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Helena Hagelin-Weaver Research Assistant Professor Ph.D., 1999, Royal Institute of Technology, Stockholm Organometallic Chemistry Homo- and Heterogeneous Catalysis Surface Characterizations Quantum Chemical Calculations Email: hhagelin@che.ufl.edu Phone: (352) 392-6585 Fax: (352) 392-9513 323 Chemical Engineering Building

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Brief Description of Current Research

We take a multidisciplinary approach to heterogeneous catalysis, using principles from organometallic chemistry, quantum chemistry, surface science, and reactor design and reaction kinetics.  The objective of our research is to obtain a fundamental understanding of heterogeneous catalysis at the atomic level.  To that end, we use nanoparticle oxides as supports for our catalysts in an attempt to prepare well-defined catalysts.  The hypothesis is that the deposition of active metal clusters of small and narrow size distributions onto the support is facilitated when starting from a nanoscopic material.  We are particularly interested in how the nanoscopic properties of these supports influence the catalytic properties.  The catalysts are therefore characterized using a number of surface science analytical techniques to determine properties that are critical for a high catalytic activity.  Both the supports and the prepared catalysts are investigated in detail using techniques such as X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectroscopy (XRD), Brunauer-Emmett-Teller (BET) surface area analysis and transmission electron microscopy (TEM).  The catalytic activity is determined in a continuous gas phase reactor system with an on-line gas chromatograph for product analysis.  The results are then examined in detail to find structure-activity relationships.  We are also using quantum chemical calculations to obtain more information about our systems.  Small clusters are used to model the catalysts and calculations on these clusters are highly relevant due to the size of the nanoparticles used in the experiments.

Our main research focus is on reactions that are environmentally advantageous.  We are currently working on hydrogen production via catalytic steam reforming and palladium-catalyzed C-H activation, and on C-C coupling of aromatic compounds.  Hydrogen is particularly attractive because it is considered a clean fuel that can be used in internal combustion engines and in fuel cells.  We are investigating catalysts that can be used in the steam reforming of biomass and alcohols to produce a high yield of hydrogen with a low CO content.  The palladium-catalyzed C-H activation reaction is environmentally advantageous since waste formation is minimized at the source.  This research area involves converting highly efficient homogeneous palladium complexes to heterogeneous catalyst systems, hence facilitating catalyst recovery and regeneration.  It is our belief that the conversion between homogeneous and heterogeneous catalysis is facilitated using nanoparticle oxides as supports in the preparation of the heterogeneous catalysts.  These nanoparticle catalysts are likely to have properties in between homogeneous catalyst complexes and conventionally prepared heterogeneous catalysts and this may justify the application of principles from organometallic chemistry. 

Major Equipment

Continuous gas-phase reactor system with an on-line gas chromatograph for product analysis

Selected Publications

• “Electron energy loss spectroscopic investigation of Ni metal and NiO before and after surface reduction by Ar⁺ bombardment”, H.A.E. Hagelin-Weaver, J.F. Weaver, G.B. Hoflund, G.N. Salaita , J. Electron Spectrosc. Relat. Phenom. Vol..134, 139-171 (2004).  
   
• “Electron energy loss spectroscopic investigation of Co metal, CoO, and Co₃O₄ before and after Ar⁺ bombardment”, H.A.E. Hagelin-Weaver, G.B. Hoflund, D.M. Minahan, G.N. Salaita,  Appl. Surf. Sci. Vol. 235,  420-448 (2004). 
   
•  “Electron Energy Loss Spectroscopic Investigation of Palladium Metal and Palladium(II) Oxide”, H.A.E. Hagelin, J.F. Weaver, G.B. Hoflund, G.N. Salaita,J. Electron Spectrosc. Relat. Phenom. Vol. 124  1-14 (2002).. 
   
• “Investigation of the Palladium Catalyzed Aromatic Coupling of Pyridine Derivatives”, H. Hagelin, B. Hedman, I. Orabona, T. Åkermark, B. Åkermark, C.A. Klug , J. Mol. Cat. A,  Vol. 164 ,137-146 (2000). 
   
• “A Solvated Transition State for the Nucleophilic Attack on Cationic (h3‑Allyl) Palladium Complexes”, H. Hagelin, B. Åkermark, P.-O. Norrby, , Chem. Eur. J., (1999)5  902-909 (1999). 
   
• “Oxygen as Oxidant in Palladium-Catalyzed Inter- and Intramolecular Coupling Reactions”, H. Hagelin, J. Oslob, B. Åkermark, Chem. Eur. J., Vol. 5, 2413-2416 (1999).