A series of in situ dodecyl trimethyl ammonium bromide (DTAB)-modified small-crystal Y zeolites have been successfully synthesized by DTAB addition to the seed synthesis procedure, which was used to create the small crystal size Y zeolites. Compared to the Y zeolites prepared without DTAB, the Y zeolites prepared with DTAB have a uniform morphology and mesoporous structure, a larger specific surface area (up to 32.3 m 2 g −1 increase), a smaller crystal size (up to 66 nm reduction), and more Bronsted acid sites (up to 55 μmol/g increase). After loading with NiW, the corresponding NiW catalysts were utilized in the hydrocracking of n-hexadecane. It is evident from the catalytic performance that the catalysts containing DTAB-modified smallcrystal zeolites have a higher yield and selectivity of primary cracking products compared with the Y zeolites without DTAB modification. Moreover, the conversion of n-hexadecane is also higher due to its low mass-transfer resistance, high dispersion, and sulfation of W species. When the molar ratio of DTAB/Al 2 O 3 is 0.15, the corresponding catalyst has the optimum balance between cracking and hydro−dehydrogenation activity. Therefore, it has the most excellent catalytic performance and a 7.3% increase in C 8 −C 12 yield.

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 Brønsted 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%.