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1.
The hetro-structured oxide thin films from metal fluorocomplex solution have been prepared by the liquid phase deposition (LPD) method. The Pt/Nb 2O 5 and Au/Nb 2O 5 composite films can be prepared from a mixed solution of niobium source, H 3BO 3, Pt(NH 3) 4Cl 2 and HAuCl 4 aqueous solutions under the ambient temperature and atmosphere. In the case of Au/SiO 2 composite film, (NH 4) 2SiF 6 solution is used as a mother solution. The Pt and Au ionic species are deposited in Nb 2O 5 and SiO 2 matrices. They are reduced to their metallic state after treatment above 200 °C. The size of dispersed particles can be controlled by heat treatment temperature. It is also clear that, gold nanoparticles are also found to interact with SiO 2, although the interaction is smaller than that with Nb 2O 5 showing the size of Au nanoparticles remain smaller in Nb 2O 5 that in SiO 2. 相似文献
2.
In situ preparation of polypyrrole (Ppy) by photo-polymerization coated on a quartz crystal microbalance (QCM) as a low humidity sensor was reported. Different concentrations of Ppy films say 0 wt.% (as blank), 0.1, 1, and 10 wt.% were investigated to measure humidity concentrations between 14.7 and 5412.5 ppm v. The adsorption/desorption behavior was also examined at humidity concentration 510.2 ppm v. The sensitivities of 0, 0.1 and 1 wt.% Ppy films at 51.5 ppm v were 0.143, 0.219 and 0.427, respectively. For 1 wt.% Ppy, the highest sensitivity was obtained. The slope and correlation coefficients ( R2) for 1 wt.% Ppy at the ranges of 14.7–898.6 ppm v were 0.0646 and 0.9909, respectively. A series of molecular simulations have been carried out to calculate bond energy for the water molecule interaction with Ppy, which was found to be 3 kcal/mol indicating the existence of hydrogen bonding during the sorption process. Based on Langmuir isotherm adsorption assumption, for 0.1 and 1 wt.% Ppy films, the association constants were 2606.30 and 5792.98, respectively. This larger association constant for 1 wt.% Ppy film explains higher sensitivity. 相似文献
3.
The resistance of a novel silica-based N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) polymeric adsorption material (TODGA/SiO 2-P) against nitric acid, temperature and γ-irradiation had been investigated. The adsorption property of the treated TODGA/SiO 2-P was evaluated by a 3 M HNO 3 solution containing 0.01 M Nd(III). It was found that both 3 and 0.01 M HNO 3 concentrations did not decrease the stability of TODGA/SiO 2-P at 25°C. The quantity of TODGA leaked from TODGA/SiO 2-P was equivalent to its solubility in the corresponding HNO 3 aqueous solution. The effect of 3 M HNO 3 on the leakage of TODGA at 80°C was significantly higher than that in 0.01 M HNO 3 as well as in all cases at 25°C. The amount of Nd(III) adsorbed towards the treated TODGA/SiO 2-P was determined in the range of 0.143–0.148 mmol/g for the HNO 3 concentration effect and 0.142–0.0506 mmol/g for the temperature effect. γ-Irradiation showed a more noticeable destruction effect on TODGA/SiO 2-P. The content of TODGA leaked increased with an increase in the γ-irradiation dose (ID) from 1.06 to 3.72 MGy in terms of the linear equation [TODGA]=794.5ID+84.0. The amount of Nd(III) adsorbed onto the irradiated TODGA/SiO 2-P decreased rapidly from 0.134 to 0.0438 mmol/g, which was lower than 0.153 mmol/g, the adsorption of fresh TODGA/SiO 2-P for Nd(III), according to the equation QNd(III)=−0.0301ID+0.160, showing that a large quantity of TODGA leaked from TODGA/SiO 2-P. The adsorbed amount of Nd(III) decreased obviously in this order: the HNO 3 concentration effect, temperature effect and γ-irradiation. 相似文献
4.
