Project Type
Poster
Publication Date
4-12-2022
Department or Program
Chemistry and Physics
College
College of Arts and Sciences
Faculty Mentor #1
Giancarlo, Leanna
Abstract
The thermodynamics and kinetics of a proposed mechanism for ammonia production from nitrogen and hydrogen gas were analyzed by utilizing transition state theory (TST) and density functional theory (DFT). The enthalpy and entropy for the overall reaction were computed via DFT functionals, PBE0 and B3LYP, and were compared to literature values for the thermodynamics of ammonia production. PBE0 produced an enthalpy and entropy for the overall reaction of -81.32 kJ/mol and -197.75 kJ/mol K with percent errors of -11.5 % and -0.18 %, respectively. In comparison, B3LYP produced an enthalpy and entropy for the overall reaction of -1923.02 kJ/mol and -244.25 kJ/mol K with percent errors of 1990 % and 24 %, respectively. Therefore, the PBE0 functional provided a better approximation to the thermodynamics of ammonia production due to the limitations of B3LYP’s empirical approximations. The approximations of B3LYP considers experimental values for specific systems and geometries; however, if the experimental values do not reflect the proposed geometries in the mechanism, it will not be as accurate. Thus, the forward and reverse rate constants of ammonia production were predicted for each step utilizing the DFT functional PBE0.