The results of an experimental study of the reaction of ethylene trimerization to 1-hexene on a chromium-pyrrole catalyst are presented. The studies were carried out in the range of pressures of 18–30 bar, temperatures of 105–20°C, and catalyst concentrations of 1.165–3.500 mg/L. A mathematical model of the used semiflow reactor is also presented. A route is proposed to describe the observed reaction products. The rate constants of the elementary stages of the process are determined by solving the inverse kinetic problem. The dependences of the ethylene absorption curves on the reaction conditions, pressure, temperature and catalyst concentration, as well as the change in the degree of ethylene over the course of the experiment are analyzed.

The paper reports the results of a kinetic and thermodynamic analysis of non-catalytic partial oxidation of methane and C2–C4 hydrocarbon/hydrogen mixtures (C/H = 1 : 4) at 1400–1700 K. The hydrocarbon conversion sequence and the time periods of the major process stages were identified for isothermal conditions. The initial stage of the oxidative conversion of C2+ hydrocarbons consists of their pyrolysis, primarily into ethylene and propylene, followed by oxidation of the pyrolysis products. In this respect, the kinetics of C2+ hydrocarbon oxidative conversion are different from those of methane conversion, marked by the almost simultaneous and significantly slower occurrence of pyrolysis and oxidation. The subsequent stages involve steam and dry reforming of the oxidation products, namely acetylene and methane; these stages continue until the main products (H2, CO, CO2, and H2O) reach an equilibrium distribution for the given temperature. The study findings are important for the optimization of various techniques for high-temperature syngas production via partial oxidation of C2+ hydrocarbons, as well as Moderate or Intense Low-Oxygen Dilution (MILD) combustion processes.

This review provides an analysis of prior research on the kinetics of the trimerization of ethylene to 1-hexene over existing chromium-based catalytic systems. It discusses the known mechanisms and reaction steps for the formation of 1-hexene as well as olefin by-products. The effects of catalytic system composition, temperature, pressure, reaction time, and the presence of hydrogen on the kinetics of 1-hexene formation are also touched upon. The kinetic models of ethylene trimerization to 1-hexene known from published literature are presented.

The high power-conversion efficiencies of hybrid perovskite solar cells encourage many researchers. However, their limited photostability represents a serious obstacle to the commercialization of this promising technology. Herein, we present an efficient method for improving the intrinsic photostability of a series of commonly used perovskite material formulations such as MAPbI3, FAPbI3, Cs0.12FA0.88PbI3, and Cs0.10MA0.15FA0.75PbI3 through modification with octenidine dihydroiodide (OctI2), which is a widely used antibacterial drug with two substituted pyridyl groups and two cationic centers in its molecular framework. The most impressive stabilizing effects were observed in the case of FAPbI3 and Cs0.12FA0.88PbI3 absorbers that were manifested in significant suppression or even blocking of the undesirable perovskite films’ recrystallization and other decomposition pathways upon continuous 110 mW/cm2 light exposure. The achieved material photostability—within 9000 h for the Oct(FA)n−1PbnI3n+1 (n = 40–400) and 20,000 h for Oct(Cs0.12FA0.88)n−1PbnI3n+1 (where n = 40–400) formulations—matches the highest values ever reported for complex lead halides. It is important to note that the stabilizing effect is maintained when OctI2 is used only as a perovskite surface-modifying agent. Using a two-cation perovskite composition as an example, we showed that the performances of the solar cells based on the developed Oct(Cs0.12FA0.88)399Pb400I1201 absorber material are comparable to that of the reference devices based on the unmodified perovskite composition. These findings indicate a great potential of the proposed approach in the design of new highly photostable and efficient light absorbers. We believe that the results of this study will also help to establish important guidelines for the rational material design to improve the operational stability of perovskite solar cells.

