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1.
Five cationic transition metal (ethylenediamine) complexes (M=Cr(III), Co(III), Ni(II), and Cu(II)):paramolybdate anion (Mo 7O 246−) have been synthesis and characterized via their elemental analysis, magnetic susceptibility ( μeff), thermal analysis (TG and DTA), FTIR spectra, and X-ray diffraction (XRD). The FTIR study suggests that the compounds prepared be of the ion-pair type ([M(en) n] m·Mo 7O 24). Thermal study showed that molybdenum in the Cr(III), and Co(III) compounds is reduced from oxidation state (VI) to (V) at high temperature. The stoichiometries of the resulting mixed oxides at elevated temperatures (500–750°C) are: Cr 2O 3·7MoO 2.5, Co 2O 3·7MoO 2.5, 6CoOCl·7MoO 2.5, 3NiO·7MoO 3 and 3CuO·7MoO 3. Above 750°C the molybdenum oxide in the ion-pair compounds start the sublimation process. X-ray diffraction of [Cr(en) 3]·Mo 7O 24, [Co(en) 3]·Mo 7O 24, and [Cu(en) 2(H 2O) 2] 3·Mo 7O 24 shows that these complexes are crystalline solids with a similar structure, while the [Ni(en)(H 2O) 4] 3·Mo 7O 24, and [Co(en)(H 2O) 2Cl 2] 6·Mo 7O 24 ion-pair compounds display a different structure. A novel technique based on photocatalysis to eliminate Cr(VI) ions, a toxic pollutant in the environment, was applied. The photoreduction of Cr(VI) to Cr(III) ion in aqueous suspensions using new-mixed oxides as photocatalysts (Cr2O3·MoO2.5, Co2O3·MoO2.5, NiO·MoO3, and CuO·MoO3) under air-equilibration and irradiation by a medium pressure mercury lamp (UV–VIS) was investigated. 相似文献
2.
The effect of oxygen concentration on the pulse and steady-state selective catalytic reduction (SCR) of NO with C 3H 6 over CuO/γ-Al 2O 3 has been studied by infrared spectroscopy (IR) coupled with mass spectroscopy studies. IR studies revealed that the pulse SCR occurred via (i) the oxidation of Cu 0/Cu + to Cu 2+ by NO and O 2, (ii) the co-adsorption of NO/NO 2/O 2 to produce Cu 2+(NO 3−) 2, and (iii) the reaction of Cu 2+(NO 3−) 2 with C 3H 6 to produce N 2, CO 2, and H 2O. Increasing the O 2/NO ratio from 25.0 to 83.4 promotes the formation of NO 2 from gas phase oxidation of NO, resulting in a reactant mixture of NO/NO 2/O 2. This reactant mixture allows the formation of Cu 2+(NO 3−) 2 and its reaction with the C 3H 6 to occur at a higher rate with a higher selectivity toward N 2 than the low O 2/NO flow. Both the high and low O 2/NO steady-state SCR reactions follow the same pathway, proceeding via adsorbed C 3H 7---NO 2, C 3H 7---ONO, CH 3COO −, Cu 0---CN, and Cu +---NCO intermediates toward N 2, CO 2, and H 2O products. High O 2 concentration in the high O 2/NO SCR accelerates both the formation and destruction of adsorbates, resulting in their intensities similar to the low O 2/NO SCR at 523–698 K. High O 2 concentration in the reactant mixture resulted in a higher rate of destruction of the intermediates than low O 2 concentration at temperatures above 723 K. 相似文献
3.
Gold loaded on TiO 2 (Au/TiO 2) catalysts were prepared using Au(I)–thiosulfate complex (Au(S 2O 3) 23−) as the gold precursor for the first time. The samples were characterized by UV–vis diffuse reflectance spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), and X-ray photoelectron spectroscopy (XPS) methods. Using Au(S 2O 3) 23− as gold precursor, ultra-fine gold nanoparticles with a highly disperse state can be successfully formed on the surface of TiO 2. The diameter of Au nanoparticles increases from 1.8 to 3.0 nm with increasing the nominal Au loading from 1% to 8%. The photocatalytic activity of Au/TiO 2 catalysts was evaluated from the analysis of the photodegradation of methyl orange (MO). With the similar Au loading, the catalysts prepared with Au(S 2O 3) 23− precursor exhibit higher photocatalytic activity for methyl orange degradation when compared with the Au/TiO 2 catalysts prepared with the methods of deposition–precipitation (DP) and impregnation (IMP). The preparation method has decisive influences on the morphology, size and number of Au nanoparticles loaded on the surface of TiO 2 and further affects the photocatalytic activity of the obtained catalysts. 相似文献
4.
