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  • 1
    Digitale Medien
    Digitale Medien
    Crystal Structure, Infrared and Solid State CP MAS NMR Characterization of [(PPh3)2AgO2CH] and of [(PPh3)2AgO2CH]·2HCO2H, a Complex of the H-Bonded [H2(HCO2)3]- Species (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 3909-3917 
    Details
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/j100012a008
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  • 2
    Digitale Medien
    Digitale Medien
    trans-Polyacetylene on sodium and cesium mordenites: a resonance Raman spectroscopic study (1993)
    s.l. : American Chemical Society
    Chemistry of materials 5 (1993), S. 1509-1517 
    Details
    ISSN: 1520-5002
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Maschinenbau
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/cm00034a022
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  • 3
    Digitale Medien
    Digitale Medien
    Spectroscopic evidence for adsorption sites located at Cu/ZnO interfaces (1995)
    Springer
    Catalysis letters 31 (1995), S. 333-340 
    Details
    ISSN: 1572-879X
    Schlagwort(e): Cu/ZnO/SiO2 catalysts ; IR adsorbed CO ; adsorbed formate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract FTIR spectra are reported of CO and formic acid adsorption on a series of Cu/ZnO/SiO2 catalysts. Peaks due to linear CO adsorbed on copper diminished in intensity as the loading of ZnO was increased. This behaviour was explained in terms of ZnO island growth on the copper surface. Similarly, reduction of the copper concentration while maintaining a constant ZnO loading also resulted in further attenuation in bands ascribed to CO chemisorbed on copper. Formic acid exposure to a Cu/SiO2 sample produced a formate species displaying a νas(COO) mode at 1585 cm−1. Addition of a small quantity of ZnO to the catalyst resulted in substantial promotion of formate growth, which was accompanied by a shift (and broadening) of the νas(COO) vibration to 1660–1600 cm−1. Since further ZnO incorporation poisoned formate creation it was concluded that formate species bonded to Cu and Zn sites located at interfacial positions had been formed. The role of such species in methanol synthesis is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00808597
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  • 4
    Digitale Medien
    Digitale Medien
    A Fourier-transform infrared study of CO2 and CO2/H2 interactions with caesium-doped copper catalysts (1996)
    Springer
    Topics in catalysis 3 (1996), S. 103-114 
    Details
    ISSN: 1572-9028
    Schlagwort(e): copper catalysts, modified with caesium ; copper catalysts, CO2/H2 adsorption
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract FTIR spectra are reported of CO2 and CO2/H2 on a silica-supported caesium-doped copper catalyst. Adsorption of CO2 on a “caesium”/silica surface resulted in the formation of CO2 − and complexed CO species. Exposure of CO2 to a caesium-doped reduced copper catalyst produced not only these species but also two forms of adsorbed carboxylate giving bands at 1550, 1510, 1365 and 1345 cm−1. Reaction of carboxylate species with hydrogen at 388 K gave formate species on copper and caesium oxide in addition to methoxy groups associated with caesium oxide. Methoxy species were not detected on undoped copper catalyst suggesting that caesium may be a promoter for the methanol synthesis reaction. Methanol decomposition on a caesium-doped copper catalyst produced a small number of formate species on copper and caesium oxide. Methoxy groups on caesium oxide decomposed to CO and H2, and subsequent reaction between CO and adsorbed oxygen resulted in carboxylate formation. Methoxy species located at interfacial sites appeared to exhibit unusual adsorption properties.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02431180
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  • 5
    Digitale Medien
    Digitale Medien
    An in situ high pressure FT-IR study of CO2/H2 interactions with model ZnO/SiO2, Cu/SiO2 and Cu/ZnO/SiO2 methanol synthesis catalysts (1992)
    Springer
    Catalysis letters 14 (1992), S. 289-295 
    Details
    ISSN: 1572-879X
    Schlagwort(e): Surface FT-IR ; methanol synthesis ; copper catalysts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract In situ FT-IR spectroscopy allows the methanol synthesis reaction to be investigated under actual industrial conditions of 503 K and 10 MPa. On Cu/SiO2 catalyst formate species were initially formed which were subsequently hydrogenated to methanol. During the reaction a steady state concentration of formate species persisted on the copper. Additionally, a small quantity of gaseous methane was produced. In contrast, the reaction of CO2 and H2 on ZnO/SiO2 catalyst only resulted in the formation of zinc formate species: no methanol was detected. The interaction of CO2 and H2 with Cu/ZnO/SiO2 catalyst gave formate species on both copper and zinc oxide. Methanol was again formed by the hydrogenation of copper formate species. Steady-state concentrations of copper formate existed under actual industrial reaction conditions, and copper formate is the pivotal intermediate for methanol synthesis. Collation of these results with previous data on copper-based methanol synthesis catalysts allowed the formulation of a reaction mechanism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00769666
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  • 6
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of highly ordered MCM-41 in an alkali-free system and its catalytic activity (1996)
    Springer
    Catalysis letters 38 (1996), S. 33-37 
    Details
    ISSN: 1572-879X
    Schlagwort(e): MCM-41 synthesis ; alkali-free gel ; n-heptane cracking ; NMR
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract MCM-41 mesoporous molecular sieve materials are synthesised using aqueous ammonia solution to adjust the pH of the reactant gel. Highly ordered MCM-41 with Si/Al ratio as low as 14 was obtained and characterised by27A1 MAS NMR, XRD, N2-adsorption, benzene sorption, and NH3-TPD measurements. The acidity of MCM-41 materials obtained in this system was conveniently generated through straightforward calcination of the as-synthesised sample. More mild acidic sites generated could be due to the avoidance of the multiple calcination procedure and/or the trace sodium species which are the poisons to Brønsted acid. The catalytic activities forn-heptane cracking and isomerization ofm-xylene were investigated, and these were in accordance with the known properties of MCM-41.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00806896
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  • 7
    Digitale Medien
    Digitale Medien
    Resonance Raman spectroscopic study of polypyrrole in CuZSM-5 (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 24 (1993), S. 523-526 
    Details
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Raman spectroscopy was employed to study the polymerization of pyrrole over a selection of copper-exhanged ZSM-5 zeolites. No polymerization occurred on catalysts of low copper content, which suggested that a critical concentration of copper(II) cations was required for reaction. On ZSM-5 materials with low Si/Al ratios, bands were detected which were characteristic of partially oxidized polypyrrole and monomeric pyrrole. The polymer was degraded in the presence of residual oxygen. It was shown that the polymer incorporated both aromatic- and quinoidal-type structures. Further, resonance Raman spectroscopy suggested that the charge carrier present in the oxidized polymer was associated with the quinoid arrangement.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jrs.1250240809
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