Theoretical and Experimental Chemistry最新文献

The thermodynamic and kinetic aspects of vapor-phase carbonylation of methanol are considered, in particular the effect of temperature on the equilibrium yield of products and probable routes of acetyls production. The influence of the catalyst composition on the course of the target process, the influence of hydrogen as a gas promoter on the selectivity/yield of acetyls, the peculiarities of the course of the tandem process (coupling of decomposition and carbonylation of methanol) are analyzed.

Nanocomposites based on crystalline carbon nitride (CGCN) and cobalt titanate (CoTiO₃) have been synthesized and characterized by a number of physico-chemical methods (electron microscopy, electron and IR spectrophotometry, luminescence spectroscopy, and X-ray diffraction). It is concluded based on the analysis of the obtained results, in particular, the luminescence characteristics and Mott–Schottky dependences, that the S-scheme of separation of photogenerated charges between components is realized during the formation of CGCN/CoTiO₃ composites. This leads to a decrease in the recombination of electron–hole pairs and an increase in the efficiency of hydrogen evolution from water–ethanol solutions when compared to the presence of CGCN. The effective quantum yield of hydrogen formation is ~90% under light irradiation at λ = 405 nm with the participation of the composite of the optimal composition.

The features of the synthesis and the structure formation of homogenous phases of Mg(II),Fe(III)-layered double hydroxides with different Mg/Fe ratio in the reaction mixtures have been investigated. The effect of synthesis conditions of the materials, arrangement and molar ratio of the cations in a brucite-like layer, and polytypes of crystalline structure on the sorption properties toward ibuprofen has been studied. The sorption isotherms of ibuprofen on the synthesized sorbents at pH₀ = 7,0 are satisfyingly fitted by the Langmuir model. The influence of the Mg²⁺/Fe³⁺ molar ratio and, respectively, the dimensions of the interlayer space on the maximum adsorption capacities toward ibuprofen in the aqueous solution is not observed. These results can be explained by the interaction of the adsorbate with the surface hydroxyl groups of brucite-like layers, as well as complexing reactions with structure-forming cations of the obtained sorbents.

Zirconium dioxide samples with different crystallinity and phase compositions have been obtained by calcination of a mixture of zirconium oxychloride and sodium bicarbonate at temperatures ranging from 150 to 800°C. It is established that amorphous ZrO₂ with an zirconium oxycarbonate admixture is formed at 150-200°C. A sample obtained at 400°C contains 50% of the tetragonal phase and 50% of the amorphous ZrO₂ phase, while a mixture of tetragonal and monoclinic phases is formed at 600°C and 800°C (83% of t-ZrO₂/17% m-ZrO₂ and 27% of t-ZrO₂/73% m-ZrO₂, respectively). It is shown that zirconium dioxide obtained at 150°C has the highest efficiency of adsorptive removal of phosphate anions from an water solution as compared with other studied samples.

New catalytic methods of hydrodehalogenation reaction of haloarenes for the disposal of toxic production waste and persistent organic pollutants, fine organic synthesis, and solution of green chemistry issues are discussed. Methods presented in the review are based on electron transfer reactions involving photo- and electrocatalytic processes, including those with the participation of metal nanoparticles. Reactions of deuterodehalogenation of haloarenes and several aspects of biological methods of the process are analyzed.

According to molecular docking results (in silico calculations), main protease M^pro of SARS-CoV-2 coronavirus can be blocked by 2-formyl-8-methyl-3-carbethoxy quinoline. The calculations as well as estimation of ADME profile (absorption, distribution, metabolism, and excretion) of this compound provide grounds to consider it as active ingredient against COVID-19 coronavirus, its efficiency is comparable with known inhibitors of SARS-CoV-2. The structure of 2-formyl-8-methyl-3-carbethoxy quinoline is determined by X-ray structure analysis.

According to the quasi-equilibrium NH₃ and CO₂ thermal desorption data, the effect of chromium in the composition of zinc-containing BEA zeolites with different Si/Al ratios on their acid–base characteristics and catalytic properties in the process of dehydrogenation of propane to propene with or without CO₂ has been determined. A positive effect on the propane conversion and the propene selectivity is found for a catalyst based on the initial Cr/ZnAlBEA zeolite (Si/Al = 17). Higher propane conversion is achieved in the process of propane dehydrogenation with the participation of CO₂ in the presence of Cr/Zn-BEA catalysts, but with lower propene selectivity when compared to the propane dehydrogenation process without CO₂.

The promising application of mechanochemical (MC) and sonochemical (SC) synthesis methods for the obtaining of nano-dispersed oxide materials with a perovskite structure (BaTiO₃, CaTiO₃, and LiNbO₃) and higher specific surface value as compared to samples obtained by traditional methods is shown. Synthesized samples exhibit high photocatalytic activity in the oxidative degradation of metronidazole and chloramphenicol drugs, as well as a promethrin herbicide in an aqueous medium exceeding known analogs. The possibilities of MC and SC in the synthesis of zinc and bismuth molybdates with the obtaining of their nanostructures with different morphologies, in particular bars, needles, rods, and spheres, are shown. It is established that prepared samples demonstrate high activity in the processes of ethanol oxidation to acetaldehyde (β-ZnMoO₄) or acetic acid (α-ZnMoO₄), oxidative dehydrogenation of hydrocarbons of the industrial fraction of oil processing with the obtaining of 1,3-butadiene (Bi₂Mo₃O₁₂).

Results of the study of CO₂ methanation on Co-containing catalysts based on Siral aluminosilicates with different SiO₂/Al₂O₃ ratios (1, 10, and 40) are presented. It is shown that methane is the main product at temperatures up to 573 K, its yield varies depending on the SiO₂/Al₂O₃ ratio of aluminosilicate. Carbon monoxide is formed along with methane at temperatures above 573 K. Maximum methane yields of 55% and 41% (at 573 K) are achieved on Co/Siral-1 and Co/Siral-10 catalysts. It is shown that catalysts reduced in a hydrogen flow are characterized by the presence of superpara/ferromagnetic particles and magnetic resonance parameters of their EMR spectra significantly depends on the SiO₂/Al₂O₃ ratio of the aluminosilicate. It is assumed that the superpara/ferromagnetic particles formed during high-temperature hydrogen treatment of Co-containing aluminosilicates are catalytically active particles in the methanation of carbon dioxide.