This paper proposes a method for synthesizing granular ZSM-23 zeolite with a high degree of crystallinity and hierarchical porous structure. This method is based on crystallizing granules composed of powdered ZSM-23 zeolite and a specially prepared amorphous aluminosilicate. It has been shown that these granules have superior mechanical strength compared to granular zeolite-containing materials, which are made from a mixture of ZSM-23 zeolite crystals and Al₂O₃. It has been demonstrated that when 0.5% of Pt granular ZSM-23 zeolite is used, with a high degree of crystallinity and a hierarchical porous structure, it exhibits higher activity and selectivity in the hydroisomerization of n-hexadecane compared to a bifunctional catalyst, which is a mechanical mixture of ZSM-23 zeolite crystals and Al₂O₃, with the metal deposited on the granules.

The high selectivity of bifunctional catalysts in the hydroisomerization of long-chain n-paraffins is a key factor for producing high-quality fuels. However, it is directly dependent on a complex balance between the topology, acidity, morphology, and crystal size of the zeolite support. To address this challenge, this work presents a comparative study of medium-pore molecular sieves (ZSM-5, ZSM-23, ZSM-48, and SAPO-11) with different structural and acidic properties. The physicochemical characteristics of the materials were investigated using a set of analytical techniques, including XRD, SEM, low-temperature N2 adsorption, and NH3-TPD. It was shown that the pore topology (3D in ZSM-5 vs. 1D in the others), chemical composition, and crystal morphology (ranging from ~50 nm nanoprisms for ZSM-48 to 200–300 nm needles for ZSM-23-80 and 1 μm needles for ZSM-23-100) determine both the textural properties and the strength and concentration of acid sites. In the hydroisomerization of n-hexadecane, the Pt/ZSM-5 catalyst, with its high concentration of strong acid sites and 3D channel pore structure, exhibited the highest activity but an extremely low isomer selectivity (7%) due to intense cracking. The best results were demonstrated by the Pt/SAPO-11 and Pt/ZSM-48 samples, which provided isomer yields of 80% and 73%, respectively. Their high efficiency is attributed to the combination of a one-dimensional pore structure, moderate acidity, and nanocrystalline size, which minimizes diffusion limitations and suppresses side reactions. Thus, controlling the topology and acidity in combination with nanocrystalline morphology is an effective strategy for the rational design of highly selective hydroisomerization catalysts.

The rational design of highly efficient bifunctional SAPO-11 catalysts for hydroisomerization of n-C₁₆ requires unprecedented control over both acidic properties and diffusion characteristics. This work systematically investigates the influence of the SiO₂/Al₂O₃ molar ratio (0.1–0.4) in the initial gel on the physicochemical and catalytic properties of SAPO-11. Using a combination of characterization techniques (XRD, SEM, TEM-SAED, ²⁹Si MAS NMR, and IR-Py), it was established that this parameter serves as a simple tool for crystal engineering. The concentration of Brønsted acid sites and the external surface area demonstrate a non-linear dependency, reaching their maximum at SiO₂/Al₂O₃ = 0.3. Further increase in silicon content reduces both crystallinity and acidity due to the transition to the dominant SM2 + SM3 incorporation mechanism and the formation of silicon islands. Notably, varying the SiO₂/Al₂O₃ ratio enables control over crystal morphology—progressing systematically from truncated cones (SiO₂/Al₂O₃ = 0.1) to flat prismatic platelets (SiO₂/Al₂O₃ = 0.2) and ultimately hierarchical spherical aggregates (SiO₂/Al₂O₃ = 0.4). In n-C₁₆ hydroisomerization, the Pt/SAPO-11(0.2) catalyst demonstrated the highest yield of i-C₁₆ compared to other samples reaching 81%. The platelet morphology ensures a minimal diffusion path (<100 nm), effectively suppressing secondary hydrocracking. This finding underscores that morphology optimization is more critical than maximizing acidity for achieving high selectivity in the context of n-C₁₆ hydroisomerization over Pt/SAPO-11.

A series of SAPO-11 and SAPO-41 molecular sieve samples were synthesized using two different aluminum sources. The physicochemical properties of the samples were characterized, and their catalytic performance was tested in hydroisomerization of n-hexadecane. The effects of the aluminum source on the morphology and size of SAPO-11 and SAPO-41 crystals were identified. Specifically, the SAPO-11 and SAPO-41 samples synthesized using aluminum isopropoxide were found to have a higher specific surface area and a higher mesopore volume than their counterparts prepared with boehmite as an aluminum source. It is further shown that SAPO-11 and SAPO-41 samples with similar acidity and similar porosity characteristics exhibit comparable catalytic performance in hydroisomerization of higher n-paraffins.

The study investigates the catalytic performance of microporous and granular micro–meso–macroporous zeolites (H-ZSM-5 and H-ZSM-5h, respectively) in synthesis of quinolines by the reaction of 2-aminoacetophenone with diketones (2,4-pentanedione or dimedone), known as the Friedländer synthesis. In the presence of H-ZSM-5h, 1-(2,4-dimethylquinolin-3-yl)ethanone ( 1a ) and 3,4-dihydro-3,3,9-trimethyl-1(2 H )-acridinone ( 1b ) were produced in 82 and 93% yields, respectively.