Heterogeneous catalytic conversion of glycerol with <Emphasis Type="Italic">n</Emphasis>-butyl alcohol

The etherification of glycerol with n-butyl alcohol at 140°C in the presence of sulfonated cation-exchange resins and zeolite catalysts in an autoclave reactor has been studied. It has been shown that styrene—divinylbenzene ion-exchange resins are effective catalysts for the production of glycerol n-butyl ethers: the glycerol conversion is about 98% with an n-butyl ether selectivity of about 88 mol % (140°C, 5 h, 5 wt % Amberlyst 36 catalyst, and 10 wt % glycerol in n-butanol). Zeolites Y and β in the H⁺ form exhibit comparable specific activity (glycerol conversion of no more than 25% under similar conditions) in combination with high selectivity for glycerol di-n-butyl ethers (up to 28%).     

Catalytic conversion of rape oil into alkane-aromatic fraction in the presence of Pd-Zn/MFI

Results on the conversion of rape oil into the alkane-aromatic fraction in the presence of a prototype of a MFI-based industrial catalyst (Si/Al = 30) promoted with 0.6 wt % Pd and 1 wt % Zn are presented. It has been shown that an increase in the process temperature from 360 to 420°C leads to a significant increase in the yield of aromatic compounds, and an increase in the substrate space velocity leads to a three-fold increase in the yield of C₄–C₆ alkanes of primarily the iso-branched structure. The genesis of active Pd and Zn clusters is discussed on the basis of X-ray data.     

Hydrogenation of aromatic hydrocarbons in the presence of dibenzothiophene over platinum-palladium catalysts based on Al-SBA-15 aluminosilicates

The hydrogenation of a 2-methylnaphthalene solution in n-heptane in the presence of dibenzothiophene (400 ppm in terms of sulfur) over Pt-Pd catalysts containing Al-SBA-15 mesoporous aluminosilicates has been studied. Supports for the catalysts contained 35 wt % Al-SBA-15 and 65 wt % γ-Al₂O₃. The Pt and Pd contents of the catalysts was 0.25 and 1.0 wt %, respectively. Experiments with the model feedstock were conducted in an autoclave at 240–260°C, an initial hydrogen pressure of 30 atm, and a substrate/metal weight ratio of 30. It has been found that a catalyst based on Al-SBA-15 with Si/Al = 5 exhibits the highest activity under poisoning with 400 ppm sulfur. Thus, the conversion of 2-methylnaphthalene at 260°C after 3 h was 85% with the selectivity for methyltetralins of 97%. The dearomatization of a hydrotreated diesel fraction with 45 ppm sulfur at 260°C at a pressure of 30 atm and a space velocity of 2.4 h^?1 has made it possible to decrease the total aromatic content, in particular reduce the concentration of polycyclic aromatic compounds to a level of less than 1 wt %.     

Aluminosilicate-supported cobalt catalysts in the Fischer-Tropsch synthesis

Cobalt catalysts supported on SIRAL aluminosilicates have been prepared and tested in hydrocarbon synthesis from CO and H₂. It has been shown that the state of the cobalt metal on the catalyst surface is determined by both the cobalt content and the support nature, in particular, by the phase composition on its surface. The reaction rate on cobalt crystallites 3–6 nm in size is lower than that on 8–13-nm crystallites. It has been found that promotion with cerium oxide considerably increases the catalyst activity, although the selectivity for C⁵⁺ hydrocarbons slightly decreases.     

Hydrogenation of aromatic compounds in the presence of dibenzothiophene over bimetallic catalysts containing mesoporous aluminosilicates

The hydrogenation of a mixture of naphthalene, tetralin, and toluene (a solution in n-heptane) in the presence of dibenzothiophene (150 and 400 ppm on a sulfur basis) over Pt-Pd catalysts containing Al-HMS mesoporous aluminosilicates has been studied. The catalyst supports contained 35 wt % Al-HMS and 65 wt % γ-Al₂O₃. The Pt and Pd loadings in the catalysts were 0.2 and 0.8 wt %, respectively. The process was carried out at 200–240°C, a pressure of 30 atm, and a weight hourly space velocity of 1.7 h^?1. It has been found that the catalyst based on Al-HMS with Si/Al = 10 exhibits the highest activity. Thus, in the hydrogenation of a model mixture containing 150 and 400 ppm of sulfur, the conversion of toluene at 240°C was 22.2 and 10.9 wt %, respectively. In the presence of this catalyst, the concentration of aromatic hydrocarbons in the hydrotreated diesel fraction decreased from 28.4 to 6.8 wt %, and the sulfur content decreased from 45 to 5 ppm.     

