Study On The Preparation And Catalytic Performance Of Ni/Al-KIT-6 Catalyst For N-Heptane Hydroisomerization

The KIT-6 was a mesoporous silicon material with cubic structure of Ia3d.Have the advantages of large specific surface area and ordered pores like traditional mesoporous materials.KIT-6 was very popular in the template selection of nano casting due to its unique three-dimensional connected channels.At the same time,it plays an important role in catalysis,adsorption and medicine.In this paper,KIT-6 and Al-KIT-6 mesoporous molecular sieve was synthesized by hydrothermal crystallization method.The effects of crystallization time,crystallization temperature,n-Bu OH addition amount and metal doping amount on the performance of KIT-6and Al-KIT-6 mesoporous molecular sieve was synthesized in detail.The physical and chemical properties of the synthesized samples were characterized by X-ray powder diffraction（XRD）,Nitrogen adsorption desorption isotherms（N₂adsorption–desorption）,NH₃temperature programmed desorption（NH₃-TPD）,Fourier transform infrared spectroscopy（FT-IR）,Scanning electron microscope（SEM）and Transmission electron microscope（TEM）.The evaluation results that P123 was removed by calcination at a high temperature assisted with ethanol and hydrochloric acid extraction,The introduction of Al atoms increases the acidity of mesoporous molecular sieve.The optimum conditions for synthesized of KIT-6and Al-KIT-6 mesoporous molecular sieve as follows:the molar ratio of n-Bu OH was 1.31,the crystallization temperature was 100℃,the crystallization time was 24 h,and the Si/Al ratio was 40:1.Ni/KIT-6 and Ni/Al-KIT-6 bi-functional catalyst were prepared by impregnation method with metal Ni as active component and KIT-6/Al-KIT-6 as supporter.The catalytic performances of of the synthesized materials were investigated by using n-heptane isomerization as a probe.The effects of Preparation conditions and Reaction conditions on the performance of Ni/Al-KIT-6 bi-functional catalyst were investigated in detail.The results show that Ni/Al-KIT-6 bi-bifunctional catalyst has better catalytic performance than Ni/KIT-6 catalyst.The evaluation results for n-heptane isomerization of 5%Ni/Al-KIT-6 catalyst showed that the conversion of n-heptane were up to 26.8%and the selectivity of isoheptane could reach 99.5%when the the metal load was 5%,H₂flow rate was 30m L·min^-1.reduction temperature was 400℃,reduction time was 4 h,weight hourly space velocity was 7.6 h^-1,and reaction temperature was 190℃.