Catalytic reactions of NO over 0--7 mol% Ba/MgO catalysts. 2: Reduction with CH{sub 4} and CO

Journal Article · Mon Nov 15 04:00:00 EST 1999 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1999.2649· OSTI ID:20003848

Xie, S; Rosynek, M P; Lunsford, J H

Barium oxide supported on magnesium oxide (Ba/MgO) is an effective catalyst at elevated temperatures for the selective catalytic reduction (SCR) of nitric oxide, with methane as the reductant. The rate of the SCR reaction is greater than either the rate of reduction with CH{sub 4}, in the absence of O{sub 2}, or the rate of decomposition of NO. At 650 C the rate of the SCR reaction over 1 mol% Ba/MgO was 0.19 {micro}mol/g s with 1% NO, 0.25% CH{sub 4}, and 0.5% O{sub 2}. The SCR reaction is believed to occur via gas-phase CH{sub 3}{sm{underscore}bullet}radicals that are formed at the surface. First-order kinetics with respect to CH{sub 4}is consistent with radical formation being the rate-determining step. The activities of the catalysts and the overall reaction order are influenced by CO{sub 2}, which is a product of the reaction, but also would be present in an exhaust stream. The inhibiting effect of CO{sub 2} is much more significant for a catalyst containing 4 mol% Ba than for one containing 1 mol% Ba. In the latter case, the NgO support modifies the basicity of the BaO. In the absence of O{sub 2}, CO also is a reductant for NO, but if O{sub 2} is present, the nonselective oxidation of CO occurs. That is, CO reacts preferentially with O{sub 2} instead of NO.

• Research Organization: Texas A and M Univ., College Station, TX (US)
• OSTI ID: 20003848
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 188; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
BARIUM OXIDES
CARBON MONOXIDE
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
MAGNESIUM OXIDES
METHANE
NITRIC OXIDE
REDUCING AGENTS
SELECTIVE CATALYTIC REDUCTION