Commercial processes for conversion of carbon-containing gases to syngas and hydrogen are considered. The techno-economic characteristics of the main hydrocarbon gas conversion processes (steam methane reforming, partial oxidation, autothermal reforming) used by world’s leading chemical and petrochemical companies and implemented on the commercial or semicommercial scale are presented. The characteristics of these processes are analyzed. The processes of steam conversion, autothermal reforming, and partial oxidation of methane have specific predominant application fields depending on the feed composition and requirements to the composition of the syngas obtained. The steam conversion can ensure the maximal H2/CO molar ratio in the syngas obtained, and the processes of autothermal reforming and partial oxidation of methane do not require external heat supply to the reactor and are simple in implementation. Analysis of the syngas market shows that the main drivers of its progress can be the need for alternative resources and the stable demand of the chemical industry.

A new process is proposed for the pyrolysis of ammonia in a filtration combustion moving bed reactor to produce hydrogen. The process can be implemented in reactors with energy recovery with a separate supply of reagents (including swiss-roll reactors, etc.). The mass-energy balance of the process is calculated. The pyrolysis products are analyzed under a condition of thermodynamic equilibrium with varying temperature and pressure. The system pressure is varied from 1 to 10 bar. The temperature range from 300 to 1100 K iss considered. It is shown that the pyrolysis of ammonia ends at a temperature of 620 K at atmospheric pressure. An increase in pressure in the system leads to a slight increase in the temperature of the pyrolysis of ammonia. The portion of hydrogen that needs to be burned to cover the energy for heating and pyrolysis of the initial ammonia in the case of an adiabatic reactor is 0.13. From one mole of ammonia it is possible to obtain 1.31 moles of hydrogen.

Конверсия богатых метан-кислородных смесей в матричном риформере протекает через несколько последовательных стадий. За быстрой стадией окислительных процессов, завершающейся практически полной конверсией кислорода (зона пламени), следует послепламенная стадия высокотемпературных эндотермических процессов, протекающих в отсутствие кислорода. В этой зоне происходит существенное увеличение концентрации Н2 и СО, а также изменение соотношения Н2 /СО. Анализ и оптимизация процессов, протекающих в послепламенной зоне, могут позволить существенно повысить выход синтез-газа и соотношение Н2 /СО. В работе на базе кинетического моделирования процессов в послепламенной зоне некаталитического парциального окисления богатых метан-кислородных смесей рассматривается их оптимизация и повышение технологических характеристик процесса. Показано, что активным конвертирующим агентом в послепламенной зоне является Н2О; увеличение температуры, с которой газовая смесь входит в послепламенную зону, приводит к увеличению выхода Н2 и соотношения Н2 /СО, а также повышает выход Н2 на моль поданного с исходной смесью СН4 .

The aim of this review is to summarize and comparatively analyze recent reports on studying carbon dioxide conversion to methanol, dimethyl ether, and C2+ hydrocarbons, in particular, olefins, by catalytic hydrogenation. It is shown that the main approaches to providing high activity and selectivity of these processes are the targeted design of catalysts and the selection of conditions for hydrogenation processes, in particular, the use of supercritical CO2 and procedures that are alternative to conventional physicochemical methods for CO2 activation (electrocatalysis, photocatalysis).

The review is devoted to generalization and comparative analysis of recent literature data on the conversion of carbon dioxide to methanol, dimethyl ether and hydrocarbons С2+, including olefins, by catalytic hydrogenation. The main ways for achieving high activity and selectivity of such processes were shown to be the deliberate design of catalysts and the selection of conditions for hydrogenation processes, particularly with the use of supercritical CO2 and alternative physicochemical methods of CO2 activation (electrocatalysis and photocatalysis).

Reducing carbon dioxide emissions during production is one of the main trends in modern oil and gas chemistry. One of the most realistic possibilities for achieving this is to involve carbon dioxide generated in technological processes as a feedstock for producing gas chemical products. The maximum effect can be achieved in the production of large-scale chemicals, such as syngas, hydrogen, and methanol. We consider such possibilities and present a new combined autothermal process for the joint production of hydrogen and methanol based on non-catalytic matrix conversion of natural gas into syngas, which allows one to almost avoid CO 2 emissions.

