Two new dyes were obtained; their D—A—π—A′ structure included benzo[d][1,2,3]-thiadiazole as an internal acceptor (A), a cyanoacrylic acid residue as a terminal anchor acceptor (A′), a 4H-cyclopenta[2,1-b:3,4-b′]dithiophene π-spacer with branched alkyl groups, and 2,3-dihydroindole condensed with carbocycles as a donor. The optical and electrochemical characteristics of the obtained dyes were determined, and solar cells based on them were assembled. The power conversion efficiency reached 3.05

A key goal of organic chemistry is to develop new principles for the control of reactions, which can be used to create promising materials demanded in all fields of scientific research and industry. This review is an overview of the scientific advances, which have been made by the N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences in the past decade within the framework of current trends in organic chemistry. The review covers the results, which are significant for fundamental research and hold great promise for the application in different areas, from the production of materials, petrochemistry, and chemical ecology to medicine, agriculture, and food industry.

Investigations of bromination of naphtho[2,3-c][1,2,5]thiadiazole-4,9-dione revealed that the reaction proceeded most efficiently with N-bromosuccinimide in sulfuric acid and depending on the reaction conditions, can give mono-, di-, tri- and tetrabromo derivatives of naphtho[2,3-c][1,2,5]thiadiazole-4,9-dione. A series of the major isomers was isolated, and their structure was proven using heteronuclear multiple bond correlation NMR spectroscopy and high-resolution mass spectrometry.

Dyes of various structural complexity, based on the fragments of 4-(2-ethylhexyl)-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole and cyanoacrylic acid, were obtained. Solar cells sensitized with these dyes were developed, and their key photophysical characteristics were determined. The power conversion efficiency reached 4.64% for the most optimal devices based on a dye with an average structural complexity containing donor and acceptor fragments linked via a thiophene bridge. This value is comparable to the values obtained in the case of solar cells based on dyes of more complex structural types.

The crystallization mechanism affects the zeolite BEA crystal morphology and texture as well as the Al distribution along its crystal and acidic properties.

A pyridazine thiadiazole acceptor (PzT) has been utilised in the synthesis of a novel low band-gap D–A copolymer PTTPz.

The mechanism of seeding of zeolite BEA via steam assisted conversion has been studied using BEA seeds with different composition. The catalysts are characterized by X-ray diffraction, scanning and transmission electron microscopy, nitrogen adsorption-desorption, Hg-porosimetry, X-ray fluorescence and TPD of ammonia, and evaluated in benzene alkylation with propene. The results show that variation of the SiO2/Al2O3 ratio from 25 to 250 in BEA seeds changes the mechanism of seeding from "core-shell" to a "dissolution" mechanism, which can serve as a tool for engineering the morphological, textural and catalytic properties of BEA zeolites. Al-rich seeds (SiO2/Al2O3 = 25) do not dissolve during gel preparation and initiate dense oriented crystal growth on their surface resulting in the formation of large polycrystals (1-2 μm) with ordered densely intergrown nanocrystallites. In contrast, Si-rich seeds (SiO2/Al2O3 = 250) dissolve into tiny fragments, which serve as individual nuclei leading to formation of tiny isolated nanocrystallites aggregated into small hierarchical aggregates with high intercrystalline mesoporosity. The decrease of particle size and formation of intercrystalline mesoporosity in hierarchical aggregates improves the accessibility of acidic sites and facilitates the diffusion of reaction products, which leads to the significant improvement of catalytic activity and reduces the deactivation resulting in higher stability with time on stream in cumene synthesis from benzene and propylene.

The review is devoted to the features of the synthesis of zeolites with nanosized crystals, which are of great interest for the processes of petroleum chemistry, gas chemistry, and organic synthesis. On the basis of analysis of published data, a classification is proposed for methods of directional control of the size of zeolite crystals. Methods for qualitative and quantitative controlling the composition of the reaction mixtures crystallized into nanoscale zeolites are considered in detail, as well as the effect of crystallization conditions on the change in the dispersity of zeolite crystals.

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.

Hydrocracking of vacuum gas oil has been studied over NiMo/zeolite-Al2O3 catalysts. Three different zeolites have been used for catalysts preparation: zeolites Beta (BEA) and Y (FAU) having small crystal size and zeolite Y modified by recrystallization (RFAU). HRTEM, low-temperature N-2 adsorption, FTIR of adsorbed CO and TPD-NH3 showed that zeolites had different crystal sizes, mesopore volume, strength and concentration of acid sites. Sulfide active component particles have been revealed to be similar in all catalysts by HRTEM and XPS. NiMo/ BEA catalyst having zeolite with the smallest average particle size and the highest concentration of Bronsted acid sites (BAS) demonstrated the highest hydrocracking activity. Selectivity to middle distillates decreased in the following order: NiMo/FAU > NiMo/RFAU > NiMo/BEA. This effect is accounted for by optimal zeolite acidity and improved availability of the acid sites for bulky molecules of the heavy feedstock.

