Yuan Meng1,Wang Haiyan2,Na SUN3,4,xu zhanyang2,2,Wang Yujia2,5
摘要： Silicoaluminophosphates SAPO-11 molecular sieves with small particle size and hierarchical pores were synthesized using a directing agent method. The effect of crystallization time on the crystal structure, morphology, pore structure properties and acid properties of SAPO-11 molecular sieves were investigated. The results of XRD, SEM, BET and NH3-TPD showed that the SAPO-11 molecular sieves with fine and uniform morphology could be synthesized in a shorter crystallization time used the directing agent method, which just unlike the SAPO-11 molecular sieves synthesized with the conventional method. With the crystallization time increased, the particle size of SAPO-11 molecular sieve was significantly reduced, and the mesoporous structure (intercrystalline pore) was generated between the particles. Furthermore, the external specific surface area and the total specific surface area reached 81.7 m2g-1 and 192.0 m2g-1, respectively, which effectively reduce the pore mass transfer resistance, significantly increase the number of acid active sites. The results of n-dodecane hydroisomerization revealed that the Pt/SAPO-11 prepared with the novel method exhibited higher catalytic activity and better hydroisomerization selectivity than the Pt/SAPO-11 synthesized by conventional hydrothermal method. Thus, the small particle molecular sieve has promising industrial applications as catalyst support.
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