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In this paper, the features of catalytic cracking of propane with a step-wise change in the composition of the catalyst from Pr2Zr2O7 to Yb2Zr2O7 were considered. For the research, samples of catalysts Pr2Zr2O7, (Pr0.75Yb0.25)2Zr2O7, (Pr0.5Yb0.5)2Zr2O7, (Pr0.25Yb0.75)2Zr2O7 and Yb2Zr2O7 were synthesized and analyzed. Analysis of the results from catalytic experiments showed that for the catalyst (Pr0.25Yb0.75)2Zr2O7, at a temperature of 700 °C, the conversion of propane reaches values of 100%, but for Yb2Zr2O7, this indicator decreases to 84%. The selectivity for ethylene is consistently reduced from 85% to 28% in several catalysts (Pr0.75Yb0.25)2Zr2O7 > Pr2Zr2O7 > (Pr0.5Yb0.5)2Zr2O7 >(Pr0.25Yb0.75)2Zr2O7 > Yb2Zr2O7. An increase in the number of surface adsorption centers leads to a predominant rupture of the C–C bond in the propane molecule with the formation of ethylene. When ytterbium ions are introduced into the catalyst, the amount of ethylene in the reaction products decreases, but the selectivity for propylene increases in the series Pr2Zr2O7 < (Pr0.75Yb0.25)2Zr2O7 < (Pr0.5Yb0.5)2Zr2O7 < Yb2Zr2O7 < (Pr0.25Yb0.75)2Zr2O7, which is associated with a decrease in the binding energy of carbon atoms in propane with the catalytic center during adsorption. [ABSTRACT FROM AUTHOR]

Unraveling the effect of solvent polarity on the ESIPT mechanism of 9,10-dihydroxybenzo[ h ]quinolone compounds. [Display omitted] • In the excited state, the strength of the hydrogen bond in the S 1 state is negatively correlated with the solvent polarity. • As the solvent dielectric constant increases, the HOMO to LUMO transition energy increases. • As the solvent dielectric constant increases, the ESIPT energy barrier of 9,10-HBQ derivatives increases. To elucidate the relationship between the excited-state intramolecular proton transfer (ESIPT) mechanism of 9,10-dihydroxybenzo[ h ]quinoline (9-10-HBQ) and the influence of solvents, for better application. This paper focuses on the investigation of hydrogen bond geometric changes, the ESIPT mechanism, and its behavior modulated by solvent polarity. The structural parameters of the ground-state (S 0) and excited-state (S 1) related to the hydrogen bond (O 1 H 2 ⋯O 3), along with the infrared vibrational spectra, core-valence bifurcation (CVB) index, hydrogen bond bond-critical point (BCP) parameters, RDG function isosurfaces, and scatter plots, reveal that the enhanced hydrogen bond strength in the S 1 state promotes the ESIPT behavior of 9-10-HBQ-PT1. Further frontier molecular orbital and natural Population Analysis (NPA) charge analyses indicate that intramolecular charge redistribution facilitates the ESIPT process. Based on the analysis of potential energy curves, transition states (TS), and intrinsic reaction coordinate (IRC) pathways, we found that the reaction energy barriers can be tuned by the solvent. For example, in cyclohexane (Cy), toluene (Tol), chloroform (TCM), and acetonitrile (ACN), the reaction energy barriers were 7.12 kcal/mol, 7.25 kcal/mol, 7.65 kcal/mol, and 8.15 kcal/mol, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] The process of propane cracking in the presence of rare earth vanadites was explored. It was shown that the samples can be attributed to mesoporous catalysts, which also contain a small amount of micropores. It was revealed that the propane conversion and the yield of light olefins grew up with an increase in the molecular weight of a catalyst, while the ethylene and propylene selectivities were enhanced; the propane conversion reached a maximum value of 96.5% with ethylene and propylene selectivities of 69.4 and 26.5%, respectively, when europium vanadite was used as a catalyst. [ABSTRACT FROM AUTHOR]

Perovskite oxides (ABO3) due to their high thermal stability and the ability to control the physico-chemical properties are considered as an alternative to traditional catalysts containing noble and transition metals. Herein, the recent research breakthroughs of GdCoO3 catalysts in experimental studies are summarized in detail. First, the perovskite-type GdCoO3 complex oxides were obtained by co-precipitation method with the various precipitators and were characterized by X-ray diffraction (XRD), low temperature nitrogen adsorption and IR spectroscopy. Physical and chemical analysis showed that the choice of precipitant doesn't significantly affect the phase composition of the perovskites. The catalytic performance of gadolinium cobaltites was discussed. It was found that the use of cobaltites obtained by co-precipitation leads to the inhibition of the side reaction of the reverse steam reforming of carbon monoxide. Finally, the investigation of the used catalysts demonstrated the formation of Gd2O2CO3 and metallic cobalt, which indicates the nature of active centres: gadolinium is the centre of CO adsorption, while hydrogen chemisorption occurs on cobalt-sites. [ABSTRACT FROM AUTHOR]

The effect of strontium substitution in the structure of the complex oxide Gd2SrFe2O7 on the production of light olefins by CO hydrogenation was investigated. Perovskite-type oxides Gd2−xSr1+xFe2O7 (x = 0; 0.1; 0.2; 0.3; 0.4) were synthesized by sol–gel technology and characterized by XRD, Mössbauer spectroscopy, BET specific area, acidity testing, and SEM. The experimental data revealed a correlation between the state of iron atoms, acidity, and catalytic performance. It was found that with an increase in the content of Sr2+ in the perovskite phase, the basicity of the surface and the oxygen diffusion rate increased. This contributed to the CO dissociative adsorption, formation of active carbon, and its further interaction with atomic hydrogen. [ABSTRACT FROM AUTHOR]

