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Vliv nosiče při hydrodesulfurizaci na sulfidu ruthenia
Gulková, Daniela ; Kaluža, Luděk ; Vít, Zdeněk ; Zdražil, Miroslav
The hydrodesulfurization of thiophene over ruthenium sulfide on Al2O3, MgO, SiO2, TiO2, ZrO2 or active carbon was studied. The catalysts (1, 3 and 6 wt.% Ru) were prepared by impregnation with aqueous RuCl3. The only exception was the Ru/MgO catalyst which was prepared by impregnation with methanolic solution of Ru acetylacetonate. The catalysts were sulfided either in a 10%H2S/H2 or 20%H2S/N2 mixture at 400 oC. Their activity was tested at 400, 370 and 340 oC. The latter catalysts were mostly more active than the former. The difference increased with the loading and depended on support, the highest being with TiO2 and ZrO2 and the lowest with alumina and active carbon. The Ru sulfide catalysts were more active than the Mo/Al2O3 catalyst with corresponding loading. The order of activity was independent of activation method.
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Vysokopovrchové hydrodesulfurizační katalyzátory MoO3/TiO2
Gulková, Daniela ; Kaluža, Luděk ; Vít, Zdeněk ; Horáček, Jan ; Macháčková, Eva ; Zdražil, Miroslav
MoO3/TiO2 were prepared by impregnation of TiO2 supports with surface areas of 140, 230 and 407 m2g-1. MoO3 loading was in the range 2-32wt.%. The point of zero charge of the supports was 5.0, 8.1 and 10.5, respectively, and decreased with MoO3 loading to the value for MoO3 (2.1). According to the point of zero charge the supports were saturated with a molybdena monolayer at approximately 12, 24 and 14 wt.%, respectively. Temperature-programmed reduction exhibited four peaks, which were assigned to the stepwise reduction (Mo6+ to Mo4+ to Mo0) of tetrahedral monolayer species, po
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Připrava katalyzátoru MoO3/TiO2 s "eggshell" a rovnoměrnou distribucí Mo metodou vodou asistovaného rozprostíráni MoO3.
Gulková, Daniela ; Kaluža, Luděk ; Vít, Zdeněk ; Zdražil, Miroslav
MoO3/TiO2 is commonly prepared by impregnation of TiO2 with a solution of (NH4)6Mo7O24 followed by calcination to remove ammonia. In the present work we used a new method called solvent-assisted (water-assisted) spreading. We have previously used the method of water-assisted spreading for the preparation of MoO3 on alumina and active carbon. The support reacts with MoO3/H2O slurry. The solubility of MoO3 is low but sufficient for the gradual dissolution and adsorption of Mo species on the support surface. The pH of MoO3/H2O (2-2.8) is lower than the point of zero charge of alumina (6-8) and of active carbon (7-8). The support surface is positively charged and this promotes adsorption of molybdenum-containing anions. The adsorption is very strong and catalysts with deep, sharp eggshell profiles of the Mo concentration are obtained. In the present work we have applied this method to the MoO3/TiO2 system.
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