Synthesis And Alkane Isomerization Reaction Research Of Sapo-11 Molecular

With the increasing of environmental protection and energy saving requirements, motor gasoline is mainly manifested on the lead-free,low sulfur and sulfur free,low aromatics,low olefin and high octane number etc.C5/C6 alkane isomerization process can meet the requirements of the new environment,at the same time,increase the light part of the octane number of gasoline,gasoline fractions and octane number have a reasonable distribution,so as to improve engine startup performance;also solve pentane oil fractions in reforming unit process where as the isomerization reaction of raw materials. therefore, C5/C6 alkane isomerization is not only one of the main process of producing high octane number clean gasoline component, but also an important way to reasonable use of catalytic reforming.This paper,on the basis of the synthesis of SAPO-11 molecular sieves,investigated n-pentane isomerization reaction performance of the SAPO-11 molecular sieves which loaded Ni,and preliminary researched the isomerization reaction mechanism.This paper researched the synthesis of SAPO-11 under hydrothermal conditions.Also It characterized by XRD,IR,TG,NH3-TPD,BET,SEM and so on.The results indicate the optimum conditions of SAPO-11 zeolite compose is: the synthetic material ratio is n(Al2O3):n(P2O5):n(DPA+DIPA):n(Si O2):n(H2O)=1:1:1:0.3:50, the p H of gelatum of admixture is 5.5,the dynamic crystallize at the temperature of 195℃ for 1d.The characterization of the results show that, the synthesis of samples having dual pore structure.Its specific surface area is up to 567m2/g. In addition, its thermal stability and hydrothermal stability both are favourable. Grain molecular sieve is spherical, crystal morphology is neat and clear and very uniform size distribution.By using dipping method and ion exchange method of the modified Ni-SAPO-11 molecular sieve as catalyst,investigated n-pentane isomerization reaction performance of the composite molecular sieves with hydrogen conditions on fixed-bed reactor.Experimental results indicated that,when the catalyst Ni loading was 3wt%, reduction of H2 flow rate of 2.0L/h and in 450℃ for 6h,and n-pentane feed rate of 10 m L/h conditions,the reaction was in 300℃ and 3.0MPa for 6h conditions, the conversion of n-pentane ratio is 61.95%, the selectivity of i-C5 reached 76.86%,overall activity of the catalyst was the highest.The initial discovery of the reaction mechanism,show that Ni-SAPO-11 molecular sieve catalysts with hydrogen under conditions of n-pentane isomerization follow carbenium ion mechanism,its activity center is composed of the metal ion Ni2+、Ni+ and molecular sieve acid center.