The properties of ZSM-12 zeolites (SiO 2 /Al 2 O 3 = 70) synthesized under hydrothermal conditions have been studied. The prepared samples were examined by X-ray phase analysis, low-temperature nitrogen adsorption–desorption, scanning electron microscopy, solid-state 27 Al NMR spectroscopy, infrared spectroscopy, NH 3 thermally programmed desorption, infrared spectroscopy of adsorbed pyridine, and X-ray fluorescence spectroscopy and investigated in the toluene disproportionation reaction under the following conditions: Т = 300–480°С, mass feedstock flow rate 1.5, 3, and 6 h –1 , Р (Н 2 ) = 10 atm. It was found that a ZSM-12 zeolite sample synthesized using monoethanol- N,N -dimethyl- N -ethylammonium bromide as a template is the most effective catalyst for the toluene disproportionation. It is shown that the toluene disproportionation occurs with the formation of benzene and a mixture of ortho -, meta -, para -xylenes. The fraction of the latter in the liquid reaction products was up to 50%.

This review provides a detailed analysis of existing methods for the synthesis of ZSM-48 zeolites using various inorganic reagents, templates, and seeds under varying process conditions (e.g., temperature and time). In particular, the effects of reagents and synthesis parameters on the resultant physicochemical properties of ZSM-48 are discussed. The paper comparatively assesses the properties of a series of ZSM-48 samples synthesized under different conditions. These properties have been characterized by X-ray diffraction, thermogravimetry, scanning electron microscopy, low-temperature nitrogen adsorption/desorption, IR spectroscopy of adsorbed pyridine, IR spectroscopy of adsorbed ammonia, and other physicochemical methods.

Four samples of ZSM-12 zeolite (MTW structural type) synthesized using various template types were tested as catalysts in m -xylene isomerization. The functionality of the catalysts was examined using solid-state 27 Al NMR spectroscopy, NH 3 –TPD, and IR spectroscopy of adsorbed pyridine. The effects of the crystallite size, acidity, and phase purity of the zeolites on the composition of the reaction products were investigated. The template used for the synthesis was found to affect the physicochemical properties and catalytic activity of the zeolites.

The review presents an analysis of the distinctive features of the structure and synthesis of silicoaluminophosphate molecular sieves such as SAPO-11 and SAPO-41. Various crystallization types are described and compared, including dry-gel conversion (DGC), solvent-free crystallization, hydrothermal crystallization, solvothermal crystallization, and crystallization in ionic liquids. The crystallization mechanisms are discussed.

The second part of the review presents the results of research on SAPO-11 and SAPO-41 molecular sieves over the last three decades, with particular emphasis on methods to control the acid properties, morphology, and secondary porous characteristics of these molecular sieves, as well as on the catalytic applications of SAPO-11 and SAPO-41 for hydroisomerization of C16+ n-paraffins. The paper discusses the current understanding of the acid site formation mechanisms in SAPO-11 and SAPO-41, as well as methods for control over the strength and concentration of the acid sites and the morphology and dispersion of the crystals. Recent advances in the synthesis of SAPO-11 and SAPO-41 with a hierarchical porous structure are described, namely the use of pore-forming templates, crystal growth modifiers, and post-synthetic treatment techniques; the pros and cons of different synthesis methods are analyzed. The report also presents the catalytic properties of bifunctional catalytic systems based on SAPO-11 and SAPO-41, including hierarchical structures, in C16+ n-paraffin hydroisomerization. Prospective uses of bifunctional catalytic systems based on SAPO-11 and SAPO-41 for hydroisomerization of base oils are described. Finally, the paper formulates the remaining fundamental problems of SAPO-11 and SAPO-41 synthesis, as well as the prospects for the utilization of these materials as components of high-performance catalysts in the oil refining and petrochemical industries.

The properties of ZSM-12 zeolites prepared under hydrothermal conditions and microwave radiation influence were studied. The prepared zeolites are characterized by a wide range of physicochemical methods of analysis: X-ray diffraction analysis, low-temperature nitrogen adsorption/desorption, scanning electron microscopy, solid-state 27Al and 29Si NMR spectroscopy, infrared spectroscopy, temperature-programmed desorption of ammonia, infrared spectroscopy of adsorbed pyridine, and X-ray fluorescence elemental analysis. The calcined zeolites were impregnated with 0.5 wt % Pt, which performs the hydrogenation function in the reaction under study. The obtained materials were studied in the m-xylene isomerization reaction under the following conditions: Т = 300–440°С, WHSV = 1 h–1, Р(Н2) = 10 atm. It was found that, on the ZSM-12 MW catalyst, owing to its high acidity and fine particles, which promote high mass transfer, it is possible to increase the yields of m-xylene isomers, in particular p-xylene, to 36–65%.

