(532bf) Bifurcation Analysis of the Oxidative Dehydrogenation of Ethane over M1 Phase Catalysts in Shallow Autothermal Reactor

The oxidative dehydrogenation of ethane (ODHE) is one of the promising processes to convert ethane to ethylene compared with traditional steam cracking. However, it is impractical to remove the heat generated by using cooled multi-tubular reactors, especially at high pressure, due to the high exothermicity of the ODHE system. An adiabatic autothermal reactor was proposed to remove heat efficiently using cold feed. In this work, we present a comprehensive ignition-extinction analysis of the ODHE shallow pancake-like autothermal reactor.

The global kinetic model of the M1 phase catalyst used was obtained from lab-scale studies and rigorous regression analysis over a wide range of pressures and temperatures of interest. It includes the main ODHE reaction as well as five side reactions. The kinetic model is used to investigate the impact of ethane to oxygen feed ratio, space time and bed length on the region of autothermal operation for varying feed temperatures. The results reveal that ethane conversion and ethylene selectivity are not monotonic at the extinction point and there exists an optimum set of design and operating conditions. We have also studied the impact of the operating pressure on the region of autothermal operation in terms of fixed linear velocity and fixed mass velocity. Our analysis shows that autothermal operation of the ODHE system is feasible at high pressure and can be superior to the traditional ethane cracking process.