Search

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.

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]

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]

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]

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]