ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Surface composition and possible rearrangement of disperse Pt and Rh catalysts: does the presence of carbon and oxygen contribute to different catalytic properties? (2000)
    Springer
    Catalysis letters 67 (2000), S. 93-98 
    Details
    ISSN: 1572-879X
    Keywords: rhodium black ; platinum black ; surface carbon ; surface oxygen ; methylcyclopentane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The surface composition of Rh and Pt blacks (as determined by XPS) shows carbon and oxygen impurities in the untreated state. Oxygen on Pt is present as adsorbed O as well as OH/H2O groups and oxidized carbon. Rh was partly oxidized to Rh2O3, in agreement with UPS showing hardly any Fermi‐edge intensity in untreated Rh as opposed to untreated Pt. High Fermi‐edge intensities indicated a predominant metallic surface after an in situ treatment with H2 at 483 K, increasing the purity (XPS) to ∼90%. This treatment reduced Rh to metal and removed its C impurity. Pt, in turn, retained much carbon after H2 treatment, present mainly as graphitic carbon. A minor amount of CO was also detected, some of the O 1s peak belonging to it. The two metals were tested in methylcyclopentane reactions. Considering the necessity of carbon for nondegradative reactions and oxygen enhancing fragmentation, a correlation is suggested between the typical impurities of Pt and Rh and their respective catalytic propensities: the high fragmentation activity of Rh and the predominant nondegradative reactions to C6 “ring opening products” on Pt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019061420659
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    An attempt to bridge the pressure and material gap with a disperse model catalyst for low-temperature alkane reforming (2000)
    Springer
    Catalysis letters 65 (2000), S. 19-23 
    Details
    ISSN: 1572-879X
    Keywords: Pt black ; n-hexane ; XPS ; UPS ; XRD ; surface carbon ; surface oxygen ; catalyst restructuring ; crystal anisotropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pt black was exposed to n〉-hexane/H2 mixtures between 483 and 663 K followed by O2 and H2 treatments at 603 K. XP and UP spectra were measured without exposing the samples to air. 20–30% carbon accumulated after hydrocarbon exposures. O2 removed most carbon. The surface C content increased after a subsequent contact with H2, C 1s showing more “atomic carbon” as opposed to graphite after n-hexane exposure. Anisotropic recrystallization of Pt black favoring (220) and (311) lattice planes occurred under hydrogen-rich conditions. Both findings were attributed to a H2-induced solid-state rearrangement; H atoms penetrating into the crystal lattice, force subsurface carbon and oxygen atoms to the surface and a concomitant restructuring would occur. Thus another “hydrogen effect” has been recognized, leading to structures favorable for skeletal reactions of alkanes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019037926168
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...