This work reports supercritical water oxidation (SCWO) of organic pollutants in industrial wastewater in the absence and presence of catalysts. To increase the efficiency of the oxidation process, the SCWO of organic compounds in industrial wastewater was performed in the presence of various iron- and manganese-containing heterogeneous catalysts (Fe-Ac, Fe-OH, and Mn-Al). The catalytic and non-catalytic SCWO of organic compounds in wastewater from PJSC “Nizhnekamskneftekhim”, generated from the epoxidation of propylene with ethylbenzene hydroperoxide in the process of producing propylene oxide and styrene (PO/SM), was performed. The effect of operational parameters (temperature, pressure, residence time, type of catalysts, oxygen excess ratio, etc.) on the efficiency of the process of oxidation of organic compounds in the wastewater was studied. SCWO was studied in a flow reactor with induction heating under different temperatures (between 673.15 and 873.15 K) and at a pressure of 22.5 MPa. The reaction time ranged from 1.8 to 4.83 min. Compressed air was used as an oxidizing agent (oxidant) with an oxidant ratio of two to four. A pseudo-first-order model expressed the kinetics of the SCWO processes, and the rate constants were evaluated. In the present work, in order to optimize the operation parameters of the SCWO process, we used the thermodynamic properties of near- and supercritical water by taking into account the asymmetric behavior of the liquid–vapor coexistence curve.

A second-generation hyperbranched polyester with the terminal carbamoyl phosphonate groups has been synthesized. The structure of the resulting polyester has been studied by IR, ¹H NMR, ³¹P NMR, and electron spectroscopy. It has been found that 25% of the terminal OH groups of polyester polyol were subjected to functionalization. Using the TGA method, the thermal stability temperature of the resulting polyester was evaluated to be 138°C. We have synthesized a complex of the resulting polyester with the Pd(II) ions, and the complex structure has been studied by IR and electron spectroscopy. The composition of the ligand–Pd(II) complex has been evaluated to be 1 : 6. We have found by the TGA method that this complex is thermally stable up to 207°C. The temperature of reduction of the Pd(II) ions by molecular hydrogen to Pd(0) has been assessed as –20.6°C. Electron microscopy has been used to demonstrate the spherical morphology of hyperbranched polyester polycarbamoyl phosphonate with Pd(0) atoms, with the predominant fraction being 1.5 μm. It has been shown that the use of hyperbranched polyester polycarbamoyl phosphonate as a catalyst provides the activation energy of 55.8 kJ/mol for hydrogenation of α-methylstyrene to cumene with the effective rate constant of 1.950×10^–2 L/(g_cat s) at 45°C and atmospheric pressure. The results indicate the prospects of using hyperbranched polyester polycarbamoyl phosphonate as a matrix to obtain catalysts for the hydrogenation of unsaturated compounds.

In the propylene oxide and styrene coproduction (PO/SM) process, styrene is produced by the catalytic dehydration of 1-phenylethanol in the presence of alumina. In addition to hydrocarbon flow, direct steam is supplied to the reactor to regulate the thermal regime and reduce the rate of side reactions and the rate of catalyst deactivation. In this work, the contribution of acid sites of different natures and strengths to the activity of catalysts based on alumina in the dehydration of 1-phenylethanol, which occurs in the presence of excess water in the temperature range of 230-300°C, was assessed. A series of catalysts were prepared using the impregnation method from aqueous solutions of sodium carbonate, ammonium molybdate, ammonium metavanadate and ammonium tungstate. The acidity of the catalysts was studied using low-temperature adsorption of carbon monoxide. The dehydration reaction is not associated with Brønsted acid sites present on the surface of alumina (frequency range of CO absorption bands ν_CO = 2155-2165 cm^–1). In the presence of Lewis acid sites of varying strength on the surface of the catalyst (ν_CO = 2238–2240, 2203–2210, and 2189–2195 cm^–1) in the temperature range up to ~250°С, the contribution to the integral dehydration of the weakest Lewis acid sites (ν_CO = 2189–2195 cm^–1) did not exceed 20%. All transition metals increase the concentration of Lewis acid sites (ν_CO = 2238–2240, 2203–2210 cm^–1), which leads to an increase in the dehydration activity of catalysts toward 1-phenylethanol.

Палладий, нанесенный на гидротермально модифицированный оксид алюминия: физико-химические и каталитические свойства Палладий, нанесенный на гидротермально модифицированный оксид алюминия: физико-химические и каталитические свойства

A comparative evaluation of the results of an experimental study and thermodynamic analysis of the chemical equilibrium in a heterophase heterogeneous catalytic reaction of cyclohexanone hydrogenation is reported. It is shown that when calculating the thermodynamic equilibrium constant of heterophase hydrogenation reactions in gas–liquid systems it is necessary to take into account the change in the enthalpy and entropy of the initial chemical system caused by hydrogen absorption. The value of the enthalpy of hydrogen absorption not only reflects the endothermic physical process of gas dissolution, but also characterizes the state of the reagents in the exothermic chemical reaction of hydrogenation. Therefore, the thermal simulation of the apparatus, in which gas absorption and chemical reaction with its participation occur simultaneously, should be performed without taking into account the heat of gas dissolution.

In the process of coproduction of propylene oxide and styrene (PO/SM), a stream containing isomeric phenylethanols is fed to the dehydration stage. In this work, the contribution of acid sites of different nature and strength to the activity of aluminum oxide-based catalysts in the dehydration reaction of 1- and 2-phenylethanols occurring in the presence of excess water in the temperature range of 230-300°C is compared. It was found that over the entire studied temperature range: the rate of intramolecular dehydration of the primary alcohol is significantly lower than the rate of dehydration of the secondary alcohol; the dehydrating activity of the catalysts with respect to both alcohols is determined primarily by acid sites of the LAS I and LAS II types; the temperature of manifestation of the dehydrating activity of LAS III type sites with respect to the primary alcohol is ~50°C higher compared to the secondary alcohol. The type of kinetic equation for the target reaction is substantiated, the values of the observed rate constants are calculated. It was found that for both alcohols the change in the pre-exponential factor is directly proportional to the change in the Arrhenius activation energy, while the observed activation energy of the dehydration reaction of the primary alcohol significantly exceeds the activation energy of the dehydration of the secondary alcohol.