A New Ammonia Kinetic Model in Ru-Catalyzed Steam-Reforming Reaction Containing N₂ in Natural Gas

Abstract

Hydrogen for building fuel cells is primarily produced by natural-gas steam-reforming reactions. Pipeline-transported natural gas in Europe and North America used to contain about 1% to 5% N2, which reacts with H2 in steam-reforming reactions to form NH3. In the case of Ru, one of the catalysts used in natural-gas steam-reforming reactions, the activity of the NH3-formation reaction is higher than that of Ni and Rh catalysts. Reforming gas containing NH3 is known to poison Pt catalysts in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) and also poison catalysts in preferential oxidation (PROX). In this study, Langmuir–Hinshelwood-based models of the NH3-formation reaction considering H2 and CO were proposed and compared with a simplified form of the Temkin–Pyzhev model for NH3-formation rate. The kinetic parameters of each model were optimized by performing multi-objective function optimization on the experimental results using a tube-type reactor and the numerical results of a plug-flow one-dimension simple SR (steam-reforming) reactor.

Keywords

• hydrogen
• reformation
• water–gas shift reaction
• kinetic model
• NH₃