Catalytic oxidation of hydrocarbons: Modeling and optical diagnostics

A major goal of reaction engineering is the attainment of a better understanding of catalytic oxidation processes. Work is currently under way to develop catalytic oxidation reactions that could potentially replace a number of important industrial processes such as steam reforming and steam cracking. While preliminary results in this field are promising, very little is understood about the underlying homogeneous and heterogeneous chemistry involved in these systems. The goal of this research is to develop techniques, both experimental and computational, that lead to a better understanding of catalytic oxidation reactions. Ultimately, this will lead to a better understanding of these systems, which will have implications for reaction optimization.; Laser-induced fluorescence was employed to study hydroxyl radical concentrations in boundary layers of catalytic gauzes. Fuel-lean combustion reactions of methane and ethane with air were studied for three catalysts: Pt, Pt-10% Rh, and Ni. Significant variance was observed between these catalysts. Specifically, Ni showed the greatest hydroxyl concentrations, followed by Pt-10% Rh, and then Pt. This is attributed to differences in surface activity. Under fuel-lean conditions, Ni is inert, the Rh in Pt-10% Rh, fairly inert, and Pt, active. The experimentally measured profiles were; compared to one-dimensional homogeneous chemistry simulations performed with GRI-Mech. Nickel experimental results and simulations gave excellent agreement. Platinum and Pt-10% Rh did not agree with simulations performed using the same inlet fuel concentration. However, these experimental results agreed with profiles for reduced fuel concentrations; the difference represents fuel consumed via surface reactions. From this, the extent of surface reaction for each system can be inferred.; Additionally, Fluent (a CFD program) was utilized to explicitly model surface chemistry using a mechanism for fuel-lean reactions of methane on platinum. The output from Fluent was input into a 1-D simulation using GRI-Mech, and these results agreed with those observed experimentally.; The results of this work have increased the understanding of catalytic oxidation systems. LEF has been developed as a tool for the experimental observation of reaction intermediates in atmospheric pressure reactions. Better understanding of these systems allows for better reactor optimization and the development of new applications for catalytic oxidation reactors.