| The subject of this thesis is the investigation of heterogeneous and homogeneous partial oxidation of light alkanes in single gauze reactors.;A single gauze has significant transparency and is usually made of Pt/Rh. During operation, the surface reacts with part of the flow, producing heat and other chemicals. The remaining part of the flow that bypasses the catalyst is heated up very fast and mixes downstream with the chemicals produced on the surface. This results in a gas phase reaction sequence that yields valuable products such as oxygenates and olefins, which are not seen in most oxidation systems. The whole process takes place in less than a millisecond.;It was found that, whereas methane and ethane present little interest because conversion of these hydrocarbons to valuable chemicals is done much more efficiently by other fast processes, n-propane, n-butane and n-pentane are very promising for selectively producing oxygenates and olefins.;n-Propane partial oxidation over a gauze is not expected to yield significant amounts of oxygenates. Current processes yield more ethylene than propylene, because of cracking due to high temperatures. However, 2/1 selectivity ratio of propylene to ethylene was observed over a single gauze, with simultaneous complete conversion of the oxygen feed and short contact times. Homogeneous chemistry calculations using a detailed mechanism agree well with experimental results.;n-Butane partial oxidation over gauzes gives at least 40% selectivity to oxygenates, with main products being acetaldehyde and formaldehyde. Homogeneous modeling qualitatively agrees with experimental trends, but improved mechanisms are required. Furthermore, two steady states were observed during experiments. Analysis of the product distribution gives vital information about active chemical routes.;n-Pentane partial oxidation over single gauzes was also examined and oxygenate selectivities as high as 60% were recorded, with major products being acetaldehyde and propionaldehyde. Higher pressure runs established the importance of homogeneous chemistry.;Finally, results on 2-D modeling of gauze reactors are presented. Numerical "experiments" were performed for methane partial oxidation over five Pt gauzes. The code was a combination of our own subroutines and the commercially available CFD program FLUENT. Detailed surface mechanisms were implemented, which accurately describe catalytic reaction. |
