Catalysis in Industry最新文献

The paper is devoted to the study of platinum-containing glass fiber catalysts (GFCs) for deep oxidation of hydrocarbons, which can be used in the processes of cleaning exhaust gases from volatile organic impurities, as well as for environmentally friendly combustion of fuels. The influence of the catalyst synthesis method on its activity in the reaction of deep oxidation of toluene was studied. The highest specific activity per unit mass of Pt is demonstrated by the conventional GFC IK-12-C102 based on a preleached zirconium-containing support; however, in terms of total activity per unit volume of the cartridge and per unit mass of the catalyst, GFC IK-12-C111 produced by the surface thermal synthesis method is more efficient. Its slightly higher platinum content is compensated by the possibility of using a significantly lighter, cheaper, and more accessible support. It has been shown that applying the precursor solution to the support by spraying instead of impregnation ensures an increase in specific activity. In addition, the influence of such properties as the structure of the glass fiber support (satin and openwork weave) and the geometry of the arrangement of the catalyst layers relative to the flow of the reaction mixture on the apparent activity of GFCs was studied. It has been shown that the most effective for deep oxidation processes is the use of satin weave as a GFC support with longitudinal orientation of the catalyst layers relative to the flow of the reaction mixture. Criterial equations for assessing the hydraulic resistance of different types of GFC packages are proposed.

This study proposes a first-order macrokinetic model for CO₂ sorption on a 10 mol % NaNO₃/MgO sorbent. According to the experimental gravimetric data, the maximum sorption capacity of the 10 mol % NaNO₃/MgO sorbent is determined and does not depend on the partial pressure of CO₂; at 320°C it is equal to 159% (based on the initial mass of the sample) or 13.4 mmol CO₂/g_sorb. The calculated value of the sorption constant k_ads at temperatures of 280–320°C and a CO₂ partial pressure of 0.50–0.75 atm is 0.017 min^–1 atm^–1. Based on the obtained kinetics, modeling of adiabatic and isothermal CO₂ adsorbers was performed within the framework of the technological scheme for producing 10 kg/h of hydrogen from natural gas at an operating pressure of 12 atm. The calculations showed that for the adsorber to function effectively intensive removal of the heat released during the sorption process is necessary. This allows for the sorption of CO₂ for 30 min at a temperature of 300°C and a gas hourly space velocity GHSV = 1170 h^–1, while the concentration of CO₂ at the outlet in dry gas does not exceed 1.5 mol %.

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.

A mathematical model that adequately describes the process of catalytic reforming—the main industrial technology for obtaining high-octane components of motor fuels in Russia and abroad is presented. The necessity of expanding the existing scheme of transformations of hydrocarbons of the gasoline series to create a model of reforming feedstocks of various origins (gasoline fractions of thermal destructive processes, hydrocracking naphtha, gas condensate) is shown. Based on the results of experimental studies using gas chromatography, as well as the calculations of thermodynamic parameters, an improved formalized reaction scheme has been compiled to take into account into account reactions involving unsaturated hydrocarbons. A kinetic model of the reforming process of the expanded gasoline fraction has been compiled. To describe the kinetic model based on the formalized scheme of hydrocarbon transformations, a matrix method was used, which makes the model more flexible to the composition of the feedstock.

The effect of the ratio of Ce and Mn oxides supported on cordierite ceramics on the structure and catalytic activity in the ozone decomposition reaction at room temperature was studied. The catalysts were prepared by impregnating cordierite ceramic blocks with citric acid at varying atomic ratios Ce : Mn. The physicochemical characteristics of the catalysts were studied using low-temperature nitrogen adsorption, X-ray phase analysis, scanning electron microscopy, and H₂ temperature-programmed reduction, and the catalytic activity of the samples in ozone decomposition was tested at high flow rate (20–50 L/min) and an initial O₃ concentration of 1–2 ppm. It has been shown that mixed oxide Ce–Mn catalysts are more active than catalysts based on individual Ce and Mn oxides. The activity passes through a maximum at the atomic ratio Ce : Mn = 1 : 2, which is due to the highly dispersed state of the supported oxides.

The influence of the ratio of active components (Fe and Cr) on the catalytic activity of FeCr/C catalysts in the oxidative dehydrogenation of ethane with CO₂ was analyzed. The best results were achieved on the 2Fe3.7Cr/C catalyst, in which the Fe : Cr ratio corresponded to the stoichiometry of iron(II) chromite FeCr₂O₄. The physicochemical characteristics of the prepared catalysts were determined and analyzed (XRD, XPS, magnetometry). Based on the totality of the data obtained, it is possible to assume the presence of the iron(II) chromite phase.

This work is devoted to the mathematical modeling of N₂O synthesis via NH₃ oxidation on a Mn/Bi/Al oxide catalyst in a microstructured split-flow reactor (MSR). The characteristics of the process are studied at different linear flow velocities, inlet ammonia concentrations, and reactor edge temperatures. Parameters are determined that endure an efficient process in the microstructured reactor under thermally admissible conditions. The possibility is shown of scaling the MSR by multiplying its geometric dimensions with no overheating in the reaction zone. Results show that in a microstructured reactor with such a configuration, the capacity for producing N₂О can be increased by around 12 times, relative to the best performance characteristics of a conventional microreactor, and the catalyst’s specific production capacity is approximately 1.5 times higher than in a traditional tubular reactor. This allows the creation of low-tonnage plants for producing high-purity nitrous oxide for different applications by scaling microreactor systems. The results in this work correspond to the concept of distributed chemicalization and contribute to overcoming the barrier between laboratory catalytic reactors and industrial-level devices.

The main laws and routes of the liquid-phase hydrogenation and isomerization of carbocyclic alkenes and dienes of the norbornene series in the presence of heterogeneous catalysts were systematized, and the reaction mechanisms were discussed. The reaction products were identified and the material balance was studied. Conditions for the hydrogenation and isomerization of the compounds were selected such as to provide the preservation of the norbornane framework. The reactivity of multiple bonds in norbornenes was assessed by experimental and quantum chemical methods. Adequate kinetic models of the processes in terms of the Langmuir–Hinshelwood approach and in the representation of multiple adsorption of substrates on a single active site were developed.

This study is focused on the effect of various base catalysts on the glycolysis of plastics based on bisphenol A (BPA) polycarbonate (PC). It has been found that the chemical degradation of PC under the action of ethylene glycol (EG) leads to the formation of the following high-added value products: BPA (PC monomer) and BPA–ethylene carbonate (EC)/(EG) co-ethers (monohydroxyethyl ether of BPA (MHE-BPA), bishydroxyethyl ether of BPA (BHE-BPA)). A quantitative assessment of the reaction product yields has been conducted. It has been found that, at a 100% PC conversion, the product yields are the following (%): BPA, 33; MHE-BPA, 50; and BHE-BPA, 17. In addition, the efficiencies of using various alkaline agents as a catalyst depending on the type of metal have been compared in this study.