The Effects of Promoter Cs Loading on the Hydrogen Production from Ammonia Decomposition Using Ru/C Catalyst in a Fixed-Bed Reactor

The hydrogen production from ammonia decomposition on commercial 5 wt.% Ru/C (C: activated carbon) catalyst with different cesium (Cs) loadings at lower temperatures of 325-400 degrees C in the fixed-bed reactor was experimentally investigated. Based on the parameters used in this work, the results showed that the ammonia conversion at 350 degrees C is increased with the increasing Cs/Ru molar ratio, and it reaches its maximum value at the Cs/Ru molar ratio of 4.5. After that, it is rapidly decreased with a further increase of Cs/Ru molar ratio, and it is even smaller than that of the pure Ru/C case at the Cs/Ru molar ratio of 6. The Cs promotion at the lower Cs/Ru molar ratios may be due to the so-called hot ring promotion. The possible mechanisms for Cs effects on the ammonia conversion at higher Cs/Ru molar ratio are discussed. At optimum Cs loading, the results showed that all the ammonia conversions at 400 degrees C are near 100% for the GHSV (gas hourly space velocity) from 48,257 to 241,287 mL/(h center dot g(cat)).

Automated summary

The study on hydrogen production from ammonia decomposition on commercial 5 wt.% Ru/C catalyst revealed that the ammonia conversion increased with increasing Cs/Ru molar ratio and reached a maximum at 4.5. However, the conversion rapidly decreased with further increase in Cs/Ru molar ratio, dropping even below that of pure Ru/C at a ratio of 6. The Cs promotion effect was attributed to hot ring promotion at lower Cs/Ru molar ratios, while the mechanisms for Cs effects on ammonia conversion at higher Cs/Ru molar ratios were discussed. At optimal Cs loading, ammonia conversions at 400°C were near 100% for gas hourly space velocities ranging from 48,257 to 241,287 mL/(h center dot g(cat)).