Ethene may be produced from dehydrogenation (=removing hydrogen) of ethane. Oxidative dehydrogenation of ethane (ODE) is a complex process involving extremely fast reactions at high temperature. Heat and reaction modelling in interplay with experiment are our tools to select the best reactor and conditions for the process.
The reactions involved in the oxidative dehydrogenation of ethane (ODE) are extremely fast and occur at high temperature. Special challenges are then connected to the mixing of reagents, heating, cooling and stabilization of reaction conditions, and there is therefore a need to develop special reactors for this application. Heat and reaction modeling of these reactors is necessary to choose the best reactor and the best conditions for the process. A better understanding of the reaction kinetics for dehydrogenation of ethane, in the presence and absence of oxygen containing species, is important in optimizing the process conditions and the reactor model.
The high reaction temperatures (up to 800-900°C) involved leads to considerations regarding the choice of analytical method, sample and sample environment. In the current project we have developed an analytical technique based on infrared emission spectroscopy which makes it possible to quantitatively study the components involved at high temperatures. The technique has been demonstrated to be applicable within wide concentration ranges in small volume flowing reactor cells (4 mm I.D.).
A kinetic model has been developed to describe the kinetics of oxidative dehydrogenation of ethane in gas phase, which has been employed to optimize the reaction towards the highest ethylene yield. A detailed reaction routine was performed to understand the key radices and reaction steps leading to the secondary reaction of ethylene and thus lower ethylene selectivity. The results were compared to the reported kinetic data of catalytic oxidative dehydrogenation. It is interesting to note that the ethylene yield obtained by the gas phase is higher than the most of reported values by catalytic ODE. The gas phase ODE provides a promises route to produce ethylene from ethane. The 1-D and 2-D reactor models were developed to design and optimize the reactor with a multiple oxygen injection to achieve the theoretic maximum yield.