This work deals with poly(ethylene oxide), PEO–MX (M=Li, K and Cs) amorphous electrolytes with −X–X −, [CF 3SO 2NCH 2(CH 2OCH 2) 2CH 2NSO 2CF 3] 2− (EDSA) and [CF 3SO 2NCH 2CH 2(CH 2OCH 2) 3CH 2CH 2NSO 2CF 3] 2− (TTSA) disulfonamide anions. These dianions have X − end-groups identical to anions [CF 3SO 2N(CH 2) 2OCH 3] − (MESA) and [CF 3SO 2N(CH 2) 3OCH 3] − (MPSA), one of which (MPSA) was reported to yield chelate-like associated species (presumably LiX 2− triplets) at concentrations above EO/Li=20 in PEO. This feature of LiMPSA, evidenced through glass transition temperature ( Tg) measurements, does not apply to Li 2EDSA and Li 2TTSA. Though none of these lithium salts form crystalline intermediate compounds with PEO, the limit of solubility of LiMESA (EO/Li=16) does not allow a clarification of this point for this salt. At lower concentrations, however, a conductivity comparison with the potassium and caesium salts shows that the apparent degree of dissociation ( = CLi+/ CLi) of LiMESA is comparable to that of LiMPSA. As opposed to both these salts and to some extent to Li 2EDSA, a much greater dissociation takes place for Li 2TTSA, the anion of which contains an inner, third ether group in its structure. 相似文献
5.
Iron(III) protoporphyrin IX (Fe(III)P), adsorbed either on single-walled carbon nanotubes (SWCNT) or on hydroxyl-functionalized SWCNT (SWCNT-OH), was incorporated within a Nafion matrix immobilized on the surface of a graphite electrode. From cyclic voltammetric measurements, performed under different experimental conditions (pH and potential scan rate), it was established that the Fe(III)P/Fe(II)P redox couple involves 1e −/1H +. The heterogeneous electron transfer process occurred faster when Fe(III)P was adsorbed on SWCNT-OH (11 s −1) than on SWCNT (4.9 s −1). Both the SWCNT-Fe(III)P- and SWCNT-OH-Fe(III)P-modified graphite electrodes exhibit electrocatalytic activity for H 2O 2 and nitrite reduction. The modified electrodes sensitivities were found varying in the following sequences: SSWCNT-OH-Fe(III)P = 2.45 mA/M ≈ SSWCNT-Fe(III)P = 2.95 mA/M > SFe(III)P = 1.34 mA/M for H 2O 2, and SSWCNT-Fe(III)P = 3.54 mA/M > SFe(III)P = 1.44 mA/M > SSWCNT-OH-Fe(III)P = 0.81 mA/M for NO 2−. 相似文献
6.
Pulse reaction method and in situ IR spectroscopy were used to characterize the active oxygen species for oxidative coupling of methane (OCM) over SrF 2/Nd 2O 3 catalyst. It was found that OCM activity of the catalyst was very low in the absence of gas phase oxygen, which indicated that lattice oxygen species contributed little to the yield of C 2 hydrocarbons. IR band of superoxide species (O 2−) was detected on the O 2-preadsorbed SrF 2/Nd 2O 3. The substitution of 18O 2 isotope for 16O 2 caused the IR band of O 2− at 1128 cm −1 to shift to lower wavenumbers (1094 and 1062 cm −1), consistent with the assignment of the spectra to the O 2− species. A good correlation between the rate of disappearance of surface O 2− and the rate of formation of gas phase C 2H 4 was observed upon interaction of CH 4 with O 2-preadsorbed catalyst at 700 °C. The O 2− species was also observed on the catalyst under working condition. These results suggest that O 2− species is the active oxygen species for OCM reaction on SrF 2/Nd 2O 3 catalyst. 相似文献
7.
