Synthesis of Lamellar Structural Flower-like SAPO-11 Molecular Sieves with Hierarchical Pores for Enhanced Selectivity of Isomeric Alkanes in Hydroisomerization

A novel SAPO-11 molecular sieve with a lamellar structure and flower-like morphology was synthesized using cationic surfactant cetyltrimethylammonium bromide (CTAB) as the surfactant and KF as the mineralizer. Meanwhile, the effect of various CTAB additions on the structure and properties of SAPO-11 molecular sieves was also investigated. A number of characterization analyses' findings reveal that, compared with conventional spherical SAPO-11 molecular sieves, flower-like SAPO-11 molecular sieves have the following advantages: (1) Flower-like SAPO-11 molecular sieves have open pores and larger mesopores, with suitable distribution of mesopores. (2) The prepared flower-like SAPO-11 molecular sieves have a lower total acid value but have a higher proportion of Bronsted acid sites, with suitable acidity. (3) The flower-like NiW/SAPO-11 catalysts have better dispersion of WS2 slabs and higher balance and proximity between metal sites and acid sites. The synthesized flower-like NiW/SAPO-11 showed significant isomerization performance and low cracking selectivity during the isomerization of n-hexadecane. When the conversion rate of n-hexadecane reached 77.0%, the yield of i-hexadecane was 59.4%.