Editor: Dr. Shane Friesen
Motivation behind the research
Palladium nanoparticles supported on carbons (Pd/C) are commonly used as catalysts for the industrial production of a vast variety of chemicals used for paints and coatings, plastics, and pharmaceuticals. Despite the industrial importance of Pd/C catalysts, many of their fundamental properties are still poorly understood. There is especially a lack of understanding of how the carbon support may influence the performance of the palladium metal. Due to this, the best carbon support is typically chosen based on trial and error, after testing carbons from different suppliers.
For years, scientists have attempted to explain the observed differences in catalytic performance, but with little success. The challenge comes from the complex nature of carbon supports that includes both the physical and chemical properties of carbons (e.g., porosity, hydrophilic-hydrophobic character, acid-base properties). This shortcoming of previous studies was identified and carefully addressed in our study.
We decreased the physical complexity of the nanocarbons by utilizing carbon nanotube supports that have a simple three-dimensional structure, similar to a hollow cylindrical tube. This simple geometry makes them easier to characterize using high resolution electron microscopes and other techniques, and makes it easier to understand the nature of the interactions between the palladium metal nanoparticles and the carbon surface. This approach demonstrated that catalytic activity is related to the chemical properties of the nanocarbon surface, to the nanocarbon electronic properties, and to the way the carbon surface interacts with the palladium atoms. While being catalytically inactive, it indirectly influences the reaction by altering the metal catalyst. We also provide a simple strategy to control the chemical nature of carbons using thermal treatments and highlight the role these properties play in the catalyst. Therefore, the work provides a foundation for the development of the next-generation of carbon-supported catalysts wherein the choice of the type of carbon can be made rationally and the efficiency of the industrial processes can be improved.
The development of better catalysts is expected to result in improved industrial production of chemicals including common chemicals and pharmaceuticals, as well as resulting in less waste. The future direction of this work would involve the investigation of more complex properties of carbons and expanding the scope for a broad array of reactions in order to widen the impact of this study. Altogether, we are very excited to explore new directions with our findings and expand the horizons of the applications of these catalysts.
Research Article: Interfacial charge distributions in carbon-supported palladium catalysts. Nature Communication, 2017.
This article was co-authored by Dr. Jean-Philippe Tessonnier, Department of Chemical and Biological Engineering, Iowa State University