Micron-sized silica gel particles were chemically modified on their surfaces with the coupling agent, γ-methacryloxypropyl trimethoxysilane (MPS), double bond was introduced onto the surfaces of silica gel particles, and the modified particles MPS–SiO 2 were obtained. Then, poly(4-vinylpyridine) (P4VP) was grafted from the silica gel surfaces, and grafting particles P4VP/SiO 2 was prepared. Finally, the coordination between grafted P4VP and cupric ions Cu 2+ was performed, and the supported complex Cu(II)–P4VP/SiO 2 was obtained. The grafting particles P4VP/SiO 2 and the supported complex Cu(II)–P4VP/SiO 2 were characterized with infrared spectra (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Cu(II)–P4VP/SiO 2 was used as a catalyst for the oxidation of ethyl benzene into acetophenone with molecular oxygen under ordinary pressure. The experimental results show that the supported complex Cu(II)–P4VP/SiO 2 can be successfully prepared via grafting polymerization of 4VP and coordination between the grafted P4VP and cupric ions Cu 2+. In oxidation of ethyl benzene into acetophenone by molecular oxygen under ordinary pressure, the supported complex Cu(II)–P4VP/SiO 2 displayed high catalytic activity and excellent catalytic selectivity up to more than 98% for the transformation of ethyl benzene to acetophenone. 相似文献
5.
Selective hydrogenation of crotonaldehyde was performed on 5% Pt/SnO 2 catalysts, in gaseous phase, at atmospheric pressure, at 353 K. Two types of catalyst were prepared using H 2PtCl 6 and Pt(NH 3) 4(NO 3) 2 as metallic precursors. Their performances were compared as a function of the reduction temperature and both catalysts were characterised by X-ray diffraction after different reduction treatments. Using the ex-chloride catalyst, the selectivity values to the unsaturated alcohol (UOL) resulted into a maximum of 45% while a selectivity as high as 70–77%, in 0–25% conversion range, was achieved by using ex-nitrate catalyst reduced at 443 K. The formation of Pt–Sn alloy on the metal particles of platinum was thought to be necessary to improve the activity and the selectivity on these catalysts. In the contrast, a presence of PtSn 2 formed at a reduction temperature higher than 473 K led to a decrease of activity and selectivity. 相似文献
6.
The effect of adding SiO 2 to a precipitated iron-based Fischer–Tropsch synthesis (FTS) catalyst was investigated using N 2 physical adsorption, H 2 differential thermogravimetric analysis, temperature-programmed reduction/desorption (TPR/TPD) and Mössbauer spectroscopy. The FTS performances of the catalysts with or without SiO 2 were compared in a fixed bed reactor. The characterization results indicated that SiO 2 facilitates the high dispersion of Fe 2O 3 and significantly influences the Fe/Cu and Fe/K contacts, which play an important role in the surface basicity, reduction and carburization behaviors, as well as the FTS performances. The incorporation of SiO 2 enhances the Fe/Cu contact, further enlarges the H 2 adsorption and promotes the reduction of Fe 2O 3 → FeO x, while the transformation of FeO x → Fe is suppressed probably due to the strong Fe–SiO 2 interaction. SiO 2 indirectly weakens the surface basicity and severely suppresses the carburization and CO adsorption of the catalyst. In the FTS reaction, it was found that SiO 2 decreases the FTS initial activity but improves the catalyst stability. Due to the lower surface basicity than the catalyst without SiO 2, the catalyst incorporated with SiO 2 has higher selectivity to light hydrocarbons and methane and decreased selectivity to the olefins and heavy hydrocarbons. 相似文献
7.
Aerosol flame pyrolysis deposition method was applied to deposit the oxide glass electrolyte film and LiCoO 2 cathode for thin film type Li-ion secondary battery. The thicknesses of as-deposited porous LiCoO 2 and Li 2O–B 2O 3–P 2O 5 electrolyte film were about 6 μm and 15 μm, respectively. The deposited LiCoO 2 was sintered for 2 min at 700 °C to make partially densified cathode layer, and the deposited Li 2O–P 2O 5–B 2O 3 glass film completely densified by the sintering at 700 °C for 1 h. After solid state sintering process the thicknesses were reduced to approximately 4 μm and 6 μm, respectively. The cathode and electrolyte layers were deposited by continuous deposition process and integrated into a layer by co-sintering. It was demonstrated that Aerosol flame deposition is one of the good candidates for the fabrication of thin film battery. 相似文献
8.
