| 초록 |
The present study has been focused on the extent of on-stream deactivation of Pt nanoparticles, dispersed on high surface area silica, in the reduction of N2O by H2 at low temperatures, such as 90oC - 135oC. A sample of a 0.65% Pt/SiO2 catalyst reduced at 400oC had very high deN2O activity even at 110oC and 102,500h-1, depending significantly on H2-to-N2O ratio, and whether or not the presence of guest molecules such as O2 and H2O. The catalyst showed the deactivation during the course of reduction even under a clean condition; however, such a deactivation profile was very reproducible when allowing repeated measurements to the deN2O reaction. In case that a catalyst sample with greater Pt loadings, representatively 1.72% Pt/SiO2, was used for this reaction, N2O conversions near 100% were obtained for ~80 h after which the activity greadually decreased with time and was finally approached to 86%, but this catalyst also possessed a quite reproducible behavior in the deactivation. It is clear that the catalyst deactivation was associated with no changes in the nanoparticles sizes, as confirmed by H2 chemisorption and XRD measurements. In order to clarify the deactivation mechanism, spectroscopic studies were conducted. |
