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1.
O. N. Krasnobaeva I. P. Belomestnykh T. A. Nosova T. A. Elizarova G. V. Isagulyants V. P. Danilov 《Russian Journal of Inorganic Chemistry》2013,58(6):644-649
A method was developed for introducing gallium into Mg-Al hydrotalcites—precursors of oxide catalysts for oxidative dehydrogenation of alkanes. Samples of oxide catalysts were synthesized that contained gallium oxide and also oxides of magnesium, aluminum, chromium, vanadium, molybdenum, and niobium in various combinations. The catalytic properties of the produced catalysts were studied in the oxidative dehydrogenation of ethane, propane, isobutane, and hexane. It was established that the addition of gallium to catalysts increases the ethylene and propylene yields in the oxidative dehydrogenation of ethane and propane. New hydroxo salts with a layered structure of the hydrotalcite type were synthesized: ternary magnesium gallium aluminum hydroxonitrate of variable composition [Al1 ? n Ga n Mg m (OH)3 + 2m ? 1][NO3 · nH2O] and quaternary magnesium gallium chromium aluminum hydroxonitrate of the composition [AlGaCrMg1.8(OH)11.6][NO3 · nH2O]; these salts were found to be isostructural. 相似文献
2.
O. N. Krasnobaeva T. A. Nosova D. F. Kondakov V. P. Danilov 《Russian Journal of Inorganic Chemistry》2018,63(9):1122-1124
A method is developed for inserting ytterbium into Mg–Al hydroxo salts that have a hydrotalcitetype layered structure, as well as for the chemical analyses of complex hydroxo salts containing ytterbium in various combinations with magnesium, aluminum, chromium, vanadium, molybdenum, and niobium. The formation conditions of these hydroxo salts have been studied by potentiometric titration, their samples have been prepared, and X-ray diffraction patterns recorded. The prepared hydroxo salt samples have been tested as precursors for oxide catalysts of oxidative dehydrogenation (ODH) of alkanes. 相似文献
3.
Indium on silica, alumina and zeolite chabazite (CHA), with a range of In/Al ratios and Si/Al ratios, have been investigated to understand the effect of the support on indium speciation and its corresponding influence on propane dehydrogenation (PDH). It is found that In2O3 is formed on the external surface of the zeolite crystal after the addition of In(NO3)3 to H-CHA by incipient wetness impregnation and calcination. Upon reduction in H2 gas (550 °C), indium displaces the proton in Brønsted acid sites (BASs), forming extra-framework In+ species (In-CHA). A stoichiometric ratio of 1.5 of formed H2O to consumed H2 during H2 pulsed reduction experiments confirms the indium oxidation state of +1. The reduced indium is different from the indium species observed on samples of 10In/SiO2, 10In/Al2O3 (i.e., 10 wt% indium) and bulk In2O3, in which In2O3 was reduced to In(0), as determined from the X-ray diffraction patterns of the product, H2 temperature-programmed reduction (H2-TPR) profiles, pulse reactor investigations and in situ transmission FTIR spectroscopy. The BASs in H-CHA facilitate the formation and stabilization of In+ cations in extra-framework positions, and prevent the deep reduction of In2O3 to In(0). In+ cations in the CHA zeolite can be oxidized with O2 to form indium oxide species and can be reduced again with H2 quantitatively. At comparable conversion, In-CHA shows better stability and C3H6 selectivity (∼85%) than In2O3, 10In/SiO2 and 10In/Al2O3, consistent with a low C3H8 dehydrogenation activation energy (94.3 kJ mol−1) and high C3H8 cracking activation energy (206 kJ mol−1) in the In-CHA catalyst. A high Si/Al ratio in CHA seems beneficial for PDH by decreasing the fraction of CHA cages containing multiple In+ cations. Other small-pore zeolite-stabilized metal cation sites could form highly stable and selective catalysts for this and facilitate other alkane dehydrogenation reactions.Indium-containing chabazite zeolites show better stability and C3H6 selectivity for propane dehydrogenation than In2O3, In/SiO2 and In/Al2O3. Extra-framework In+ is identified as the stable active site upon reduction of an impregnated sample. 相似文献
4.