The paper reports the synthesis of embryonic and highly crystalline ZSM-5zeolites withSiO2/Al2O3ratios of 50 to 400, as well as the examination and comparative evaluation oftheir physicochemical properties by XRD, low-temperature nitrogenadsorption/desorption, ammonia TPD, and TEM methods. The Ni-W sulfide catalystsprepared in situ from the embryonic andhighly crystalline ZSM-5 were investigated in a hydrocracking reaction of1-methylnaphthalene (50 atm H2, 380°C, 5 h). Thecatalytic systems based on embryonic ZSM-5 were found to promote, to a largerextent, the hydrogenation and migration of the methyl group on the naphthalenering.

This review presents the analysis of the characteristic features of the structure, synthesis methods, and physicochemical properties of embryos that form the basis of ZSM-5 zeolites. Various physicochemical characteristics of the embryos and nanocrystals of ZSM-5 (X-ray diffraction, textural characteristics, morphology, infrared and nuclear magnetic resonance spectroscopy) are discussed and compared, and their similarities and differences are analyzed.

This review presents an analysis of the structure, synthesis, and physicochemical properties of zeolites of the MWW structural type. Various physicochemical characteristics of zeolites MCM-22, MCM-36, MCM-49, and MCM-56 (X-ray diffraction data, textural characteristics, morphology, IR and NMR data) have been discussed and compared, and their similarities and differences have been evaluated.

Using the benzene alkylation reaction with propylene, the catalytic properties of heterogeneous catalysts are compared under conditions of simultaneous action of permanent deactivating factors (atmospheric pressure, increased volume feed rate) on the samples under study. For a comparative evaluation of the tested catalysts, a mathematical analysis of the experimental data on the concentration of the desired alkylation product vs. the time of the catalyst operation was carried out, and a corresponding empirical formula was derived. To compare the activity of catalysts, the power coefficient of the function was proposed as a catalyst activity factor f. A relationship between the value of this factor and the rate of deactivation of the catalyst under the conditions of the experiments was derived.

The effect of ultrasonication on the efficiency of ion exchange in a binder-free pelleted NaX zeolite (the molar ratio Si/Al = 1.34) has been studied using successive treatments with calcium, lanthanum, and ammonium nitrate solutions at 80°C with intermediate calcining after each ion exchange step in comparison with the ion exchange performed under identical conditions without sonication. It has been found that the ultrasonic treatment (a current of 2.6 A) at 80°C in a solution makes it possible to achieve a deep exchange of sodium cations in the zeolite framework (less than 0.3 wt % residual sodium oxide). The comparison of the physicochemical and catalytic properties of the catalyst samples obtained of shows a substantial advantage of the method of ultrasound-assisted ion exchange due to the almost complete exchange of sodium for the multicharged cations.

A comparative study of the trends in ion exchange of NaX zeolite (molar ratio Si/Al = 1.34) pelletized without binder has been performed using successive treatment with calcium, lanthanum, and ammonium nitrate solutions at 80°C with intermediate calcination after each ion exchange stage or by ion exchange in an autoclave at 180°C with calcium nitrate and lanthanum and ammonium nitrate solutions without intermediate calcinations. It has been found that for the complete replacement of sodium cations in the zeolite framework (less than 1 wt % residual sodium oxide), a fourfold ion exchange at 80°C with vigorous stirring and intermediate calcinations or a twofold ion exchange at 180°C in an autoclave without intermediate calcinations is required. Comparison of the physicochemical and catalytic properties of the obtained catalyst samples with almost identical chemical composition has shown a significant advantage of ion exchange in the autoclave, since the zeolite retains its initial structural characteristics.

The features of interaction of ethane with a circulating microspherical solid oxygen-carrier contact in a flow-through riser reactor have been revealed. The effects of temperature and residence time of hydrocarbons (HCs) in the reactor on the performance characteristics of the process have been examined. Under optimum conditions, the conversion of ethane can be as high as 12%, and the selectivity for ethylene is higher than 90%. The results of determination by X-ray photoelectron spectroscopy of relative atomic ratios of elements in the surface layer of the fresh catalyst and catalyst samples discharged from the unit after the set of experiments are presented.