| Catalytic combustion has been examined on a fundamental level in situations close to industrial conditions. Few studies previously have been able to accomplish this primarily because of high surface reaction rates, multiple steady states (surface ignition and extinction), and homogeneous reactions which exist at high surface temperature and near atmospheric pressures. Catalytic combustion was studied using a unique combination of experimental observations of the catalytic and gas-phase combustion bifurcation behavior (ignition and extinction) and detection of desorbing radicals during surface combustion with laser induced fluorescence (LIF).;The surface and gas-phase bifurcations (ignition and extinction points) of oxidations of methane, propane, ammonia, and methane/ammonia mixtures were monitored in an atmospheric flow reactor, giving essential information on kinetic and mass transfer limits as well as defining important operating parameters for combustion and oxidation reactions. After mapping out regimes where surface combustion or gas-phase combustion dominate, surface combustion was further examined using laser induced fluorescence (LIF) and mass spectrometry in a low pressure reactor. Kinetic mechanisms for the reactions at high surface temperature were determined by fitting experimental results to numerical simulations from a detailed mechanistic model of the surface reaction in a CSTR reactor. These two studies although quite different, afford a unique ability to monitor surface combustion in similar conditions to industry and to gain fundamental knowledge of the processes which dominate catalytic combustion. |
