Abstract
The incorporation of >30% silica in alumina prior to platinum impregnation improves the NOx conversion efficiency in the 200-300 °C range from 45 to 57% and reduces light-off temperature. Further increase in the amount of silica to 50% is detrimental to NOx conversion efficiency. The 1H and 29Si NMR of the materials suggest that this trend is probably related to the surface acidity. The analyses of these materials by X-ray powder diffraction and electron microscopy do not reveal significant differences. Additional NOx conversion in the 350-450 °C range with a maximum of 30% at 400 °C can be achieved if a rhodium-impregnated 30% silica-alumina. Rh-30% SiO2-Al2O3, is placed upstream of Pt-30% SiO2-Al2O3. It is important to note that mixing Pt-30% SiO2-Al2O3 with Rh-30% SiO2-Al2O3 does nor enhance conversion efficiency or effective temperature range.
Original language | English |
---|---|
Pages (from-to) | 3818-3822 |
Number of pages | 5 |
Journal | Langmuir |
Volume | 16 |
Issue number | 8 |
DOIs | |
State | Published - Apr 18 2000 |
Externally published | Yes |