Abstract: Catalysts based on Keggin-type heteropolyacids and reduced Pt-Ce oxides supported on silica were prepared for their use in isomerization of n-hexane in the presence of hydrogen. These mixed oxides were either used alone or mixed with silica-supported heteropolyacids. The catalysts after oxidation, reduction, and catalytic tests were characterized byX-raydiffraction, Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy, thermogravimetry, and N2 adsorption. The objective of the present study is the selection of the catalyst having the best isomer (branched) yield under optimum operating conditions (reaction temperature, reduction temperature, flow duration, etc.). The results show that the presence of the reduced oxides is not only beneficial for eliminating coke deposition but also effective for maintaining the structure of silica-supported heteropolyacids during reaction. Moreover, the better activity and the higher selectivity for isomers can be found with these samples.

Key words: heteropolyacid, n-hexane, isomerization, platinum, cerium