N 2O 5 reacts with O 2− ion in LiCl---KCl eutectic at 450° to give NO 3−. By analogy to the salts of the other oxides of Group V, NO 3− can be considered as metanitrate and is expected to give—under appropriate conditions—the corresponding pyro-salt. Experiments are described in which the O 2− ion in LiCl---KCl melt is potentiometrically titrated with KNO 3. The titration curves show an inflexion at the composition corresponding to pyronitrate, N 2O 74−. The formation of pyronitrate in KNO3 melts is also established. Strong oxide-ion donors, eg Na2O2 or NaOH, or electrolytically generated O2− ion, react slowly with the melt to produce a compound of less basic character. The reaction is zero-order with respect to O2− and has an activation energy of ca 6·17 Kcal/mole. Pyronitrate in molten KNO3 possesses a basicity comparable to that of the carbonate ion in the same melt. It readily lends its oxide ion to strong acids eg, Cr2O72− and PO3−. X-ray diffraction patterns of NO3−-N2O74− mixtures show peaks that can be correlated to the new anion. 相似文献
8.
Human health is deteriorating due to the effluent containing heavy metal ions and organic dyes. Hence, photoreduction of Cr(VI) to Cr(III) and degradation of rhodamine B (RhB) using a novel photocatalyst is particularly important. In this work, h-BN/NiS 2/NiS composites were prepared via a simple solvothermal method and a double Z-scheme heterojunction was constructed for efficiently removing RhB and Cr(VI). The 7 wt-% h-BN/NiS 2/NiS composites were characterized via a larger specific surface area (15.12 m 2·g –1), stronger light absorption capacity, excellent chemical stability, and high yield of electrons and holes. The experimental result indicated that the photoreduction efficiency of the 7 wt-% h-BN/NiS 2/NiS photocatalyst achieved 98.5% for Cr(VI) after 120 min, which was about 3 times higher than that of NiS 2/NiS (34%). However, the removal rate of RhB by the 7 wt-% h-BN/NiS 2/NiS photocatalyst reached 80%. This is due to the double Z-scheme heterojunction formed between NiS 2/NiS and h-BN, which improved the charge separation efficiency and transmission efficiency. Besides, the influence of diverse photogenerated electron and hole scavengers upon the photoreduction of Cr(VI) was studied, the results indicated that graphene-like h-BN promoted transportation of photoinduced charges on the surface of the h-BN/NiS 2/NiS photocatalyst via the interfacial effects. 相似文献
9.
Nanoparticles of Ce xZr 1−xO 2 ( x = 0.75, 0.62) were prepared by the oxidation-coprecipitation method using H 2O 2 as an oxidant, and characterized by N 2 adsorption, XRD and H 2-TPR. Ce xZr 1−xO 2 prepared had single fluorite cubic structure, good thermal stability and reduction property. With the increasing of Ce/Zr ratio, the surface area of Ce xZr 1−xO 2 increased, but thermal stability of Ce xZr 1−xO 2 decreased. The surface area of Ce 0.62Zr 0.38O 2 was 41.2 m 2/g after calcination in air at 900 °C for 6 h. TPR results showed the formation of solid solution promoted the reduction of CeO 2, and the reduction properties of Ce xZr 1−xO 2 were enhanced by the cycle of TPR-reoxidation. The Pd-only three-way catalysts (TWC) were prepared by the impregnation method, in which Ce 0.75Zr 0.25O 2 was used as the active washcoat and Pd loading was 0.7 g/L. In the test of Air/Fuel, the conversion of C 3H 8 was close to 100% and NO was completely converted at λ < 1.025. The high conversion of C 3H 8 was induced by the steam reform and dissociation adsorption reaction of C 3H 8. Pd-only catalyst using Ce 0.75Zr 0.25O 2 as active washcoat showed high light off activity, the reaction temperatures ( T50) of 50% conversion of CO, C 3H 8 and NO were 180, 200 and 205 °C, respectively. However, the conversions of C 3H 8 and NO showed oscillation with continuously increasing the reaction temperature. The presence of La 2O 3 in washcoat decreased the light off activity and suppressed the oscillation of C 3H 8 and NO conversion. After being aged at 900 °C for 4 h, the operation windows of catalysts shifted slightly to rich burn. The presence of La 2O 3 in active washcoat can enhance the thermal stability of catalyst significantly. 相似文献
10.
