NAM29 Plenary Lectures
The plenary sessions will consist of lectures by the recipients of the , the , and the . The award winners are summarized below, with full biographical details following.
- Jos茅 G. Santiesteban is the recipient of the Houdry Award. Read more at .
- Phillip Christopher and David Flaherty are the 2025-2026 recipients of the Emmett Award. Read more at .
- Bert Weckhuysen is the 2025 recipient of the Michel Boudart Award.
2025 Paul H. Emmett Award Winner
Phillip Christopher
University of California - Santa Barbara
Title of plenary lecture:
"Atomically Dispersed Pt-Group Metal Catalysts: Active Site Structure, Function and Design"
I will highlight efforts focused on: (1) the synthesis and characterization of uniform atomically dispersed Pt active sites, (2) the development of structure-function relationships, (3) the local restructuring of these active sites due to changes in environmental conditions and (4) atomically dispersed Rh based catalysts for alkene hydroformylation.
2026 Paul H. Emmett Award Winner
David Flaherty
Georgia Institute of Technology
Title of plenary lecture:
"Charting New Waters: Activities, Active Sites, and Reactive Structures in Dynamic Environments"
Catalytic reactions on solid materials form the foundation of chemical manufacturing, yet many phenomena that impact these systems challenge current understanding. Among other examples, these challenges appear vividly in the contributions of liquids and solvent molecules on catalysis upon surfaces of metal nanoparticles and within the confines of zeolites. We demonstrate that solvent-surface interactions change activities of reactive species within pores of molecular dimensions, form new reactive structures in situ, and open reaction pathways distinct from those at gas-solid interfaces.
Solvent molecules surround and interact with catalytic sites in ways that change reaction rates and selectivities by orders of magnitude. Within zeolite pores, reactions that form and consume epoxides exhibit rates and selectivities that depend on dimensions and polarity of surrounding voids in addition to the strength of covalent interactions. As a consequence, rates and selectivities span many orders of magnitude at active sites with indistinguishable electronic structure. These results indicate the topology of the catalyst changes the structure of solvation shells that form about reactive species and evolve concomitantly. Together, spectroscopy, calorimetry, and kinetics indicate that the reorganization of solvents near active sites contribute systematically to activation barriers that determine the performance of these reactions. These phenomena remain important also in the absence of a visible liquid-phase, because spontaneous condensation and pore filling leads to significant densities of solvents within micropores even at elevated temperatures.
Water and organic solvents interact with metal nanoparticles to introduce reaction pathways and reactive structures that are otherwise absent. Seemingly simple reactions among hydrogen and oxygen proceed more rapidly by heterolytic pathways that emerge in protic solvents. The kinetics of these reactions depend on the local coordination of metal atoms and reactions that communicate from a distance by electron conduction, solvent mediated charge transfer, and catalyst polarization. The variable length-scales of the processes permit bifunctional reactivity across a local collection of atoms, a complete nanoparticle, or greater distances. Reactions among metal nanoparticles and organic solvents and additives form surface organometallic structures in situ that act as redox mediators and facilitate the oxidation of hydrogen and reduction of oxygen. These themes extend to aerobic oxidations of more complex organic substrates that indicate these phenomena contribute to many classes of reactions on solid catalysts where their impact remains unrecognized.
2025 Eugene J. Houdry Award Winner
Jos茅 G. Santiesteban
ExxonMobil Research and Engineering Company
Title of plenary lecture:
"Zeolite-Based Catalyst Technologies at the Forefront: Tackling the Pressing Challenges Today and in the Future."
