catalytic reforming of n-heptane on platinumniobium supported on gamma-alumina

the series of mono-metallic and bi-metallic catalysts have been prepared by impregnatingwith solutions containing compound of h2ptc15,nbc15 and lml hc1 (0.1 mol). the activityand selectivity of the catalysts have been determined under conditions at 450-500°c, 15-30atm. molar ratio h2/c7h16=5 and vvh=1.5/h for converting n-heptane. under theseexperimental conditions it has been established that the conversion of n-heptane intobranched aliphatic isomers is catalyzed by a bifunctional mechanism. the results show thatwhen nb is present, the catalysts are much more stable and have much higher selectivities forisomerization reaction. at a given conversion the bimetallic catalysts produce much lowerconcentrations of cracked products. it is shown that nb modifies the acidity of the support,resulting to higher selectivity for isomerization and lower selectivity for cracking and alsomodifies the properties of the pt.