| AVS 66th International Symposium & Exhibition | |
| Fundamental Discoveries in Heterogeneous Catalysis Focus Topic | Thursday Sessions |
| Session HC+SS+TL-ThA |
| Session: | Reaction Pathways and Addressing Challenges for Energy Production in the 21st Century & Heterogeneous Catalysis Graduate Student Award Presentation |
| Presenter: | Rebecca Fushimi, Idaho National Laboratory |
| Authors: | Y. Wang, Idaho National Laboratory M.R. Kunz, Idaho National Laboratory G. Yablonsky, Washington University in Saint Louis R. Fushimi, Idaho National Laboratory |
| Correspondent: | Click to Email |
Pulse response experiments in a pure diffusion reactor significantly increase the number of gas/solid collisions for probing kinetic interactions but maintain straightforward transport modeling by avoiding gas phase dynamics. Using inverse-diffusion methods [1] the millisecond time-dependence of the reaction rate can be calculated as it responds to the forced concentration dynamic. More importantly, in this experiment the gas and surface concentrations are decoupled and their influence on the transformation rates of reactants and products can be studied.
Vacuum pulse response studies of ammonia decomposition on polycrystalline Fe, Co and a CoFe bimetallic preparation were conducted to investigate the microkinetic features that lead to very distinct global performance [2]. We present dynamic atomic accumulation; a new measure used to characterize the ability of a complex surface to regulate adsorbed species. We find Fe can support hydrogenated species with a longer surface lifetime that either CoFe or Co. From the time-dependence of the rate we find Co can support two mechanistic pathways for H2 production. The quantitative rate, gas and surface concentration data of microkinetic reaction steps explain why materials with cobalt perform better at a global level.
1. Redekop, E.A., et al., The Y-Procedure methodology for the interpretation of transient kinetic data: Analysis of irreversible adsorption. Chem. Eng. Sci., 2011. 66(24): p. 6441-6452.
2. Wang, Y., et al., Transient Kinetic Experiments within the High Conversion Domain: The Case of Ammonia Decomposition. Catalysts, 2019. 9(1): p. 104.