Andrey V. Chistyakov

The possibility of reusing mesoporous Sibunit as an adsorbent for 2,4-dichlorophenoxyacetic acid was studied. The effectiveness of using microwave radiatio

The adsorption activity of a carbon material based on lignin modified with iron salts and carbonized under the influence of microwave radiation in relation

The influence of the synthesis conditions on the performance of Pd–Cu ethanol-to-butanol conversion catalysts was studied. The optimum conditions for forming the most active system 0.2%Cu/0.3%Pd/Al₂O₃ are as follows: sample synthesis by Al₂O₃ impregnation from aqueous solutions of Pd and Cu nitrates; deposition of the metal precursors in succession; total content of Pd and Cu in the sample 0.5 wt %; Pd : Сu molar ratio 1 : 1; catalyst reduction temperature 200^○С. As shown by TEM, XPS, TPD-NH₃, TPR-H₂, XRD, and N₂ adsorption, the surface of the most active catalyst contains Pd⁰Cu⁰ particles with the mean size of 4 ± 2 nm. The bimetallic particles are an alloy with the fcc structure and Pd : Cu ratio of 40 : 60. At 275^○C, the performance of 0.2%Cu/0.3%Pd/Al₂O₃ is 182 × 10^–4 mol h^–1 g^–1. The value obtained is higher by several orders of magnitude than the performance of the reference catalysts M₁/Al₂O₃ (M₁ = Fe, Ni, Co) and by an order of magnitude than that of the reference catalysts M₂/Al₂O₃ (M₂ = Ru, Rh, Pt, Pd, Pt–Re, Ni–Mo).

In this study, we present the results of lignin and fuel oil conversion to hydrogen, synthesis gas, and liquid hydrocarbons in the presence of nano-sized cobalt-containing systems in a microwave-assisted plasma catalytic process. The deposition of a small amount of cobalt on lignin increases its microwave absorption capacity and provides plasma generation in the reaction zone. The role of Co-containing particles in the above catalytic reactions is probably to activate the carbon bonds of lignin, which substantially increases the microwave absorption capacity of the system as a whole. The subsequent use of the cobalt-containing residue of lignin conversion as a catalytic system and MWI-absorbing material results in active fuel oil pyrolysis in a plasma catalytic process to afford gaseous and liquid hydrocarbons. In the plasma catalytic pyrolysis, fuel oil conversion is probably accompanied by the conversion of the organic matter of the residue and agglomeration of cobalt oxide particles.

The present study investigates the regularities in the conversion of ethanol and water/ethanol mixtures in the presence of Au–M/MFI/Al₂O₃ modified zeolite catalysts, where M = Cu, Ni, and Pd. The conversion products of ethanol, fusel oils, and of a model ethanol/acetone/1-butanol (ABE) mixture were investigated in detail. Transmission electron microscopy (TEM) revealed that supported metal particles mostly aggregate into bimetallic clusters 8–15 nm in size. The variations in product selectivity were found to be caused by coking and, therefore, by a declining concentration of acid sites on the catalyst surface.

Conversion of mixtures of fuel oil with iron-containing substrates (carbon adsorbent and lignin, both modified with 0.5 wt % Fe) to hydrocarbon products and hydrogen was studied. The use of microwave radiation in the presence of the above-indicated iron-containing substrates capable of its absorption with the generation of breakdown phenomena and plasma is a promising approach to rapid processing of stable organic compounds of petroleum and natural origin into hydrocarbon products used in organic synthesis and for production of fuel components.

The study is devoted to the conversion of tar and iron-modified lignin under the action of microwave radiation. Lignin containing 0.5 wt % Fe absorbs about 80% of the supplied microwave radiation (2.45 GHz), which leads to a rapid increase in temperature in the reaction zone with the formation of plasma. During the conversion of a lignin (0.5 wt % Fe)/tar blend a wide range of gaseous and liquid hydrocarbons was produced, therewith the amount of light hydrocarbons was 75%. The solid carbon residue containing iron(III) oxide clusters is also characterized by the ability to absorb microwave radiation; it was employed as a catalyst and as a plasma generator in the 2nd cycle of the converting only tar under the influence of microwave radiation. The structure of nanosized iron-containing components was studied by transmission electron microscopy, X-ray diffraction, and Mössbauer spectroscopy, which made it possible to describe their genesis.

The paper reports first comprehensive geological, petrographic, mineralogical, and geochemical data on one of the world’s oldest Tiksheozero ultramafic‒alkaline‒carbonatite complex (~1.99 Ga), which belongs to the Mid-Paleoproterozoic igneous province of the Baltic Shield. The complex was formed in three intrusive phases. The first phase is composed of the low-alkali mafic‒ultramafic rocks: dunites, wehrlites, clinopyroxenites, and gabbro. The rocks of the second phase are alkaline ultramafic rocks represented mainly by jacupirangites (alkaline clinopyroxenites) and foidolites (melteigites, ijoliltes, and urtites), with subordinate olivinites, alkaline gabbro, and nepheline syenites. The third intrusive phase is made up of carbonatites. Geochemical and mineralogical data indicate that all three phases were derived from different primary melts. It is shown that the nepheline syenites were obtained by fractionation of foidolites. A model of formation of such complexes through decompressional melting of mantle plume head enriched in carbonate fluid is proposed.