A research team from Caltech and UCLA Samueli School of Engineering demonstrates a promising way to effectively convert carbon dioxide to ethylene, an important chemical used in the production of plastics, solvents, cosmetics and other important products worldwide.
Scientists have developed nanoscale copper conductors 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 catalyst formed favors the production of ethylene over hydrogen or methane. A study detailing the advance was published in Natural catalysis.
“We are on the brink of fossil fuel depletion, along with the global challenges of climate change,”
Ethylene currently has a global annual production of 158 million tons. Much of this is converted to polyethylene, which is used in plastic packaging. Ethylene is processed by hydrocarbons, such as natural gas.
“The idea of using copper to catalyze this reaction has been around for a long time, but the key is to speed it up so that it’s fast enough for industrial production,” said William A. Goddard III, co-author of the study, and Charles and Mary Ferkel of Caltech. , Professor of Chemistry, Materials Science and Applied Physics. “This study shows a solid path to this brand, with the potential to transform ethylene production into a greener CO2 which would otherwise enter the atmosphere. “
Use of copper to start carbon dioxide (CO2) reduction in ethylene reaction (C2З.4) suffered two strikes against him. First, the initial chemical reaction also produces hydrogen and methane – both undesirable in industrial production. Second, previous experiments leading to ethylene production did not last long, with the conversion efficiency declining as the system continued to operate.
To overcome these two obstacles, the researchers focused on the design of copper nanowires with highly active “steps” – similar to a set of stairs arranged on an atomic scale. An intriguing finding of this joint study is that this step on the surfaces of the nanowires remains stable under the reaction conditions, contrary to the common belief that these high-energy characteristics will be smoothed out. This is the key to both the durability of the system and the selectivity in the production of ethylene instead of other end products.
The team demonstrated a degree of conversion of carbon dioxide to ethylene greater than 70%, much more efficient than previous projects, which gives at least 10% less under the same conditions. The new system operates for 200 hours, with a small change in conversion efficiency, a major advance for copper-based catalysts. In addition, a comprehensive understanding of the structure-function relationship illustrates a new perspective for the design of highly active and durable CO2 reduction catalyst in action.
Huang and Goddard have often been collaborators for many years, with Goddard’s research group focusing on the theoretical causes behind chemical reactions, while Huang’s group creating new materials and conducting experiments. The lead author of the article is Chungseok Choi, a graduate student in materials science and engineering at UCLA Samuel and a member of Huang’s laboratory.
Reference: “Highly active and stable stepped Cu surface for improved electrochemical CO2 reduction to C2З.4”By Chungseok Choi, Soonho Kwon, Tao Cheng, Mingjie Xu, Peter Tieu, Changsoo Lee, Jin Cai, Hyuck Mo Lee, Xiaoqing Pan, Xiangfeng Duan, William A. Goddard III and Yu Huang, September 7, 2020, Natural catalysis.
DOI: 10.1038 / s41929-020-00504-x
Other authors in this study are from UC Irvine; Soochow University, China; Hong Kong University of Science and Technology; and the Korean Institute of Science and Technology.
The study was supported by the Office of Naval Research, the US Department of Energy and the National Science Foundation, with additional support from the National Research Foundation of Korea, the Irvine Materials Research Institute and ExxonMobil.