existing dam to suit that purpose. If your state does not have a suitable site, build in an adjacent state or contract with another utility that has a suitable site.
With regard to your comment “The physical size of [fluid] batteries would be a problem, and fluid batteries also pose severe safety risks. If you think nuclear power gets opposition then think how difficult it would be to get approval for large battery storage”.
Well… not to trying to be offensive but the fact is I’m quite familiar with the environmental impact statements and hazard assessments associated with planned fluid battery projects – in particular one that was to be located in Mississippi in the early 2000’s (It was a polysulfide bromide regenerative fuel cell process). The hazard levels simply weren’t that high and there was no public resistant to the project . Unit size was 12 Mw and covered a mere 2 acres. The project was never completed because the company that owned the technology ran into scale-up problems and went broke before it could solve the problem. Concept wise, I’m more an advocate of the vanadium redox process myself; but the vanadium research/development communities products are currently in the 0.5 Mw/Unit range. This is too low a capacity to garner my immediate interest. I’ll start to get excited when the 10 plus Mw/unit range is achieved.
Regarding your comment “In the days of ‘town gas’ was used as an energy store”. I’m not aware of any storage mechanism (use of tanks etc) associated with town gas. If you could point to a source I’d happy to look it over. In my view the magnitude of storage required to meet systems needs requires roughly the same type/capacity of underground storage currently contemplated for CAES or seasonal natural gas storage. Loads issue can last a long as three days, so many people underestimate the amount of energy storage capacity required to pay for storage systems. As a general rule of thumb you’re looking at building roughly 24-30 hours of energy storage capacity with an expectation of fully discharging the stored capacity in 20-24 hours – to ride out mult-day incidents and optimize the economic benefits. Above ground storage is possible; but too expensive at this level of storage and the hazard assessment for high volume above ground CO storage is going to be tough – much tougher than ammonia storage. So I’d have to have a pretty compelling argument to use the CO2 to CO process to over the other options.
I’ll make one final set of observations regarding CO from CO2 process viability for energy storage.
The CO2 to CO process produces a gas that is distinctly different from ‘town gas’. Town-gas was typically produced by adding steam to the input air; so, the gas usually contained a considerable amount hydrogen in addition to CO. The hydrogen gave the gas a higher caloric value and improved flame stability. This distinctly different from the pure CO gas produced by the CO2 to CO process.
Should one attempt to use a pure low-caloric CO gas source in today’s technology I can foresee practical process problems. To begin, to meet the 15 minute start-up limit described above, we would likely have to use a Combustion Turbines (CT) to produce the electrical generation needed.
Today’s Combustion Turbines (CTs) are designed to use natural gas. In particular, a modern CT is designed to minimize NOx and CO emissions while burning natural gas. When one substitutes natural gas with say a coal-based syn-gas one has to modify both the sny-gas and the CT. Essentially one typically optimizes the syn-gas’s original CO/H2 ratio to increase the gas heat content (add H2) to ensure complete combustion and minimize CO emissions at ppm levels. The increased H2 also increases the flame stability which helps prevent flame-out and back-flash issues. The down side of increasing the H2 content is that the flame temperature increases NOx production. To counter NOx production, excess dilution air is added to the CT which lowers the gas temperature, but at the expense of unit energy efficiency… as the compressor providing the dilution air has to handle the increased air volume.
So, you’re likely to run into some problems when you try to feed a pure CO feedstock into these CTs. First off, I strongly suspect you’re going to hit serious flame stability issues – which can lead to safety issues… risk of flame-out and flash-back. Plus the flame stability issues could damage the CT due to intermittent mechanical shock. So, selling this concept to utility executives is going to be a “hard sell”. And good luck trying to get CT manufactures to modify their designs for a CO-only feed. We been trying to get a syn-gas optimized CT for many years.
Next, the CT’s combustion efficiency is likely to go down – way down – resulting in much higher CO emissions. So, at first blush, meeting the unit’s CO emission limit looks highly problematic.
Now one might try to argue that we could adjust the CO/H2 ratio using upstream CO shift reactors. But, the reality is we need steam to drive the reaction and CO Shift reactors operate a high temperature. So is unlikely that we’d be able to get the these systems operating in required 15 minute time-frame.
Likewise we can’t raise the steam in a steam system, simply because we can’t steam operational in the required time-frame.
