Determining the Electrocatalytic Oxidation Mechanism of 1,2-propanediol Using Density Functional Theory

Open Access
Author:
Brady, Brian Matthew
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Michael John Janik, Thesis Supervisor
  • Michael John Janik, Honors Advisor
  • Themis Matsoukas, Faculty Reader
Keywords:
  • Density Functional Theory
  • catalysis
  • electrocatalysis
  • biomass
  • reaction mechanism
Abstract:
The electrocatalytic oxidation of 1,2-propanediol to form lactic acid and pyruvic acid was studied using Density Functional Theory (DFT). Previous studies have indicated that on a gold surface with applied potential, 1,2-propanediol will selectively oxidize to lactic acid at low potentials and pyruvic acid at high potentials. The study of this particular reaction mechanism can serve as a model for converting biomass into industrially valuable chemicals. Also, understanding the reaction mechanism can lead to improved catalyst formulation. It is difficult to experimentally determine the reaction mechanism as the concentrations of the reactive intermediates cannot be measured. Density Functional Theory, a computational quantum mechanical modeling method, was used to determine the energies of all intermediate species to elucidate the mechanism. A reaction energy diagram was formulated to determine the most energetically favorable path from products to reactants. The results indicate that the preferred mechanism proceeds through deprotonation of the terminal carbon to form a lactaldehyde intermediate which leads to the formation of lactic acid. At low potentials, there is a high energy step between lactic and pyruvic acid which is unfavorable and thus lactic acid is the dominant product. At high potentials, this oxidation step is more favorable as pyruvic acid is a more stable product leading to pyruvic acid being the dominant product.