(451c) Forced Dynamic Operation of Propylene Selective Oxidation to Acrolein in a Catalytic Foam Reactor: Reactor Model Development

Acrolein serves not only as a direct biocide but also as precursor for acrylic and amino acids. Its inherent toxicity, however, poses challenges to large-scale production, storage, and transportation. These challenges can in part be addressed by distributed production in smaller, modular reactors under non-steady state reaction conditions. We find that certain forced dynamic operating (FDO) conditions for the selective oxidation of propylene over an industrial mixed metal oxide catalyst can increase the acrolein yield beyond the steady-state performance, and spatiotemporal characterization attributes the highest activity to sites located in the middle of the foam reactor bed. Given the highly non-linear response of the reaction system, a comprehensive transient reactor model is required to further optimize the dynamic conditions (e.g., frequency, cycle duty).

To this end, we model a porous foam reactor, which offers practical advantages in modular and transient operation design. Our 1+1D porous foam reactor model couples transport processes with a transient kinetic model of propylene oxidation. The reaction kinetics are adapted from a previous report [1] and the model parameters were fitted using available steady-state experimental data at different temperatures to achieve better than 80% correlation. To predict performance under FDO conditions, we introduce additional surface species and reactions to capture dynamic oxygen storage properties along the reactor and as function of wash-coat depth. This modification enables us to replicate the FDO peak observed above the steady state, where the stored oxygen at certain catalyst surface coverage is presumed to exhibit the highest activity. Our comprehensive model provides a critical tool for further optimization of the dynamic process and to maximize the yield to acrolein in a practical reactor configuration for distributed manufacturing.

References:

[1] Redlingshöfer, Hubert, et al. Ind. Eng. Chem. Res. 42.22 (2003): 5482-5488.