The formation of silicoaluminophosphate gels using boehmite, Al isopropoxide, and di-n-propylamine as a template of silicoaluminophosphate gels as well as their subsequent crystallization into SAPO-11 molecular sieves was studied in detail using X-ray fluorescence spectroscopy (XRF), powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N₂ adsorption–desorption methods. The effect of the chemical and phase composition of silicoaluminophosphate gels on the physicochemical properties of SAPO-11 molecular sieves was shown. The secondary structural units that the AEL lattice is composed of were found to be formed at the initial stage of preparation involving aluminum isopropoxide. Several approaches to control their morphology and secondary porous structure are also proposed.

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.

In this article, we report the results of research the formation of silicoaluminophosphate gels under changing gel aging conditions and the influence of an aluminum source (boehmite), characterized by different properties. The samples of initial gels were characterized by XRF, X-ray diffraction, MAS NMR ²⁷Al and ³¹P, and scanning electron microscopy (SEM). Products of crystallization were characterized by XRF, X-ray diffraction, MAS NMR ²⁷Al and ³¹P, scanning electron microscopy (SEM), N₂-physical adsorption, and IR spectroscopy with pyridine adsorption. It has been established that the chemical and phase composition of aging gels and the products of further crystallization is conditioned by the size of the crystals and the porous structure of boehmite. Methods of management the morphology and secondary porous structure of SAPO-11, including the hierarchical porous structure, are proposed based on the use of boehmits characterized by different properties and changing the aging conditions of the initial gels. SAPO—based catalyst with a hierarchical porous structure showed excellent catalytic performance in dimerization of α-methylstyrene with a high degree of conversion and selectivity for linear isomers.

Among the most selective catalytic systems for the hydroisomerization of C₁₆₊ n-paraffins, catalytic systems based on SAPO-11 are quite promising. In order to increase the activity and selectivity of these bifunctional catalysts, it is necessary to reduce the diffusion restrictions for the reacting molecules and their products in the microporous structure of SAPO-11 by reducing the crystal size. To solve this problem, we have studied the influence of different templates (diethylamine, dipropylamine, diisopropylamine, and dibutylamine) on the physicochemical properties of reaction gels and SAPO-11 silicoaluminophosphates during their crystallization. Using XRD, SEM, and NMR techniques, we found that regardless of the template used, the reaction gel after the aging process at 90 °C is an AlPO₄·2H₂O hydroaluminophosphate. At the same time, the nature of the template affects the morphology and crystal sizes of the intermediate alumophosphate, AlPO₄·2H₂O, and the molecular sieves, SAPO-11. The acidic properties and the porous structure characteristics of SAPO-11 are also affected by the template. A template was proposed to enable the synthesis of nanoscale SAPO-11 crystals. The influence of the morphology and crystal size of SAPO-11 on the catalytic properties of a bifunctional catalyst based on SAPO-11 in the hydroisomerization of hexadecane was investigated.

This study aimed to investigate the influence of the content of crystalline (10, 30, 60%) and amorphous (90, 70, 40%) aluminosilicates in the starting granules prepared for the synthesis of hierarchical ZSM-5 zeolite on the physicochemical properties, activity, selectivity, and stability of the resulting materials in the Skraup reaction for quinoline synthesis. As the ZSM-5 content in the parent granules was raised from 10 to 60%, increasing trends were observed for the micropore volume (from 0.10 to 0.13 cm³/g) and mesopore volume (from 0.05 to 0.19 cm³/g) in the granules of the resultant hierarchical zeolites H-ZSM-5_h(10, 30, 60). At the same time, the macropore volume decreased from 0.34 to 0.29 cm³/g. The H-ZSM-5_h(60) sample had the highest concentration of acid sites and exhibited the highest activity and selectivity in the Skraup reaction, as evidenced by 72% yield of quinolines. Moreover, this sample exhibited the highest stability, H-ZSM-5_h(60) remained stable for 9 h, whereas the activity of H-ZSM-5_h(10) and H-ZSM-5_h(30) dropped after 3–4 h.

Using XRD, ²⁷Al and ³¹P MAS NMR, Raman spectroscopy, SEM, TEM, N₂ adsorption–desorption, and IR spectroscopy with pyridine adsorption, we studied the influence of the aluminum source and the aging temperature of the gel with the following composition: 1.0Al₂O₃·1.0P₂O₅·0.2SiO₂·1.5DPA·30H₂O, on the properties of the formed intermediate phases and the products of their subsequent crystallization in SAPO-11 molecular sieves. It has been established that by changing the nature of the aluminum source and the gel aging temperature, it is possible to synthesize various intermediate silicoaluminophosphates (amorphous, layered, AlPO₄·2H₂O) and control the morphology and size of the crystals formed during further crystallization of the SAPO-11 molecular sieves. The high stability and selectivity of the synthesized SAPO-11 nanoscale sample in the reaction of vapor-phase isomerization of cyclohexanone oxime to caprolactam were shown.