Adsorption of nitrous oxide on metallic copper catalysts

Narita, K.; Takezawa, Nobutsune; Kobayashi, Haruo; Toyoshima, Isamu

doi:10.1007/bf02065064

Cited by 30 publications

(16 citation statements)

References 5 publications

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“…Bulk catalyst compositions were measured by atomic absorption spectroscopy (AAS). Copper metal surface areas were measured by N 2 O (Matheson, ultrahigh purity) decomposition on pre-reduced samples at 363 K. A chemisorption stoichiometry of 0.5:1 O:Cu s was used in order to estimate Cu surface areas and dispersions [37,38].…”

Section: Catalyst Characterizationmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis of higher alcohols on copper catalysts supported on alkali-promoted basic oxides

Hilmen

Ginés

et al. 1998

Applied Catalysis A: General

102

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K±Cu y Mg 5 CeO x and Cs±Cu/ZnO/Al 2 O 3 are selective catalysts for the synthesis of alcohols from an H 2 /CO mixture at relatively low pressures and temperatures. CO 2 produced in higher alcohol synthesis and water±gas shift (WGS) reactions reversibly inhibits the formation of methanol and higher alcohols by increasing oxygen coverages on Cu surfaces and by titrating basic sites required for aldol-type chain growth steps. Inhibition effects are weaker on catalysts with high Cu-site densities. On these catalysts, the abundance of Cu sites allows reactants to reach methanol synthesis equilibrium and maintain a suf®cient number of Cu surface atoms for bifunctional condensation steps, even in the presence of CO 2 . The addition of Pd to K±Cu 0.5 Mg 5 CeO x weakens CO 2 inhibition effects, because Pd remains metallic and retains its hydrogenation activity during CO hydrogenation. Basic sites on Mg 5 CeO x are stronger than on ZnO/Al 2 O 3 and they are more ef®ciently covered by CO 2 during alcohol synthesis. K and Cs block acid sites that form dimethylether and hydrocarbons. Alcohol addition studies show that chain growth occurs predominantly by aldol-type addition of methanol-derived C 1 species to ethanol and higher alcohols, following the rules of base-catalyzed aldol condensations. The initial C±C bond formation required for ethanol synthesis, however, proceeds directly from CO, at least on K±Cu y Mg 5 CeO x catalysts. A detailed kinetic analysis shows that chain growth probabilities are very similar on K±Cu y Mg 5 CeO x and Cs±Cu/ZnO/Al 2 O 3 catalysts. The growth probabilities of C 1 chains to ethanol and of iso-C 4 chains to higher alcohols are much lower than for other chain growth steps. # 1998 Elsevier Science B.V.

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Section: Catalyst Characterizationmentioning

confidence: 99%

“…However, simultaneous WGS reactions modify this ratio, as illustrated by the combination of reactions (2) and (4) resulting in reaction (5). [37,38]) to the total number of Cu atoms in the catalyst.…”

Section: Methanol Synthesismentioning

confidence: 99%

Synthesis of higher alcohols on copper catalysts supported on alkali-promoted basic oxides

Hilmen

Ginés

et al. 1998

Applied Catalysis A: General

102

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show abstract

“…The temperature programmed reduction (TPR) of a Cu/MgO/CeO 2 catalyst indicated that copper reduction took place in the temperature range of 493-553 K. After H 2 reduction, reaction temperature was decreased to 363 K in He and N 2 O was introduced by pulse injection through the sample loop. As reported in the literature [78], [79], the optimum titration temperature was 358-368 K, at which the oxidation of copper by N 2 O is sufficiently mild that only the surface copper is oxidized to Cu(I). At temperatures > 393 K, bulk oxidation of copper occurs.…”

Section: Determination Of Copper Surface Areamentioning

confidence: 67%

“…The number of chemisorbed O atoms was obtained from the amount of N 2 O consumed and the N 2 produced. A saturation coverage of 0.5:1 O:Cu s was used to estimate Cu surface area and dispersion [78], [79]. Cu dispersion is defined as the ratio of surface Cu (Cu s ) to the total number of Cu atoms in the catalyst.…”

Section: Determination Of Copper Surface Areamentioning

confidence: 99%

Isobutanol-Methanol Mixtures From Synthesis Gas

Iglesia¹

1998

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“…After H2 reduction, reaction temperature was lowered to 90 O C in a helium flow and nitrous oxide was then introduced by pulse injection through the sample loop. As reported in the literature [25,26], the optimum titration temperature was 85 O C -95 OC, at which the oxidation of copper by N2O is sufficiently mild that only the surface copper is oxidized and only to the Cu(1) oxidation state. At temperatures > 120 'Cy bulk oxidation of copper will occur.…”

Section: Determination Of Copper Surface Areamentioning

confidence: 82%

Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 January--31 March 1995

Iglesia¹

1995

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Adsorption of nitrous oxide on metallic copper catalysts

Cited by 30 publications

References 5 publications

Synthesis of higher alcohols on copper catalysts supported on alkali-promoted basic oxides

Synthesis of higher alcohols on copper catalysts supported on alkali-promoted basic oxides

Isobutanol-Methanol Mixtures From Synthesis Gas

Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 January--31 March 1995

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