E. D. Sushchenko T. S. Kharlamova T. I. Izaak O. V. Vodyankina 《Kinetics and Catalysis》2017,58(5):630-641
The physicochemical properties of V2O5/Al2O3 and MgO–V2O5/Al2O3 supported catalysts (Mg : V = 1 : 1, 2 : 1, and 3 : 2) obtained by consecutive impregnation of the support with solutions of vanadium and magnesium precursors are studied using a complex of mutually complementary methods (XRD, Raman spectroscopy, UV–Vis spectrometry, and TPR-H2). The effect of the formation of surface magnesium vanadates of various composition and structure on the catalytic properties of the supported vanadium oxide catalysts in the oxidative dehydrogenation of propane is studied. The introduction of magnesium in the samples and an increase in its content, accompanied by a change in the structure of the surface vanadium oxide phases from polymeric VO6/VO5 species to surface metavanadate species, magnesium metavanadate, and further to magnesium divanadate, significantly affects their catalytic properties in the reaction of the oxidative dehydrogenation of propane to propylene. 相似文献
5.
O. N. Krasnobaeva I. P. Belomestnykh T. A. Nosova D. F. Kondakov V. P. Danilov 《Russian Journal of Inorganic Chemistry》2018,63(11):1419-1423
Oxide catalyst samples for the oxidative dehydrogenation (ODH) of alkanes were prepared by heat treatment of precursors, namely, hydrotalcite-related magnesium aluminum double hydroxo salts containing ytterbium, as well as magnesium, aluminum, chromium, vanadium, molybdenum, and niobium in various combinations. Their catalytic activities were studied. Some catalysts were found to have high efficiency in ODH of ethane, propane, and isobutane, increasing the product yield and enhancing the reaction selectivity. 相似文献
6.
O. N. Krasnobaeva I. P. Belomestnykh T. A. Nosova D. F. Kondakov T. A. Elizarova V. P. Danilov 《Russian Journal of Inorganic Chemistry》2016,61(9):1074-1079
A method is developed to incorporate europium into Mg–Al hydrotalcites, which are precursors for oxide catalysts of oxidative dehydrogenation (ODH) of alkanes; samples of oxide catalysts are prepared, where europium oxide and gallium, magnesium, aluminum, chromium, vanadium, molybdenum, and niobium oxides are contained in various combinations. The catalytic properties of these catalysts in the reactions of ethane, propane, and butane ODH are studied. The incorporation of europium into some of our studied multicomponent catalysts enhances the reaction selectivity and increases yields of desired products. 相似文献
7.
O. N. Krasnobaeva I. P. Belomestnykh T. A. Nosova D. F. Kondakov T. A. Elizarova V. P. Danilov 《Russian Journal of Inorganic Chemistry》2017,62(7):879-885
A method is developed for incorporating praseodymium into magnesium–aluminum hydrotalcites, which are precursors for oxide catalysts for oxidative dehydrogenation (ODH) of alkanes. Oxide catalyst samples that contain praseodymium and various combinations of magnesium, aluminum, chromium, vanadium, molybdenum, and niobium are prepared. The catalytic properties of the prepared catalysts in ethane, propane, and butane ODH reactions are studied. Into some of our studied multicomponent catalysts, the incorporation of praseodymium enhances the reaction selectivity and increases yields of desired products. 相似文献
8.
Ray L. Frost Sara J. Palmer Laure-Marie Grand 《Journal of Thermal Analysis and Calorimetry》2010,101(3):859-863
Insight into the unique structure of layered double hydroxides (LDHs) has been obtained using a combination of X-ray diffraction and thermal analysis. Indium containing hydrotalcites of formula Mg4In2(CO3)(OH)12·4H2O (2:1 In-LDH) through to Mg8In2(CO3)(OH)18·4H2O (4:1 In-LDH) with variation in the Mg:In ratio have been successfully synthesised. The d(003) spacing varied from 7.83 Å for the 2:1 LDH to 8.15 Å for the 3:1 indium containing LDH. Distinct mass loss steps attributed to dehydration, dehydroxylation and decarbonation are observed for the indium containing hydrotalcite. Dehydration occurs over the temperature range ambient to 205 °C. Dehydroxylation takes place in a series of steps over the 238–277 °C temperature range. Decarbonation occurs between 763 and 795 °C. The dehydroxylation and decarbonation steps depend upon the Mg:In ratio. The formation of indium containing hydrotalcites and their thermal activation provides a method for the synthesis of indium oxide-based catalysts. 相似文献
9.
