Partial oxidation of ethane to ethylene

Many questions about the process of partial oxidation of ethane to ethylene have been left unanswered, and this thesis will attempt to answer those questions through experimentation and computer simulations. We begin with a mental picture of the partial oxidation process, called the two-zone model. In the first zone, exothermic oxidation of ethane or preferential hydrogen oxidation occurs, and the heat from these reactions drives the endothermic dehydrogenation of ethane to ethylene in the second zone.; We use a downstream sampling technique to examine the roles of oxidative and non-oxidative chemistry as well as the roles of heterogeneous and homogeneous chemistry. For Pt, considerable ethane is consumed after the 10 mm catalyst and significant oxygen breakthrough occurs. Without hydrogen addition, approximately half of the ethane chemistry occurs after the Pt catalyst, and with hydrogen addition, almost all of the ethane chemistry occurs after the Pt catalyst. For Pt-Sn, most of the ethane and almost all of the oxygen are consumed within the 10 mm catalyst. The front face of the Pt-Sn catalyst is 150°C to 200°C hotter than Pt, and the back face of the Pt-Sn catalyst is 100°C hotter than Pt. These results further support the two-zone model and help to quantify the reactions occurring in the two zones.; Computer simulations are able to predict the species and temperature profiles observed in the experiments. For these simulations, we use the Mims-Dean mechanism for the homogeneous chemistry and the Seo-DonsI mechanism for the heterogeneous chemistry.; Since the addition of tin is unlikely to improve the activity of the Pt catalyst, we suggest that the primary role of tin is to prevent ethane decomposition to carbon on the catalyst surface, which would ultimately lead to CO and CO2. This implies that the Pt-Sn catalyst would have more platinum sites free for O2 adsorption, which in turn leads to more hydrogen oxidation on the Pt-Sn surface, a higher catalyst temperature, and less CO and CO2 production.