The effect of the substitution of cobalt into the GdFeO3 perovskite structure on the selective hydrogenation of CO was investigated. A series of GdCoxFe1−xO3 (x = 0; 0.2; 0.5; 0.8; 1) samples were synthesized by sol-gel technology and characterized by XRD, BET specific area, DSC, TG, EDX and XPS. The experimental data made it possible to reveal a correlation between the state of iron and cobalt atoms, the fractions of surface and lattice oxygen, and catalytic characteristics. It has been found that varying the composition of GdCoxFe1−xO3 complex oxides leads to a change in the oxygen-metal binding energy in Gd-O-Me, the ratio of metals in various oxidation states, and the amount of surface and lattice oxygen, which affects the adsorption and catalytic characteristics of complex oxides. [ABSTRACT FROM AUTHOR]

Ethanol has become a viable feedstock for basic organic synthesis. The catalytic conversion of ethanol provides access to such chemicals as diethyl ether, ethyl acetate, and acetaldehyde. Carbonaceous materials are extensively studied as supports for heterogeneous catalysts due to their chemical and thermal stability, high surface area, and tunable texture. In this paper, ethanol conversion over K10Co3.7Mo12S-catalysts supported on novel activated carbon (AC) materials (i.e., novel powder-AC (DAS and YPK-1), fiber non-woven AC material (AHM), and fabric active sorption (TCA)) was investigated. The catalysts were prepared by the incipient wetness co-impregnation method followed by sulfidation. The catalysts were characterized by employing N2 adsorption–desorption measurements, TEM, SEM/EDX, UV–Vis spectroscopy, and XRF. Catalytic performance was assessed in a fixed-bed down-flow reactor operating at 320 °C, 2.5 MPa, and with continuous ethanol feeding in an He atmosphere. Activity is highly dependent on the support type and catalyst's textural properties. The activity of the fiber-supported catalysts was found to be greater than the powder-supported catalysts. Ethanol conversion at T = 320 °C, P = 2.5 MPa, and GHSV = 760 L h−1 kgcat−1 increased as follows: (38.7%) KCoMoS2/YPK-1 < (49.5%) KCoMoS2/DAS < (58.2%) KCoMoS2/TCA < (67.1%) KCoMoS2/AHM. Catalysts supported by powder-AC enhanced the formation of MoS2-crystallites, whereas the high acidity of fiber-AC seemed to inhibit the formation of MoS2-crystallites. Simultaneously, a high surface area and a microporous catalytic structure enhance the formation of oxygenates from hydrocarbons. The dehydration and dehydrogenation reactions, which led to the creation of ethene and acetaldehyde, were shown to require a highly acidic catalyst, while the synthesis of ethyl acetate and higher alcohols required a less acidic catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] The influence of textural characteristics on the catalytic performance of supported KCoMoS 2 catalysts was explored to provide essential information for the design of better catalysts for the synthesis of higher alcohols (C 1 –C 5) from syngas. Syngas conversion was carried out over KCoMoS 2 catalysts supported on various mesoporous (alumina and carbon-coated alumina) and microporous (two types of powdered activated carbons) materials. The experimental results show that catalysts supported over microporous materials exhibit higher catalytic activity in HAS from syngas than catalysts based on mesoporous materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Molybdenum promotion was used to increase the resistance of a cobalt catalyst for the Fischer–Tropsch synthesis to sulfur poisoning. A series of experiments on adding 1,3,5-trithiane to synthesis gas (sulfur content of 1 ppm) showed that the Co–Mo /Al 2 O 3 catalyst regained its initial activity after 8 h of operation. In comparison, catalysts not containing molybdenum experienced a significant irreversible loss of activity that was not recovered after stopping the addition of 1,3,5-trithiane to the feed. [ABSTRACT FROM AUTHOR]

[Display omitted] • KCoMoS 2 catalysts supported on activated carbons were more active in ethanol conversion. • Acidity of catalysts did not have a direct effect on total conversion but it influenced product yields. • Oxygenate yields were higher under a He atmosphere compared to a H 2 atmosphere. • TOF number in ethanol conversion increased with a decrease in dispersion of KCoMoS 2 species. • Resulting oxygenates and their derivatives can have a mixing octane number > 113. The effect of alumina, carbon-coated alumina (CCA), and two commercial activated carbons (ACs) supports on trimetallic KCoMoS 2 catalysts for ethanol conversion was studied. Supports and catalysts were characterized using high-resolution transmission electron (HRTEM) microscopy, UV spectral analysis of pyridine adsorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and N 2 physisorption to study their structural properties and morphology. The reactions were carried out under hydrogen and helium reaction atmospheres in a fixed-bed reactor. Catalysts supported on various ACs were found to be more active than those supported on γ-Al 2 O 3 and CCA. The turnover frequency (TOF) in all the studied reactions increased both with an increase in the average length ( L ¯ ) and with a decrease in dispersion (D). Product yields were higher under a helium atmosphere compared to a hydrogen atmosphere. Conversion of ethanol is supposed to occur on MoS 2 -based catalysts with account for the nature of the support and effects of the reaction atmosphere. The influence of catalyst acidity on product distribution and conversion was investigated; acidity was found to have no direct effect on total conversion, yet it influenced product yields. [ABSTRACT FROM AUTHOR]