Catalysis in Industry最新文献

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).

An adsorbent consisting of a granular NаX zeolite with a hierarchical porous structure and a high degree of crystallinity and phase purity is used for the efficient drying and purification of natural and associated gases from H₂S. The possibility of using KZhV, MP KAKh, KCh-2, and KR-2 kaolins produced in Russia as temporary binder materials during its production is studied. It is found that KZhV and MP KAKh kaolins do not require additional treatment to prepare such an adsorbent. KCh-2 and KR-2 kaolins require additional dispersion.

The effect of the content of metallic (Co–Al₂O₃/SiO₂ catalyst) and acidic components (ZSM-5 zeolite in H-form) on the properties of a bifunctional catalyst for the integrated synthesis of low-pour-point diesel fuel by the Fischer–Tropsch method has been studied. The catalysts in the form of a composite mixture with a binder (boehmite) have been characterized by XRD, BET, and TPR methods. The tests are conducted in a fixed-bed flow reactor at a pressure of 2.0 MPa, a temperature of 240°C, and a gas space velocity of 1000 h^–1. The activity and selectivity of catalysts and the fractional and hydrocarbon compositions of products as a function of the ratio of components have been compared. It has been found that the synthesis productivity with respect to С₅₊ hydrocarbons and selectivity to products of the С₁₁–C₁₈ diesel fraction with a high content of isomeric products correlate with the ratio of metallic and acidic components in the catalyst composition. The catalyst recommended for use in diesel fuel production has a composition with a ratio of metallic and acidic components of 1.17.

A way of hydrodebrominating 2,3,4,5-tetrabromothiophene (1) to 3,4-dibromothiophene (2) on a 5% Pd/Sibunit catalyst is proposed. The effect of solvent, alkaline agent, temperature, and concentration of 1 on the yield of 2 is studied. The optimum conditions are catalyst : substrate mass ratio, 1:10; temperature, 80°С; H₂ pressure, 0.7 MPa; solvent, dimethylformamide; alkaline agent, triethylamine in amounts of 2.2 mol per 1 mol of substrate 1. The yield of 2 is 97.5% in this case. The catalyst can be reused in at least 15 cycles with high yields of 2. The new approach appears to be highly productive with little waste, compared to the conventional chemical reduction of 1 with zinc in CH₃COOH.

This study concerns the effect of water-soluble polymers with different structures on the sorption properties of unregenerable lime-based sorbents of carbon dioxide. It is shown that introducing water-soluble polymers into the composition of sorbents can either prolong or shorten the periods of their protective effect. To explain these findings, the porous structure of sorbents is studied, the transport of carbon dioxide is modeled using molecular dynamics, and coefficients of the diffusion of СО₂ in water–polymer solutions are calculated. Modelling results correlate with data from sorption experiments: a stronger dynamic sorption capacity is obtained for a sorbent when a water–polymer medium with a greater coefficient of СО₂ diffusion is added. These results can be used to optimize systems for separating carbon dioxide from gaseous mixtures and intensify mass transfer in systems for the photo- and electrocatalytic conversion of СО₂ into useful products.

In this paper, the development of catalytic technologies used aboard a vehicle for purifying exhaust gases is estimated and forecasted. According to forecasts, in the next decade, the total production of vehicles will exceed 1 billion units and 75% of them will be equipped with internal combustion engines, which should necessarily be accompanied by an exhaust gas purification system. The development of catalytic technologies for purifying vehicle exhaust gases is mutually stimulated by the tightening of environmental standards and improving the internal combustion engines. For example, to date, the European standards have gone from Euro 1 to Euro 6d. The introduction of Euro 7 standards in Europe and the introduction of their counterparts in a number of countries by 2025 is planned. In addition, this paper discusses the concepts of systems that purify the exhaust gases of gasoline and diesel engines to meet the Euro 7 standards.

The widespread use of aluminum oxides to synthesize heterogeneous catalysts in petroleum chemistry and oil refining makes it necessary to determine the factors that influence the efficiency of catalytic systems. However, there have been no studies on the effect of amorphous aluminum oxide in aluminum oxide catalysts on the characteristics of a catalytic reaction. The amount of amorphous aluminum hydroxides and oxides is generally not certified, but they can considerably worsen the performance of a catalyst. Amorphous aluminum oxide samples obtained from two different precursors are studied in this work via X-ray phase analysis, low-temperature nitrogen adsorption, electron microscopy, and thermally programmed desorption of ammonia. The catalytic properties of the samples are studied in the vapor phase dehydration of 1-phenylethanol to styrene. It is shown for the first time that the transformation of amorphous aluminum oxide during the catalytic reaction lowers the conversion of alcohol from 84 (for a fresh catalyst) to 64% (for a regenerated sample). The crystallization of amorphous aluminum oxide through high temperature treatment contributes to an increase in catalytic indicators. However, they do not reach the required values because of a strong drop in the textural characteristics and acidic properties of an aluminum oxide surface.

A study is performed to establish the main factors that allow regulation of the activity and selectivity of the synthesis of solketal from glycerol and acetone, and the acidic and catalytic properties of mordenite zeolites (MOR, SiO₂ : Al₂O₃ = 29.2) and faujasite (FAU, SiO₂ : Al₂O₃ = 14.9; 97 and 810). The reaction is studied in a methanol solution at an acetone : glycerol molar ratio of 2.5 and a temperature of 25–50°C. Using zeolites, the main product is solketal with a selectivity of 88.1–94.7%. It is shown that the main factors determining the conversion of glycerol and the yield of solketal are the accessibility of the reagents to active sites, the number and strength of acid sites, and their resistance to the toxic action of water molecules that form during the reaction.

Results of studying the Pd/C and Pd/O powder catalysts synthesized by the deposition of 0.5 and 1.0 wt % Pd on carbon materials (Sibunit 159k, thermal carbon black T-900, Vulcan XC-72R) and oxide supports (Ox: γ-Al₂O₃, Cr₂O₃, Ga₂O₃, TiO₂, Ta₂O₅, and V₂O₅, diatomaceous earth FW-70) and their catalytic properties in the partial hydrogenation of sunflower oil were described. Using a Parr fixed-bed reactor, comparative tests of the catalysts in the kinetic mode conducted to determine their activity (SCA, V₀) and trans-isomerization selectivity parameters (S_tr). The effect of the average particle size of supported palladium (d_CO) on these parameters in a wide range of d_CO values was discussed.

The effect of the support nature on the hexane isomerization reaction parameters for SiO₂- and Al₂O₃-supported sulfated zirconia catalysts with different textural characteristics has been studied. It has been shown that a higher hexane conversion is achieved in the presence of sulfated zirconia catalysts supported on aluminas. Using IR spectroscopy of adsorbed CO, it has been found that, in the Al₂O₃-supported catalysts, the concentration of Brønsted acid sites (BAS) characterized by adsorbed CO with an absorption band at 2170 cm^–1 and strong Lewis acid sites (LAS) characterized by adsorbed CO with absorption bands at 2210 and 2224 cm^–1 is higher than that in the SiO₂-supported catalysts. In the Al₂O₃-supported catalysts with different textural characteristics, an increase in the contribution of LAS to the total acidity leads to a significant increase in the high-octane 2,2-dimethylbutane yield and the hexane isomerization depth.