A series of BEA-type zeolites with SiO2/Al2O3 ratios of about 50 were synthesized by steam-assisted (SAC) and hydrothermal crystallization (HTC) in fluoride and alkaline media. Their physicochemical properties were characterized by low-temperature nitrogen adsorption, XRD, SEM, XRF, and NH3-TPD. The catalytic performance was investigated in liquid-phase toluene disproportionation. The SAC-synthesized samples were distinguished by a higher concentration of acid sites. The BEAs prepared by SAC in alkaline media exhibited a higher activity in toluene disproportionation. The samples synthesized in fluoride media, both by steam-assisted and hydrothermal crystallization, proved to be comparable in activity.

This study investigates the effects of FAU(Y) crystal size (350, 450, and 850 nm) on the physicochemical properties and catalytic performance of CsNaY samples in the alkylation of aniline with methanol. The physicochemical properties of the samples were examined by SEM, X-ray fluorescence analysis, low-temperature nitrogen adsorption, XRD, NH3–TPD, IR spectroscopy of adsorbed chloroform, and 27Al MAS NMR. Reducing the zeolite crystal size was found to strengthen the CsNaY basic properties and enhance the selectivity towards N-alkylated products. The highest activity and stability in aniline methylation was achieved by the CsNaY sample consisting of 450-nm crystals that had a Na+ for Cs+ ion exchange degree of 64% and was modified with CsOH. This sample provided aniline conversion of 95% and the selectivity towards N-alkylated product of 99.8%.

Mesoporous CeO2 has been prepared under hydrothermal conditions at 110–170°С in the presence of ionic and nonionic surfactants and characterized by SEM, low-temperature nitrogen adsorption–desorption, X-ray powder diffraction, and DTA–TG techniques. All synthesized samples had a specific surface area of up to 110 m2/g and a pore diameter of about 4 nm. It has been shown that the use of surfactants of various nature affects not only the final morphology of the oxide, but also its porous structure characteristics and chemical composition of its samples. It has been found that the use of ultrasound in the synthesis affects the specific surface area and average pore size of the samples.

The review compiled by colleagues and students of B.V. Romanovsky, a professor at the Moscow State University, considers his scientific works published in the period from 1959 to 2019. By detailed analysis, it has become possible to identify five main areas that determine the scientific heritage of B.V. Romanovsky: (1) the development of kinetic methods for the study of catalysis on amorphous and crystalline aluminosilicates, (2) development of methods for studying the adsorption and acid properties of molecular sieves, (3) the development of mechanistic concepts in zeolite catalysis, (4) the design of molecular sieve catalysts for heterogeneous catalytic processes; and (5) the creation of new catalytic systems based on inclusion compounds. A particular emphasis is made on the pioneering work of Romanovsky on the creation of “ship-in-bottle” systems, which initiated a new direction in zeolite catalysis.

A single-stage gas-phase synthesis of isoprene from formaldehyde and isobutylene in the presence of Al–BEA and Nb–BEA zeolite catalysts containing different amounts of aluminum and niobium has been studied. The physicochemical properties of the catalysts have been studied by low-temperature nitrogen adsorption, infrared spectroscopy of adsorbed CO, X-ray fluorescence analysis, and ammonia TPD methods. Catalytic tests have shown that, at similar formaldehyde conversion values, the isoprene selectivity is higher in the presence of the Al-containing BEA catalysts. It has been found that Al–BEA with Si/Al = 12 exhibits the highest activity in isoprene synthesis.