Direct conversion of ethanol and fusel oils to alkane–aromatic hydrocarbons in the presence of a pilot Pd–Zn/TsVM catalyst

The conversion of ethanol and fusel oils to a С₃–С₁₂ alkane–aromatic fraction with high activity and selectivity in the presence of the Pd–Zn/TsVM pilot catalyst has been demonstrated. It has been shown that the ethanol conversion to alkanes and aromatic hydrocarbons in the presence of this catalyst proceeds by various routes to give ethylene and diethyl ether as intermediate products providing a 90–95% yield on the converted ethanol carbon basis for the target С₃–С₁₂ fraction containing up to 40% of branched alkanes.     

Oxidative conversion of ethane involving lattice oxygen of molybdenum systems modified with aluminum,gallium, or yttrium oxide

Oxidative conversion of ethane on the molybdenum oxide MoO₃ mixed with 0–95% Al₂O₃, Ga₂O₃, or Y₂O₃ has been studied in the pulse mode at 600°C. It has been revealed that the components of these systems undergo strong interaction, which leads to enhanced ethane conversion and an increased selectivity for ethylene with a decrease in the MoO₃ content. The 5%MoO₃–95%Al₂O₃ system has proved the most effective in the oxidative dehydrogenation of ethane, with the selectivity for ethylene reaching 90% at an ethane conversion of 30 wt %.     

Enhancement of the Fischer–Tropsch process for producing long-chain hydrocarbons on a cobalt–alumina–silica gel catalyst

The effects of the H₂/CO ratio, pressure, temperature, and the reaction-gas recycle ratio on the selectivity for hydrocarbons (HCs), including long-chain C₃₅₊ HCs, in the Fischer–Tropsch synthesis over a supported industrial cobalt–silica gel catalyst have been studied. The synthesis parameters have been as follows: a pressure of 2.0 or 6.0 MPa, an H₂/CO ratio of 1–5, a recycle ratio of 2–6, a temperature of 150–240°C, and a gas hourly space velocity of 1000 h^?1. It has been shown that gas recycling provides thermal stability in the catalyst bed, significantly increases the yield of C₃₅₊ HCs, and makes it possible to control the group and fractional composition of the synthesis products.     

Conversion of gas condensate on zinc-containing Ultrasil type high-silica zeolite

The catalytic properties of zinc-modified, Ultrasil type high-silica zeolite in thermal catalytic conversion of gas condensate to produce olefins and aromatic hydrocarbons have been studied. Methods for controlling the product composition by varying zinc concentration and by steaming the modified zeolite have been proposed. It has been shown that the treatment of Zn–H-Ultrasil leads to the formation of Brønsted type weakly acidic OH group having an absorption band at 3670 cm^–1, which reduces the contribution of hydrogen redistribution reactions and enhances selectivity for lower C₂–C₄ olefins.     

Conversions of mixtures of propane and benzene on Pt,Re/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> + H-zeolite systems

The conversion of C₆H₆: C₃H₈C mixtures on mixed catalysts composed of the metal catalysts Pt,ReOx/Al₂O₃ and zeolites Y, M, and ZSM-5 in the H form was studied. The products of benzene dehydroalkylation by propane and propane dehydrogenation products are formed at 180–350°C. It has been shown that propane is activated on the metal catalysts and C₆H₆ interacts with the zeolites yielding the C₆H₇ ⁺ intermediate, which acts as an agent of proton transfer from a zeolite to a metal catalyst, and another intermediate C₉H₁₃⁺ (I). Cumene, alkylbenzenes, and propene are formed as a result of the conversion of I. A comparison of the results of the conversion of these mixtures on the composite catalysts with different zeolites shows that the formation of cumene and propene is thermally controlled and the formation of the other products is kinetically controlled. It has been concluded that the coupling of the redox properties of the metal catalysts with the acid-base properties of the zeolite catalysts facilitates the low-temperature transformations of the mixtures.     

Joint aromatization of butane and hexane on alumina-platinum catalysts

It has been found that the joint aromatization of C₄ and C₆ alkanes proceeds during the conversion of a butane and hexane mixture on alumina-platinum catalysts. It has been shown that a necessary condition for realization of the joint aromatization is the presence of highly dispersed platinum as ionic species (Pt^σ) and “hard” Lewis acid sites (L_z) of a catalyst. It has been determined that an optimum L_z/Pt^σ ratio for joint conversion reaction of light alkanes is from 1 to 2.     

