Hydroisomerization-cracking of n-octane on Pt/WO42--ZrO2 and Pt/SO42-- ZrO2. Effect of Pt load on catalyst performance

J M. GRAU; J. C. YORI; J. M. PARERA

APPLIED CATALYSIS A-GENERAL

Elsevier Sci. B.V.

Lugar: Amsterdam; Año: 2001 vol. 213 p. 247 - 257

0926-860X

The hydroconversion (isomerization–cracking) of n-octane was studied at 300◦C, 1.5MPa, WHSV = 4 and H2/nC8 = 6 using oxoanion promoted zirconia with different Pt concentrations (0.1, 0.5 and 1%) as catalysts. Tungstate was added to zirconia by impregnation with ammonium meta-tungstate or tungstic acid solutions and calcined at 800◦C. Sulfate was added by impregnation with 2N H2SO4 and calcined at 620◦C. Isooctanes are intermediate products that are cracked to C3–C5 alkanes with predominance of isoalkanes. Sulfate zirconia is the most active and selective catalyst to cracking products. The addition of 0.1% of Pt produces an increase in activity and stability, respect of the support without metal. However, the increase in Pt content (0.5 and 1.0%) produces a decrease in nC8 conversion and in cracking products. The metallic properties of Pt are decreased by its strong interaction with the support, mainly with sulfate zirconia; at the same time, Pt decreases the acid cracking activity of the support.