ChemInform Abstract: Higher Alcohol and Oxygenate Synthesis Over Cesium‐Doped Cu/ZnO Catalysts

Nunan, John; Bogdan, Charles E.; Klier, K.; Smith, Kevin J.; Young, C.-W.; Herman, R.G.

doi:10.1002/chin.198926061

Cited by 19 publications

(36 citation statements)

References 1 publication

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“…Higher Cs concentrations also lead to lower methyl acetate formation rates, suggesting that Cs addition favors aldol condensation reactions over esteri®cation reactions or that Cs promotes the conversion of acetate to ethanol, in contrast with earlier reports [5], which found that selectivities to esters and alcohols followed similar trends. Our results are consistent with the involvement of similar intermediates in esteri®cation and aldol condensation steps; species such as adsorbed acetaldehyde are likely to participate both in methyl acetate formation and in 1-propanol formation.…”

Section: Effect Of Cs Concentration On the Synthesis Of Higher Alcoholscontrasting

confidence: 95%

“…Recent results suggests that ethanol is formed directly from CO on K±Cu 0.5 Mg 5 CeO x catalysts [32], but via methanol condensation steps on Cs±Cu/ZnO/Al 2 O 3 [20,32]. Although methanol is not involved in the formation of ethanol on K±Cu 0.5 Mg 5 CeO x , it acts as a C 1 precursor in the synthesis of 1-propanol and 2-methyl-1-propanol from ethanol [33,34].…”

Section: Introductionmentioning

confidence: 99%

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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: Effect Of Cs Concentration On the Synthesis Of Higher Alcoholscontrasting

confidence: 95%

Section: Introductionmentioning

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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“…According to Mazanec, only the coupling of two C, aldehyde (acetaldehyde) species occurs in this aldol condensation step; C,, C, and C, aldehyde species all have too low a concentration to be of any importance. Measurements of Nunan et al [57] in which injection of 2-propsnol were made to the feed gas did not lead to 2-methyl-1-propanol (isobutanol); this result appears to contradict the reaction mechanism put forward by Mazanec [48]. Since Nunan et al have used a Cu/znO+Cs catalyst and Mazanec a ZnO or ThO, catalyst, different reaction routes probably occur over the different catalysts.…”

Section: More Recently Proposed Mechanismsmentioning

confidence: 95%

“…Nunan et al [57] have provided further details of the surface involved in this kinetic model. Using "C-NMR they have derived the scheme given in Figure 6.…”

Section: The Aldol Condensation Mechanismmentioning

confidence: 99%

The synthesis of higher alcohols using modified Cu/ZnO/Al2O3 catalysts

1992

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This paper gives a review of research work in the synthesis of higher alcohols over catalysts based on Cu/ZnO/Al,O,, emphasizing three main topics: (i) the effect on selectivity of the addition of several compounds to this catalyst, (ii) the effect on selectivity of the reaction conditions used, and (iii) the reaction network leading to the different products found. Although the use of aLkali compounds has been studied most extensively, other corn~un~, for example those containing manganese, also appear to be promising additives. The process conditions are rather critical and this may cause some practical difficulties in industrial plants. An extended aldol condensation mechanism is proposed which can explain the product distribution found.

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“…Methanol and higher alcohol synthesis rates were previously shown to reach a maximum with increasing alkali loading [20]- [40]. The amount required for optimum higher alcohol synthesis depends on the identity of the alkali added and also on the density of acid sites on the catalyst [41].…”

Section: Effect Of Cs Concentrationmentioning

confidence: 99%

Isobutanol-Methanol Mixtures From Synthesis Gas

Iglesia¹

1998

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ChemInform Abstract: Higher Alcohol and Oxygenate Synthesis Over Cesium‐Doped Cu/ZnO Catalysts

Abstract: ChemInform Abstract (from H2/CO synthesis gas).

Cited by 19 publications

References 1 publication

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

The synthesis of higher alcohols using modified Cu/ZnO/Al2O3 catalysts

Isobutanol-Methanol Mixtures From Synthesis Gas

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