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.

The study investigated the effects of the concentration of secondary amines with various molecular weights (specifically, diethylamine, di-n-propylamine, diisopropylamine, and di-n-butylamine), which were used as templates, on the crystallization performance of AlPO₄-11 molecular sieves. For this purpose, various analytical methods such as XRD, SEM, and N₂ adsorption/desorption were employed. The template concentration (more specifically, the template/Al₂O₃ ratio) was shown to have a major effect on the phase composition of the crystallization products. However, for each template under study, a high-phase-purity AlPO₄-11 could be synthesized only within a narrow range of template/Al₂O₃ ratios. The study demonstrated the effects of template type on the morphology and dispersion of AlPO₄-11 molecular sieves.

Проведены исследования активной фазы и каталитических свойств кобальтовых катализаторов синтеза Фишера–Тропша, промотированных марганцем и приготовленных методом пропитки. В качестве носителя использовали силикагель марки КСКГ, обладающий монодисперсной структурой со средним диаметром пор, равным 12–16 нм. Содержание кобальта в полученных образцах составило 20,8-21,8 мас.%, марганца – 0,5-2 мас.% Исследование структурных характеристик катализаторов осуществляли методами рентгеновской дифракции, просвечивающей электронной микроскопии, температурно-программированного восстановления и температурно-программированной десорбции водорода. Каталитическую активность и селективность образцов в процессе синтеза углеводородов оценивали в проточном режиме при давлении 0,1 МПа, объемной скорости газа (ОСГ) 100 ч^–1, температурах 150–220 °С и соотношении СО к водороду в синтез-газе 2:1. Предварительное восстановление катализаторов осуществляли водородом при температуре 400 °С. В составе образцов с марганцем подтверждено формирование твердых растворов оксидов металлов типа xCo₃O_4–(1–x)Mn₃O₄. Показано, что процесс восстановления Co₃O₄ определяется составом и структурой твердых растворов компонентов, являющихся трудновосстанавливаемыми соединениями. Определены особенности промотирующего действия марганца в зависимости от концентрации. Введение 0,5–2 мас.% добавки позволяет регулировать состав и микроструктуру оксидных соединений кобальта, свойства металлического Co, повышает каталитические характеристики: активность, селективность по С₅₊ и снижает выход метана. Показано, что в зависимости от содержания добавки металла усиливаются проявления структурного (при концентрации 0–1 мас.%) или электронного (при концентрации 2 мас.%) промотирующего действия марганца. Оптимальная концентрация марганца составляет 1 мас.%. Катализатор характеризуется минимальным средним размером кристаллитов, наибольшей величиной удельной поверхности металлического кобальта и максимальными каталитическими показателями.

The influence of the thermophysical characteristics of biochars obtained by hydrothermal carbonization of peat on the yield and composition of producer gas

It is shown that the Fischer–Tropsch synthesis in the presence of Co–xMn/SiO₂ cobalt catalysts with a manganese content of 0.5–2 wt % is characterized by high activity and C₅₊ hydrocarbon selectivity. The optimum concentration of manganese as a promoter is 1 wt %. The influence of manganese on the state of the surface of the catalysts in oxide and reduced forms is studied by a number of physicochemical methods. The formation of solid solutions of cobalt and manganese oxides of the xCo₃O₄–(1−x)Mn₃O₄ type is confirmed. The relationship between the promoting effect of manganese and the structure of active sites and the character of adsorption of H₂ and CO on the surface of the catalysts is ascertained.

Scientific interest in the processes of forming the structure of magnetic spinels and composites based on them is due to the possibility of synthesis of materials with multifunctional properties. The process of formation of cobalt (II) nanocrystalline ferrite and CoFe2O4/C composite material is studied. The mechanism of formation of structure of materials including a stage of formation of hydroxides of transition elements, precursors on the basis of complex connections of cations of iron and cobalt with citric acid and their subsequent destruction at heating is offered. The synthesized materials were characterized by x-ray phase analysis, electron microscopy, low-temperature nitrogen adsorption, Debye-Scherrer methods. It is shown that cobalt (II) ferrite has a developed surface, the value of the surface area according to the BET method is 16 m2/g, the average size of the crystallites determined by the Debye-Scherrer equation is 4.0 nm. Activated carbon with a specific surface area of 685 m2/g was used to prepare the composite material. The resulting composite material has a surface area of 222 m2/g, the average crystallite size of 1.1 nm. Cobalt (II) ferrite, included in the composition of the composite material CoFe2O4/C, has a slightly higher value of the lattice parameter, compared with pure cobalt (II) ferrite, which is associated with a decrease in the degree of spinel inversion. The synthesized composite material was tested in the process of adsorption of copper (II) cations from an aqueous solution. It is shown that CoFe2O4/C exhibits an increased adsorption capacity for copper (II) cations in comparison with pure activated carbon, despite a decrease in the specific surface area. The result is explained by the involvement of cobalt (II) ferrite in the adsorption process. The obtained materials may be of interest as catalysts, adsorbents.