V. F. Tret’yakov

The catalytic conversion of bioethanol to hydrocarbon fuel: A review and study

The problems associated with producing hydrocarbons from bioethanol on the basis of new zeolite-containing catalysts are considered. A flexible technology is devised for converting bioethanol to engine fuel, olefins, and aromatic hydrocarbons—important products for the petrochemical industry. The economic and environmental prospects for replacing fossil fuels with alternative fuels are analyzed. A scheme for a mechanism that allows precision control over the process of bioethanol conversion is proposed. The possibility of hydrogenating a liquid fraction derived from bioethanol and containing aromatic hydrocarbons in order to produce hydrocarbon fuels of various types is studied. A sample of a reactive synthetic fuel meeting the technical requirements for synthetic hydrocarbon aviation fuel for gas-turbine engines was obtained.

Properties of surface compounds in methanol conversion on γ-Al2O3: Data of in situ IR spectroscopy

In situ IR spectroscopic studies show that a formate, an aldehyde-like complex, and bridging and linear methoxy groups exist on the alumina surface involved in methanol conversion. In the absence of methanol in the gas phase, the interaction between two bridging methoxy groups yields dimethyl ether in the gas phase. When methanol is present in the gas phase, it interacts with methoxy groups on the surface. This reaction makes the main contribution to the formation of dimethyl ether. The linear methoxy group undergoes conversion via several routes. The main route is desorption with methanol formation in the gas phase, and no more than 10% of the linear methoxy groups are converted into formate and aldehyde, which are CO2 sources in the gas phase. In the absence of methanol in the gas phase, the conversion rate of the methoxy groups is independent of the presence of water and oxygen. A scheme of the surface reactions is suggested to explain the conversion of the methoxy groups.

Spectroscopic study of the properties of surface compounds in methanol conversions on Cu/γ-Al2O3

The reactions of methanol on the (10% Cu)/γ-Al2O3 surface were studied by the spectrokinetic method (simultaneous measurements of the conversion rates of surface compounds and the product formation rates). Bridging and linear methoxy groups result from the interaction of methanol with surface hydroxyl groups. Formate and aldehyde-like complexes form by the oxidative conversion of the linear methoxy groups. Hydrogen forms via the recombination of hydrogen atoms on copper clusters, and the hydrogen atoms result from interconversions of surface compounds. The source of CO2 in the gas phase is the formate complex, and the source of CO is the aldehyde complex. In the absence of methanol in the gas phase, dimethyl ether forms by the interaction between two bridging methoxy groups. When present in the gas phase, methanol reacts with methoxy groups on the surface. The roles of oxygen and water vapor in the conversions of surface compounds are discussed.

Initiated conversion of ethanol to divinyl by the Lebedev reaction

A synergistic effect has been revealed upon hydrogen peroxide initiation of the catalytic ethanol-to-divinyl conversion process, proposed by S.V. Lebedev, on the (K2O)ZnO/γ-Al2O3 catalyst. The efficiency of the initiator has been examined, depending on the form of aluminum oxide, hydrogen peroxide concentration in the system, and the linear velocity of the feed stream. The behavior of the process characteristics has been analyzed and a kinetic model of the process has been proposed on this basis, enabling the selectivity of the initiated reaction to be controlled.

Properties of surface compounds in methanol conversion on copper-containing catalysts based on CeO2 according to in situ IR-spectroscopic data

Formate and carbonate complexes and bridging and linear methoxy groups were detected on the surfaces of CeO2 and 5.0% Cu/CeO2 under the reaction conditions of methanol conversion using IR spectroscopy. The reaction products were H2, methyl formate, CO, CO2, and H2O. The bridging and linear methoxy groups were the sources of formation of bi- and monodentate formate complexes, respectively. Methyl formate was formed as a result of the interaction of the linear methoxy group and the formate complex. The study demonstrated that the recombination of hydrogen atoms on copper clusters and the decomposition of methyl formate were the main reactions of hydrogen formation. Formate and carbonate complexes were the source of CO2 formation in the gas phase, and the decomposition of methyl formate was the source of CO. It was found that the addition of water vapor to the reaction flow considerably decreased the rate of CO formation at a constant yield of hydrogen. The effects of water vapor and oxygen on the course of surface reactions and the formation of products are discussed. To explain the mechanism of methanol conversion, a scheme of surface reactions is proposed.