The development of noncatalytic procedures for processing hydrocarbon gases is an important way to increase the efficiency of gas-chemical processes and decrease their power consumption. The paper deals with thermodynamic and kinetic modeling of noncatalytic processes of the partial oxidation and steam and carbon dioxide conversion of methane in the temperature interval 1400–1800 K and with analysis of the process for syngas production by matrix conversion of rich methane–oxygen mixtures. Comparison of the kinetic calculations with the experimental data demonstrated the possibility of applying published models to the description of the matrix conversion of methane. The possibility of developing a highly efficient technology based on noncatalytic partial oxidation of hydrocarbons for the syngas production without СО 2 emission into the environment is discussed.

The paper reports the results of a kinetic and thermodynamic analysis of non-catalytic partial oxidation of methane and C-2-C-4 hydrocarbon/hydrogen mixtures (C/H = 1 : 4) at 1400-1700 K. The hydrocarbon conversion sequence and the time periods of the major process stages were identified for isothermal conditions. The initial stage of the oxidative conversion of C2+ hydrocarbons consists of their pyrolysis, primarily into ethylene and propylene, followed by oxidation of the pyrolysis products. In this respect, the kinetics of C2+ hydrocarbon oxidative conversion are different from those of methane conversion, marked by the almost simultaneous and significantly slower occurrence of pyrolysis and oxidation. The subsequent stages involve steam and dry reforming of the oxidation products, namely acetylene and methane; these stages continue until the main products (H-2, CO, CO2, and H2O) reach an equilibrium distribution for the given temperature. The study findings are important for the optimization of various techniques for high-temperature syngas production via partial oxidation of C2+ hydrocarbons, as well as Moderate or Intense Low-Oxygen Dilution (MILD) combustion processes.

A variety of natural and anthropogenic sources of hydrocarbon gases make a significant contribution to the global emission of greenhouse gases. Reducing the anthropogenic emission of industrial hydrocarbon gases is impossible without new technologies that would allow their cost-effective utilization. The paper describes a number of new promising technologies based on autothermal gas-phase processes of partial oxidation and oxidative cracking of various hydrocarbons, such as associated petroleum gases, coalbed methane, refinery gases, and biogas, which open up prospects for a significant reduction in their flaring or emission into the atmosphere. Among the technologies under consideration are those involving their processing for subsequent use in the energy sector and low-tonnage production of various demanded chemicals.

One of the most realistic possibilities for reducing anthropogenic carbon dioxide emissions is its involvement as a feedstock in various processes for producing gas chemical products. First of all, it is advisable in the production of the largest-tonnage products, such as syngas, hydrogen and methanol. The paper considers the possibility of involving carbon dioxide in non-catalytic autothermal processes of the production of these products. A combined process for the production of methanol and hydrogen without CO2 emission based on the matrix conversion of natural gas into syngas is presented.

The review contains a comparative analysis of studies on the production of hydrogen and syngas based on the processes of partial oxidation of natural gas and other types of gas feedstock. The results presented in the literature show the high potential of non-catalytic autothermal processes of partial oxidation of hydrocarbons for the development of gas chemistry and energetics. The partial oxidation of hydrocarbons makes it possible to overcome such serious shortcomings of traditional syngas production technologies as technological complexity and high energy and capital intensity. The features of non-catalytic partial oxidation of hydrocarbon gases, the obtained experimental results and the results of kinetic modeling of various options for the implementation of the process, which confirm the adequacy of the kinetic mechanisms used for the analysis, are considered in detail. Examples of industrial implementation of processes based on partial oxidation and proposed alternative options for its organization are considered. Designs of reactors used to ensure stable conversion of rich mixtures of hydrocarbons with an oxidizer are presented. The possibility of obtaining other chemical products by partial oxidation of hydrocarbons is discussed.

