Noble Metal Wax Hydrocracking Catalysts Supported on High-Siliceous Alumina

Amorphous silica−aluminas formed by alumina obtained from the sililation of aluminum alkoxides with othosicilic acid were used as support material for the preparation of bifunctional hydrocracking catalysts. Brønsted acidity, which was observed for the support with 40% silica (Siral40), was absent in the material with 75% silica (Siral75). Impregnation with Pt or Pt and W, however, generated not only Brønsted acidity on Siral75 but also resulted in a higher platinum dispersion relative to Siral40. The PtW75 catalyst showed the behavior of ideal hydrocracking during hydrocracking of n -hexadecane. A high-quality diesel was obtained with high selectivity even at conversion levels above 90% during hydrocracking of Fischer−Tropsch wax. The performance of the PtW75 catalyst proved to be comparable or even better than the commercial catalyst tested.