The catalytic properties of tungstated zirconia in <Emphasis Type="Italic">n</Emphasis>-heptane isomerization

The catalytic properties of zirconia modified with different amounts of tungstate anions in the hydroisomerization of n-heptane and its mixtures with benzene or toluene have been studied. It has been found that at a low temperature of 170°C, the yield of isoheptanes reaches 62.8% with a fairly high selectivity of 87.6% on the Pt/WO₄²⁻/ZrO₂ catalyst prepared by impregnation to contain 17.6 mol % tungstate anions. Under the same conditions, the yield of isoheptanes on a sulfated Pt/SO₄²⁻/ZrO₂ catalyst is as low as 14.0% with a selectivity of 20.3%. The hydroisomerization process effectively occurs on the tungstated catalyst in the presence of benzene or toluene.     

Effects of Impregnation Solvents on Catalytic Performance of Co-Ru-ZrO2/γ-Al2O3 Catalyst for Fischer-Tropsch Synthesis

Abstract

Used ZrO₂ modified γ-Al₂O₃ as support, Co-Ru catalysts were prepared by incipient impregnation method. The effects of impregnation solvents on the performances of catalysts were examined. The catalyst was prepared with ethanol solution and high Co dispersion was obtained, exhibiting highest activity of CO hydrogenation, very low methane selectivity, and high heavy hydrocarbon C₅ ⁺ selectivity. The catalysts were prepared with aqueous solution and methanol solution, and the reaction behaviors were similar. The solvent isopropanol caused the lowest catalytic activity and highest methane selectivity. Increasing the reaction temperature enhanced the CO hydrogenation rate, and the CO conversion slightly increased the CO₂ selectivity and favored the formation methane and light hydrocarbons, while the chain growth probability decreased. For the catalyst prepared with ethanol, the CO conversion, the CH₄ selectivity, and the C₅ ⁺ selectivity were 94.16%, 5.65%, and 88.2%, respectively, and the chain growth probability was 0.87 at 493 K, 1.5 MPa, 800 h^?1, and n(H₂):n(CO) = 2.0 in feed.     

Effect of Vanadium Introduction on the Activity of NiMo/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts in the Hydrotreating of Diesel Fractions

The influence of the introduction of V₂O₅ into NiMo/Al₂O₃ catalysts on their activity in hydrodesulfurization (HDS) and hydrogenation reactions of the components of petroleum fractions has been studied. The activity of the synthesized catalysts has been determined in the straight-run diesel and light coker gas oil hydrotreating processes in a flow-through unit under hydrogen pressure. The most active catalyst for HDS and hydrogenation of polycyclic aromatic hydrocarbons has been synthesized using VMo₁₂ heteropoly compounds: the activity increases by 6–10 and 11–13 wt % in HDS and PAH hydrogenation, respectively, at different temperatures. It has been shown that the activity of the regenerated catalyst further impregnated with the vanadium compound in HDS and PAH hydrogenation increases by 2–5 rel. %, as compared to the regenerated catalyst.     

A study of Pt/WO<Subscript>4</Subscript><Superscript>2−</Superscript>/ZrO<Subscript>2</Subscript> catalyst deactivation in the hydroisomerization of heptane and a heptane–benzene mixture

The dynamics of the catalytic properties of a Pt/WO₄ ^2?/ZrO₂ catalyst (17 mol % WO₄ ^2?) in the hydroisomerization of heptane and a heptane–benzene mixture as a function of reaction time and temperature has been studied. It has been found that the heptane conversion decreases in the initial reaction period (within 2 h) and the isohexane selectivity symmetrically increases at 170–280°C, with the benzene hydrogenating activity decreasing at 250°C and higher temperatures. The observed changes in catalytic properties are attributed to the partial deactivation of both the acid and hydrogenation components of the catalyst. X-ray photoelectron spectroscopy has revealed the formation of carbon deposits on the catalyst surface; the structure of the deposits is determined by the reaction medium composition. The composition of the products formed on the catalyst after heptane hydroisomerization is mostly represented by aliphatic polymers of the “poly-С_хН_y” type, which are capable of blocking the active sites that catalyze the cracking reactions. The addition of benzene to heptane has led to the formation of graphite-like carbon deposits; this feature is apparently responsible for a decrease in both the acidity and hydrogenation activity of the catalyst. The phase state and textural characteristics of the catalysts are stable under the isomerization reaction conditions.     

