Thermodynamic assessment of effect of ammonia, hydrazine and urea on water gas shift reaction

Abstract

In the present study, thermodynamic calculations have been carried out on water gas shift reaction in presence of some selected chemical additives such as ammonia, hydrazine, and urea to understand their impact on the hydrogen generation and carbon suppression. The calculations were performed in a temperature range of 300-1300 K at constant pressure (1 bar) while varying the amount of additives from 0.5 to 2 mol. The results suggest that urea has the highest potential for hydrogen enrichment; however, it also increases carbon formation within the investigated conditions, as compared to other additives, ammonia and hydrazine, which suppress carbon formation along with assisting in hydrogen production. Hydrazine was found to be the most effective in reducing carbon and a molar ratio of N2H4:CH4:CO of 1.5:1:1 was sufficient for completely removing carbon throughout the temperature range of 300-1300 K, as compared to 2:1:1 M ratio for NH3:CH4:CO. Both, ammonia and hydrazine, being hydrogen storage materials release hydrogen along with suppressing carbon, which results in suitable conditions for sustained long term catalytic experiments where catalyst poisoning by coking can be eliminated.