(415i) Numerical Modeling of Chemical Looping Oxidative Dehydrogenation of Ethane in a Packed Bed Reactor | AIChE

(415i) Numerical Modeling of Chemical Looping Oxidative Dehydrogenation of Ethane in a Packed Bed Reactor

Authors 

Cai, R. - Presenter, North Carolina State University
Brody, L., North Carolina State University
Tian, Y., North Carolina State University
Neal, L., North Carolina State University
Bose, A., North Carolina State University
Li, F., North Carolina State University
Chemical looping oxidative dehydrogenation (CL-ODH) of ethane is a promising alternative to steam cracking for ethylene production. Accurate reactor modeling is of critical importance in order to efficiently scale up and implement this new technology. In this study, a one-dimensional, heterogeneous packed bed model was developed to simulate the CL-ODH of ethane to ethylene with Na2MoO4 promoted CaTi0.1Mn0.9O3 redox catalysts. The reaction kinetics was described by coupling the widely accepted reaction scheme for steam cracking of ethane with oxidation kinetics of H2 and C2H4. The competition between H2 and C2H4 for active oxygen species on the surface of the redox catalyst was also determined and implemented in the reactor model. The temperature variation in the different CL-ODH steps and the temperature distribution along the bed were also carefully considered. The feasibility and accuracy of this model were validated by experiments conducted in a relatively large packed bed reactor with 200 g catalysts. The results showed that C2H6 conversion, C2H4 yield, CO2 selectivity, and CH4 yield all increased with the bed height and the reaction temperature but decreased with the total flow rate. The existence of H2 significantly suppressed the oxidation rates of C2H4, and 2%H2 decreased CO2 selectivity by 30%-50%. The released heat during the regeneration step substantially increased the bed temperature, leading to a much higher initial temperature during the reduction step. The model is subsequently used to optimize the operating parameters and reactor design for the CL-ODH process.

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