The bimetallic [Pt(NH 3) 4] 2[W(CN) 8][NO 3]·2H 2O is characterised by single-crystal X-ray diffraction [S.G. P2 1/ m(11), a=8.0418(7), b=19.122(2), c=9.0812(6) Å, Z=2]. All platinum centres have the square-plane D4h geometry with average dimensions Pt(1)–N 2.042(2) and Pt(2)–N 2.037(10) Å. The octacyanotungstate anion has the square-antiprismatic D4d configuration with average dimensions W(1)–C 2.164(13), C–N 1.140(12), W(1)–N 3.303(5) Å. The structure exhibits two different mutual orientations of Pt versus W units resulting in Pt(2)–W(1), W(1) * separations of 4.77(2), 4.55(2) * and Pt(1)–W(1) of 6.331(8) Å. A centrosymmetric structure reveals groups of two distinct columns: the first is formed by intercalated NO 3− between parallel [Pt(1)(NH 3) 4] 2+ planes and the second consists of [W(CN) 8] 3− interlayered by, parallel to square faces of W-antiprisms, [Pt(2)(NH 3) 4] 2+. The structure is stabilised through a three-dimensional hydrogen bond network via nitrogen atoms of cyanide ligands, hydrogen atoms of NH 3 ligands, water molecules and oxygen atoms of NO 3− counteranions. The vibrational pattern and the range of ν(CN) frequencies attributable to the electronic environment of W(V) and W(IV) are consistent with the ground state Pt(II)↔W(V) charge transfer. 相似文献
9.
A new class of proton conducting glass membranes for hydrogen fuel cell applications are being developed using phosphotungstic acid. These glasses are being design to yield high proton conductivities could be potential substitutes for electrolytes in H 2/O 2 fuel cell. P 2O 5–SiO 2–PWA glasses have been non-crystalline phases confirmed by structural studies. The glass materials showed good mechanical and thermal stability, and also found a maximum proton conductivity of 9.1 × 10 −2 S/cm at 90 °C and 30% RH. The average pore size less than 5 nm was determined by Barrett–Joyner–Halenda (BJH) desorption method. The electrochemical activity was investigated by polarization curves and current–voltage profiles. A maximum power density value of 10.2 mW/cm 2 was obtained using 0.15 mg/cm 2 of Pt/C loaded on electrode and 5P 2O 5–87SiO 2–8PWA glasses at 30 °C and 30% humidity. 相似文献
10.
采用液相沉积法(LPD)制备了纳米氧化锆沉积硅胶色谱固定相(ZrO 2/SiO 2), 并将其应用于亲水作用色谱分离中. 考察并比较了ZrO 2/SiO 2、 硅胶(SiO 2)和氧化锆(ZrO 2) 3种色谱固定相在不同有机调节剂比例、 不同pH值及不同盐浓度的流动相条件下的色谱行为. 结果表明, 制备的ZrO 2/SiO 2色谱柱不仅具有SiO 2色谱柱高柱效的优点, 表面沉积的纳米氧化锆还能有效屏蔽硅羟基, 有利于碱性物质的保留和分离, 表现出良好的亲水作用色谱性能. 将ZrO 2/SiO 2色谱柱用于4种脱氧核苷和5种碱性化合物的分离, 均得到了较好的效果, 展现出其作为色谱固定相良好的应用前景. 相似文献
11.
The reaction between transition metal alkoxides and benzyl alcohol provides a novel soft chemistry route to metal oxide nanoparticles. The method allows the preparation of nanocrystals of two important transition metal oxides, namely V 2O 3 and Nb 2O 5. Although the reaction temperatures of 200–220 °C are comparably low, the obtained particles are highly crystalline. According to TEM investigations, the V 2O 3 crystals exhibit particle sizes between 20 and 50 nm, and the Nb 2O 5 crystals display platelet-like particle shapes with sizes of 50–80 nm, without any indications of amorphous character. 相似文献
12.