Effect of methanol, ethanol, and formaldehyde addition on the steam conversion of methane in the presence of nickel catalysts of various porous structure

The effect of CH₂O, CH₃OH, and C₂H₅OH on the methane conversion and the CO, CO₂, and coke yield in the methane steam conversion on commercial nickel catalysts for steam reforming C 11-9-09 (12.8 wt % Ni/α-Al₂O₃) and hydrogenation (54.0 wt % Ni/kieselguhr) was studied at a temperature of 750°C and an H₂O:CH₄ ratio of 1.5–2.0. The action of these compounds was studied both individually and for their joint presence in the methane-steam mixture. Their effect on the reaction depends on the pore structure of the catalyst. Using the catalyst C 11-9-09 as an example, it was found that the introduction of formaldehyde into steam suppressed the methane conversion into C_s and high-boiling-point carbon compounds and gave the desired products with a yield close to the equilibrium value. When all three additives were present in the steam, ethanol was responsible for the formation of C_s.     

Dimethyl ether in the processing of associated petroleum gas to a mixture of synthetic hydrocarbons

The development of single-stage synthesis of dimethyl ether (DME) from synthesis gas makes it possible to obtain hydrocarbons directly from DME. The effect of the nature and concentration of components of the vapor–gas mixture that arrives at the stage of DME conversion to liquid hydrocarbons on activity and selectivity of a zinc–palladium zeolite catalyst has been examined. It has been found that and increase in DME concentration to more than 20 vol % in the reaction stream leads to lowering both DME conversion and gasoline selectivity and increasing the yield of byproducts. The presence of components such as H₂, CO, H₂O in the vapor–gas mixture ensures high stability of the catalytic system. Switching from the flow-through to the recycle operation mode increases the catalyst selectivity for gasoline, decreases the formation of durene, and reduces catalyst coking.     

Hydroisomerization of n-dodecane on bifunctional catalysts containing mesoporous aluminosilicates

The hydroisomerization of n-dodecane on bifunctional catalysts with mesostructured aluminosilicates as an active component has been studied. Aluminosilicates with an Si/Al atomic ratio of 5 to 48 have been prepared using hexadecylamine as a template. Catalyst supports contained 35 wt % mesoporous material and 65 wt % ??-Al₂O₃. The platinum loading of the catalysts was 0.5% of the support mass. It has been found that the catalysts based on mesoporous aluminosilicates with an Si/Al ratio of 10 and 22 exhibit the highest selectivity. In their presence, the conversion reaches 43?C46 wt % with the selectivity for iso-C₁₂H₂₆ of more than 90%.     

Specifics of the stearic acid deoxygenation reaction on a copper catalyst

Decarbonylation of stearic acid, which is industrially manufactured from oils and fats, to higher olefins on a Cu/γ-Al₂O₃ catalyst has been first studied. It has been shown that the selectivity for heptadecenes is 67% and that for CO is close to 100% at 350°C. The activity of this catalyst in the further hydrogenation of resulting heptadecenes to heptadecane is well below that of a palladium catalyst. The conversion is slightly varied when hydrogen pressure increases from 4 to 14 bar; however, the selectivity for olefins increases and the selectivity for paraffins remains low. According to quantum-chemical simulation data, hydrides form on the surface of copper clusters in the presence of hydrogen. It is presumably these compounds that inhibit the side oligomerization reaction of olefins. The hydrogen-to-water concentration ratio does not affect the selectivity for CO and CO₂; the only effect of the presence of water is a decrease in the stearic acid conversion rate.     

Optimization of reaction condition on the product selectivity of Fischer–Tropsch synthesis over a Co–SiO2/SiC catalyst using a fixed bed reactor

The Fischer–Tropsch (FT) synthesis is an important method for producing valuable key raw materials such as heavy and light hydrocarbons in various industries. The effects of process conditions (temperature of 503–543 K, pressure of 10–25 bar, and gas hourly space velocity (GHSV) of 1,800–3,600 Nml g _cat^?1 h^?1) on the FT product distribution using Co–SiO₂/SiC catalyst in a fixed bed reactor were studied by the design of experimental procedure and the Taguchi method. The optimization of the reaction conditions for the production selectivity of C₂–C₄ and heavy hydrocarbon (C₅₊) that has not been completely indicated elsewhere was investigated. The effect of operating conditions on the average carbon number distribution, dispersion, and skewness was also studied. Data analysis indicated the highest selectivity for the light hydrocarbons at a pressure of 20 atm, GHSV of 2,400 Nml g _cat^?1 h^?1, and temperature of 543 K resulting in a highest selectivity for heavier hydrocarbons (C₅₊) and the minimum amount of methane in the reaction products that is optimal at the pressure of 10 atm, GHSV of 1,800 Nml g _cat^?1 h^?1, and a temperature of 503 K. Furthermore, based on the surface plot, temperature has more significant effects than the other parameters. In addition, the obtained results indicated that the maximum average number of carbon was obtained in a pressure of 10 atm and a temperature of 503 K.