The physicochemical properties of catalysts synthesized from zeolites of the BEA and MWW framework types using pseudoboehmite as a binder and their catalytic activity in benzene alkylation with propylene in the gas-phase and liquid-phase modes have been studied. It has been found that the MWW-based catalyst is characterized by stronger acidity in terms of both amount and strength of acid sites; however, the catalytic activity of this sample is inferior to that of zeolite BEA. The observed effect is attributed to the higher accessibility of acid sites in the three-dimensional system of zeolite BEA. With respect to some parameters, such as cumene selectivity and on-stream stability, zeolite MWW is superior to zeolite BEA; the difference is attributed to the structural features of these zeolites.

Transformations of granules based on kaolin and phosphoric acid under conditions of vapor-phase crystallization in a mixture of water vapor and a structure-directing agent have been studied. It has been shown that silicoaluminophosphate granules obtained in the presence of dipropylamine, triethylamine, or tetramethylammonium hydroxide as a structure-directing agent consist of a shell formed by dense nonporous cristobalite, tridymite, and berlinite phases and the core made mainly of microporous crystalline silicoaluminophosphates. The formation of the shell, which ensures the strength of the silicoaluminophosphate granules, is due to the interaction of steam with the material of the granules at the initial stages of vapor-phase crystallization. It has been established that the selectivity of the structure-directing action of the amines under vapor-phase crystallization conditions basically corresponds to the template hydrothermal synthesis. It has been assumed that the specific features of the structure-directing action of dimethylamine during vapor-phase transport synthesis are due to its low boiling point, which ensures the primary contact of the granules with template, rather than water molecules. As a result, the products of the transformation of granules in the presence of a mixture of dimethylamine and water do not contain dense nonporous phases and are cocrystallized silicoaluminophosphate and calcium aluminosilicate with the gismondine structure.

The features of hydrothermal crystallization of reaction mixtures RM-I and RM-II that are similar in chemical composition and differ in the order of mixing of the reactants, have been studied in detail. It has been shown that changing the sequence of mixing the reactants during the preparation of the reaction mixture (RM) leads to the formation of aluminosilicate solid gels of different compositions and determines the formation mechanism of the BEA zeolite crystalline structure. It has been established that the addition of a source of silicon at the initial step of mixing the reactants (RM-I) leads to the formation of an aluminum-rich aluminosilicate gel, the charge of which is compensated by alkali metal cations, with the TEA(+) cations occurring in solution. Adding a source of aluminum at the initial steps of mixing the reactants (RM-II) leads to the formation of amorphous aluminosilicate hydrogel with occluded TEA(+) cations, the chemical composition of which is close to that of the final zeolite. It has been shown that during crystallization of RM-I the formation of nuclei apparently occurs in solution. According to the infrared spectroscopy data, during crystallization of RM-II the formation of secondary structural fragments of BEA zeolite occurs in the bulk of the solid phase. The products of separated hydrothermal transformation of solid and liquid phases isolated by centrifugation from RM-I and RM-II at the initial steps of the synthesis have been studied. It has been demonstrated that in order to obtain zeolite Beta crystals without admixtures of other phases it is necessary to have not only a high concentration of TEA(+) cations, but also a high concentration of aluminum in the reaction mixture.

The effect of the chemical composition of nanocrystalline zeolites BEA on their physicochemical and catalytic properties in benzene alkylation with propylene is studied. It is shown that a decrease in the Al2O3 content in the reaction mixture during the synthesis of nanocrystalline zeolites leads to a decrease in the size of both the primary nanocrystals and their aggregates. The acidic properties of nanocrystalline zeolites BEA correlate with the aluminum concentration in the samples. The high concentration of acid sites of about 1400 μmol/g and the developed surface of zeolites BEA represented by nanocrystal aggregates provide a high activity of the samples and a high selectivity for the target product—cumene—owing to a decrease in the contribution of side reactions, namely, the secondary alkylation and oligomerization of propylene.

