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1.
A series of MoO3/ZrO2–Al2O3 catalysts was prepared and investigated in the sulfur-resistant methanation aimed at production of synthetic natural gas. Different methods including impregnation, deposition precipitation, and co-precipitation were used for preparing ZrO2–Al2O3 composite supports. These composite supports and their corresponding Mo-based catalysts were investigated in the sulfur-resistant methanation, and characterized by N2 adsorption–desorption, XRD and H2-TPR. The results indicated that adding ZrO2 promoted MoO3dispersion and decreased the interaction between Mo species and support in the MoO3/ZrO2–Al2O3 catalysts. The co-precipitation method was favorable for obtaining smaller ZrO2 particle size and improving textural properties of support, such as better MoO3 dispersion and increased concentration of Mo6+ species in octahedral coordination to oxygen. It was found that the MoO3/ZrO2–Al2O3 catalyst with ZrO2Al2O3 composite support prepared by co-precipitation method exhibited the best catalytic activity. The ZrO2 content in the ZrO2Al2O3 composite support was further optimized. The MoO3/ZrO2–Al2O3 with 15 wt % ZrO2 loading exhibited the highest sulfur-resistant CO methanation activity, and excess ZrO2 reduced the specific surface area and enhanced the interaction between Mo species and support. The N2 adsorption-desorption results indicated that the presence of ZrO2 in excessive amounts decreased the specific surface area since some amounts of ZrO2 form aggregates on the surface of the support. The XRD and H2-TPR results showed that with the increasing ZrO2 content, ZrO2 particle size increased. These led to the formation of coordinated tetrahedrally Mo6+(T) species and crystalline MoO3, and this development was unfavorable for improving the sulfur-resistant methanation performance of MoO3/ZrO2–Al2O3 catalyst. 相似文献
2.
A series of MoO3/γ-Al2O3 catalysts with different Mo surface densities (Mo atoms/nm2) has been prepared by incipient wetness impregnation method. Structural characteristics of the prepared catalysts were investigated
by atomic absorption spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy, N2 adsorption at −196 °C, and temperature-programmed reduction (TPR). The catalytic activities of the prepared catalysts were
tested by cyclohexene conversion between 200 and 400 °C. XRD results indicated that molybdenum oxide species were dispersed
as a monolayer on the support up to 4.04 Mo atoms/nm2, and the formation of crystalline MoO3 was observed above this loading. FTIR and TPR results showed that molybdenum oxide species were present predominantly in
tetrahedral form at lower loading, and polymeric octahedral forms were dominant at higher loading. Cyclohexene conversion
reaction proceeded mainly through the simple dehydrogenation pathway in the studied temperature range 200–400 °C and was found
to be highly dependent on MoO3 dispersion. 相似文献
3.
A. O. Turakulova A. N. Kharlanov A. V. Levanov O. Ya. Isaikina V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(1):17-25
Ce0.46Zr0.54O2 solid solution prepared using a cellulose template was employed as a carrier for vanadium catalysts of the oxidative dehydrogenation of propane. The properties of VO х /Ce0.46Zr0.54O2 catalyst (5 wt % vanadium) are compared with the properties of the neat support. The carrier and catalyst are studied by means of BET, SEM, DTA, XRD, and Raman spectroscopy. It is shown that the CeVO4 phase responsible for the ODH process is formed upon interaction between vanadate ions and cerium ions on the surface of the solid solution. The catalytic properties of the catalyst and the support are studied in the propane oxidation reaction at temperatures of 450 and 500°C with pulse feeding of the reagent. It is found that the complete oxidation of propane occurs on the support with formation of CO2 and H2O. Three products (propene, CO2, and H2O) form in the presence of the vanadium catalyst. It is suggested that there are two types of catalytic centers on the catalyst’s surface. It is concluded that the centers responsible for the complete oxidation of propane are concentrated mainly on the carrier, while the centers responsible for propane ODH are on the CeVO4. 相似文献
4.
