Characterization of SnO{sub 2}/Al{sub 2}O{sub 3} lean NO{sub x} catalysts
- Northwestern Univ., Evanston, IL (United States). Dept. of Chemical Engineering
SnO{sub 2}/Al{sub 2}O{sub 3} prepared with SnCl{sub 2} impregnation onto sol-gel Al{sub 2}O{sub 3} and calcined at 800 C is one of the most active catalysts for lean NO{sub x} reduction with propene under high partial pressures of O{sub 2} (15%) and H{sub 2}O (10%) and space velocity (30,000 h{sup {minus}1}). An unusual feature of this catalyst is the independence of maximum NO conversion over a wide range of Sn contents (1 to 10 wt% Sn). This catalyst is, however, sensitive to other preparation variables such as the nature of Sn precursor and the calcination temperature. X-ray photoelectron spectroscopic results indicate that Sn is present in the +4 oxidation state irrespective of Sn loadings. X-ray diffraction, temperature-programmed desorption, and temperature-programmed reduction results indicate a wide range of oxo-tin cluster sizes as well as different ratios of amorphous and crystalline SnO{sub 2} present in samples with different Sn loadings. The Sn(IV) in the amorphous SnO{sub 2} fraction can be reduced to Sn(II) below 450 C in the TPR experiments. In fact, all of the SnO{sub 2}/Al{sub 2}O{sub 3} catalysts have very similar H{sub 2} uptake features below 450 C. In view of the fact that they also have very similar catalytic properties, it appears likely that easily reducible amorphous SnO{sub 2} is an active phase for lean NO{sub x} catalysis in these samples.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 362063
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 184; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
Similar Records
In2O3/Al2O3 Catalysts for NOx Reduction in Lean Condition
Lean NO{sub x} reduction over Au/Al{sub 2}O{sub 3}