Selective NO reduction by propane over commercial oxide catalysts and their mechanical mixture: I. Synergistic effect

In the reaction of NO reduction by propane in excess oxygen, the activity of a binary mixture of commercial oxide catalysts is higher than should be expected if it were proportional to the activities of separate catalyst components. This synergism reveals itself in the fact that the conversion of NO and C3H8 is higher when the catalyst is a mechanical mixture than the sum of conversions over separate catalysts, all other conditions being the same. Based on the kinetic and thermal desorption measurements, the experimental conditions are found under which the synergism is observed. A hypothetical mechanism is proposed.

Microwave enhancement of the toluene steam dealkylation reaction in the presence of Ni-Co-Cr/Al/Al2O3 catalyst

The results of examining the feasibility of enhancement of the toluene steam dealkylation reaction by microwave irradiation of the reaction medium are presented. It has been found that the most likely cause of the positive effect of microwave radiation on the reaction rate is an increase in the preexponential factor of the Arrhenius equation for the temperature dependence of the reaction rate. This effect is presumably due to an increase in the active surface area of the catalyst formed by the microwave-assisted thermal treatment.

The mechanism of selective NOx reduction by hydrocarbons in excess oxygen on oxide catalysts: VI. Spectroscopic and kinetic characteristics of surface complexes on a Ni-Cr oxide catalyst

The reaction mechanism of the selective catalytic reduction of NOx by propane in the presence of O2 on a commercial Ni-Cr oxide catalyst was studied using in situ IR spectroscopy. It was found that nitrite, nitrate, and acetate surface complexes occurred under reaction conditions. Considerable amounts of hydrogen were formed in the interaction of NO + C3H8 + O2 or C3H8 + O2 reaction mixtures with the catalyst surface. The rates of conversion of the surface complexes detected under reaction conditions were measured. The resulting values were compared to the rate of the process. It was found that, at temperatures lower than 200°C, nitrate complexes reacted with the hydrocarbon to form acetate complexes; in this case, the formation of reaction products was not observed. In the temperature region above 250°C, two reaction paths took place. One of them consisted in the interaction of acetate and nitrate complexes with the formation of reaction products. The decomposition of NO on the reduced surface occurred in the second reaction path. Nitrogen atoms underwent recombination, and oxygen atoms reoxidized the catalyst surface and reacted with the activated hydrocarbon to form CO2 and H2O in a gas phase.

Reaction paths of the formation and consumption of nitroorganic complex intermediates in the selective catalytic reduction of nitrogen oxides with propylene on zirconium dioxide according to in situ fourier transform IR spectroscopic data

Nitrate, acetate, and nitroorganic complexes were detected on the surface of ZrO2 under the reaction conditions of nitrogen oxide reduction with propylene using Fourier transform IR spectroscopy. The nitroorganic complex was formed in the reaction between acetate and nitrate complexes by the replacement of the carboxyl group in the acetate complex by the nitro group. Monodentate nitrate was the most reactive species in this process. The adsorption of various nitroorganic substances was studied. It was found that the nitroorganic complex was structurally analogous to the nitromethane molecule bound to the surface through the nitro group. The experimental data led us to a conclusion that nitroorganic compounds were subsequently consumed in reactions with nitrate complexes. In this surface reaction, monodentate nitrate was also the most reactive species. The presence of oxygen had no effect on the consumption of the nitroorganic complex.

Reaction paths of the formation and consumption of nitroorganic complex intermediates in the selective catalytic reduction of nitrogen oxides with propylene on zirconia-pillared clays according to in situ spectroscopic data

It was found that the adsorption and catalytic properties of nanosized ZrO2 particles as the pillar constituents of ZrO2-pillared clay and bulk ZrO2 are essentially different. The interaction of NO with the surface of bulk ZrO2 resulted in the formation of three types of nitrate complexes. Only two nitrate species were formed on ZrO2-pillared clay (the monodentate species was absent). Only an acetate complex was formed in the interaction of a mixture of propylene and oxygen with the surface of bulk ZrO2, whereas an isopropoxide complex was the main propylene activation species on ZrO2-pillared clay. On the surface of ZrO2-pillared clay, isopropoxide and nitrate intermediates formed a complex structurally similar to adsorbed dinitropropane. On the surface of bulk ZrO2, acetate and monodentate nitrate complexes formed a complex structurally similar to adsorbed nitromethane. The dinitropropane complex on ZrO2-pillared clay was consumed in reactions with surface nitrates. The decomposition reaction of a dinitropropane compound with the formation of acetate complexes and ammonia predominated on the surface containing no nitrate complexes in the absence of NO + O2 from a gas phase. The found differences in reactant activation species and their thermal stabilities explained differences in the activities of bulk ZrO2 and nanosized ZrO2 particles as pillars in pillared clay in the course of the selective catalytic reduction of nitrogen oxides with propylene in an excess of oxygen.