Chemical trapping of surface intermediates in methanol synthesis by amines

Vedage, G.; Herman, R.G.; Klier, K.

doi:10.1016/0021-9517(85)90120-4

Cited by 35 publications

(14 citation statements)

References 22 publications

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“…suggests that disproportionation of methylamines was not the dominant pathway for the formation of (CH&N as well as (CH3)2NH. This observation is consistent with the mechanism of methanol synthesis from CO/H2 over Cu/ZnO catalyst revealed by a chemical trapping study (82). In that study, it was concluded that the lower substituted amines, R(R')NH, trapped the aldehydic It is also consistent with the current understanding of the mechanism of amine alkylation from alcohol and amine or ammonia over Cu catalysts (103), in which the N-containing species react with the surface aldehydic species formed from decomposition of the alcohol to give the alkylation products.…”

Section: Co-cp -A and 11co-c P-bsupporting

confidence: 91%

Probe molecule studies: Active species in alcohol synthesis. Final report, July 1993--July 1994

Blackmond¹,

Wender²,

Oukaci³

et al. 1994

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To develop a better understanding of the mechanism of C2+ alcohol formation from CO/H2 over Co-Cu based catalysts, investigations were carried out by several physical and chemical catalyst characterization techniques, alteration of catalyst reduction condition, CO hydrogenation reaction and in-situ addition of nitromethane as a probe molecule to C0/H2 at steady state. It was demonstrated that the presence of cobalt in a Cu/ZnO based catalyst drastically reduced the activity of Cu for methanol synthesis and significantly suppressed the promotional effect of C 0 2 on methanol formation by blocking or deactivating the copper metal sites, and the copresence of cobalt metal and copper metal did not necessarily promote the formation rates of C2+ alcohols. The reduction treatments using high H2 partial pressure (2 1 atm) at high temperature (> 300OC) were found possible to improve extent of reduction of cobalt without causing sintering of copper metal particles, which consequently increased the local atomic ratio of Coo/Cuo and resulted in dramatic enhancement in the catalyst activity and selectivity for the synthesis of C2-C6 alcohols. A reasonable particle size of cobalt.meta1 in contact with copper metal was suggested to be a key factor in constructing the active sites for the formation of C2+ alcohols. The interaction of CH3N02 with the reaction network of CO hydrogenation over the Cu and Co-Cu based catalysts provided evidence suggesting that the aldehydic methanol intermediate formed from CO and H2 was also involved in the chain growth of C2+ alcohol formation.

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Section: Co-cp -A and 11co-c P-bsupporting

confidence: 91%

Probe molecule studies: Active species in alcohol synthesis. Final report, July 1993--July 1994

Blackmond¹,

Wender²,

Oukaci³

et al. 1994

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“…For the experiment with 0.05% NH 3 , no NH 3 signal was detected, since it is converted to the methylamines monomethylamine (MMA), dimethylamine (DMA) and trimethylamine (TMA) (Supplementary Fig. 10) reacting with oxygen-containing intermediates of methanol synthesis such as formate 26,27 . This means that the NH 3 signal of the 0.5% HPPE represents the part of the injected NH 3 , which does not interact with the catalyst surface, because the position of the signal is equal to the temporary dilution.…”

Section: Resultsmentioning

confidence: 99%

“…The consecutive reaction of NH 3 to TMA is one reason for this correlation. NH 3 requires the highest number of methylation steps until the final product TMA is formed, resulting in the longest blocking of active sites as well as in the highest consumption of oxygen-containing intermediates 26,27 . In contrast, TMA only blocks the active sites by adsorption, since no further methylation is possible ( Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

Identifying the nature of the active sites in methanol synthesis over Cu/ZnO/Al2O3 catalysts

2020

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The heterogeneously catalysed reaction of hydrogen with carbon monoxide and carbon dioxide (syngas) to methanol is nearly 100 years old, and the standard methanol catalyst Cu/ ZnO/Al 2 O 3 has been applied for more than 50 years. Still, the nature of the Zn species on the metallic Cu 0 particles (interface sites) is heavily debated. Here, we show that these Zn species are not metallic, but have a positively charged nature under industrial methanol synthesis conditions. Our kinetic results are based on a self-built high-pressure pulse unit, which allows us to inject selective reversible poisons into the syngas feed passing through a fixed-bed reactor containing an industrial Cu/ZnO/Al 2 O 3 catalyst under high-pressure conditions. This method allows us to perform surface-sensitive operando investigations as a function of the reaction conditions, demonstrating that the rate of methanol formation is only decreased in CO 2-containing syngas mixtures when pulsing NH 3 or methylamines as basic probe molecules.

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“…For example, 50 to 100% selectivity to methylisopropylamine was obtained at 80 to 20% isopropylamine conversion over a Cu/ZnO catalyst at 180 to 215 • C and 7.7 MPa [130,131]. However, the amount of methanol and CO 2 byproducts was higher than that of amines, even at low CO conversion.…”

Section: Amination Of Carbon Monoxide and Carbon Dioxidementioning

confidence: 99%

“…However, the amount of methanol and CO 2 byproducts was higher than that of amines, even at low CO conversion. The reaction proceeds directly via an adsorbed intermediate of methanol synthesis (likely formyl or hydroxycarbene species, Scheme 14), and the amination of methanol is negligible [131].…”

Section: Amination Of Carbon Monoxide and Carbon Dioxidementioning

confidence: 99%

Amination Reactions

Mallát

Baiker

Kleist

et al. 2008

Handbook of Heterogeneous Catalysis

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The sections in this article are Introduction Amination of Alcohols Aliphatic Alcohols Amination over Metal Catalysts (Dehydrogenation Route) Amination over Solid Acid Catalysts (Dehydration Route) Amino Alcohols, Polyalcohols Amination of Phenols Amination of Carbonyl Compounds (Reductive Alkylation) Reaction Mechanism Catalysts, Reaction Conditions Selective Synthesis of Primary, Secondary, or Tertiary Amines Amination with Bifunctional Amines or Carbonyl Compounds Heterocyclic Ring Formation Stereoselectivity Amination of Carboxylic Acids and Esters Amination of Alkenes and Alkynes (Hydroamination) Amination of Ethers Amination of Halogen Compounds Amination of Haloalkanes Amination of Haloaryls Amination of Hydrocarbons Amination of Carbon Monoxide and Carbon Dioxide

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Chemical trapping of surface intermediates in methanol synthesis by amines

Cited by 35 publications

References 22 publications

Probe molecule studies: Active species in alcohol synthesis. Final report, July 1993--July 1994

Probe molecule studies: Active species in alcohol synthesis. Final report, July 1993--July 1994

Identifying the nature of the active sites in methanol synthesis over Cu/ZnO/Al2O3 catalysts

Amination Reactions

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