Fenglin Huang Canchang Chen Fan Wang Bing Wang Lulu Zhang Suhong Lu Kelun Li 《Catalysis Surveys from Asia》2017,21(3):143-149
The effect of calcination temperature (350–650?°C) on the structure and catalytic activity of Co3O4–CeO2 mixed oxides prepared by sol–gel method was investigated by XRD, H2-TPR, O2-TPD and formaldehyde (HCHO) oxidation. The Co3O4–CeO2 calcined at 450?°C (Co3O4–CeO2-450) exhibited the best performance, showing that the complete oxidation of HCHO was achieved at temperature as low as 80?°C. The results of characterizations revealed that the Co3O4–CeO2-450 had excellent catalytic activity due to the larger specific surface area, the best reducibility and more abundant surface active oxygen species. 相似文献
5.
P. P. Fedorov V. K. Goncharuk I. G. Maslennikova I. A. Telin T. Yu. Glazunova 《Russian Journal of Inorganic Chemistry》2016,61(2):239-242
A phase diagram of the PbF2–SnF2 system has been studied by differential thermal analysis and X-ray powder diffraction. The system forms Pb1–хSnхF2 (х ≤ 0.33) solid solution and three compounds. Pb2SnF6 decomposes in solid state by a peritectoid reaction at 350°С; Pb3Sn2F10 and PbSnF4 melt by peritectic reactions at 565 and 380°С, respectively. The eutectic coordinates are 180°С, 90 mol % SnF2. 相似文献
6.
D. N. Titov A. V. Ustyugov O. P. Tkachenko L. M. Kustov Ya. V. Zubavichus A. A. Veligzhanin N. V. Sadovskaya I. V. Oshanina L. G. Bruk O. N. Temkin 《Kinetics and Catalysis》2012,53(2):262-273
The state of the active constituents of the freshly prepared PdCl2-CuCl2/γ-Al2O3 catalyst for the low-temperature oxidation of the carbon monoxide by molecular oxygen was studied by X-ray absorption spectroscopy
(XAS), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance IR Fourier transform spectroscopy
(DRIFTS). It was shown that copper in the form of a crystalline phase of Cu2Cl(OH)3 with the structure of the mineral paratacamite and palladium chloride in an amorphous state occurred on the surface of γ-Al2O3. According to XAS data, the local environment of palladium consisted of four chlorine atoms, which formed a flat square with
an increased distance between palladium and one of the chlorine atoms. The evolution of the local environments of copper and
palladium upon a transition from the initial salts to the impregnating solutions and chlorides on the surface of γ-Al2O3 was considered. The role of γ-Al2O3 in the formation of the Cu2Cl(OH)3 phase was discussed. It was found by the DRIFTS method that linear (2114 cm−1) and bridging (1990 and 1928 cm−1) forms of coordinated carbon monoxide were formed upon the adsorption of CO on the catalyst surface. The formation of CO2 upon the interaction of coordinated CO with atmospheric oxygen was detected. Active sites including copper and palladium
were absent from the surface of the freshly prepared catalyst. 相似文献
7.
8.
L. B. Serezhkina E. V. Peresypkina A. V. Virovets I. V. Medrish D. V. Pushkin 《Russian Journal of Inorganic Chemistry》2009,54(10):1577-1580
Single crystals of Cs[(UO2)2(C2O4)2(OH)] · H2O were synthesized and structurally studied using X-ray diffraction. The compound crystallizes in monoclinic space group P21/m, Z = 2, with the unit cell parameters a = 5.5032(4) Å, b = 13.5577(8) Å, c = 9.5859(8) Å, β = 97.012(3)°, V = 709.86(9) Å3, R = 0.0444. The main building units of crystals are [(UO2)2(C2O4)2(OH)]? layers of the A2K 2 02 M2 (A = UO 2 2+ , K02 = C2O 4 2? , and M2 = OH?) crystal-chemical family. Uranium-containing layers are linked into a three-dimensional framework via electrostatic interactions with outer-sphere cations and hydrogen bonds with water molecules. 相似文献
9.
Zh. V. Akhmerkina E. V. Peresypkina A. V. Virovets L. B. Serezhkina 《Russian Journal of Inorganic Chemistry》2008,53(9):1396-1400
Single crystals of Ba3[UO2(C2O4)2(NCS)]2 · 9H2O are synthesized and studied by X-ray diffraction. The crystals are orthorhombic, space group Fddd, Z = 16, and the unit cell parameters are a = 16.253(3) Å, b = 22.245(3) Å, c = 39.031(6) Å. The main crystal structural units are mononuclear complex groups [UO2(C2O4)2NCS]3? of the crystal-chemical family (AB 2 01 M1 (A = UO 2 2+ , B01 = C2O 4 2? , M1 = NCS?) of the uranyl complexes linked into a three-dimensional framework by electrostatic interactions and hydrogen bonds involving oxalate ions and water molecules. 相似文献
10.
