Did you know that the most toxic vehicle emissions happen within the first five minutes of starting the vehicle?
Chemical engineer Nicholas Nelson works to solve this by developing special materials-called catalysts-for commercial deployment in automotive emission applications. “The biggest vehicle emissions occur while the catalytic converter is cold,” said Nelson. “We aim to develop catalysts that can function at lower temperatures and capture these emissions.”
Catalysts make chemical transformations, such as controlling vehicle emissions by altering toxic, smog-producing gases into less-toxic products, possible. Ultimately, catalysis research helps create better catalysts to improve our everyday lives and bring us closer to achieving a sustainable future.
In the new Energy Sciences Center (ESC) at Pacific Northwest National Laboratory (PNNL), scientists like Zdenek Dohnalek, Mal-Soon Lee, and Nicholas Nelson are deploying tools from the atomic to industrial scales toward the goal of creating better, more efficient catalysts.
The energy and environmental challenges facing our nation are large and complex. Catalysts can help solve some of these challenges toward a cleaner and more sustainable future. Multi-disciplinary collaborations, like the ones fostered at the ESC, are key to solving these problems.
“Two key pieces to solving any catalyst puzzle are determining the structure and energetics of the reactive site, as well as determining the kinetics of the catalyzed reaction-that is, how much faster does it occur. For the structural piece, we use imaging to provide a three-dimensional view of the surface, spectroscopy to give more information on the identity of catalytic sites, and theory to understand the structure and energetics of the system at the atomic scale,” said PNNL Laboratory Fellow Zdenek Dohnalek. “By having researchers in all three structural fields working together at the ESC, we can build new connections and foster deeper collaborations to get a fuller picture of catalysis and ultimately inform the synthesis of better catalytic materials.”
Dohnalek uses techniques such as scanning probe microscopy to obtain an atomistic understanding of the catalyst structure and reactivity. He collaborates with theoretical scientists, like computational scientist Mal-Soon Lee, to verify experimental observations-or vice versa-and determine general structure-reactivity relationships.
Recently, these two teamed up to study oxide clusters on oxide substrates-an important class of catalysts-used in a wide variety of applications, such as biomass-to-fuel reactors.
Dohnalek used scanning tunneling microscopy to probe the surface of a molybdenum oxide catalyst on a titanium dioxide surface. Lee then employed simulations to re-create the structure of the material at the atomic level and compared the results to Dohnalek’s experimental data.
“We can use simulations to make sense of experimental results,” said Lee. She utilized existing computational methods and developed new ones to compare her calculations with experimental data.
Lee has seen the power of computation grow over the course of her career. “In the past, calculations were only used to supplement experimental data in the field of catalysis. Now, we are beginning to lead the design of new catalysts using computation,” said Lee.
Partnerships with industry can also help bring laboratory results to society. Nelson collaborates with companies like BASF and General Motors to reduce the use of precious metals such as platinum, rhodium, and palladium as catalysts in vehicles while increasing catalytic efficiency. He uses infrared spectroscopy to uncover the identity of different catalytic sites and inform the design of better catalysts.
Working together to create better energy and environmental solutions
Though Dohnalek, Lee, and Nelson each specialize in different research areas, they see the benefits of being together at the Energy Sciences Center. “At the ESC, we are together under one roof,” said Nelson. “Not only is this more efficient for our individual research projects, but it also allows us to better connect with colleagues in catalysis research.”
“Having expertise across all areas of catalysis together allows us to overcome the limitations of individual techniques,” said Dohnalek. “Well-defined model experimental systems further serve as high-quality benchmarks for theoretical calculations. We can then use these combined results to inform the synthesis of materials at the next level.”