INVESTIGADORES
PADRO Cristina Liliana
artículos
Título:
Increased Sulfur Tolerance of Pt/KL Catalysts Prepared by Vapor-Phase Impregnation and Containing a Tm Promoter
Autor/es:
G. JACOBS, F. GHADIALI, A. PISANU, C. PADRÓ, A. BORGNA, W. ALVAREZ AND D. RESASCO
Revista:
JOURNAL OF CATALYSIS
Editorial:
Elsevier
Referencias:
Año: 2000 vol. 191 p. 116 - 127
ISSN:
0021-9517
Resumen:
Tm-containing Pt/KL catalysts were prepared by a variety of
techniques, including incipient wetness impregnation (IWI), ion
exchange (IE), and vapor-phase impregnation (VPI) methods. The
Pt morphology resulting from the addition of Tm and Pt sequentially,
using the VPI method, was found to yield the greatest enhancement
to the aromatization performance of the Pt/KL catalysts
studied. The presence of Tm in the sequential VPI Pt/Tm/KL
catalyst resulted reproducibly in a catalyst with higher Pt dispersion
than that in an unpromoted VPI catalyst, as determined by
EXAFS analysis and DRIFTS of adsorbed CO. VPI catalysts give
more finely dispersed Pt clusters than either conventional IWI or
IE methods. From TPO of poisoned catalysts, Tm was also found
to act as a getter for sulfur, so it delays the poisoning of Pt under
sulfur-containing feeds, as further evidenced by reaction studies. In
addition, the initial activity of the Tm-promoted VPI catalysts was
found to be higher than that of the unpromoted Pt/KL VPI catalysts,
suggesting that Tm may directly modify Pt or even participate in
accelerating the aromatization reaction. The amount and method
of incorporation of Tm were found to be critical to the morphology
of the Pt clusters and, subsequently, to catalyst performance under
sulfur-free and sulfur-poisoned reaction conditions. While the sequential
vapor-phase impregnation method with a small amount
of Tm (0.15%) yielded a catalyst with improved catalytic properties,
some of the other methods such as coimpregnation of Pt and
Tm were found to hinder the dispersion of Pt. This may cause the
blocking of the L-zeolite channels, as demonstrated by DRIFTS of
adsorbed CO, and a higher deactivation rate in the reaction