PREPARATION OF Ni/(ZSM-5/MCM-41) CATALYSTS AND THEIR CATALYTIC PERFORMANCE FOR HEPTANE ISOMERIZATION

Abstract

Abstract: ZSM-5/MCM-41 composite molecular sieves were prepared by hydrothermal method using ZSM-5 as silicon source, NaOH as alkali source and cetyltrimethylammonium bromide (CTAB) as template agent, and the metal-acid center bifunctional catalyst was prepared by impregnating the supported metal Ni. The effects of alkali dissolution conditions and Ni loading on the structure and properties of the catalyst were investigated by means of X-ray diffraction spectroscopy, N2 adsorption-desorption, ammonia temperature-programmed desorption, transmission electron microscopy and other characterization methods, then the catalytic performance of catalyst for n-heptane isomerization was evaluated. The results showed that the optimum NaOH concentration, the optimum alkali solution temperature and the optimum alkali solution time were 1.5 mol/L, 40 °C and 30 min respectively, and the obtained composite molecular sieve had a suitable acidity and a typical microporous/mesoporous composite structure. After Ni was loaded, Ni was dispersed uniformly on the surface of composite molecular sieve. Using 2%Ni/ZSM-5/MCM-41 as catalyst, the conversion of n-heptane was 65.44% and the selectivity of iso-heptane was 70.59% at 290 °C.

Key words: ZSM-5, MCM-41, composite zeolite, isomerization, porous material

References

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