Catalysis in Industry最新文献

A way of producing high-octane gasoline from associated petroleum gas (APG) by combining APG aromatization with Fischer–Tropsch (FT) synthesis is proposed. APG aromatization is studied experimentally in a flow setup at a pressure of 0.1 MPa and temperatures of 450–600°C on ZnO/ZSM-5/Al₂O₃ catalyst. It is shown that the conversion of С₃₊ hydrocarbons is greatest in the 550–600°C range of temperatures to reach 22.7–27.8%, while the yield of aromatics is 8.8–10.9%. FT synthesis is studied on hybrid Co-Al₂O₃/SiO₂/ZSM-5/Al₂O₃ catalyst at a temperature of 250°C, a pressure of 1.0 MPa, and GHSV = 1000 h⁻¹. One liter of an experimental synthetic gasoline fraction is produced on a pilot setup to analyze its principal physicochemical properties and possible qualities of utilization. Calculations show that blending the gasoline fraction of FT synthesis with products of APG aromatization allows the octane number to be raised from 78.5 to 92.8 while the density grows from 710 to 778 kg/m³. The proposed engineering solutions can be used for converting APG into high-octane synthetic gasoline on modular Gas-to-Liquids (GTL) units.

Studies on the development of a homogeneous process for the low-temperature oxidation of carbon monoxide in the presence of a platinum group metal + vanadium-containing heteropoly acid (HPA) catalyst system have been described. Optimum reaction conditions to provide the maximum rate of CO oxidation to CO₂ have been determined, features of reaction kinetics have been found, and a mechanism has been proposed. It has been shown that systems based on a Pd^II aqua complex exhibit high activity and productivity; however, they have low stability and are used on stream only at a pH below 1.5. The stability of the catalyst can be increased by the simultaneous introduction of σ- and π-donor ligands into the system; however, the use of a Pt^IV complex in the presence of catalytic amounts of palladium salt in a ratio of 100/1 is more effective. Switching from HPA solutions with a low vanadium atom content (H₇PMo₈V₄O₄₀) to high-vanadium solutions of modified compositions (H₁₀P₃Mo₁₈V₇O₈₄) provides an increase in the activity and productivity of the system, while the shapes of the kinetic curves and the general laws governing CO oxidation are preserved. The combined homogeneous Pt^IV + Pd^II + H₁₀P₃Mo₁₈V₇O₈₄ catalyst remains stable during multicycle use without loss of activity, does not have an induction period in on-stream performance, and can be used at a pH of 0.7−2.5, which simplifies the hardware support of the process.

The use of renewable resources to produce marketable chemicals is an alternative to conventional processes based on petrochemical synthesis. The main approaches to producing organic acids from glucose and cellulose as components of renewable biomass are discussed. Biotechnological approaches to producing glycolic, glutaric, mesaconic, muconic, isobutyric, lactic, 3-hydroxypropionic, succinic, itaconic, and adipic acids are compared with catalytic approaches. It is shown that the biotechnological production of succinic and lactic acids has been implemented on an industrial scale, and a number of other organic acids can be synthesized by biotechnological methods provided that the productivity of their producers is increased.

The catalytic alkylation of benzene with a multicomponent mixture consisting of products from the thermal pyrolysis of higher paraffins and containing a wide fraction of olefins of various structures is studied. Methanesulfonic acid, which has weak corrosion properties compared to industrial catalytic systems, is used as a homogeneous catalyst. Using two-dimensional gas chromatography to analyze the composition of both the initial multicomponent raw material and the products of alkylation allow the selection of the initial process conditions and the correct calculation of such parameters for assessing efficiency as selectivity and conversion. Depending on the raw material, the selectivity to linear alkylbenzene (LAB) is ranged within 82.4–88.3%; for 2-LABs, it is 29.2–41.3% at ~90% olefin conversion.

Results of studying Pt and Pd γ-alumina supported catalysts in the hydrogen oxidation reaction for use in helium concentrate (HC) purification processes were described. The properties of the synthesized catalysts were compared with the properties of a foreign reference catalyst. The “ignition” and deactivation of the catalysts at room temperature in a laboratory reactor using a mixture simulating an HC were studied while simulating conditions at the inlet of an industrial adiabatic reactor; the properties of the catalysts were studied at temperatures of 200, 250, and 300°C under conditions simulating the occurrence of the reaction in the middle zone and at the outlet from an industrial reactor. The secondary hydrogen formation process at temperatures of 250–300°C was studied and attributed to the steam reforming of methane and ethane present in the model mixture simulating HC. The results of the study can be used to develop domestic catalysts for the purification of helium extracted from natural gas.

