Volume 65, Nº 4 (2024)

Kinetics of the of the reaction of gas-phase hydrogenolysis of bytillactate over 45.5%Cu/SiO2 catalyst was investigated. The catalyst provides high specific productivity (6 gPG g_cat^–1 h^–1), bytillactate conversion (up to 99.5%) and selectivity to produce 1,2-Propylene glycol (up to 97%) at 180°С, which allows us to consider the investigated reaction as promising for industrial synthesis of 1,2-Propylene glycol. As a result of the research, the influence of process conditions (pressure, ratio of reagents, concentration of products, temperature) on the reaction rate was established, a kinetic equation was obtained, the values of the kinetic parameters of this equation were determined, which makes it possible to adequately describe the experimental data, and the effective activation energy of the reaction was calculated.

In this work, the Suzuki reaction was studied under conditions of competing substrates in the presence of catalysts, containing Pd^II or Pd⁰ nanoparticles, synthesized using a sulfonated amorphous aromatic polymer as a support. The paper discusses the influence of reaction conditions (stirring rate, temperature, nature of the base), as well as various pairs of competing aryl halides (bromides and iodides) containing both electron-donating and electron-withdrawing groups. It was shown for the first time that aryl bromides containing electron-withdrawing groups in the p-position with respect to the halogen are capable of noticeably slowing down the conversion of each other, as well as stopping the conversion of other aryl bromides in the presence of Pd⁰ nanoparticles as a source of catalytically active forms of palladium. Additives of sodium salt anions (chloride, bromide and acetate) are able to prevent the reaction from stopping.

A new catalytic system for the production of dimethyl maleate (DMM) and dimethyl fumarate (DMF) by acetylene oxidative carbomethoxylation is proposed. It is shown that in the PdBr₂-LiBr – РсСо – MeOH system, DMM is predominantly formed. The effect of HBr, thiourea (Tu) and solvent additives on the rate of DMM Z/E isomerization reaction is studied. It is shown that the use of an additional organic solvent and a decrease in the methanol concentration increase in Z/E isomerization rate and leads to DMF formation. A mechanism for DMM, DMF and dimethyl succinate formation is proposed (DMS).

Lignin, a large-scale waste from the processing of lignocellulose biomass, is a promising raw material to obtain products with high added value. The processes of lignin depolymerization lead to the formation of oxygen-containing compounds, a.i. phenol derivatives. Since the depolymerization of lignin involves many reactions, including the conversion of monomers, the purpose of this work is to study the ways of conversion of phenol, anisole, guaiacol, syringol, eugenol, hydroquinone, and p-ethylphenol both as individual components and in a mixture during its catalytic processing. The experiments were carried out in the medium of propanol-2 in the presence of Ni–Ru/SiO₂@HPS catalyst varying the process conditions. The composition of the products of conversion lignin monomers was studied. The main ways of the transformation of monophenols were found to be hydrogenation of the aromatic ring, deoxygenation and hydrogenation of the resulting aromatic hydrocarbons. The rate of component consumption during the conversion of the mixture was found to be lower than that for the individual substrates. A study of the process temperature and the partial pressure of hydrogen on the conversion of a mixture of substrates was carried out. Aromatic hydrocarbons were chosen as target products in this work. The optimal conditions for the conversion of a mixture of substrates in terms of process rate and selectivity to aromatic hydrocarbons were estimated to be a temperature of 280°C, a partial pressure of hydrogen 3.0 MPa.

The kinetic regularities of methylcyclohexane dehydrogenation into toluene and hydrogen on the supported Pt,Sn/γ-Al₂O₃ catalyst in the gas phase have been studied in detail. Based on the results of kinetic experiments, using the advancement and discrimination of hypotheses, an adequate structural kinetic model of the reversible process has been created. It is based on a mechanism that includes four routes involving the bifunctional active center of the catalyst and its two adsorption complexes: with hydrogen and with toluene.