(274f) Topological Analysis of Catalytic Decomposition of Ammonia for Hydrogen Production

Authors: 
Vilekar, S. A., Worcester Polytechnic Institute
Fishtik, I., Worcester Polytechnic Institute
Datta, R., WPI


The storage of hydrogen presents very significant technological barrier for fuel applications in the automobile industry. Chemical storage of hydrogen has been suggested in the form of NH3, which is actually a very effective and inexpensive hydrogen carrier that is available in large quantities and can be easily catalytically (with Ru or Fe) reformed to produce hydrogen at around 500 ºC via 2NH3 ↔ N2 + 3H2, representing about 5.9 wt% hydrogen. Our new graph-theoretic approach is, therefore utilized for mechanistic and kinetic analysis of the NH3 decomposition reaction network based on reaction route theory and their analogy with electrical circuits, in order to unravel the reaction mechanism and kinetics which provides unprecedented insights into catalytic reaction mechanism and microkinetics. These reaction networks are similar to flow graphs which follow Kirchhoff's current (flux) and potential law, thus allowing for rigorous flux and kinetic analysis.

Furthermore, the reaction circuitry allows a reduction of the network by a direct and transparent comparison of the reaction step resistances. Moreover, the rate-limiting steps are identified without any ad hoc assumptions, based on which a rate expression is derived that compares well with our experimental data.