Design And Performance Adjustment Of Catalyst On Gasoline Hydroisomerization

The clean gasoline depends on deep hydrogenation which results in the decrease of octane number.In order to solve the problem,gasoline hydroisomerization process gets more attention.The development of efficient isomerization catalyst is the key factor in the process.As bifunctional catalysts,the catalytic persormance are affected by active components and the synergism between them.Therefore,it is important to optimize the acidic component and investigate the interaction between metal and acidic components.SAPO-11 was synthesized via dry gel method.The acidity,particle size and morphology were controlled by the addition of silicon,CTAB and HF,respectively.Ni/SAPO-11 and Pt/SAPO-11 catalyst were prepared by the impregnation method.The effect of metal loadings and acidic sites on isomerization performance and the synergism between two components were investigated.The results showed that the silicon content and chemical environment in the framework determined the acidity of SAPO-11.With the increase of silicon addition,the substitution changed from SM2 to SM3 improving the medium acidic sites.The addition of CTAB can not decrease the particle size,but also enhance the acidic sites of SAPO-11 due to the induction of more silicon into framework.Therefore,the isomerization acitivity of Ni/SAPO-11 was improved,but excessive acidic sites broke the match of two components lowing the selectivity of iso-heptane.The morphology of SAPO-11 changed from irregular particles to rod-like monocrystal,and the length of rod increased the iso-heptane selectivity.In addition,the decrease of SAPO-11 particle size improved the activity and anti-coking deposit performance of Ni/SAPO-11.According to the hydroisomerization results of Ni/SAPO-11 with different metal loadings and acidic sites,there was an obvious synergistic relationship between Ni and SAPO-11.Excessive acidic sites or metal loadings decreased the isomeric hydrocarbon selectivity.High isomerization performance of Ni/SAPO-11 was obtained by match of two components.The n-heptane conversion,iso-heptane selectivity and yield could reach 73.09%,51.16% and 37.39%,respectively.The isoparaffin yield was up to 39.31%.