E. A. Il’inchik T. M. Polyanskaya K. G. Myakishev 《Russian Journal of General Chemistry》2007,77(7):1148-1154
The structure of tri-μ2-disulfido-μ3-thiotris(diethyldithiocarbamato)-S,S′-triangle-trimolybdenum iodide [Mo3(μ3-S)(μ2-S2)3(Et2NCS2)3]I was determined. The compound was characterized by differential thermal analysis and IR, Raman, and X-ray electronic spectroscopy. 相似文献
11.
K. S. Kislitsina N. A. Shchadneva R. I. Khusnutdinov 《Russian Journal of Organic Chemistry》2018,54(7):992-995
The system hydrogen peroxide–hexafluoroacetone sesquihydrate effectively oxidizes adamantane in the presence of VO(acac)2 to afford 64% of adamantan-1-ol in tert-butyl alcohol or 76% of adamantan-2-one in a mixture of acetic acid with pyridine. 相似文献
12.
P. N. Bourosh O. A. Bologa M. Gdaniec Yu. A. Simonov N. V. Gerbeleu 《Journal of Structural Chemistry》2005,46(3):488-493
A new Co(III) complex of 1,2-cyclohexanedionedioxime and thiocarbamide with an SO 4 2? anion and solvation water molecules in the outer sphere has been synthesized and its structure has been defined. Orthorhombic crystals, a = 11.659(2) Å, b = 26.448(5) Å, c = 30.142(6) Å, V = 9295(3) Å 3, Z = 8, dcalc = 1.599 g/cm3, space group Pbca; final R index is 0.0578 for 8221 reflections with I > 2σ(I). In the octahedral Co(III) complex, two 1,2-cyclohexanedionedioxime residues lie in the equatorial plane, while two thiocarbamide molecules are in the axial plane. Intramolecular bonds: N-H…O and O-H…O type hydrogen bonds and π-π interactions that stabilize the complex cations. In crystal, the components are linked by N-H…O and O-H…O hydrogen bonds into a 3D framework. 相似文献
13.
V. N. Serezhkin A. G. Verevkin O. P. Smirnov V. P. Plakhtii 《Russian Journal of Inorganic Chemistry》2010,55(10):1600-1606
A powder of deuterated rubidium diselenatouranylate dihydrate Rb2UO2(SeO4)2 · 2D2O has been studied by neutron diffraction. The compound is orthorhombic, space group Pna21, with the following unit cell parameters: a = 13.654(2) Å, b = 11.863(2) Å, c = 7.625(1) Å, Z = 4, R F = 3.77, R I = 6.12, and χ2 = 2.21. Basic structure units are [UO2(SeO4)2 · D2O]2? layers belonging to the AB 2 2 M1 crystal-chemical group (A = UO 2 2+ , B2 = SeO 4 2? , M1 = D2O) of uranyl complexes. The hydrogen atoms if the water molecules involved in the layer form intralayer hydrogen bonds with the terminal oxygen atoms of selenate ions. The outer-sphere water molecules are coordinated to the rubidium ions and are involved in hydrogen bonding with oxygen atoms of neighboring [UO2(SeO4)2 · D2O]2? layers. 相似文献
14.
A. I. Klyndyuk E. A. Tugova O. N. Karpov E. A. Chizhova M. V. Tomkovich V. M. Kononovich 《Russian Journal of General Chemistry》2016,86(10):2282-2287
The sequence of phases appearance during the formation of Bi1–xNdxFeO3 solid solutions in powder oxides mixtures of bismuth, neodymium, and iron has been determined. It has been shown that the closeness of the reaction mixture composition to that of the individual compound (BiFeO3 or NdFeO3) is essential for the realization of the series of phase transformations yielding solid solutions of multiferroics Bi1–xNdxFeO3 as the final product, due to the prevalence of various interphase contacts in the starting reaction zone. 相似文献
15.
