Characterization of the metallic phase in nanocrystalline ZnAl2O4-supported Pt catalysts

2011 ◽  
Vol 257 (6) ◽  
pp. 2394-2400 ◽  
Author(s):  
Wiktoria Walerczyk ◽  
Mirosław Zawadzki ◽  
Janina Okal
Keyword(s):  
Metallic Phase ◽  
Pt Catalysts ◽  
Supported Pt Catalysts

scholarly journals Characterization of Zeolite-supported Pt Catalysts by Image Analysis

2003 ◽  
Vol 9 (S02) ◽  
pp. 752-753
Author(s):  
J. O. Huertas Flores ◽  
J. R. J. Zumarán Farfán ◽  
M. I. Pais da Silva ◽  
P. M. Jardim ◽  
S. Paciornik
Keyword(s):  
Image Analysis ◽  
Pt Catalysts ◽  
Supported Pt Catalysts

A Single Turnover (STO) Characterization of Supported Palladium Catalysts

1987 ◽  
Vol 111 ◽  
Author(s):  
Robert L. Augustine ◽  
David R. Baum
Keyword(s):  
Palladium Catalysts ◽  
Active Sites ◽  
Pt Catalyst ◽  
Catalyst Characterization ◽  
Pt Catalysts ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
Pd Catalysts ◽  
Supported Pt Catalysts

AbstractWhile the STO catalyst characterization procedure has been applied to a variety of supported Pt catalysts, application of this technique to the characterization of supported Pd catalysts showed that there were several significant differences between the Pt and the Pd catalysts. Under STO reaction conditions each surface site on a Pt catalyst reacts only once so there is a 1:1 relationship between the product composition and the densities of the various types of active sites present. With Pd catalysts under these same conditions, alkene isomerization takes place so readily that the amount of isomerized product formed depends on the contact time of the reactant pulse with the catalyst so there is no direct relationship between the amount of isomerization and the number of isomerization sites present. On Pt there are some direct saturation sites present on which H2 is rather weakly held. Such sites are not present on Pd catalysts. The reactive surface of supported Pt catalysts remains constant on long exposure to air. With Pd catalysts exposure to air results in a decrease in saturation site densities which can be reversed by re-reduction of the surface with H2 under ambient conditions but not completely under what can be termed “reaction conditions” where the extent of surface re-reduction decreases with catalyst age.

scholarly journals Influence of the Reduction Temperature and the Nature of the Support on the Performance of Zirconia and Alumina-Supported Pt Catalysts for n-Dodecane Hydroisomerization

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 88
Author(s):  
Diana García-Pérez ◽  
Maria Consuelo Alvarez-Galvan ◽  
Jose M. Campos-Martin ◽  
Jose L. G. Fierro
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Catalytic Properties ◽  
Catalytic Performance ◽  
Major Influence ◽  
Pt Catalysts ◽  
Reduction Temperature ◽  
Metal Dispersion ◽  
Tungsten Oxides ◽  
Supported Pt Catalysts

Catalysts based on zirconia- and alumina-supported tungsten oxides (15 wt % W) with a small loading of platinum (0.3 wt % Pt) were selected to study the influence of the reduction temperature and the nature of the support on the hydroisomerization of n-dodecane. The reduction temperature has a major influence on metal dispersion, which impacts the catalytic activity. In addition, alumina and zirconia supports show different catalytic properties (mainly acid site strength and surface area), which play an important role in the conversion. The NH3-TPD profiles indicate that the acidity in alumina-based catalysts is clearly higher than that in their zirconia counterparts; this acidity can be attributed to a stronger interaction of the WOx species with alumina. The PtW/Al catalyst was found to exhibit the best catalytic performance for the hydroisomerization of n-dodecane based on its higher acidity, which was ascribed to its larger surface area relative to that of its zirconia counterparts. The selectivity for different hydrocarbons (C7–10, C11 and i-C12) was very similar for all the catalysts studied, with branched C12 hydrocarbons being the main products obtained (~80%). The temperature of 350 °C was clearly the best reduction temperature for all the catalysts studied in a trickled-bed-mode reactor.

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