V. Rodríguez-González R. Gómez M. Moscosa-Santillan J. Amouroux 《Journal of Sol-Gel Science and Technology》2007,42(2):165-171
Platinum catalysts supported on indium-doped alumina were prepared by the sol–gel method. The method allows the incorporation
of In3+ in the alumina network. The indium-doped alumina supports showed narrow pore size distribution (5.4–4.0 nm) and high specific
surface areas (258–280 m2/g). The 27Al NMR-MAS spectroscopy identified aluminum in tetrahedral, pentahedral, and octahedral coordination; however, the intensity
of the signal assigned to aluminum in pentahedral coordination diminishes with the increase of the content of indium. Total
acidity determined by ammonia thermodesorption diminishes strongly in Pt/In–Al2O3 catalysts, suggesting a selective deposit of platinum over the acid sites of the support. The effect of the support in the
platinum catalytic activity was evaluated in the n-heptane dehydrocyclization reaction. The selectivity patterns for such reaction were modified substantially in the doped
Pt/In–Al2O3 catalysts, in comparison with the Pt-In/Al2O3–I coimpregnated reference catalyst. As an important result, the formation of benzene was suppressed totally over the indium-doped
alumina sol–gel supports with a high content (3 wt%) of indium. 相似文献
10.
The Pt/MgAlO x catalysts, in which a mixed aluminum–magnesium oxide obtained by the heat treatment of corresponding layered double hydroxides was used as a support, were studied. The effects of the nature of active-component precursors ([PtCl6]2–, [PtCl4]2–, and [Pt3(CO)6] 6 2- ), and the Mg/Al ratio in the support on the anchoring of complexes, the disperse state of platinum, and the properties of the obtained catalysts in the reactions of propane and n-decane dehydrogenation were found. 相似文献
11.
V. M. Bondareva E. V. Ishchenko T. Yu. Kardash A. V. Ishchenko G. A. Zenkovets V. I. Tropin V. I. Sobolev 《Russian Journal of Applied Chemistry》2017,90(7):1136-1142
Supported oxide catalysts of the overall composition V0.3Mo1Te0.23Nb0.12/nAl–Si–O (n = 0, 10, 25, 35, 50, and 70 wt %) were tested in oxidative dehydrogenation of ethane and were characterized by chemical analysis, X-ray diffraction analysis, and transmission electron microscopy. The use of the Al–Si–O support in a wide range of its content (from 10 to 50 wt %) favors formation of nanodomains of the active М1 phase ensuring higher, compared to the bulk catalysts, activity in oxidative dehydrogenation of ethane. The formation of secondary phases of aluminum molybdate and vanadium–molybdenum double oxide, observed at the support content increased over 35 wt %, leads to worsening of the catalytic properties. 相似文献
12.
13.
Oxidative dehydrogenation ofn-butane and propene has been studied on six Mg−Al−Fe oxide catalysts prepared by thermal decomposition of layered double hydroxides
with a hydrotalcite-like structure, possessing Mg2+ and Al3+ ions in the brucite-like layers, and hexacyanoferrate in the interlayers. In all cases, CO2 and H2O are formed, together with minor amounts of ethylene and methane. On the solids prepared from hexacyanoferrate(II), formation
of benzene is also observed. 相似文献
14.
D. T. Gokak A. G. Basrur D. Rajeswar G. S. Rao K. R. Krishnamurthy 《Reaction Kinetics and Catalysis Letters》1996,59(2):315-323
Four lithium metal precursors (LiNO3, CH3COOLi, LiOH, LiCl) have been used as promoters in Pt–Sn/Al2O3 catalysts to improve activity, selectivity and stability in a modeln-decane dehydrogenation reaction. Acidity, TPR and TPCO measurements have shown that the precursors affect the acid site distribution in the support, modify the reducibility and dispersity of Pt–Sn active species, coke lay-over patterns, stability and also selectivity for formation of monoolefins in the dehydrogenation ofn-decane. 相似文献
15.
The activity of samples containing indium in the selective catalytic reduction (SCR) of NO with C1-C4 hydrocarbons depends on nature of the carrier, Al2O3, ZrO2, the quantity of indium oxide, and the method of its introduction. The most active catalysts (2.5–5.0% In2O3/Al2O3) are stable to water and are characterized by a large overall concentration of oxide centers.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 2, pp. 107–111, March–April, 2007. 相似文献
16.
