Catalytic performance and kinetic modeling of n-hexane isomerization over phosphomolybdic acid (HPMo) combining palladium and platinum supported on metal-organic framework MIL-101(HPW)

Abstract

A metal-organic framework MIL-101(HPW) was synthesized by hydrothermal reaction, and phosphomolybdic acid (HPMo) was synthesized by its precursor solution. Then (Pd + Pt)/HPMo/MIL-101(HPW) with different wt% were prepared by the impregnation method. The synthesized samples were characterized by XRD, FT-IR, NH₃-TPD, N₂ adsorption, FESEM, and TGA, and their performances were investigated in n-hexane isomerization. Under the optimized operating conditions (temperature of 180 °C, H₂/nC₆ molar ratio of 2, and WHSV of 3 h⁻¹), the appropriate yield for the nC₆ isomerization was provided. The (0.2%Pd + 0.3%Pt)/50%HPMo/MIL-101(HPW) sample showed a lifetime of 720 min with 92.5% iC₆ selectivity and 75.3% nC₆ conversion. Kinetic modeling of the n-hexane isomerization reaction was also performed, in which the classical bifunctional mechanism was used to calculate the kinetic parameters. The validity of the bifunctional behavior was proved by the high value of the statistical correlation coefficient of this model. The apparent activation energy of this mechanism was calculated at 42.5 kJ mol⁻¹.

Keywords:

• nC₆ isomerization
• HPMo
• MIL-101(HPW)
• palladium
• platinum
• kinetic study

Acknowledgments

This work was financially supported by the Iran National Science Foundation (INSF). The authors acknowledge the financial support of the Babol Noshirvani University of Technology through grant program No. BNUT/370152/400.