Catalysis in Industry最新文献

The results of testing the technology of preparing a bifunctional cobalt catalyst used to synthesize hydrocarbons from CO and H₂, obtained by extruding a mixture of Co-Al₂O₃/SiO₂ catalyst and HZSM-5 zeolite powders with a binder (boehmite) under industrial conditions (two batches of 50 kg each) are presented. The catalyst technology is tested on equipment at the Ishimbay Specialized Chemical Catalyst Plant (Russia). The resulting samples of industrial catalyst are studied via XRF, H₂-TPR, and DTG, and tested in the synthesis of hydrocarbons from CO and H₂ at 250°C, a pressure of 2.0 MPa, and a gas hourly space velocity of 1000 h⁻¹. It is shown that the bifunctional cobalt catalyst for producing low pour-point diesel fuel under industrial conditions allows properties of the catalyst obtained under laboratory conditions to be reproduced. The technology for obtaining the catalyst can be recommended for the production of industrial batches. It is found that changing the conditions of the catalyst’s heat treatment and the presence/absence of a peptizer and pore former do not appreciably reduce the productivity of C₅₊ hydrocarbons. The amount of the diesel fraction in C₅₊ products obtained on industrial catalyst samples remains at the same level as on the laboratory catalyst sample. At the same time, the low-temperature properties of diesel fuel obtained on all catalyst samples have similar values. The best low-temperature properties of diesel fuel are obtained on an industrial sample synthesized without a peptizer and a pore-forming component. The cloud point and the point of liquid loss are −16 and −24, respectively.

The review discusses the latest advances in the study of heterogeneous metal-containing catalysts for the production of an environmentally friendly energy carrier—hydrogen—by the dehydrogenation of formic acid (FA), which is an available and low-toxic substance. Although the activity of homogeneous catalysts in the FA dehydrogenation reaction is higher than that of heterogeneous catalysts, the use of the latter makes it possible to simplify the technology and improve the environmental safety of hydrogen production from FA. An increase in the efficiency of heterogeneous FA dehydrogenation catalysts based on noble metals (Pd, Au, Ag) is achieved by developing novel methods for synthesizing monometallic, bimetallic, and trimetallic nanoparticles on various supports. The review compares the efficiency of various heterogeneous nanocatalysts in the FA dehydrogenation reaction and discusses various factors (metal nature, nanoperticle size and composition, support nature) that affect the activity and hydrogen selectivity of the catalysts. A significant increase in activity in the FA dehydrogenation reaction is achieved by intensifying the interaction of metal nanoparticles with the surface of a chemically modified support, which contributes to a decrease in the size of nanoparticles, an increase in the uniformity of their distribution on the support, and a change in the electronic state of the metal. Advances in the development of industrial heterogeneous catalysts for the production of pure hydrogen from FA will provide a significant contribution to the development of hydrogen power engineering.

The authors study the effect of the content of zeolite ZSM-22 (15–70 wt %) in a support on the physicochemical properties of Pt/ZSM-22–Al₂O₃ catalysts. The dependence of the yield and composition of sunflower oil hydrodeoxygenation products on these catalysts on the temperature (310–340°C), pressure (3‒5 MPa), and weight hourly space velocity (WHSV) (0.8–3 h⁻¹) is determined. The possibility is shown of the full hydrodeoxygenation of sunflower oil with the formation of C₅₊ hydrocarbons containing up to 72% of iso-paraffins with yields of 75–79 wt %.

Novel WO₃–ZrO₂ (WZ) catalysts with palladium as an active metal on porous alumina supports of various phase compositions have been synthesized. Aluminas from Sasol molded in the form of extrudates (E) and spherical aluminas (S), in which the phase composition is presented by θ-Al₂O₃, δ-Al₂O₃, and α-Al₂O₃ alumina, have been used as supports. It has been shown that the phase composition of the support has a significant effect on the activity of supported Pd/WZ catalysts based on it. Upon transition from a set of θ- and δ-Al₂O₃ phases to the θ- and α-Al₂O₃ phase composition has led to an increase in the activity of the catalysts, as evidenced by a shift of 10–30°C in the temperature dependences of the heptane conversion to lower temperatures. The appearance of the α-Al₂O₃ phase is accompanied by a decrease in the specific surface area of the catalysts, which leads to an increase in the density of acid sites and, as a consequence, a change in activity. The Pd/WZ catalysts supported on S aluminas are characterized by a higher acidity (3.7–6.3 μmol/m²) as compared to the samples supported on E aluminas (2.8–3.6 µmol/m²). The high acidity of the Pd/WZ/S catalysts intensifies the heptane cracking side reactions to form gaseous C₁–C₄ hydrocarbons. In turn, the moderate acidity of the Pd/WZ/E catalysts contributes to a higher selectivity to heptane isomers (89.2–89.3% at a heptane conversion of 81.5–83.2%) as compared to the catalysts supported on S supports (isomerization selectivity of 84.9–85.6% at a heptane conversion of 80.4–81.4%).