Mohamed Mustapha Bouhent Zoubir Derriche Renaud Denoyel Claude Forano 《Journal of solid state chemistry》2011,184(5):1016-15007
[Mg1−x Alx(OH)2][(NO3)x, nH2O] Layered Double Hydroxide (LDH) sorbents with variable Mg/Al molar (R=(1−x)/x) ratios were investigated for adsorption of azo dye, orange II (OII) at various pH and temperature conditions. Mg2AlNO3 displays the highest adsorption capacity with 3.611 mmol of OII per gram of Mg2AlNO3 at 40 °C. Adsorption isotherms have been fitted using the Langmuir model and free energy of adsorption (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated. The experimental values for ΔG° in temperature range between 10 and 40 °C were found to be negative indicating that a spontaneous process occurred. Positive calculated enthalpy values, characteristic of an endothermic process were found. Characterization of solids (PXRD, FTIR, UV-vis, TGA/DTA, adsorption isotherm BET analysis, SEM and Zetametry) before and after adsorption showed that adsorption proceeds in two steps. First, adsorption occurs at the LDH surface, followed by intercalation via anion exchange. 相似文献
17.
O. N. Krasnobaeva I. P. Belomestnykh G. V. Isagulyants T. A. Nosova T. A. Elizarova D. F. Kondakov V. P. Danilov 《Russian Journal of Inorganic Chemistry》2008,53(8):1176-1181
Methods are developed for the synthesis of precursors for oxide catalysts containing iron hydroxocarbonate and magnesium aluminum hydroxocarbonate with hydrotalcite-type layered structure and decavanadate and paramolybdate ions in anionic interlayers. These precursors are used to synthesize oxide catalysts for oxidative dehydrogenation of alcohols and alkanes with high selectivity and good yields of the desired product in conversion of ethane to ethylene and alcohols to carbonyl compounds. 相似文献
18.
O. N. Krasnobaeva I. P. Belomestnykh T. A. Nosova T. A. Elizarova G. V. Isagulyants V. P. Danilov 《Russian Journal of Inorganic Chemistry》2012,57(12):1540-1544
A method of doping magnesium aluminum hydrotalcites, which are precursors for oxidative dehydrogenation oxide catalysts of various compositions, with copper(II) was developed, and copper(II)-containing oxide catalyst samples were synthesized. The catalytic properties of these catalysts were studied in the oxidative dehydrogenation of ethane, propane, and hexane. The conversion of ethane into ethylene on the copper-containing catalysts was established to proceed with high selectivities (90?C97%) and at low temperatures (400?C450°C). 相似文献
19.
O. N. Krasnobaeva I. P. Belomestnykh G. V. Isagulyants T. A. Nosova T. A. Elizarova T. D. Teplyakova D. F. Kondakov V. P. Danilov 《Russian Journal of Inorganic Chemistry》2007,52(2):141-146
Synthesis methods have been developed for the precursors of oxide catalysts that include the combination of magnesium nickel cobalt aluminum hydroxocarbonate, with a layered hydrotalcite-type structure and decavanadate and paramolybdate ions in the anion layers, and bismuth hydroxocarbonate. On the base of these precursors, multicomponent oxide catalysts have been manufactured for the oxidative dehydrogenation (OD) of light alkanes. Some of these catalysts showed high selectivities and high product yields in the conversion of ethane to ethylene. 相似文献
20.
Viktor Hlukhyy 《Journal of solid state chemistry》2005,178(1):79-84
Phase analytical investigations in the system magnesium-iridium-indium revealed the magnesium-rich intermetallics Ir3.30(1)Mg17.96(4)In0.74(4) and Ir3Mg17.1(1)In1.9(1). The samples were prepared from the elements via induction melting in glassy carbon crucibles in a water-cooled sample chamber and subsequent annealing. Both intermetallics were investigated by X-ray powder and single-crystal diffraction: C2/c, Z=4, a=979.1(1), b=2197.4(2), , β=105.79(1)°, wR2=0.0434, 3076 F2 values, 108 variables for Ir3.30(1)Mg17.96(4)In0.74(4), and a=983.39(8), b=2211.4(2), , β=105.757(6)°, wR2=0.0487, 3893 F2 values, and 115 variables for Ir3Mg17.1(1)In1.9(1). Both compounds show solid solutions. In Ir3.30(1)Mg17.96(4)In0.74(4), the indium site shows an occupancy by 69.9(4)% In+30.1(4)% Ir, and one magnesium site has a small mixed occupancy with indium, while nine atomic sites in Ir3Mg17.1(1)In1.9(1) show Mg/In mixing with indium occupancies between 1.2(3)% and 14.8(3)%. The relatively complex crystal structure is of a new type. It can be explained by a packing of coordination number 10 and 12 polyhedra around the iridium atoms. The crystal chemical peculiarities and chemical bonding in both intermetallics is briefly discussed. 相似文献