Coprecipitated CuO-MnO{sub x} catalysts for low-temperature CO-NO and CO-NO-O{sub 2} reactions

Journal Article · Thu Jul 01 04:00:00 EDT 1999 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1998.2347· OSTI ID:684565

Spassova, I; Khristova, M; Panayotov, D; Mehandjiev, D ^[1]

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1. Bulgarian Academy of Sciences, Sofia (Bulgaria). Inst. of General and Inorganic Chemistry

The activity of the mixed copper-manganese oxides CuO-MnO{sub x} (1.5 < x < 2), obtained by coprecipitation and activated at 300 C, has been studied for CO-NO and CO-NO-O{sub 2} reactions. As shown by magnetic susceptibility data, X-ray diffraction, FTIR spectra, and catalytic tests, an interaction between CuO and MnO{sub x} with formation of a disordered mixed oxide with a spinel-like structure is the cause of the high activity of CuO-MnO{sub x} samples. At ambient temperature (25 C) both adsorption and interaction of CO and NO become more intense with increasing atomic fraction of copper content Cu/Cu + Mn up to 0.53 (catalyst C5M5). For the most active sample C5M5, the degree of NO conversion to N{sub 2} attained with a CO + NO + O{sub 2} + Ar mixture is almost the same as that obtained with a CO + NO + Ar mixture. A Langmuir-Hinshelwood mechanism is proposed for both (CO-NO and CO-NO{sub 2}) interactions at ambient temperature. With increasing temperature under the conditions of a CO + NO + Ar mixture, reduction of the catalyst surface starts. This leads in turn to depression of the CO-NO reaction at temperatures up to 130 C (low-temperature region) and to progressive acceleration of the CO-NO reaction at temperatures above 130 C (middle-temperature region). In the presence of oxygen (a CO + NO + O{sub 2} + Ar mixture), CuO-MnO{sub x} catalysts have an even higher activity over a wide temperature range (75--300 C).

• OSTI ID: 684565
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 185; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION CONTROL
CARBON MONOXIDE
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
COPPER OXIDES
MANGANESE OXIDES
NITRIC OXIDE
REDUCTION