Dehydrocyclization of n-heptane over Pt catalysts supported on Al- and Si-promoted TiO2

• Dehydrocyclization reaction is sensitive on Pt supported over Al- and Si-modified TiO2.
• Increase in catalytic activity is observed according to the type of promoted cation.
• Increase in resistance to catalyst deactivation is observed as a function of promoter content.
• Acidic density and Pt dispersion are noticeable modified by Al- and Si-addition to TiO2.

The effect of content of Si- and Al-promoted TiO2 catalysts in the dehydrocyclization of n-heptane was studied. The sol–gel method was used to prepare pure TiO2 and mixed oxides with 1%, 3% and 10% of Al2O3 and SiO2. The structure and surface characterization (XRD, N2 sorption, H2 chemisorption, NH3 uptake) revealed that the promoted cations were dispersed in the TiO2 lattice, modifying structural and surface properties of catalysts. Dehydrocyclization activity and toluene yields were useful test reaction to detect the effect of content of cations in both acidic and catalytic properties of promoted catalysts. Increase in the TOF was observed as a function of cation content, hand in hand with the increase of overall reaction rate and supported Pt dispersion. The effects in both catalytic activity and deactivation resistance could be explained by the metal-support contact theory, which relates the atomic coordination of promoters with changes in catalytic activity and chemisorption properties of Pt supported on TiO2.

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