Ammonia decomposition kinetics over LiOH-promoted, α-Al2O3 -supported Ru catalyst

A LiOH-promoted Ru-based catalyst was recently reported to have a high TOF of 17.7 s(-1) at 623 K, compared to 2.7 s(-1) for an un-promoted Ru-based catalyst, and has been reproduced for this study to develop further understanding of the catalyst activity under a range of conditions. The kinetic values were calculated using a Temkin-Pyzhev-like power law rate expression model. Reaction orders, pre-exponential factors (A) and activation energies (E) were calculated for two temperature ranges, 623-748 K, and 748-873 K. The TOF of this catalyst at 623 K is not similar to that previously reported, being only 1.6 s(-1) in this study. A follow-up CFD analysis supports the fact that the kinetic model effectively describes performance of the catalyst at a range of temperatures and pressures, and can be used in the future on similar catalysts. H-2 partial pressure has an inhibitory effect on the rate of decomposition of NH3 at all temperatures, not just near or below 673 K as previously proposed in the literature, however equilibrium decomposition is still possible with sufficient catalyst loading. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.