2025 Michel Boudart Award Winner
Bert Weckhuysen
Utrecht University
Title of plenary lecture:
"Operando Spectroscopy of Heterogenous Catalysts: Foundation, Developments & Applications"
Introduction
For more than a century, scientists have been hunting for the 鈥渁ctive site鈥� in catalysis, thereby elucidating the reaction and deactivation mechanisms of important processes for the production of fuels, chemicals and materials, including plastics and coatings. This ambition is certainly not a trivial one as the concept of 鈥渁ctive site鈥�, originally proposed by Hugh Taylor [1], remains to date elusive. Catalysts have been found to be highly dynamic and evolve as a function of the reaction environment (e.g., composition, temperature and pressure) as well as reaction time. If we wish to capture these dynamics, advanced analytical methods have to be developed and applied to spatiotemporally image catalysts at work. This notion lead about 25 years ago to the foundation of the field of 鈥渙perando spectroscopy鈥�, which has evolved into an important area of research. The term was proposed by Miguel Banares, Eric Gaigneaux, Gerhard Mestl and me at the 220th American 91成人短视频 Society (ACS) National Meeting in Washington, D.C. (USA) in 2000 [2]. The concept of operando spectroscopy is outlined in Figure 1. Crucial is the aspect that spectroscopic measurements must be performed under realistic reaction environments to ensure that the obtained physicochemical data captures relevant information on the catalytic process and hence may interrogate the behavior of the active site [3]. Although simple in its principle, striving towards a true operando experiment is far from trivial, as the conditions for performing spectroscopy measurements are not well aligned with the conditions for performing catalytic measurements. This contradictio in terminis becomes even more apparent when realizing that catalysts should be best studied (a) in their chemical and structural complexity (e.g., shaped catalyst bodies, containing binders and additives) as used in industrial reactors and (b) under industrial-like conditions, including the presence of e.g. poisons, and transient reaction conditions [4-6]. In the past 25 years, many research groups have worked towards closing this 鈥渙perando gap鈥�, thereby refining our understanding of the 鈥渁ctive site鈥� concept. This is the topic of this talk, thereby focusing on developments and applications accomplished within our group.
Results and Discussion
This Michel Boudart Award Plenary Lecture starts with some historic notions leading to the foundation of the field of operando spectroscopy, thereby emphasizing the pros and cons of some catalyst characterization works from the 1950鈥�1990s. The second part of the talk focuses on important scientific and technical developments of the operando methodology. Three aspects will be highlighted, namely the need for: (a) multiscale characterization approaches, going from the reactor down to the active site; (b) multimodal characterization approaches, integrating complementary methods and (c) catalyst particles as operando temperature and catalytic performance sensors. The third part of the talk discusses three showcases, which illustrates the complexity of defining what an 鈥渁ctive site鈥� may look like in reality. It will be shown how catalysts for CO2 and CH3OH conversion spatiotemporally evolve, how the active sites are in-situ created within the catalyst particles placed in a reactor bed and how they further evolve during these catalytic processes. These examples lead to different notions on what an active site may be in a working catalyst, and they highlight the importance of synthesis and pretreatment (i.e., the deliberate transformation of a 鈥減recatalyst鈥� into its active form) in designing catalyst materials with the intrinsic potential to generate the highest 鈥渄ensity of selective and stable active sites鈥�. The lecture ends with some reflections on what we have learned after 25 years of operando spectroscopy research, what its implications are of our understanding of the concept of active site and how a potential roadmap for future operando spectroscopy studies may look like. These ideas will be confronted with ideas proposed by Michel Boudart during his influential career [7].
Figure 1. Operando spectroscopy approach for studying catalyst materials at work. In this case, electromagnetic radiation is directed into a reactor, thereby measuring spectroscopic data as a function of time, while at the same time catalytic performance is measured. Both sets of data allow to develop structure-composition-performance relationships. This information is not only important to improve existing catalyst materials, but also develop entirely new ones.
Significance
Operando spectroscopy has turned after 25 years of development into an important field of research. This methodology approaches more and more industrial-like reaction environments and catalyst materials complexity. Further closing this 鈥渙perando gap鈥� results in more insights in reaction and deactivation mechanisms, thereby providing practical leads to develop new catalyst formulations and monitor the 鈥渃atalyst health鈥� during real-life operation.
References
1. Taylor, H.S., Proc. Royal Society A: Math., Phys. & Eng. Sci. 108, 105 (1925).
2. Weckhuysen, B.M., in In-Situ Spectroscopy of Catalysts 鈥� Ed. Weckhuysen, B.M., American Scientific Publishers, pp. 1-11 (2004).
3. Weckhuysen, B.M., Phys. Chem. Chem. Phys. 5, 4351 (2003).
4. Meirer, F., and Weckhuysen, B.M., Nat. Rev. Mater. 3, 324 (2018).
5. Vogt, C., and Weckhuysen, B.M. Nat. Rev. Chem. 6, 89 (2022).
6. Hartman, T., Geitenbeek, R.G., Wondergem, C.S., van der Stam, W., Weckhuysen, B.M., ACS Nano 14, 3725 (2020).
7. E.g., Boudart, M., in The Surface Chemistry of Metals and Semiconductors 鈥� Ed. Gatos, H.C., John Wiley & Sons, pp. 409-420 (1960).
