Mesoporous SAPO-11 Zeolite: Synthesis Characterization And Catalytic Application

Due to unique channel structure, SAPO-11 was commercially used as support of hydro-isomerization catalyst, but the predominant presence of micropores in SAPO-11 molecular sieves also imposes diffusion limitations on reactions. According to these problem, we explore the synthesis, characterization and catalytic application of SAPO-11 in this paper.1) Using hexadecyl phosphoric acid instead of tetradecylphosphoric acid as template successfully introduced mesoporous channel into SAPO-11 molecular sieve, the mesoporous pore volumethe of sample was 0.30 cm3/g, The crystallization time has no obvious impact on texture of samples but the acidity of samples will be influence when the crystallization time too short, in addition, the difficult of removing the template will impact the catalytic application of the samples.2) SAPO-11 synthesized in common Al2O3-P2O5-Dipropylamine-H2O system has additional mesoporosity (di-n-propylamine abbreviated as DPA), the mesopore volume being 0.09 cm3/g with the formation of a core (microporous SAPO-11)/shell (mesoporous SAPO-11 aggregate) structure. Using the SAPO-11 as a seed added into the Al2O3-P2O5-Dipropylamine-H2O system can improve the mesoporosity of the mesoporous SAPO-11. Tests indicated hierarchical SAPO-11 molecular sieve with mesopore volume up to 0.40 cm3/g can be synthesized in Al2O3-P2O5-Dipropylamine-H2O system with 2-10% SAPO-11 molecular sieve as seed. SEM and TEM studies indicate the formation of SAPO-11 nanorods with ultra-small diameter (5 nm). A crystallization kinetic study indicated that 6 h is sufficient for the formation of highly crystalline hierarchical SAPO-11 molecular sieve. The texture and acidity of hierarchical SAPO-11 can be controlled by changing the crystallization time. Based on the experimental results, the formation of hierarchical SAPO-11 is an integrated effect of the burst nucleation and special rod shape of SAPO-11 nanocrystal and the role of seed is promoted nucleation by increasing the surface area of the liquidesolid interface.3) Explore hydrogenation deoxidization isomerization of fatty acid methyl ester over the mesoporous SAPO-11 molecular, the addition of the mesoporous SAPO-11 molecular promote the hydrogenation deoxidization isomerization of fatty acid methyl ester. The best supplementation of mesoporou SAPO-11 molecular was 60%, and load the Pt metal on catalyst would promote the isomerization of the fatty acid methyl ester.4) In the process of exploring the suitable carrier except SAPO-11 in hydrogenation deoxidization isomerization we found that change the ratio and condition of the IZM-2 can synthesize multiple channel zeolite with interconnection cross structure contain three kinds of channel structure microporous/mesoporous/macporous.