An inexpensive tin-based catalyst can selectively convert carbon dioxide into three widely produced chemicals: ethanol, acetic acid, and formic acid.
Emissions from many industrial activities hide carbon dioxide (CO), an untapped resource.2). These substances, which are greenhouse gases and contributors to global warming, can instead be captured and converted into value-added chemicals.
In a joint project involving the U.S. Department of Energy's (DOE) Argonne National Laboratory, Northern Illinois University, and Valparaiso University, scientists reported a family of catalysts that efficiently convert CO .2 With ethanol, acetic acid or formic acid. These liquid hydrocarbons are among the most produced chemicals in the United States and are found in many commercial products. For example, ethanol is a key ingredient in many household products and an additive in nearly all U.S. gasoline.
The catalyst is based on tin metal deposited on a carbon support. ?”If fully developed, our catalyst could convert CO.2 “It is produced as a valuable chemical from a variety of industrial sources,” said Di-Jia Liu. “These sources include fossil fuel power plants, biofermentation and waste treatment facilities.” Liu is a senior chemist at Argonne and a senior scientist at the Pritzker School. PhD in molecular engineering from the University of Chicago.
The method used by the research team is called electrocatalytic conversion, which means that CO2 The catalytic conversion is driven by electricity. By varying the size of tin used, from single atoms to tiny clusters and larger nanocrystals, the team was able to control CO.2 Converted to acetic acid, ethanol, and formic acid, respectively. Selectivity for each of these chemicals was greater than 90%. “Our discovery that the reaction pathway changes with catalyst size is unprecedented,” Liu said.
Computational and experimental studies have revealed several insights into the reaction mechanisms forming the three hydrocarbons. One key insight is that when the plain water used in the conversion is converted to heavy water (deuterium is an isotope of hydrogen), the reaction pathway changes completely. This phenomenon is called the isotope effect. It has never been observed in CO before.2 conversion.
This research was assisted by two DOE Office of Science user facilities at Argonne: the Advanced Photon Source (APS) and the Center for Nanoscale Materials (CNM). “We used the hard X-ray beam available at APS to capture the chemical and electronic structures of tin-based catalysts with different tin contents,” said Argonne physicist Chengjun Sun. Additionally, the high spatial resolution possible with transmission electron microscopy of CNM directly imaged the arrangement of tin atoms with varying catalyst loadings, from single atoms to small clusters.
According to Liu, “Our ultimate goal is to use locally generated electricity from wind and solar to produce desired chemicals for local consumption.”
This requires incorporating newly discovered catalysts into low-temperature electrolyzers to perform CO.2 Converting it to electricity supplied by renewable energy. Low-temperature electrolysers can operate close to ambient temperature and pressure. This allows rapid starting and stopping to accommodate intermittent supplies of renewable energy. It is an ideal technology to achieve this goal.
“Being able to selectively produce only the chemicals needed near the site can help reduce CO2.2 Liu mentioned transportation and storage costs. “This will truly be a win-win situation for businesses adopting our technology locally.”
Support for the research came from DOE's Office of Advanced Manufacturing and the Office of Energy Efficiency and Renewable Energy within the Office of Industrial Efficiency and Decarbonization. Additional support was provided by Argonne's Laboratory Directed Research and Development Fund.