Effect of SO2 and H2O on the N2O decomposition in the presence of O2 over Ru/Al2O3

Catalyst evaluation and kinetic analysis was performed on the catalytic decomposition of N2O to N2 over a Ru/Al2O3. An oxygen rich feed containing SO2 and H2O were used in order to examine their influence on the catalyst activity. An Al2O3 support was used with various Ru loadings (1–4%). No enhancement in the activity was observed for Ru loadings higher than 2%. The performance of the Ru/Al2O3 catalyst was tested using various pretreatment procedures. The activity of the catalysts changed with pretreatment procedure that was followed: calcinations at 600 °C in inert, reducing and oxidizing atmosphere. The initial temperature of each experiment affected the catalyst activity, as well. The effect of the presence of SO2 (0–500 ppm) and/or H2O (0–10%) in the feed on the catalytic activity was also measured. A shift of the N2O conversion versus temperature curve towards higher temperatures was observed when SO2 and H2O were added, either separately or simultaneously, into the feed. The inhibition caused by SO2 was attributed to the formation of sulphates while that caused by water to the competitive chemisorption of H2O and N2O on the same active sites. Finally, kinetic and TPD studies showed that N2O is catalytically decomposed to N2 both in absence and presence of poisonous gases.