Iron oxide and chromia supported on titania-pillared clay for selective catalytic reduction of nitric oxide with ammonia
- State Univ. of New York, Buffalo, NY (United States)
- Univ. of Michigan, Ann Arbor, MI (United States)
TiO{sub 2}-pillard clay (PILC) with high surface area, large pore volume, and large interlayer spacing was used as the support for mixed Fe{sub 2}O{sub 3} and Cr{sub 2}O{sub 3} as the catalyst for selective catalytic reduction (SCR) of NO with NH{sub 3}. The Fe/Cr ratio was varied at a fixed total amount of oxide dopant of 10% (wt). The Fe-Cr/TiO{sub 2}-PILC with Fe/Cr=3 showed the highest activity. Compared with commercial V{sub 2}O{sub 5}/TiO{sub 2} catalysts, the activity (on a per gram basis) of the doped pillared clay was approximately twice as high under H{sub 2}O- and SO{sub 2}-free conditions and was approximately 40% higher under conditions with H{sub 2}O and SO{sub 2}. In addition, its activity for SO{sub 2} oxidation was only 20%-25% of that of the V{sub 2}O{sub 5}-based catalysts. TPD of NH{sub 3} on the Fe-Cr/TiO{sub 2}-PILC catalyst showed that both M=O and M-OH (M=Fe or Cr) were necessary for the SCR reaction. In situ IR spectra of NH{sub 3} showed that there was a higher Bronsted acidity than the Lewis acidity on the surface under reaction conditions and that there existed a direct correlation between the SCR activity and the Bronsted acidity among pillared clays with different Fe/Cr ratios. These results, along with the transient response to O{sub 2}, indicated that a similar mechanism to that on the V{sub 2}O{sub 5} catalyst was operative. The TiO{sub 2}-pillared clay used as the support also contributed to the high activity of the Fe-Cr catalyst. The TiO{sub 2} pillars combined with the tetrahedral SiO{sub 2} surfaces of the clay apparently gave rise to a high dispersion of Fe{sub 2}O{sub 3}. 52 refs., 10 figs., 5 tabs.
- DOE Contract Number:
- FG22-93PC93217
- OSTI ID:
- 486377
- Journal Information:
- Journal of Catalysis, Vol. 164, Issue 1; Other Information: PBD: Nov 1996
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
20 FOSSIL-FUELED POWER PLANTS
40 CHEMISTRY
54 ENVIRONMENTAL SCIENCES
IRON OXIDES
CATALYTIC EFFECTS
CHROMIUM OXIDES
TITANIUM OXIDES
CLAYS
NITRIC OXIDE
SELECTIVE CATALYTIC REDUCTION
AMMONIA
OXIDATION
CATALYST SUPPORTS
CATALYSTS
TEMPERATURE DEPENDENCE
ABSORPTION SPECTROSCOPY
HETEROGENEOUS CATALYSIS
SURFACE AREA
BROENSTED ACIDS
LEWIS ACIDS