Advanced Materials

SHARE

Chemistry and Physics at Interfaces

Molecular Beam Studies for Elucidating "Spillover" - Diffusion of Molecules Across Surface Interfaces


Transport phenomena play an important role in the chemical kinetics of practical catalytic processes and other interfacial processes (geochemical, separations, energy storage, biological, etc.).  In these systems, adsorbates can migrate from one surface to an adjacent surface, and this phenomenon is called “spillover”.  Spillover has been postulated in hydrogen storage, steam reforming of ethanol and methane, and in the Fisher-Tropsch process.  Currently the factors that control spillover are not understood due to the lack of experimental capabilities.  The aim of this project is to overcome these experimental challenges and to elucidate the factors that govern spillover.  This will enable the design of new catalytic systems that combine adsorption properties of one surface with the reaction properties of an adjacent surface.  In this project, we have built an instrument to study spillover.  The key aspects of this instrument are the abilities to 1) create adjacent well-defined surfaces, 2) selectively expose gas molecules to only one surface using a molecular beam, and 3) measure the migration of the molecules between the two surfaces using reflection infrared absorption spectroscopy and/or line of sight mass spectrometry.  Transport phenomena play an important role in the chemical kinetics of practical catalytic processes and other interfacial processes (geochemical, separations, energy storage, biological, etc.).  In these systems, adsorbates can migrate from one surface to an adjacent surface, and this phenomenon is called “spillover”.  Spillover has been postulated in hydrogen storage, steam reforming of ethanol and methane, and in the Fisher-Tropsch process.  Currently the factors that control spillover are not understood due to the lack of experimental capabilities.  The aim of this project is to overcome these experimental challenges and to elucidate the factors that govern spillover.  This will enable the design of new catalytic systems that combine adsorption properties of one surface with the reaction properties of an adjacent surface.  In this project, we have built an instrument to study spillover.  The key aspects of this instrument are the abilities to 1) create adjacent well-defined surfaces, 2) selectively expose gas molecules to only one surface using a molecular beam, and 3) measure the migration of the molecules between the two surfaces using reflection infrared absorption spectroscopy and/or line of sight mass spectrometry.  

ASK ORNL

We're always happy to get feedback from our users. Please use the Comments form to send us your comments, questions, and observations.