At present, my problem with CO2 to CO concepts is that they don’t meet my real world operational needs – it looks like a process in search problem. If someone can point me to a CO2 to CO process layout that will actual meet a utilities needs I’d happy to be look at it. But, as it stands I’m not seeing the “carrot”.
Regards, Kforestcat
Kforestcat:
Thankyou for your post at February 2, 2014 at 8:57 pm.
You provide much useful information. Thankyou.
As my earlier posts in this thread demonstrate, I strongly agree with you that – assuming safety issues are resolved – the only thing which matters is economics. And I note you say
Well… not to trying to be offensive but the fact is that your comment I quote supports what I said and you have answered; i.e. I wrote
Your report says the example you cite did prove the battery project to be not viable because technical problems of scale-up caused the company to go broke.
I am not convinced by your claims that MWh stored as compressed air does not pose a severe disaster risk.
We seem to broadly agree about hydro and about pumped storage.
I am surprised that you ask
Every town that had a ‘gas works’ used gasometers to store gas (i.e. an energy store). Here is a picture which shows what they look like.
And I am fully aware of the differences between ‘towns gas’ and natural gas (i.e. methane or propane) and I am surprised that my comments in this thread have not – at least – hinted that.
We are not discussing ‘towns gas’ in this thread. We are discussing CO2–>CO with possible controlled addition of H2. I see no reasons for such a gas to have problems of flame stability.
Anyway, we are discussing potential tech. and there is no flame in fluidised bed combustors. Some are multi-fuel: we burned wet sewage as fuel in a PFBC.
You say
The problem exists of need for large scale energy storage for electricity grid smoothing.
CO2–>CO is a potential solution to it.
Unless and until efficient CO2–>CO exists there is no point in anybody designing a “process layout that will actual meet a utilities needs”.
Research to obtain efficient CO2–>CO is the subject under discussion in this thread.
Richard
@ur momisugly Richard & Kforestcat al
Here is the sad side of it.
In Ernst G.Riesenfeldts Lehrbuch der anorganischen Chemie from 1946 4rth edition at Nobelinstituttet Stockholm I find notation of the Carbonyls. Reference Hieber 1931.
Fe(CO)5
FeH(CO)4
Cr(CO)6
CoH(CO)4
Ni(CO)4
Mo(CO)6
W(CO)6
Comment: “Diese sind in der beständigen Carbonylen und Carbonylwasserstoffen zu stabilen 18er-Schalen zusammengetreten…
They make psevdo- noble- gas outer shell- structures. “Und dass man das Metall als 0-werig ansehen muss”
and then the pity: “Die zerstörende Wirkung von Wassergas auf Eisen zb in Gasometern mit stark wassergashältigem Leuchtgas.. blablabla…”
It is eating iron you see, and further stainless steel as you can see from the formulas,….
The carbonyls do not dissolve in water, but dissolve easily in gasoline for instance, and distill over and pass through any physical filter and oxidize with air and condens water in the tank into dark brown metal carbonates. Making the brown hairs of the Tiger on the tank, that further clog the carburator allways in the most critical and dangerous situations.
Tigers do not belong in the tank, but they get into there anyway and eat the metals and clog the carburators.
White tigers are quite especially dangerous. Analysis show Zink- carbonate sediments in the carburator after having passed all filters.. That is explainede as Grignards reaction between obscure products from the cracker with freshly galvanized tank waggons.
Sulphide being a catalyst for the formation of carbonyls.
on sulphur:
Galvanized 3/8 Iron chains keep in seawater in the Oslofjord. But slightly further up in Tyrifjorden with Freshwater and silur & fossile vulcanism, they start to eat under the zink layer if there is a hole, until the iron is eaten all through, leaving a dark FeS- mud behind.
That is Fe & Sulphur bacteriæ in the bottom muds of the freshwater relict fjord. .
They make a big feast, probably reducing SO4– from the water to sulphide by ignoring the zink and eating metallic Fe under it quite greedy with proper teeth of Sulphur..
Titanic is now halfway eaten up the same way.
It is “Early life”.(Fe and sulphur bacteriæ)
They eat meteorite iron leaving the nickel and platinum contents behind.
Conclusion:
There is a lot of possible activities and potensials in the universe even where stainless steel has been used, relating to Carbonyls, sulphur, and Cyanide. I see also Fe Nitrosyl discussed.
Thus I believe that wherever you find pure iron and iron ore of any kind in the universe,, it is proof of water, and of early life. CO also playing a role in the system.