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 dealumination of nanosized zeolites is an important scientific problem, which should be solved to improve the activity of catalysts based on this zeolite in a broad range of heterogeneous catalytic reactions, particularly in commercial processes. However, the smaller the required size of the synthesized crystals, the lower the Si/Al ratio and the lower the degree of dealumination of this material can be achieved. In this study, the dealumination of zeolites Y with a crystal size of 50–1100 nm by treatment with ammonium hexafluorosilicate and steam heat treatment is discussed. It is shown that the dealumination with ammonium hexafluorosilicate is a “gentler” method in terms of structure preservation, whereas the dealumination by steam heat treatment provides a higher Si/Al ratio in the products; however, this method is inapplicable for crystals smaller than 500 nm, because it leads to the complete degradation of the structure. However, nanosized crystals can be dealuminated by treating with ammonium hexafluorosilicate. In this case, the degree of dealumination is close to 40%. A significant disadvantage of this method is the formation of a SiO 2 film on the crystal surface; this feature substantially restricts the use of the ammonium hexafluorosilicate treatment in the synthesis of cracking catalysts.

The effect of ultrastable zeolite Y recrystallization on the properties of NiMo/USY-Al2O3 hydrocracking catalyst has been studied. The mesoporosity, being introduced as the result of zeolite Y recrystallization, is mainly preserved at the subsequent steps of NiMo catalysts preparation. The total concentration of Bronsted acid sites in the catalysts varies proportionally to that for the corresponding zeolites used for preparation. It is observed that the higher the recrystallization degree the lower the concentration of strong Bronsted acid sites in the catalysts. UV-vis DRS, HRTEM and XPS data suggest that the state of supported Ni and Mo is similar for the catalysts prepared with parent and recrystallized zeolites. The catalysts based on recrystallized zeolites have significantly higher activity in hexadecane hydrocracking as compared to the catalyst obtained using parent zeolite. This effect is rationalized in terms of the improved accessibility of zeolite acid sites after recrystallization. Moreover, the mesoporosity introduced by zeolite Y recrystallization has a positive effect on the selectivity of NiMo/USY-Al2O3 hydrocracking catalyst.

The effect of the nature of the binding component (Al2O3, SiO2, kaolin) on the physicochemical and catalytic properties of catalysts based on a hierarchical zeolite of the MWW framework type in benzene alkylation with propylene has been studied. The best results have been obtained using Al(OH)(3) as an Al2O3 precursor. This precursor does not have an adverse effect on the acidic properties of the catalyst and thereby provides an increase in the yield of the desired product, i.e., cumene. The addition of kaolin to this catalyst does not affect the strength characteristics; however, the presence of this binder leads to a decrease in the number of acid sites in the sample.

Features of the synthesis and physicochemical properties of a new class of materials— hierarchical MWW zeolites (HZ-MWW), prepared via recrystallization—are studied. Recrystallization is done in two stages in an alkaline solution containing cetyltrimethylammonium bromide. The effect the type of precursor and the concentration of alkali have on the morphological, textural, and acidic properties of HZ-MWW is studied. It is shown the recrystallization of a layered precursor under mild conditions in a 0.5 M NaOH solution slightly alters the porous structure while preserving the morphology of the zeolite crystal. It is established that an increase in the degree of recrystallization in 1 and 2 M NaOH solutions is accompanied by the fragmentation of crystals, growth of the external surfaces of materials, and the formation of a mesoporous phase formed by ordered pores around 3 nm in size. The evolution of the HZ-MWW porous structure is traced during the preparation of the hydrogen form with acidic properties. It is concluded that the ion exchange of HZ-MWW in ammonium nitrate solution washes out the amorphous phase and changes the texture of the H-forms of HZ-MWW, compared to the detemplated Na-forms. The acidic properties of HZ-MWW correlate with the Si/Al ratio and samples of the micropore volume.

Hydrocracking of vacuum gas oil was studied over micro-mesoporous zeolite based catalysts, obtained by zeolite Y recrystallization. The contribution of mesoporosity in recrystallized materials was varied by adjusting the content of alkali and the temperature of hydrothermal treatment. The increase of recrystallization degree results in the increase of mesopore to micropore volume of zeolite Y as well as to the decrease of the contribution of strong Bronsted acid sites in faujasite cages and the increase of the contribution of Bronsted acid sites in mesopores. The highest hydrocracking activity and middle distillates yield is achieved over NiMo catalyst obtained with micro-mesoporous material with low degree of recrystallization. This effect is due to the improved accessibility of active sites and easier transport of bulky molecules provided by mesopores, on the one hand, and optimal zeolitic acidity, on the other hand. The highest selectivity to middle distillates is achieved over catalyst with the highest degree of zeolite recrystallization. This observation can be explained by the decrease of the contribution of strong BAS (bridging Si-O(H)-Al groups) accompanied by the increase of concentration of BAS in mesopores.