Catalytic property of Pt/AlSBA-15 in selective catalytic reduction of NO
- PDF / 432,860 Bytes
- 8 Pages / 593.972 x 792 pts Page_size
- 74 Downloads / 211 Views
Catalysis Letters Vol. 110, Nos. 3–4, September 2006 ( 2006) DOI: 10.1007/s10562-006-0116-9
Catalytic property of Pt/AlSBA-15 in selective catalytic reduction of NO Kwang Seok Oh and Seong Ihl Woo* Department of Chemical & Biomolecular Engineering and Center for Ultramicrochemical Process Systems, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu Daejeon, 305-701 Korea
Received 17 May 2004; accepted 19 June 2006
Pt-supported on mesoporous SBA-15 catalysts (Pt/SBA-15) have been investigated for selective catalytic reduction of NO by propene in excess oxygen. Catalytic activity of Pt/SBA-15 can be improved by the post-synthesis modification of Al into SBA-15. The resulting material (AlSBA-15) retains a hexagonal order and physical properties of the parent SBA-15 and shows new acid sites. Increased acid sites are confirmed by NH3-TPD. Medium acid site appeared at 200 C and broad strong acid site appeared above 250 C. A certain degree of support acidity of Pt/AlSBA-15 increased the NO conversion, but when there are too many acid sites, carbon deposition becomes extensive and lead to decrease the NO conversion. The influence of different Pt loadings on the catalytic properties was also investigated. KEY WORDS: Pt/AlSBA-15; post-synthesis modification; support acidity; carbon deposition.
1. Introduction Selective catalytic reduction (SCR) of NO in leanburn diesel engine exhausts is a world wide challenging research subject that has been extensively studied due to the increasingly severe emission limitation, which culminated in an agreement in Kyoto. Nitrogen oxides, formed during combustion processes in power plants, wastes incinerators and diesel engines, are the major air pollutants leading to the formation of photochemical smog and acid rain. A large number of catalysts for NO reduction have been screened within last three decades, zeolite based catalysts (Cu/ZSM-5, Pt/ZSM-5) were founded as active catalysts in lean burn condition. Particularly, Pt/ZSM-5 catalyst was reported to be very active for SCR at low temperature [1–5] and showed a high stability in the presence of H2O and SO2 [6, 7]. In addition, supported Pt catalysts have shown high activity in real exhaust gas treatment application and appear to be promising candidates for the SCR of NO. It has also been reported that different catalyst supports have remarkable effects on the activity of the resulting catalyst for NO reduction [8]. Chen and Kawi [9] reported that the NO reduction activity of aluminum containing Pt/MCM-41 has shown higher NO removal performance than that of Pt/MCM-41 and hydrothermal stability in the presence of steam and Woo and co-workers [10, 11] also reported that Pt/V/MCM-41 showed high NO reduction activity in the presence of SO2. These results draw our attention to investigate the use of other material as the catalyst supports for NO reduction. Even though MCM-41 has a high thermal stability, it loses its structure during the exposure to *To whom correspondence should be addressed. E-mail: siwoo@kaist.
Data Loading...
