Home – Home – Jornals – Chemistry for Sustainable Development 2022 number 1

A review of systematic studies of unbranched radical-chain reactions by the example of pyrolysis of hydrocarbons and dichloroethane with the participation of heterogeneous catalysts is presented. It is shown that the determining role in catalytic pyrolysis is played not by the concentration of surface or gas-phase active centres but by the total concentration of free radicals per unit reaction volume, which determines the heterogeneous-homogeneous nature of the process. Four types of surface impact on the process have been identified: inhibitory, neutral, accelerating the heterogeneous or homogeneous components of the process. A phenomenological model of these reactions and experimental evidence of its validity are proposed. For catalysts that accelerate the homogeneous component, the effect of “ignition” of the catalyst activity is detected, and its nature is explained. The concept of catalysis spheres is introduced - the areas above the catalyst with an increased concentration of radicals. Its dimensions and conditions of existence are determined. Experimental criteria for the emergence of the sphere are determined. Techniques of purposeful selection and synthesis of catalysts, selection of methods of technological arrangement of radical-chain heterogeneous-homogeneous processes are shown.

The analytical survey over the literature data and results of the studies carried out by the authors into the physicochemical characteristics and catalytic properties of highly dispersed massive polymetallic Ni-Mo-W and Ni-Mo catalysts, and carbide-containing Mo₂C/C catalysts of the core - shell type is presented. Catalytic carbon systems in which the active centres are functional oxygen-containing surface groups are also considered. It is shown that all the catalytic objects under consideration may be successfully synthesized by means of mechanochemical activation.

Generalizing analysis of the ecological aspects of the development and application of materials and chemical technologies promising for management of the Arctic zone and cold regions is carried out. The requirements to the Arctic materials and technologies both in their functionality and in relation to minimization of environmental impact are discussed. The problems related to the arrangement of Arctic raw material processing at mining sites are discussed.

Some questions related to applying liquid para-hydrogen in hydrogen energy are considered. The necessity to organize a business consortium for accelerated development of the technological basis for manufacture, storage and transportation of liquid para-hydrogen is discussed; the achievements of Boreskov Institute of Catalysis in the field of catalyst development and investigation of the process of ortho-para conversion of hydrogen are presented. According to low-waste technologies involving modern domestic materials, newly updated catalysts based on bulk iron oxide (BIC-5-1M) and on nickel oxide supported on the novel alumina support (BIC-5-4M) for ortho-para conversion of hydrogen were developed. Their catalytic activity was demonstrated to be comparable with the catalysts developed previously under the leadership of R. A. Buyanov, BIC-5-1 and BIC-5-4, which were applied in the industrial process of liquid para-hydrogen production. A technology of BIC-5-1M catalyst manufacturing was developed, and a pilot catalyst batch of 1 t was prepared for experimental-industrial trials.

The development of scientific directions initiated by R. A. Buyanov, Corresponding Member of the Russian Academy of Sciences, laid the foundations of the methods to synthesize catalytic nanocarbon materials. As a continuation of his ideas, the studies in the area of thermocatalytic synthesis of carbon-mineral supports were carried out at the Institute of Combustion Problems (Almaty, Kazakhstan). A review of the recent works on the formation of carbon nanotubes and nanocarbon sorbents is presented, the areas of their practical application are described. Results of the studies of the synthesis of carbon nanotubes on the catalysts obtained by means of solution combustion on glass cloth and the development of flexible heating elements on this basis are considered.

The major directions of applying polymer nanocomposite materials for the protection of the environment and humans are considered in the review. The potential of using highly porous materials and cross-linked hydrogels with incorporated nanoparticles for the purification of waste and natural waters from heavy metals, dyes, and antibiotics is demonstrated. Highly porous polymer materials with magnetic nanoparticles can be used as efficient sorbents for oil-spill cleanup from the surface of water bodies. Incorporation of anisotropic carbon and metal nanoparticles into highly porous polymer materials is a promising strategy for creating nanocomposite materials for electromagnetic radiation shielding.

This review considers the history of the development and implementation of the method of gibbsite thermal activation in Russia, the physicochemical foundations of the method, and the outlooks for its use for the preparation of supports and catalysts based on aluminium oxide. The contribution of R. A. Buyanov and his collaborators to the development of scientific foundations and the practical application of the thermal activation method is considered.

The studies carried out by us during the recent years aimed at the use of three new families of porous metal-organic frameworks NIIC-10, NIIC-20 and NIIC-30 (NIIC - Nikolaev Institute of Inorganic Chemistry) for the separation of industrially significant mixtures of hydrocarbons, in particular ethane and ethylene, benzene and cyclohexane, as well as the isomers of xylene, are evaluated.