The process of dealumination of mordenites differing in morphology and crystal size obtained under identical conditions from reaction mixtures of similar composition has been studied. Parameters that have been chosen to change the morphology and crystal size are the dry matter concentration in the reaction mixture, the pH of the reaction mixture, the crystallization time, the presence of crystalline seeds, and agitation during the synthesis. Dealumination has been performed by heat treatment at 700°C followed by acid treatment. It has been shown that the stability of the mordenite crystal framework to dealumination depends on the thickness of the primary needle crystal, which forms the basis of large zeolite crystals, not on the size of the zeolite crystal as a whole. With a decrease in the average needle crystal thickness from 250 to 90 nm, the Si/Al molar ratio in the crystal lattice, determined from 29Si NMR data, increases from 6.8 to 9.5. The dealumination is accompanied by a change in the texture of large mordenite crystals associated with a decrease in the packing density of the primary needles.

Studies on the preparation and catalytic action of zeolites in the form of nanosized crystals are reviewed. Examples of successful synthesis of nanosized zeolites of the FAU, MFI, BEA, and MOR structural types and their use in such processes of petroleum chemistry and refining as catalytic cracking, hydrocracking, hydroisomerization, oligomerization, transalkylation, conversion of methanol and acetone to olefins, and other processes are given. The progress and prospects of using nanosized zeolites in slurry reactors comprising three-phase systems, in which individual zeolite particles are dispersed in a liquid medium, are considered.Keywords: nanosized zeolites, catalytic cracking, hydrocracking, transalkylation, slurry reactor

The influence of MEL zeolite synthesis conditions on the set of physicochemical properties and catalytic activity of the zeolites in the oligomerization reaction of butylenes has been studied. The number of synthesis stages and the concentration of tetrabutylammonium hydroxide template in the reaction mixture have been used as the variable parameters for the synthesis of MEL zeolites. It has been found that the use of two-stage crystallization comprising the low-temperature stage at 90°C and the high-temperature stage at 170°C promotes a decrease in the size of MEL zeolite crystals and provides a more complete involvement of the source materials in the crystallization process. The interval of template concentration in the reaction mixture in which the pure phase of zeolite MEL free of zeolite MFI can be obtained has been determined. It has been shown that during the two-stage crystallization of the reaction mixture with a template/SiO2 molar ratio of 0.2, MEL zeolite is formed with crystals of 200–300 nm in size, whose surface is depleted in aluminum. It has been found that the nanocrystalline zeolite MEL exhibits high resistance to deactivation in the oligomerization reaction of butylenes due to a decrease in the number of acid sites on the outer surface of nanocrystals. No significant differences in the product distribution have been revealed for the oligomerization of butylenes on zeolites of the MEL and MFI structural types possessing identical physicochemical properties.

Propylene epoxidation with hydrogen peroxide on titanosilicates with different Si/Ti ratios and various states of titanium in the catalysts, prepared by hydrothermal crystallization according to two different procedures, has been investigated. It has been demonstrated that a change in the pH of the crystallizing gel leads to a change in the sequence of titanium insertion in the zeolite structure at a hydrothermal synthesis temperature of 170°C. It was shown that titanium incorporated in the zeolite framework in the tetrahedral positions is an active site in the epoxidation reaction, whereas titanium in the form of titanium dioxide leads to unproductive degradation of hydrogen peroxide.

The production of isobutylene from acetone over micro–mesoporous catalysts with different mesopore contents, which have been prepared using hydrothermal recrystallization of mordenite (MOR) zeolite modified with cesium acetate by incipient wetness impregnation, has been studied. It has been shown that cesium is inserted into the cation positions during the modification, at the same time the number of Brønsted acid sites in the samples decreased. It has been found that an increase in the content of mesopores in the catalyst leads to an increase in the initial rates of acetone conversion and isobutylene formation as a result of removing diffusion limitations. Brønsted acid sites have been shown to be preferable for the selective production of isobutylene from acetone. Micro–mesoporous materials operate more stably as compared to microporous materials.

It is shown that the structural features of biporous silica and concentration of hydroxyl groups on the surface determined the regularities of hemoglobin adsorption on silica. It is concluded that the limiting values of protein adsorption per unit of the adsorbent surface fell as the temperature of adsorbent synthesis rose from 80 to 120°C and increased when a solubilizer (trimethylbenzene) was introduced.