30 December 2022 in Eastern-European Journal of Enterprise Technologies
Pomegranate seed and peel powders are suitable for the production of pectin, oil, proteins and as biologically active additives for food enrichment. Knowledge of the chemical composition and thermal changes of powders allows to control the technological regimes, yield and quality of the final product. As a result of the studies, the chemical composition and thermal properties of a finely dispersed pomegranate peel and seed powder subjected to heat treatment by X-ray diffractometry, IR-, EPR spectroscopy and thermal analysis (TG/DTG/DSC) have been carried out. X-ray diffractometry showed that the crystal structures present in the original samples, when heated in air at 110 °C for 30 min. are destroyed and in all cases the samples pass into the amorphous state, a noticeable difference is found in the position and intensity of the observed bands in the spectra in the initial and heat-treated samples. IR spectroscopy data show that drying the samples at 105 °C in air for 30 min leads to a significant change in the chemical composition of the powders. EPR spectroscopy showed the presence of paramagnetism in the samples and identified organic radicals and paramagnetic centers from Fe3+ ions. The features of the change in the chemical composition during drying of samples, which are characteristic of drying processes, namely, are the result by dehydration, dehydroxylation and denaturation of protein compounds that make up this process, have been established. Temperature intervals (54.2–147.9 and 71.7–95.4 °C, 147.9–343.7 and 343.7–466 °C) associated with changes in the composition of organic compounds, contained in the powders were determined.
1 March 2022 in Theoretical and Experimental Chemistry
1 January 2023 in Chemical Problems
IMInstitute of Catalysis and Inorganic Chemistry named after M.Naghiyev
Institute of Catalysis and Inorganic Chemistry named after M.Naghiyev
SMSOCAR Downstream Management
SOCAR Downstream Management
+4
Mono-, bi- and trinuclear carbinol derivatives of ferrocene C5H5FeC5H4-C(CH3)2OH (I), [C5H5FeC5H4]2C(CH3)OH (II), [C5H5FeC5H4]3C-OH (III) were synthesized. the thermal stability and thermodynamics of the pyrolysis of these compounds have been studied. The composition and structure of the synthesized compounds were established by elemental analysis (AAS, C, H analysis), 1H NMR, IR, and UV/visible spectroscopy. In the IR spectra of these compounds there are absorption bands with ν(OH) =2910-3040 cm-1 and ν(OH) = 3080-3190 cm-1 , and in the 1H NMR spectra there are absorption bands with chemical shift values δ(OH) = 4.29-4.18 ppm for OH groups that differ in position and are due to the formation of intra- and intermolecular associates with the participation of OH groups. The electronic absorption spectra indicate the presence of characteristic absorption bands in compounds I-III at λmax = 270 (I), 278 (II), and 285 nm (III). It is shown that when samples are heated from room temperature to 700 °C in an inert gas flow, the residual mass of compounds I-III is 2.05, 20.24, and 66.96% of the initial mass, respectively, and these compounds decompose to form nanosized iron particles. /iron oxide and carbon. The values of the melting temperature and saturation magnetization of nanosized iron particles formed during the pyrolysis of ferrocene and its derivatives I-III are calculated.
30 March 2024 in Himia, Fizika ta Tehnologia Poverhni
IAInstitute of Catalysis and Inorganic Chemistry Azerbaijan
Institute of Catalysis and Inorganic Chemistry Azerbaijan
+1
Samples of MnOx-Na2WO4/SiO2 based on a mesoporous silica matrix were synthesized using manganese acetate, sodium tungstate, tetraethoxysilane (TEOS) as precursors and cetyltrimethylammonium bromide (CTAB), citric acid and triethanolamine as pore generating agent and characterized by scanning electron microscopy with energy dispersive elemental analysis (SEM/EDS), X-ray diffractometry (XRD), electron magnetic resonance (EMR), N2 adsorption-desorption measurements and tested as a catalyst for the reaction of oxidative condensation of methane (OCM). It is shown that the MnNaW/SiO2 catalyst consists of Mn2O3, MnO2, Na2WO4 and SiO2 phases. The EMR and SEM/EDS data indicate a noticeable effect of the reaction conditions on the surface structure and the distribution of catalytically active components in the catalyst structure. Significant changes in the values of the specific surface area and pore volume of the samples with increasing temperature and duration of the reaction were found (the values of the specific surface area and pore volume, respectively, 116.8 m2/g and 0.590 cm3/g - up to and 46.1 m2/g and 0.232 cm3/g after 15 hours of catalyst operation in the OCM reaction at 800 °C). It has been shown that under the conditions of the OCM reaction, the elemental composition of the surface of the MnOx-Na2WO4/SiO2 catalyst changes, and the degree of change depends on the duration of the OCM reaction. Under the influence of the reaction mixture CH4/O2, the content of Mn and W decreases in the first two hours, and the trend towards a decrease in their amount on the catalyst surface with an increase in the duration of the OCM reaction is generally preserved. A detailed X-ray phase analysis also indicates a change in the phase composition of this catalyst under the influence of the CH4/O2 reaction mixture. It is assumed that under the reaction conditions (700–800 °C) the MnOx-Na2WO4/SiO2 catalyst is silicon dioxide particles basely with the cristabolite structure, the surface of which is coated with molten sodium tungstate containing nanosized particles of MnOx structures activated by sodium ions and WOx.
22 October 2024 in Eurasian Chemico-Technological Journal
Boehmite samples with compounds of the composition (C5H5)2FeMnX2(μ-CO)n, where X=Cl, Br and n=1.2, precipitated at room temperature from tetrahydrofuran solutions and then heated in an air flow up to 873 K were obtained and characterized using X-ray diffractometry, infrared Fourier spectroscopy, electron magnetic resonance and temperature-programmed desorption methods. It was shown that the thermal decomposition of these compounds applied to the boehmite samples in the range from room temperature to 873 K occurs stepwise and consists of at least two stages. The first stage of thermal decomposition occurs in the range of 453–753 K, and the second – in the range of 813–843 K. The XRD data show that when calcining at 873 K the boehmite samples with the applied compounds of the above composition and containing these compounds less than 10 wt.%, the diffraction patterns show only reflections characteristic of poorly crystallized aluminum oxide. However, the electron paramagnetic resonance (EPR) spectra of these samples clearly show intense signals characteristic of superpara/ferromagnetic particles of iron and manganese oxides, as well as EPR signals from isolated Fe3+ substituting Al3+ ions in the aluminum oxide structure. EPR spectra most of the iron and manganese is stabilized on the surface of poorly crystallized aluminum oxide in the form of nanostructured iron and manganese oxides.
1 January 2018 in Journal of Structural Chemistry
The work describes in detail the structure of a coordination platinum(II) compound with the sulfur-and nitrogen-containing biologically active β-mercaptoethylamine ligand NH2CH2CH2SH which...