A technology for producing hydrogen and carbon nanotubes from natural gas has been developed. The design of a pilot installation was developed and tested in the decomposition of natural gas using a series of CoO-MoO₃-Fe₂O₃-Al₂O₃ catalysts_. The optimal catalyst composition 30 % CoO-7 % MoO₃-25 % Fe₂O₃-Al₂O₃ was identified. This catalyst makes it possible to obtain 30 L of hydrogen and 12 g of carbon nanotubes from natural gas with 1 g of the catalyst at moderate temperatures (700-750 °C). It was demonstrated that the installation for natural gas processing could operate in a continuous mode with an additional catalyst supply. The concentration of hydrogen in the methane-hydrogen mixture at the reactor outlet reaches 80 vol. %.

The literature data and experimental results of the authors on the state of bismuth in the solutions of chloric and nitric acids, as well as on the synthesis of various bismuth compounds with the participation of polynuclear complexes, are systematized and summarized. It is shown that hydrolytic processing of bismuth-containing nitric solutions through bismuth precipitation at the process temperature of 65±5 °C and рН 0.7-1.0 in the form of compound [Bi6O4(OH)4](NO3)6 • H2O, followed by its transformation by means of washing with water into the compound [Bi6O5(OH)3](NO3)5 • 3H2O allows efficient separation of bismuth from impurity metals, which leads to a high-purity product with lead, silver and copper content less than 1 • 10-5 %. It is established that these compounds may be used as precursors to obtain high-purity compounds: basic bismuth carbonate, gallate, succinate, as well as medium bismuth nitrate, citrate, ditartrate trihydrate. It is stated that the complex [Bi6O4(OH)4]6+ is the initial cationic form for hydrolytic precipitation of bismuth from solutions; only the ratio of bridging oxo and hydroxo groups changes during hydrolysis, with the conservation of the Bi6O82+ core, which serves as the central structural unit. It is shown that the addition of sodium tribromophenolate to the bismuth-containing nitric solution results in the formation of bismuth oxohydroxotribromophenolate [Bi6O6(OH)2](C6H2Br3O)4. It is determined that bismuth precipitates from chloric and nitric solutions after the addition of even oxohydroxocarboxylates in the form of the compounds with the composition Bi6O4(OH)4(СnH2n + 1COOO)6 (n = 2-22), where (СnH2n + 1COOO)- is the carboxylic acid anion. Bismuth precipitation from nitric solutions in the form of laurate and stearate allows efficient purification of bismuth from impurity metals. A comparison of bismuth extraction with di-2-ethylhexylphosphoric acid from nitric solutions in the form of solvated complex Bi(C16H34O2POO)3 • 2C16H34O2POOH and oxohydroxodialkylphosphate Bi6O4(OH)4(C16H34O2POO)6 is carried out. In the latter case, extracts concentrated with respect to bismuth can be obtained, which provides substantial broadening of the possibilities to use extraction-based processes in the technology of obtaining bismuth compounds.

The synthesis of amide complexes of O,O-di(alkyl)aryldithio phosphates of metals (Co, Cu, Zn) with acetamide, benzamide and salicylamide was carried out. It was found that one of the advantages of these amido complexes is the absence of odour amines and the possibility of their use in neutral, acidic and hydrocarbon media. The composition and structure of the obtained amido complexes were confirmed by analytical procedures and IR spectroscopy. The anticorrosion properties of preservation liquids based on the synthesized amido complexes with the spent turbine oil T-30 were studied on steel plates in three media: in a G-4 hydrochamber (temperature 40±2 °C, humidity 95±3 %); in seawater; in the 0.001 % solution of sulphuric acid. Their high efficiency against corrosion was revealed.

Dimethyl-, diethyl[1-allyl(3-α-naphthylprop-2-ynyl)]ammonium and -piperidinium bromides were synthesized by alkylation of dimethyl-, diethyl[1-allyl(3-α-naphthylprop-2-ynyl)]amines and -piperidine, obtained by Stevens rearrangement of dimethyl-, diethylallyl(3-α-naphthylprop-2-ynyl)]ammonium and -piperidinium bromides, with allyl or propargyl bromides. 2,2-Dimethyl-, 1-allyl-3 a ,4-dihydronaphtho[ f ]piperidinium bromides were obtained through base-catalyzed cyclization of dimethylallyl[1-allyl(3-α-naphthylprop-2-ynyl)]ammonium and -piperidinium bromides in the yields of 90 and 88 %, respectively. It is shown that the interaction of propargyl analogs with a catalytic amount of the base leads to the formation of compounds of unknown structure.

Predictive analysis of the state and course of works aimed at the construction of nanosized robots of different types and purposes is presented on the basis of literature and own sources of information. Two principally different methods of their construction are distinguished:
1. Molecular assembly or another manual version. The human factor is decisive here.
2. Alternative method. Nature itself creates the functional structures to govern nanotechnologies. The problem is in finding them and programming.
The first method turned out to be too complicated and attractive only in imagination, as in the saying: the devil is in the details.
The second method turned out to be great luck. On the basis of the available knowledge, the previously unknown natural phenomenon possessing the functional structure was found and decrypted. A physicochemical nanosized robot (PCNR) has been created, and the scientific basis of the technology to manufacture PCNR for different purposes have been established.