Preparation Of Ni/ZrO₂-SiO₂ Catalysts And Study Of Its Catalytic Performance Of N-Heptane Isomerization

With the promotion of the new Euro III,Euro IV fuel standards,people also put forward higher requirements for clean fuel production.In order to meet this requirement,the quality of gasoline must be towards the high octane number,high oxygen content,lead-free,low vapor pressure and low aromatics in the direction of development.The isomerization process of alkanes has advantages of flexible operation,low cost and save resources,and is an important means of producing clean gasoline with high octane value.So in recent years,the development of new and efficient catalysts for alkane isomerization has become one of the hotspot in the field of catalysis.ZrO₂-SiO₂ is a kind of two element complex oxides with many excellent properties.These excellent properties make the development trend of ZrO₂-SiO₂ composite oxides in the catalytic field much more than other molecular sieves.In this paper we prepared Ni/ZrO₂-SiO₂ catalysts with ZrO₂-SiO₂ composite oxide,and Ni/ZrO₂-SiO₂ catalysts wered used for the catalytic isomerization of n-heptane.The main results are as follows:1.Using Ni as the active component and ZrO₂-SiO₂ complex oxide as the support,Ni/ZrO₂-SiO₂ bifunctional catalyst was prepared by alcohol water solution heating method and co precipitation method,respectively.The effects of preparation methods,pH value,calcination temperature and the metal content of Ni on the reaction of isomerization of n-heptane were investigated.The results showed that the Ni/ZrO₂-SiO₂ catalyst prepared by the coprecipitation method exhibited the best performance of isomerization,When the pH value is 8,the loading of the metal Ni is5 wt%,and the calcination at 600? for 5 h.2.Ni/ZrO₂-SiO₂ catalyst was modified by rare earth La to obtain Ni-La/ZrO₂-SiO₂ catalyst,XRD,FT-IR,BET,SEM and other methods were used to characterize the effect of rare earth La on the structure and catalytic performance of the catalyst.The results show that the addition of rare earth La can not only stabilize the crystal structure of the catalyst,but also increase the dispersion of Ni on the surface of the support.Under the condition that after loading La load Ni,the conversion of n-heptane and isomerization selectivity to i-heptane can reach42.53%and 83.19%,respectively,when the cotent of Ni was 5 wt%,La content was 3wt%,Si/Zr=2:1,calcination temperature was 600?,reduction temperature was 425?,the reaction temperature was 240?.