Adsorption of Light Alkanes on the Surface of Substrates with Varying Symmetry and Composition

Adsorption plays an integral role in a variety of fundamentally and technologically important processes such as lubrication, gas separation and purification, wetting behavior, energy storage, heterogenous catalysis, biologically inspired materials, and the theory of phase transitions. As a result, adsorption phenomena are extensively studied in chemistry, physics, and biology each for uniquely different reasons. The homologous series of normal alkanes represent a class of organic molecules that are important in the fuel industry. From a fundamental perspective, the series of normal alkanes provide a route whereby physical and chemical properties relevant to adsorption can be examined with only subtle changes in molecular size and length. The alkanes also exhibit a well-known odd-even effect in some condensed phase physical properties. In the current study, the physical adsorption properties of the normal alkanes (methane-decane) on MgO, graphite, and boron nitride were investigated using volumetric adsorption isotherms and molecular dynamics simulations. This portion of the study focuses on determining the thermodynamics of adsorption as well as predicting the adsorption structures and dynamics. As a secondary study, the chemical adsorption of ethanol was examined on the surface of transition-phase aluminas using volumetric adsorption, temperature-programmed desorption, and inelastic neutron scattering. The purpose of this work was to observe the surface-catalyzed reaction of chemically bound ethanol with Lewis and Brø[oe]nsted acid sites present on the aluminas in-situ. The results of the projects described have significant implications in the design of new materials for gas separation and purification as well as heterogenous catalysis.