The activation of highly efficient cobalt catalysts for Fischer–Tropsch synthesis has been studied taking into account the transformation of the resulting structures and the presence of a heat-conducting percolation network of metallic aluminum. The effect of the temperature, process duration, reducing gas composition, and reducing gas hourly space velocity on the degree of reduction and the specific surface area of the active catalyst component has been studied. The above characteristics have been determined by low- and high-temperature oxygen titration on a chromatographic sorption unit and by temperature-programmed reduction. The tests have shown the possibility of decreasing the temperature and the hydrogen concentration in the gas to achieve the required parameters during reduction to synthesize a highly efficient catalyst system. The parameters of this system in Fischer–Tropsch synthesis (CO conversion, liquid hydrocarbon productivity) are comparable to or better than for a catalyst reduced under standard conditions.

The synthesis of C₅–C₁₈ alkenes in the presence of a zeolite-containing Co–Al₂O₃/SiO₂/ZSM-5/Al₂O₃ catalyst in flow and recycle flow operation modes at a temperature of 250°C, a pressure of 2.0 MPa, a gas hourly space velocity (GHSV) of 1000 h⁻¹, an H₂/CO ratio of 1.70 in the feed gas, and recycle ratios of 4, 8, and 16 has been studied. It has been found that the process parameters (selectivity and productivity with respect to C₅₊ hydrocarbons) pass through a maximum at a recycle ratio of 8. The use of gas recycling, unlike the flow synthesis mode, makes it possible to control the product composition. An increase in the recycle ratio in a range of 4–16 leads to an increase in the content of synthesized C₅–C₂₀ alkenes from 53.9 to 65.7 wt %. The use of a zeolite-containing catalyst, compared with a Co–Al₂O₃/SiO₂ catalyst, intensifies the formation of C₈–C₁₂ alkenes by 3.3 times: their content increases from 13.5 to 44.2 wt % at identical recycle ratios, pressures, and an H₂/CO ratio of 1.70 in the feed gas. It has been found that with an increase in the recycle ratio, the deactivation rate of the zeolite-containing catalyst decreases; this fact can be attributed to a decrease in the partial pressure of water in the reaction volume.

Aluminum oxides are the most common component used in the design of heterogeneous catalysts of oil refining and petrochemistry. The optimum characteristics of aluminum oxide supports and catalysts (e.g., specific surface area, pore size, and phase and impurity compositions) correspond to the type of hydrocarbon feedstocks and technological process. In light of the trend toward import substitution, it is becoming ever more relevant to study the market for domestic producers of aluminum hydroxide feedstocks used in the synthesis of aluminum oxides. In this work, domestic commercial samples of aluminum hydroxides are investigated via X-ray diffraction, simultaneous thermogravimetry/differential scanning calorimetry, low-temperature nitrogen adsorption, and elemental analysis. It is established that the objects of study are most often inhomogeneous in phase and contain iron, silicon, and calcium impurities. The effect of degree of crystallinity and the sizes of coherent scattering regions in aluminum hydroxides with a predominantly boehmite structure (and in some cases, aluminum hydroxides containing bayerite) on the textural characteristics of synthesized aluminum oxides is demonstrated.

The kinetics of n-butane dehydrogenation to butadiene is studied with temperature (T) variation of 550–625°C, duration of dehydrogenation stage (t) of 5–30 min, and space velocity (V) of 4400–35 200 h⁻¹ on industrial catalyst K-CrO_x/γ-Al₂O₃ at a fraction of 56–94 μm. The catalyst is stabilized before studies. The granulated catalyst in a reduction–dehydrogenation–regeneration cycle at 593°C, and then as a fraction of 56–94 μm in dehydrogenation–regeneration cycle at 650°C. The maximum selectivity toward butadiene of ~25 mol % is achieved with n-butane conversion of 26–30% (V = 35 200 h⁻¹), T = 600 °C, and t = 5 min, while the maximum yield of butadiene ~10 mol % is obtained with an increase in conversion up to ~50% (V = 8800 h^–1) under the same conditions. Raising T to 625°C and t to 30 min and lowering V to ~4400 h^–1 increases the selectivity toward by-products to ~50 mol %. It is found that the energy of activation for the rates of product formation falls in the order by-products > butylene > butadiene. A kinetic model is proposed that describes the formation of butadiene via butylene, the formation of ethane/ethylene and methane/propylene by-products during butylene hydrocracking, and secondary conversions of by-products, plus the formation of coke and its effect on catalyst activity. In the model, the inhibition of dehydrogenation reactions by components of reaction mixture is described by a mechanism in which the limiting stage is a surface reaction on two active centers. The adequacy of the kinetic model is confirmed by good agreement between the calculated and experimental results.

Mathematical modeling for the autothermal reforming of hexadecane, propane, and methane in the presence of catalyst modules of different geometric shapes has been conducted. It has been shown that a module shape that is convex toward the oncoming reaction stream can increase the maximum temperature in the frontal zone, whereas a concave shape contributes to a more uniform temperature distribution throughout the entire length of the catalyst bed. In addition, the effect of the reaction flow rate on the change in the temperature gradient has been studied; the results can subsequently be used to prevent local overheating and catalyst deactivation. The results obtained can be used as a basis for future research in the field of autothermal reforming and optimization of geometric parameters of catalysts for the conversion of hydrocarbon fuels to synthesis gas.