Layered double hydroxides (LDHs) containing Mg 2+ and Al 3+ in the basic layers and NO −3 as an interlayer anion were synthesized by the method of coprecipitation (pH 10). By changing the Mg 2+/Al 3+ ratio (1.5–4.5), the charge density on the (NO 3)–MgAl–LDH sheets was varied. After pillaring with Fe(CN) 3−6, which was based on an anion exchange process, the interlayer space became accessible. This was reflected in the large created surface areas and micropore volumes. The applied models for the calculation of the micropore size distributions (Maes–Zhu–Vansant and Horvath–Kawazoe) gave matching results, revealing narrow distributions for all the samples, with the majority of the pores smaller than 0.71 nm. A correlation was found between the Mg 2+/Al 3+ ratio and the resulting microporosity after pillaring. The optimal ratio was situated around 3.3, resulting in a pillared [Fe(CN) 6]–MgAl–LDH with a Langmuir surface area of 499 m 2/g and a micropore volume between 0.158 ml/g (μPV min) and 0.177 ml/g (μPV max). As an alternative, direct coprecipitation of the pillared LDHs was evaluated. This one-step mechanism proved to be a method producing similar results. Taking all this into consideration, one can conclude that hexacyanoferrate(III) complexes form ideal anionic pillars for the creation of microporous layered double hydroxides. 相似文献
11.
Three compounds, K 2(H 2O) 4H 2SiMo 12O 40 · 7H 2O (1), K 2Na 2(H 2O) 4SiW 12O 40 · 4H 2O (2), and Na 4(H 2O) 8SiMo 12O 40 · 6H 2O (3) have been synthesized and structurally characterized by single-crystal X-ray analysis, IR, and thermogravimetry. Compounds 1 and 2 both show the high symmetry trigonal space group P3 221 and a novel 3D network structure. The Keggin anions [SiM 12O 40] 4−(M = Mo, W) are linked by potassium or sodium cations to generate hexagon-shaped channels along the c-axis, in which water molecules are accommodated. Compound 3 is tetragonal, space group P4/mnc constructed from [SiMo 12O 40] 4− anions and Na ions. 相似文献
12.
Hydroxyapatite (Ca 10(PO 4) 6(OH) 2: HAP) was co-substituted with Ti(IV) and antibacterial ions (Ag +, Cu 2+ or Zn 2+) (HAPTiM), by coprecipitation and ion-exchange methods. Both HAPTiAg and HAPTiCu coated on porous spumous nickel film showed high efficiency for killing Escherichia coli and Staphylococcus aureus in the dark and under weak UVA irradiation, respectively. Moreover, their bactericidal activities were much higher than that of P25-TiO 2 film. The studies of ESR revealed that not only O 2− was formed on HAPTiM, HAPTi, HAP and P25-TiO 2 films under weak UVA irradiation, but also at ambient temperature without light O 2− was generated on HAPTiCu, HAPTiAg, and HAPTi. The redox couples of Cu 0/Cu 2+ and Ag 0/Ag + in the structure of HAPTiCu (Ag) caused the transfer of electron leading to the O 2− generation under the above conditions. The higher bactericidal activities of HAPTiM were due to the synergy of the oxidation role of the O 2− and the bacteriostatic action of antibacterial ions. The process of the damage of the cell wall and the cell membrane was directly observed by TEM, and further confirmed by the determination of potassium ion (K +) leakage from the killed bacteria. 相似文献
13.
The adsorption of N 2 on a copper ion-exchanged ZSM-5 sample (CuZSM-5) prepared by ion exchange using an aqueous solution of copper propionate, Cu(C 2H 5COO) 2, was examined at room temperature by measuring the FT-IR spectra, adsorption isotherms and heat of adsorption. This sample was found to be extremely efficient in terms of N 2 adsorption with regard to both the amount and the energy (i.e., heat) of adsorption, compared with samples prepared by a conventional ion-exchange method using an aqueous solution involving Cu 2+ and simple counter ions, Cl − or NO 3−. To clarify the specificity of the newly-prepared sample, the ion-exchange of ZSM-5 with Cu 2+ was carried out by employing aqueous solutions involving Cu 2+ and various types of counter ions [propionate (C 2H 5COO −), acetate (CH 3COO −), formate (HCOO −), chloride (Cl −) and nitrate (NO 3−) ions]. When the ion exchange was performed by using a Cu(C 2H 5COO) 2 or Cu(CH 3COO) 2 solution, the Cu 2+ species with propionate or acetate ligand (in the monomer state) were ion-exchanged in ZSM-5, as confirmed by the DR, EPR and FT-IR spectra for CuZSM-5. In contrast, Cu 2+ species were present in the form of aquo-complexes in samples prepared with other solutions. This distinct difference can be ascribed to the difference in the p Ka values of the counter ions; carboxylate ions, with a high p Ka value, are inclined to form a complex with Cu 2+. Using this newly applied Cu(C 2H 5COO) 2 solution, the present ion-exchange method has the potential to develop new effective materials that possess the specific adsorption and catalytic properties of CuZSM-5. 相似文献
14.
