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.