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A series of metal–acid bifunctional catalysts with varying quantities of platinum and tungstophosphoric acid (TPA) supported on zirconium oxide were prepared by co-impregnation method. In skeletal isomerization of n-pentane using catalyst with 1% Pt and 30% TPA loadings the conversion of the reactant which was close to the equilibrium conversion reached ca. 65% and the selectivity towards the product was as high as ca. 97% at atmospheric pressure and relatively low reaction temperature (200 °C). The phase structure, chemical structure, surface physicochemical properties, surface element oxidation states and hydrogen reduction behavior of the catalysts were well-characterized via XRD, FT-IR, N2 adsorption–desorption determination (BET), XPS and TPR. The effects of Pt and TPA loadings, calcination temperature, reaction temperature and weight hourly space velocity (WHSV) on the catalytic performance were investigated. In addition, a long period catalytic stability test of the catalyst with optimal Pt and TPA loadings was carried out, which indicated that the bifunctional catalyst was in possession of good stability in skeletal isomerization along with high catalytic activity under the experimental conditions.

Skeletal isomerization of n-pentane in the presence of hydrogen has been studied over Pt-promoted H3PW12O40 (TPA)/MCM-41 bifunctional catalyst. A series of solid acid catalysts with different loading amount of TPA and Pt were prepared and characterized by XRD, FT-IR and XPS. The optimal catalytic activity of Pt-TPA/MCM-41 was observed with 2% Pt and 30% TPA. According to the cracked products distribution, this is typical of a monomolecular bifunctional metal-acid mechanism. Further, catalysts with different combination of noble metals (Pt, Pd and Ru), heteropoly acids (HPAs) (TPA, tungstosilicic acid (TSA), and molybdophosphoric acid (MPA)) and supports (MCM-41, SBA-1 and SiO2) were also synthesized and their catalytic performances were compared.