Zdrojový dokument:Scientific papers of the University of Pardubice. Series A, Faculty of Chemical Technology. 20/2014
ISSN:1211-5541
Abstrakt:
Parameters that affect the catalytic behaviour of vanadium-containing
mesoporous silicas in oxidative dehydrogenation reaction of propane are mainly
aggregation state of surface VOx species and reducibility of vanadium species.
Type and conditions of synthesis have big impact on the nature of vanadium
species and, therefore, influence significantly catalytic properties. Two vanadiumcontaining
mesoporous silica catalysts were synthesized by different techniques
(including direct synthesis from hydrogel containing vanadium precursor and wet
impregnation of SBA-15 mesoporous silica by vanadyl acetylacetonate) and their
physico-chemical and catalytic properties were studied and compared. Direct
synthesis of vanadosilicate led to catalysts with non-uniform mesoporosity, but
exhibiting better spreading of vanadium on the surface resulting in species with lower degree of polymerization compared to impregnated catalyst. It is reflected
in higher iso-conversional selectivity of directly synthesized catalyst towards
propene.