A research team from Caltech and UCLA Samueli School of Engineering has shown a promising way to efficiently convert carbon dioxide into ethylene, an important chemical used to make plastics, solvents, cosmetics and other important products globally.
Scientists developed nano-scale copper wires with specially shaped surfaces to catalyze a chemical reaction that reduces greenhouse gas emissions while generating ethylene, a valuable chemical. Computational studies of the reaction show that the shaped catalyst favors the production of ethylene over hydrogen or methane. A study detailing the advance was published in Catalysis of nature.
“We are on the brink of fossil fuel depletion, coupled with the challenges of global climate change,” said Yu Huang, co-author of the study and professor of materials science and engineering at UCLA. “The development of materials capable of efficiently transforming greenhouse gases into value-added fuels and chemical raw materials is a key step in mitigating global warming, moving away from the extraction of increasingly limited fossil fuels. This integrated experiment and theoretical analysis present a sustainable path towards carbon dioxide recycling and utilization. “
Currently, ethylene has a global annual production of 158 million tons. Much of this is transformed into polyethylene, which is used in plastic packaging. Ethylene is processed from hydrocarbons, like natural gas.
“The idea of using copper to catalyze this reaction has been around for a long time, but the key is to accelerate the speed so that it is fast enough for industrial production,” said William A. Goddard III, co-author of the study and Charles and Mary Ferkel of Caltech, professors of chemistry, materials science and applied physics. “This study shows a solid path to that brand, with the potential to transform ethylene production into a greener industry using CO.2 otherwise it would end up in the atmosphere. “
Using copper to initiate carbon dioxide (CO2) reduction in reaction of ethylene (C2H.4) suffered two strikes against it. First, the initial chemical reaction also produced hydrogen and methane, both of which are undesirable in industrial production. Second, previous attempts leading to ethylene production did not last long, with the conversion efficiency dwindling as the system continued to operate.
To overcome these two hurdles, the researchers focused on designing copper nanowires with highly active “steps”, similar to a series of ladders arranged at the atomic scale. An interesting finding from this collaborative study is that this pattern of steps across the surfaces of the nanowires remained stable under the reaction conditions, contrary to the general belief that these high-energy characteristics would smooth out. This is the key to both system durability and selectivity in the production of ethylene, instead of other end products.
The team demonstrated a carbon dioxide-to-ethylene conversion rate of over 70%, much more efficient than previous projects, which produced at least 10% less under the same conditions. The new system ran for 200 hours, with little change in conversion efficiency, a big step forward for copper-based catalysts. Furthermore, the comprehensive understanding of the structure-function relationship illustrated a new perspective for designing highly active and durable CO2 reduction catalyst in action.
Huang and Goddard have been frequent collaborators for many years, with Goddard’s research group focusing on the theoretical reasons behind chemical reactions, while Huang’s group created new materials and conducted experiments. The lead author of the article is Chungseok Choi, a graduate student in materials science and engineering at UCLA Samueli and a member of Huang’s lab.
Electrochemical reduction of carbon dioxide into ethanol
Chungseok Choi et al, Highly active and stable stepped copper surface for greater electrochemical reduction of CO2 to C2H4, Catalysis of nature (2020). DOI: 10.1038 / s41929-020-00504-x
Researchers Discover Effective Pathway to Convert Carbon Dioxide to Ethylene (2020, September 17)
recovered on September 17, 2020
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