Catalytic Reforming of n -Heptane on Platinum-Tungsten Supported on Gamma-Alumina

摘要

The mono-metallic and bi-metallic catalysts have been prepared by impregnating with solutions containing a compound of H2PtCl6, WO3 and 1 ml HC1 (0.1 mol). It should be noted that the catalysts' activity and selectivity have been determined under these conditions: 450-500°C, and 15-25 atm by H2. For converting n-heptane, the molar ratio H2/C7H_(16) is 5, and LHSV is 1.5 ml/h. It has been proved that, under these experimental conditions, the conversion of n-heptane into branched aliphatic isomers is catalyzed by a bifunctional mechanism. The results indicate that in the presence of W, the catalysts have much higher selectivity and stability for isomerization reaction. At a given conversion, the bi-metallic catalysts produce much lower concentrations of cracked products. According to the tests, W modifies the support acidity resulting to the higher selectivity for isomerization and the lower one for cracking, and it also modifies the Pt properties.