Pt/Al2O3Catalysts and Pt–Sn/Al2O3Catalysts Prepared by Two Different Methods: Hydrogen Pressure Effects in the Reactions ofn-Hexane

摘要: Abstract Pt–Sn/Al2O3catalysts were prepared using two different methods, namely, by “traditional” coimpregnation with H2PtCl6and SnCl4and a “new” method in which the bimetallic complex precursor [Pt(NH3)4][SnCl6] is on support. Their catalytic activity and selectivity inn-hexane reactions studied as function of hydrogen pressure (60–480 Torr) compared those monometallic Pt/Al2O3catalysts H2PtCl6or [Pt(NH3)4]Cl2as Pt precursors. Pt/Al2O3ex [Pt(NH3)4]Cl2showed very low dispersion exhibited high attributed to multiatomic ensembles. The results catalysts can be rationalized terms phases being present, PtSn alloy phase plus fine distribution. Pt–Sn/Al2O3from contains metals better dispersion, resulting larger number atomically dispersed surface active sites. This catalyst gave more isomers (and methylcyclopentane) fewer fragments less benzene than sample. Pt–Sn/Al2O3sample possessed good long-term stability. sample lost some its hydrogenolysis during long use; i.e., it approached properties Both samples are potential candidates isomerizing aromatic selectivities (up 75% isohexanes methylcyclopentane opposed maximum 20% benzene). could explained sufficiently geometric model, electronic interactions playing important role phenomena observed.