Synthesis of Pt/PMA-MIL-101 Catalyst and Its Performance in n-Heptane Isomerization

Hydroisomerization of n-heptane is an efficient method for producing gasoline with a high octane number. The focus of this study was to find a highly efficient catalyst that could both promote the conversion of n-heptane and inhibit the cracking side reaction. MIL-101(Cr) is a chromium-based metal-organic framework(MOF) with good hydrothermal stability, and exhibits a three-dimensional pore structure that is similar to that of zeolites. Using phosphomolybdic acid(PMA;H3PMo12O40·x H2O) can increase the number of Br?nsted acid sites on MIL-101(Cr), which contributes to improving the catalytic performance during isomerization. In this study, 0.4%Pt/PMA-MIL-101(Cr) catalyst was successfully crystallized at 220 ℃ using a hydrothermal synthetic method. The results showed that the synthesized samples were mesoporousmicroporous composite materials with the typical octahedral structure, and the MIL-101(Cr) framework was not damaged following modification with PMA. It was found that 0.4%Pt30% PMA-MIL-101(Cr) exhibited the best performance for isomerization of n-heptane, with a conversion rate and selectivity at 260 °C of 47.6% and 96.6%, respectively. After five hours of reaction, the conversion rate and selectivity of the catalyst remained above 38% and 80%, respectively.