PREPARATION OF MESO-MICROPOROUS COMPOSITE BETA-MCM-41 AND ITS CATALYTIC PERFORMANCE FOR n-HEPTANE HYDROISOMERIZATION

Abstract

Abstract: The meso-microporous composite Beta-MCM-41 (denoted as BM-41) was prepared by nano-assembly of cationic surfactant cetyltrimethylammonium bromide (CTAB) with Beta zeolite treated with NaOH solution，and hydrogen-based composite HBeta-MCM-41(denoted as HBM-41) was prepared by ion-exchange between BM-41 and NH4Cl. The catalyst Pt/HBM-41 with 0.4% Pt loading (w) was prepared with HBM-41 as support, and applied to the hydroisomerization of n-heptane. The samples were characterized by X-ray diffraction, N₂ adsorption-desorption, and Fourier transform infrared spectroscopy. The catalysts were evaluated at 240 ℃, atmospheric pressure and mass space velocity of 2.46 h^-1. The results showed that Pt/HBM-41 exhibited higher isomerization selectivity (87.01%) and higher n-heptane conversion rate (78.75%) in three catalysts with the same Pt loading: Pt/HBeta, Pt/MCM-41, Pt/HBM-41, the yield of isoheptane was the highest (68.52%). This can be attributed to Beta-MCM-41 combining the excellent diffusion properties of the two-dimensional hexagonal mesoporous MCM-41 with the superior acid properties of Beta zeolite.

Key words: n-heptane, hydroisomerization, micro-mesoporous composites, platinum, Beta-MCM-41

References

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