In this work, sorbents based on magnesium oxide MgO modified with NaNO₃ taken in a concentration of 5–50 mol % have been synthesized and studied by various methods. It has been shown that the optimum synthesis method is impregnation of the MgO precursor. The optimum concentration of NaNO₃ as a modifier is 10 mol %; this concentration provides a sorption capacity of 6.5 mmol CO₂/g_sorb within 1 h of sorption at 320°C and a CO₂ content of 50 vol %. The sorption capacity achieved in 10 consecutive sorption–desorption cycles for 10 mol % NaNO₃ is 4.5–5.5 mmol CO₂/g_sorb within 30 min of sorption at 50 vol % CO₂ and temperatures of 300 and 350°C for the sorption and desorption stages, respectively. It has been found that an increase in the total sorption pressure to 10 atm makes it possible to decrease the sorption temperature to 220–260°C, and the achieved sorption capacity is 4.0 mmol CO₂/g_sorb at 25 vol % CO₂, which is almost 2 times higher than the sorption capacity value at 1 atm. It has been shown that treatment with steam and hydrogen does not lead to a significant change in the sorption properties and phase composition of MgO modified with NaNO₃.

It has been shown that solketal can be synthesized from glycerol and acetone irradiation in the presence of montmorillonite (MM) modified with an aqueous solution of 0.25 mol/L of HCl (0.25M HCl/MM). The reaction has been studied in a methanol solution at an acetone/glycerol molar ratio of 2.45–7.53, a catalyst concentration of 1.2–2.8 wt % (based on glycerol weight), and 30–56°C. It has been shown that solketal is the major product with a selectivity of 96.1–99.2%. The maximum solketal yield of 91.3% with a 98.6% selectivity is obtained within 15 min of reaction at an acetone/glycerol molar ratio of 7.53, a catalyst loading of 2.3 wt % (based on glycerol weight), and 56°C. The catalytic properties of 0.25M HCl/MM in the reaction under microwave and thermal heating conditions have been compared. It has been shown that the solketal yield in the reaction under MW irradiation is 2 times higher than that in the process with thermal heating.

The authors study the effect of the type of zeolite (SAPO-11, ZSM-22, ZSM-23, and ZSM-12) in a support (ratio zeolite : Al₂О₃ = 30 : 70) on the physicochemical properties of Pt/Al₂O₃-zeolite catalysts and the composition of products from the hydrodeoxygenation of sunflower oil on them. The possibility of the complete hydrodeoxygenation of sunflower oil at temperatures of 320–350°C, a pressure of 4 MPa, and a weight hourly space velocity (WHSV) of 1 h⁻¹ is shown with 75–82% yields of liquid products. The fraction of iso-alkanes and the yield of direct hydrodeoxygenation products grow along with the concentration of Brønsted acid sites in a catalyst in the order 1%Pt/Al₂O₃-ZSM-22 < 1%Pt/Al₂O₃-ZSM-12 < 1%Pt/Al₂O₃-ZSM-23 < 1%Pt/Al₂O₃-SAPO-11.

In this paper, the physicochemical and catalytic properties of SAPO-11 and SAPO-41 molecular sieves granulated with a binder material and promoted with 0.5 wt % Pt have been studied in the isodewaxing of a hydrotreated diesel fraction. It has been shown that the introduction of ~30 wt % of boehmite, which transforms into alumina under calcination, into the granules leads to a decrease in the micropore volume by 50–70% and an increase in the external specific surface area of the material by 6–12% as compared to the highly dispersed samples of the above molecular sieves. It has been found that, at 340°C, 3 MPa, 2.0 h⁻¹, and H₂/feedstock = 800 m³/m³, both samples of bifunctional catalysts provide the production of diesel fuel with a pour point of –42°C and a yield of ~91–92 wt %.

The authors study the effect of the tungsten oxide in the supports of 0.5% Pt/WO_x-Al₂O₃ catalysts on their acidity, deposited platinum dispersity, and catalytic properties in the hydrodeoxygenation of sunflower oil. It is shown that the of Brønsted acid sites on its surface grows, and the dispersity of deposited platinum in the ready catalyst is reduced when the content of the modifier is increased. The studied samples ensure complete sunflower oil conversion in a hydrogen atmosphere at a liquid weight hourly space velocity (WHSV) of 1 h⁻¹, a temperature of 380°C, and a total pressure of 4 MPa the composition of the support. A nearly stoichiometric yield of C₅₊ products at a level of 82–86 wt % is attained. The acidic properties of the 0.5% Pt/WO_x-Al₂O₃ system determine the possibility for synthesizing the components of diesels with high contents of iso-alkanes as a result of sunflower oil hydrodeoxygenation. Using a catalyst with a nominal tungsten content of 15 wt % WO₃ brings the content of iso-paraffins up to 74% with complete conversion of the initial feedstock for no less than 24 h.

An essay on the scientific activities of the Russian organic chemist and chemical engineer Sergei Alekseevich Fokin (1865–1917) is presented. The name of the scientist is not widely known although he has made the main contribution to the development of oleochemistry and creation of the industrial process of fat hydrogenation in Russia, and his merits have been appreciated by domestic and foreign researchers.