CHE: Combined experimental and theoretical study of solvent effects in heterogeneous catalysis

Oregon State University, Corvallis OR

Investigators

Abstract

Many chemical processes essential for our energy future depend on heterogeneous catalysis, here, the use of a solid material to aid in chemical conversion of molecules in the liquid state. Examples of important heterogeneous catalysis processes include biomass conversion to liquid fuels and chemical feedstocks, electrocatalysis in fuel cells, and photoelectrocatalysts for solar energy harvesting and storage. The fundamental insights that result from a study of the solid catalyst surface and the molecules adsorbed to it are able to help in the design of new and more effective catalysts. Dr. Liney Arnadottir is studying catalytic processes at the atomic level both with advanced theoretical calculations of model catalyst-adsorbate complexes and by measuring electronic structure with x-ray photoelectron spectroscopy (XPS). Broader impacts of the research are far-reaching in the development of more efficient catalytic systems. In a parallel effort, broader impacts are made in the development of human resources. In this study, Dr. Arnadottir provides significant mentorship of graduate student and undergraduate student researchers in both the scientific and educational realms. In interactive training with the Dr. Arnadottir, students apply and hone their own mentoring skills by nurturing high school students recruited from underrepresented groups as a part of a yearly, one-week long residential summer camp at Oregon State University known as the Summer Experience in Science and Engineering for Youth (SESEY). The mentoring activities during the SESEY camp provide critical communication skills to the up-and-coming generation of new scientific leaders and also exposes them to the need for continued STEM outreach activities. In this study, Dr. Liney Arnadottir of Oregon State University combines surface characterization of acetic acid and ethanol in solvent environments using near ambient pressure X-ray Photoelectron Spectroscopy (NAP-XPS) with theoretical modeling using Density Functional Theory (DFT) calculations. With this combined experimental and computational project, Dr. Arnadottir is able to elucidate solvent effects in catalysis and thus gain the fundamental understanding required to predict how solvents change the rates of elementary steps in catalytic reaction mechanisms. Dissociation of acetic acid is the first step of vinyl acetate synthesis, which is of great industrial interest. Acetic acid and ethanol represent common functional groups in larger oxygenates with broad scientific interest. Three solvents are investigated in this study: water, which is a common and widely used solvent; 1,4 dioxane, which has been shown to enhance hydrodeoxygenation activity of Pd(111) over water; and heptane, representing a non-polar solvent. Broader impacts of the research are far-reaching in the development of more efficient catalytic systems. In a parallel effort, broader impacts are made in the development of human resources. Theoretical and experimental studies are performed in a closely-coupled feedback loop intended to improve the investigative efficiency and to serve as a learning vehicle for the mentorship of the graduate and undergraduate student researchers. Underrepresented high school students are part of the research team, brought in through a mini-research project as a part of the Summer Experience in Science and Engineering for Youth (SESEY) camp at Oregon State University. All graduate and undergraduate students in this project serve as mentors for the SESEY participants providing the opportunity to participate in outreach activities and develop their ability to teach, mentor and communicate their research to different audiences. This carefully designed study provides valuable insights into catalytic solvent effects, allows identification of trends regarding the interactions between solvent and adsorbed reaction intermediates, and simultaneously creates a vehicle for training the next generation of STEM leaders.