Manganese Oxide Catalysts Supported on TiO2, Al2O3, and SiO2: A Comparison for Low-Temperature SCR of NO with NH3
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- 作者：Panagiotis G. Smirniotis ; Pavani M. Sreekanth ; Donovan A. Peñ ; a ; Robert G. Jenkins
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2006
- 出版时间：September 13, 2006
- 年：2006
- 卷：45
- 期：19
- 页码：6436 - 6443
- 全文大小：366K
- 年卷期：v.45,no.19(September 13, 2006)
- ISSN：1520-5045
文摘
A series of TiO2-, Al2O3-, and SiO2-supported manganese oxide catalysts were prepared, characterized, andcatalytically tested for selective catalytic reduction (SCR) of NO with NH3 in the presence of excess oxygenat low temperatures (373-523 K). Various commercial supports were used in this study to find out the influenceof surface area, support nature (acidic, basic), and crystalline phase on SCR activity. XRD studies reveal thepresence of anatase and rutile phases for titania supports and the existence of 
-alumina in the case of aluminasupport. Silica support was amorphous. No independent lines corresponding to the crystalline MnO2 wereobserved on pure anatase and rutile samples. However, the presence of MnO2 was confirmed on other supportsby XRD. BET surface area values suggest that specific surface area of the supports was decreased afterimpregnating with MnO2. The FT-IR and ammonia TPD studies indicate the presence of two types of acidsites on these catalysts, and the acidic strength of the catalysts is higher than the corresponding pure supports.XPS results revealed the presence of two types of manganese oxides, MnO2 (642.4 eV) and Mn2O3 (641.2eV), on all the samples. The SCR performance of the supported Mn catalysts decreased in the followingorder: TiO2 (anatase, high surface area) > TiO2 (rutile) > TiO2 (anatase, rutile) > -Al2O3 > SiO2 > TiO2(anatase, low surface area). Quantitative NO conversion with 100% N2 selectivity was achieved at 393 Kwith Mn supported on TiO2 (anatase). TiO2-supported MnO2 catalysts showed more promising SCR activitythan Al2O3- or SiO2-supported manganese oxide catalysts. Various characterization techniques suggest thatLewis acid sites, a high surface concentration of MnO2, and redox properties are important in achieving highcatalytic performance at low temperatures.
-alumina in the case of aluminasupport. Silica support was amorphous. No independent lines corresponding to the crystalline MnO2 wereobserved on pure anatase and rutile samples. However, the presence of MnO2 was confirmed on other supportsby XRD. BET surface area values suggest that specific surface area of the supports was decreased afterimpregnating with MnO2. The FT-IR and ammonia TPD studies indicate the presence of two types of acidsites on these catalysts, and the acidic strength of the catalysts is higher than the corresponding pure supports.XPS results revealed the presence of two types of manganese oxides, MnO2 (642.4 eV) and Mn2O3 (641.2eV), on all the samples. The SCR performance of the supported Mn catalysts decreased in the followingorder: TiO2 (anatase, high surface area) > TiO2 (rutile) > TiO2 (anatase, rutile) > -Al2O3 > SiO2 > TiO2(anatase, low surface area). Quantitative NO conversion with 100% N2 selectivity was achieved at 393 Kwith Mn supported on TiO2 (anatase). TiO2-supported MnO2 catalysts showed more promising SCR activitythan Al2O3- or SiO2-supported manganese oxide catalysts. Various characterization techniques suggest thatLewis acid sites, a high surface concentration of MnO2, and redox properties are important in achieving highcatalytic performance at low temperatures.