Several Mg–Y binary ribbons with Y content up to 17.9 at.% were fabricated by melt-spinning. X-ray diffraction (XRD) revealed that the phase structure changes with increasing Y content from extended solid solution to partially amorphous, and then fully intermetallic Mg 24Y 5. Anodic potentiodynamic polarization performed in 0.01 M NaCl electrolyte (pH=12) revealed improved anodic passivity behavior compared to pure Mg for all the Mg–Y alloys. X-ray photoelectron spectroscopy (XPS) revealed that the improved passivity of Mg–Y was more related to the elemental oxidation state rather than the concentration of the surface components. To study the effect of Cl − ion on the passivity behavior, anodic potentiodynamic and potentiostatic polarization were performed on Mg–17.9 at.% Y in alkaline (pH=12) NaCl electrolytes containing Cl − ion in the concentration range from 0.00 to 0.50 M. The passive films formed in 0.01 M NaCl electrolyte were similar to the native film, which were composed of MgO and Y 2O 3. No CO 32− and Cl − ions were incorporated into the passive film. The passivity was significantly degraded in the electrolytes containing higher Cl − concentration (0.1 and 0.5 M). Detailed XPS revealed that the surface films under these conditions were composed of much hydrated species Mg(OH) 2 and YOOH and/or Y(OH) 3 and CO 32− was incorporated into the surface film. The incorporation of Y 2O 3 in the passive film was given as the reason for the enhanced passivity properties of Mg–Y ribbons. The mechanism of Cl − and CO 32− ions to the degradation of the passivity was discussed. 相似文献
15.
The production and decay of singlet molecular oxygen ( 1O 2) in TiO 2 photocatalysis were investigated by monitoring its phosphorescence under various reaction conditions. First, the effects of additives such as KBr, KSCN, KI, H 2O 2, and ethanol on the amount of 1O 2 produced by photo excitation of P25 TiO 2 were measured. The same additives were employed to investigate the effect on the amount of O 2− produced. Comparison between the effects on 1O 2 and O 2− suggested that 1O 2 is formed by the electron transfer mechanism, the reduction of molecular oxygens to O 2− by photogenerated electrons and the subsequent oxidation of O 2− to 1O 2 by photogenerated holes. The formation of 1O 2 decreased at pH < 5 and pH > 11, indicating that the intermediate O 2− is stabilized at the terminal OH site of the TiO 2 surface in the pH range of 5 < pH < 11. Eighteen commercially available TiO 2 photocatalysts were compared on the formation of 1O 2 and O 2− in an aqueous suspension system. The formation of 1O 2 was increased with decreasing size of TiO 2 particles, indicating that a large specific surface area causes a higher possibility of reduction producing O 2− and then a large amount of 1O 2 is formed. The difference in the crystal phase (rutile and anatase) did not affect the formation of 1O 2. 相似文献
16.
A series of La(Co, Mn, Fe) 1−x(Cu, Pd) xO 3 perovskites having high specific surface areas and nanosized crystal domains was prepared by reactive grinding. The solids were characterized by N 2 adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature programmed desorption (TPD) of O 2, NO + O 2, C 3H 6, in the absence or presence of 5% H 2O, Fourier transform infrared (FTIR) spectroscopy, as well as activity tests towards NO reduction by propene under the conditions of 3000 ppm NO, 3000 ppm C 3H 6, 1% O 2, 0 or 10% H 2O, and 50,000 h −1 space velocity. The objective was to investigate the influence of H 2O addition on catalytic behavior. A good performance (100% NO conversion, 77% N 2 yield, and 90% C 3H 6 conversion) was achieved at 600 °C over LaFe 0.8Cu 0.2O 3 under a dry feed stream. With the exposure of LaFe 0.8Cu 0.2O 3 to a humid atmosphere containing 10% water vapor, the catalytic activity was slightly decreased yielding 91% NO conversion, 51% N 2 yield, and 86% C 3H 6 conversion. A competitive adsorption between H 2O vapor with O 2 and NO molecules at anion vacancies over LaFe 0.8Cu 0.2O 3 was found by means of TPD studies here. A deactivation mechanism was therefore proposed involving the occupation of available active sites by water vapor, resulting in an inhibition of catalytic activity in C 3H 6 + NO + O 2 reaction. This H 2O deactivation was also verified to be strictly reversible by removing steam from the feed. 相似文献
17.