A thermodynamic assessment of biogas conversion regimes with the production of hydrogen and synthesis gas is out. The air conversion of the original and dried biogas, as well as conversion with an increased oxygen content in the air, is studied. Model mixtures of high-calorie (50 vol % methane) and low-calorie (25 vol % methane) biogas are considered. Calculations are performed for mixtures with an adiabatic combustion temperature of at least 1000 K. It is shown that during air conversion of low-calorie dry biogas, the maximum content of hydrogen and carbon monoxide in gaseous products can be 22.3 and 20.8 vol %, respectively. With air conversion of high-calorie dry biogas, the maximum content of hydrogen and carbon monoxide in gaseous products can reach 26.0 and 16.3 vol %, respectively. At an oxygen content of 41 vol %, the conversion of low-calorie dry biogas makes it possible to obtain a gas with a content of 31.0 vol % hydrogen and 28.3 vol % carbon monoxide. With an oxygen content of 41 vol %, the conversion of high-calorific dry biogas makes it possible to obtain a gas with a hydrogen content of 39.0 vol % hydrogen and carbon monoxide content of 25.0 vol %.

The kinetic patterns of the attainment of the equilibrium product composition in non-catalytic processes of partial oxidation and of steam and carbon dioxide reforming of hydrocarbons in the temperature range 1400–1800 K, characteristic of these processes, were analyzed. The need for such analysis is caused by the rapidly increasing consumption of natural gas as a chemical feedstock and by growing attention to environmental problems, in particular, to a decrease in СО 2 emissions or to partial CO 2 utilization. The forward and reverse water gas shift reactions (WGSRs) play an important role in approach to the equilibrium product composition in these processes. Analysis has shown that the elementary reactions characteristic of forward and reverse WGSRs start to play a significant role long before the equilibrium in the system is attained. Already in the intermediate steps of the process, the distribution of the major reaction products, Н 2 , СО, Н 2 О, and СО 2 , almost corresponds to the equilibrium value of K t = ([H 2 ][CO 2 ])/([CO][H 2 O]), close to the WGSR equilibrium constant K eq , and further conversion of the products occurs at K t values close to K eq .

Cyclic biscarbonates were synthesized from CO2 and diepoxides in the presence of a chromium(III) salen complex. The effect of the reaction conditions on the process kinetics, recorded by monitoring the CO2 absorption during the reaction, has been studied for the first time. After complete conversion of diepoxides to cyclic biscarbonate, the same catalytic system was used in the reaction of biscarbonates with diamines to form polyhydroxyurethanes. The thermal characteristics of the synthesized polymers are mainly determined by the structure of the diepoxide and, to a lesser extent, by the nature of the amine used in the second stage of the process.

Based on thermodynamic calculations, an assessment is made of the modes of the noncatalytic conversion of natural gas to produce synthesis gas. The following modes of conversion are considered: air and steam-air, with an increased oxygen content and an increased initial temperature of the mixture. The results of calculations for mixtures with an adiabatic combustion temperature not lower than 1000 K are presented, since at lower temperatures unreacted methane appears in the products. It is shown that when air is used as an oxidizing agent, the maximum content of hydrogen and carbon monoxide in gaseous products can be 28.2 and 13.2 vol %, respectively, at the equivalence ratio φ = 2.6. In this case, the maximum yields of hydrogen and carbon monoxide are 1.65 and 0.77 moles from 1 mole of methane, respectively. In the case of the steam-air conversion of methane, the maximum yield of hydrogen and carbon monoxide is less than in the case of air conversion. In the conversion of methane with an increased oxygen content, the maximum hydrogen yield is lower and that of carbon monoxide is higher than in the conversion of air. An increase in the initial temperature of the mixture leads to an increase in the adiabatic combustion temperature and the yield of carbon monoxide, as well as to a decrease in the yield of hydrogen in the products.