Transport and Reactivity at the Ionic Liquid-Gas Interface

Montana State University, Bozeman MT

Investigators

Abstract

In this project supported by the Chemical Structure, Dynamics, and Mechanisms-A Program of the Division of Chemistry, Prof. Timothy K. Minton and his group at Montana State University explore the chemical structure and reactivity of the surfaces of ionic liquids (ILs), which are a class of liquids that are finding important applications, for example, in gas separation and catalysis. ILs are also potentially important for sustainable chemical processing because they are non-volatile and resistant to degradation by heat. The Minton group directs beams of atoms and molecules at the surfaces of ILs, and infers details about surface structure and chemical reactivity from the angles, velocities, and identities of the atoms and molecules that emerge from the surface. The experimental results are compared with theoretical calculations (also done by the Minton group). The ultimate goal of this project is to enable an "understanding-driven" approach to designing and optimizing ionic liquid systems for useful applications. The project uses experimental atomic and molecular beam scattering techniques based on mass-spectrometric detection, which is a general technique that provides dynamical scattering data in exquisite detail and does not rely on spectroscopic detection schemes that are limited to relatively few scattered species. The experiments are being closely linked with molecular dynamics simulations of liquid surfaces and mixed quantum mechanics/molecular mechanics calculations of gas-surface interaction dynamics. This joint experiment/computation project expands the scope of inelastic and reactive collisions of atoms and molecules on IL surfaces, with aims to (1) extend the use of reactive atoms as analytical probes of liquid surface structure, (2) quantify the factors that influence the connection between reagent gases and supported IL-phase (SILP) catalysts, and (3) uncover the mechanisms by which an ionic liquid surface may control the reaction of two reagent molecules. Outreach is actively promoted through the creation of a new Interactive Scattering Dynamics (ISD) web app, which is employing a graphical user interface to visualize atom-surface scattering processes through preloaded lessons and through user directed experimentation. The ISD web app may be preloaded on a tablet or laptop browser tab, thus providing a very portable teaching/learning resource to aid understanding of liquid surface structure and the dynamics of gas-liquid collisions.