Microwave dielectric properties of (Zn 1/3Nb 2/3) 0.40(Ti 1−xSn x) 0.60O 2 ceramics were investigated as a function of SnO 2 content (0.15 ≤ x ≤ 0.30). A single phase with tetragonal rutile structure was obtained through the entire composition. The unit-cell volume of the specimens was increased with SnO 2 content, due to the larger ionic radius of Sn 4+ (0.69 Å) than that of Ti 4+ (0.605 Å) for octahedral site. Dielectric constant ( K) of the sintered specimens was affected by the dielectric polarizability. Quality factor ( Qf) was dependent on the degree of reduction of Ti 4+ ion. With an increase of SnO 2 content, the temperature coefficient of resonant frequency ( TCF) of the specimens decreased due to the decrease of the octahedral distortion of rutile structure. 相似文献
18.
Layered double hydroxide pillared by Paratungstate A ion, Mg 12Al 6(OH) 36(W 7O 24)·4H 2O, was prepared via anion exchange reaction of the synthetic precursor, Mg 4Al 2(OH) 12TA· xH 2O (TA 2−=terephthalate), and [W 7O 24] 6− ion. Some physico-chemical properties were measured and the preparation conditions were studied. Trace aqueous organocholorine pesticide, hexachlorocyclohexane (HCH), was totally degraded and mineralized into CO 2 and HCl by irradiating a Mg 12Al 6(OH) 36(W 7O 24)·4H 2O suspension in the near UV area. Disappearance of trace HCH follows Langmuir–Hinshelwood first-order kinetics. The model and mechanism for the photocatalytic degradation of HCH on the Mg 12Al 6(OH) 36(W 7O 24)·4H 2O were proposed, indicating that the interlayer space is the reaction field, and that photogeneration of OH√ radicals are responsible for the degradation pathway. 相似文献
19.
γ-Al 2O 3 supported vanadium oxides were modified by tungsten and molybdenum oxides in order to improve dispersion and selectivity towards olefins in propane oxidative dehydrogenation (ODH). Both vanadium–tungsten and vanadium–molybdenum catalysts were obtained by adsorption of mixed isopolyanions (VW 5O 195−, V 2W 4O 194−, VMo 5O 195− and V 2Mo 4O 194−) from aqueous solutions. The isopolyanion solutions were characterized by UV-Vis and 51V NMR spectroscopy. Vanadium, vanadium–tungsten and vanadium–molybdenum precursors and catalysts were also characterized by UV-Vis (diffuse reflectance) and solid state 51V NMR spectroscopy. An improved selectivity to propene in the presence of tungsten and molybdenum in VO x/γ-Al 2O 3 was observed and attributed to dilution of vanadium by tungsten or molybdenum oxides on the γ-Al 2O 3 surface. 相似文献
20.
In the frame of research aimed at developing new synthetic procedures of multimetallic Nb-based catalysts, peroxo complexes of niobium(V) of general formula A I3[Nb(O 2) 4] and A I3[Nb(O 2) x(H yL)]· nH 2O (A I: NH 4+, CN 3H 6+ (gu); L: oxalate, tartrate, citrate) have been prepared and characterized on the basis of elemental and thermal analysis, FTIR and 13C-NMR spectra. The crystal structure of (gu) 3[Nb(O 2) 4] and (gu) 3[Nb(O 2) 2(C 2O 4) 2]·2H 2O have been determined. The application of the obtained Nb complexes as precursors for the preparation of silica-supported Nb–Mo–O catalysts has been demonstrated. Combining Nb peroxo-carboxylato compounds with analogous Mo(VI) compounds in a silica-impregnation method carried out in aqueous medium leads to the formation of the supported Nb 2Mo 3O 14 phase. 相似文献
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