R. F. Samigullina M. V. Rotermel I. V. Nikolaenko T. I. Krasnenko 《Russian Journal of Inorganic Chemistry》2016,61(2):156-160
Phase equilibria were studied in the Nb2O5–CdO system in the Nb2O5-rich region including CdNb2O6 and Cd2Nb2O7. It was determined that CdNb2O6 and Cd2Nb2O7 in air are stable to 1150 and 1120°C, respectively, and that, above these temperatures, there is solid-phase decomposition of niobates with CdO release in the gas phase. Along with the cadmium oxide evaporation, the Cd2Nb2O7 decomposition is accompanied by the formation of cadmium metaniobate CdNb2O6 and the CdNb2O6 decomposition results in the formation of niobium oxide Nb2O5. No thermal events were observed in the differential thermal analysis curve for a 1: 1 CdNb2O6–Cd2Nb2O7 mixture heated to 1100°C in air, which suggests that there are neither phase transformations in cadmium niobates, nor a eutectic within this temperature and concentration ranges. A study of the morphology of compacted samples of niobates determined specific conditions for producing dense composite ceramics, a mixture of niobates, that is suitable for using as a dielectric material. 相似文献
16.
Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates.
These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC2O4 as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite
Na2Cu2+(C2O4)2·2H2O.
High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two
higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and
857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison
the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost
at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II)
oxalate as compared to the synthetic compound which is the dihydrate. 相似文献
17.
B. Li Y. Y. Wang W. Q. Luo Y. H. Zhang 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(3):1619-1625
Radiation-induced degradation of the weakly and strongly 4-vinylpyridine basic ion exchange resins by gamma radiolysis was investigated in the presence of air and liquid water. This study is focused on evaluating the radiolytic gases (H2, CO, CO2 and CH4) and liquid products (water-solute TOC and NH4 +). The weakly basic resin yielded lower amounts of H2 and CO and higher amounts of CO2 than those of the strongly basic resin. Moreover, the strong basic resin tended to yield greater amounts of NH4 +. Resins were characterized by the FTIR spectroscopy technique and the results showed that the resins structures are relatively stable. 相似文献
18.
I. V. Medrish E. V. Peresypkina A. V. Virovets L. B. Serezhkina 《Russian Journal of Coordination Chemistry》2008,34(8):629-634
The single crystals of Rb2[(UO2)2(C2O4)2(SeO4)] · 1.33H2O were synthesized and studied by X-ray diffraction. The crystals are monoclinic, space group P21/m, Z= 2, the unit cell parameters: a = 5.6537(8), b = 18.736(3), c = 9.4535(15) Å, β = 98.440(5)°, V = 990.6(3) Å3, R 1 = 0.0506. The main structural units of the crystal are infinite layers of [(UO2)2(C2O4)2(SeO4)]2?, corresponding to the crystal chemical group A2K 2 02 B2 (A = UO 2 2+ , K02 = C2O 4 2? , B2 = SeO 4 2? ) of uranyl complexes. The uranium-containing layers are united into a three-dimensional framework through the electrostatic interactions with the outer-sphere rubidium ions and the hydrogen bonding system involving the outer-sphere water molecules. 相似文献
19.
P. S. Gordienko A. P. Suponina S. B. Yarusova S. B. Bulanova G. F. Krysenko V. A. Kolzunov 《Russian Journal of Applied Chemistry》2009,82(9):1505-1509
The possibility and kinetic aspects of formation of X-ray amorphous calcium monosilicate in the model system CaSO4·2H2O-Na2O·SiO2 at room temperature were studied. 相似文献
20.
Yu. E. Lebedeva N. V. Popovich L. A. Orlova A. S. Chainikova O. Yu. Sorokin M. L. Vaganova D. V. Grashchenkov 《Russian Journal of Inorganic Chemistry》2017,62(8):1032-1037
The effects caused by modifying additives, namely nonionic surfactants (Tween 80 and Neonol AF 9-6) and oxides (B2O3 and HfO2), on the rheology, film formation, and phase formation in the yttrium aluminum silicate system prepared by sol–gel technology were studied. The effect of 1 wt % HfO2 additions on the activation energy of crystallization was studied. 相似文献