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OAK RIDGE, Tenn.,—In a new twist to waste-to-fuel technology, scientists at the Department of Energy’s Oak Ridge National Laboratory have developed an electrochemical process that uses tiny spikes of carbon and copper to turn carbon dioxide, a greenhouse gas, into ethanol. Their finding, which involves nanofabrication and catalysis science, was serendipitous. Video follows. “We discovered somewhat by accident that this material worked,” said ORNL’s Adam Rondinone, lead author of the team’s study published in ChemistrySelect. “We were trying to study the first step of a proposed reaction when we realized that the catalyst was doing the entire reaction on its own.” The team used a catalyst made of carbon, copper and nitrogen and applied voltage to trigger a complicated chemical reaction that essentially reverses the combustion process. With the help of the nanotechnology-based catalyst which contains multiple reaction sites, the solution of carbon dioxide dissolved in water turned into ethanol with a yield of 63 percent. Typically, this type of electrochemical reaction results in a mix of several different products in small amounts. “We’re taking carbon dioxide, a waste product of combustion, and we’re pushing that combustion reaction backwards with very high selectivity to a useful fuel,” Rondinone said. “Ethanol was a surprise — it’s extremely difficult to go straight from carbon dioxide to ethanol with a single catalyst.” The catalyst’s novelty lies in its nanoscale structure, consisting of copper nanoparticles embedded in carbon spikes. This nano-texturing approach avoids the use of expensive or rare metals such as platinum that limit the economic viability of many catalysts. “By using common materials, but arranging them with nanotechnology, we figured out how to limit the side reactions and end up with the one thing that we want,” Rondinone said. The researchers’ initial analysis suggests that the spiky textured surface of the catalysts provides ample reactive sites to facilitate the carbon dioxide-to-ethanol conversion. “They are like 50-nanometer lightning rods that concentrate electrochemical reactivity at the tip of the spike,” Rondinone said. Given the technique’s reliance on low-cost materials and an ability to operate at room temperature in water, the researchers believe the approach could be scaled up for industrially relevant applications. For instance, the process could be used to store excess electricity generated from variable power sources such as wind and solar. “A process like this would allow you to consume extra electricity when it’s available to make and store as ethanol,” Rondinone said. “This could help to balance a grid supplied by intermittent renewable sources.” The researchers plan to refine their approach to improve the overall production rate and further study the catalyst’s properties and behavior. ORNL’s Yang Song, Rui Peng, Dale Hensley, Peter Bonnesen, Liangbo Liang, Zili Wu, Harry Meyer III, Miaofang Chi, Cheng Ma, Bobby Sumpter and Adam Rondinone are coauthors on the study, which is published as “High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode.” The work was supported by DOE’s Office of Science and used resources at the ORNL’s Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.
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Znanstvenici iz laboratorija Oak Ridge National Laboratory u SAD-u "slučajno" su otkrili kako preokrenuti proces sagorijevanja, time pretvarajući ugljični dioksid nazad u gorivo, piše Independent. Znanstvenici su se prilikom procesa koristili nanotehnologijom, a zapravo su htjeli pretvoriti ugljični dioksid u metanol, a ne etanol. Kako su materijali korišteni u procesu vrlo jeftini, znanstvenici smatraju da bi se ovaj postupak mogao koristiti u industriji, na primjer u čuvanju viška energije stvorene u elektranama. - Uzimamo ugljični dioksid, otpadni produkt sagorijevanja i zatim taj proces sagorijevanja okrećemo prema nazad kako bismo dobili korisno gorivo - kratko je objasnio proces dr. Adam Rondinone, glavni autor studije o ovom procesu koja je objavljena u časopisu ChemistrySelect. Rondinone je također izložio sve pozitivne efekte ovog procesa: - Etanol već danas možete koristit kao gorivo za vozila, bez modifikacija. S druge strane, ugljični dioksid je problem. Ako ga koristimo, onda sprječavamo da odlazi u atmosferu - smatra Rondinone. Sam postupak tim iz laboratorija proveo je uz pomoć katalizatora napravljenog od ugljika, bakra i dušika, a kao okidač za reakciju korištena je struja. - Očekivali smo da će proces biti kompliciraniji, a do otkrića smo donekle došli igrom slučaja. Pokušavali smo proučiti prvu fazu očekivane reakcije kad smo shvatili da katalizator provodi sasvim drugu reakciju. Etanol je za nas bio iznenađenje. Otopina ugljičnog dioksida rastvorena u vodi pretvorena je u etanol u povratu između 63 i 70 posto, što znači da se većina CO2 i električne energije potrebne za njegovu proizvodnju ne gubi, nego pretvara u etanol, objasnili su znanstvenici kojima je sljedeći cilj dodatno pospješiti efikasnost procesa čija je praktična primjena potencijalno epohalno važna.