Structure and properties of bifunctional catalysts based on zirconia modified by tungsten oxide obtained by polymeric precursor method

• Published in: Applied catalysis. A, General General, 2008-06, Vol.342 (1), p.56-62
• Main Authors: Garrido Pedrosa, Anne M., Souza, Marcelo J.B., Marinkovic, Bojan A., Melo, Dulce M.A., Araujo, Antonio S.
• Format: Article
• Language: English
• Subjects: Catalysis; Chemistry; Exact sciences and technology; General and physical chemistry; n-Heptane isomerization; Synthesis; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Tungsten oxide; Zirconia
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2007.12.036

Bifunctional catalysts of Pt/WO x –ZrO 2 (PWZ) type with 1 wt% of Pt and 10, 15 and 20 wt% of tungsten were synthesized by polymeric precursor calcined at 600, 700 and 800 °C and characterized by several techniques. Such catalysts were active in the n-heptane isomerization with high selectivity to branched product. ▪ Bifunctional catalysts of Pt/WO x –ZrO 2 (PWZ) type with 1 wt% of Pt and 10, 15 and 20 wt% of tungsten were synthesized by polymeric precursor method and after they were calcined at 600, 700 and 800 °C. The structural and textural properties of the catalysts were by X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), N 2 adsorption measurement, temperature programmed reduction by derivative thermogravimetry (TPR–DTG) and transmission electron microscopy (TEM). X-ray diffractogram revealed the presence of tetragonal ZrO 2 and platinum (Pt) as the main phases. The infrared spectra of the catalysts showed bands due O–W–O and W O bonds. The catalysts showed specific surface area values in the range of 30–160 m 2 g −1. TPR profile showed reduction peaks at high temperatures that were related with the reduction of WO x species. Such catalysts were active in the n-heptane isomerization with high selectivity to branched product.