A possibility of antimony oxide as a catalyst for the selective oxidation of methane with oxygen to formaldehyde was investigated. The activity measurement was carried out at an atmospheric pressure and at 873 K, where the homogeneous gas-phase reaction was negligible. Oxidized diamond (O-Dia)-supported antimony oxide catalyst produced 1.3 mmol h −1 g-cat −1 of formaldehyde with a formaldehyde selectivity of 23%. On the other hand, SiO 2 supported antimony oxide catalyst exhibited negligible catalytic activity. XRD and UV–vis analyses revealed that -Sb 2O 4 was formed on the oxidized diamond while Sb 6O 13 was formed on SiO 2. Selective oxidation of methane to formaldehyde seemed to proceed on -Sb 2O 4 with moderate activity and selectivity to formaldehyde, via a redox cycle of -Sb 2O 4 and Sb 2O 4−x. On the other hand, Sb 6O 13 on SiO 2 was stable under the reaction conditions and the selective oxidation occurred only slightly. 相似文献
13.
The Fischer–Tropsch synthesis (FTS) performances of iron-based catalysts promoted with/without potassium compounds containing different acidic structural promoters (Al 2O 3, SiO 2, and ZSM-5) were studied in this research. Characterization technologies of temperature-programmed reduction with CO (CO-TPR), powder X-ray diffraction (XRD) and Mössbauer effect spectroscopy (MES) were used to study the effect of K–structural promoter interactions on the carburization behaviors of catalysts. It showed that the addition states of potassium (K–Al 2O 3, K–SiO 2, K–ZSM-5 and K-free) have a significant influence on the formation of iron carbides, which shows a following sequence in promotion of carburization: K–Al 2O 3 > K–SiO 2 > K–ZSM-5 > K-free. The FTS reaction test was performed in a fixed bed reactor. It is found that Fe/K–Al 2O 3 catalyst leads to the highest CO conversion, Fe/K–ZSM-5 catalyst shows the highest H 2 conversion, and Fe/K-free catalyst shows the lowest CO and H 2 conversion. As for the hydrocarbon selectivity, Fe/K–SiO 2 catalyst yields the lowest methane and the highest C 5+ products, Fe/K–ZSM-5 catalyst yields higher methane and the highest liquid hydrocarbon product, whereas Fe/K-free catalyst yields the highest methane and the lowest C 5+ products. These results can be explained from the interaction between potassium and structure promoters, and the spillover of reactants or intermediates from Fe sites to the surfaces of structural promoters. 相似文献
14.
The co-pyrolysis of a petroleum residue with two different sources of titanium (tetrabutyl-ortotitanate (TBO) or titanium carbide nano-powder) was carried out to obtain mesophase pitches containing TiO 2 or TiC nanoparticles. Co-pyrolysis is an appropriate technique to achieve a good dispersion and low particle size. In the case of TBO, TiO 2 nanoparticles (5–20 nm) are observed, which are forming aggregates, the largest of them being 1–2 μm. In the case of TiC nano-particles, they are more difficult to disperse and larger aggregates are formed, although the final material is rather homogenous. The chemistry of pyrolysis for the production of doped and undoped mesophase pitches has been followed by means of solvent insolubility, XRD, XPS, FTIR and elemental analysis. They show evidences of promotion of the formation of mesophase in the presence of the titanium-containing particles, especially in the presence of TiO 2. The final materials can be of great value as precursors to produce high density titanium doped graphites for nuclear and space applications. 相似文献
15.
Nanoparticles are expected to be applicable to inhalation as carrier but there exist disadvantages because of their size. Their deposition dose to the lung will be small. To overcome this problem and utilize nanoparticles for inhalation, we have prepared nanocomposite particles as drug carriers targeting lungs. The nanocomposite particles are prepared as drug-loaded nanoparticles–additive complex to reach deep in the lungs and to be decomposed into nanoparticles when they deposit into lung. In this study, we examined the effect of preparation condition – inlet temperature, size of primary nanoparticles and weight ratio of primary nanoparticles – on the property of nanocomposite particles. When the size of primary nanoparticles was 400 nm and inlet temperature was 90 °C, only the nanocomposite particles containing between 45 and 55% of primary nanoparticles could be decomposed into nanoparticles in water. On the other hand, when the inlet temperature was 80 °C, nanocomposite particles were decomposed into nanoparticles independent of the weight ratio of primary nanoparticles. Also, the aerodynamic diameter of the nanocomposite particles was between 1.5 and 2.5 μm, independent of the weight ratio of primary nanoparticles. When the size of primary nanoparticles was 200 nm and inlet temperature was 70 °C, nanocomposite particles were decomposed into nanoparticles independent of the weight ratio of primary nanoparticles. Also, the aerodynamic diameters of them were almost 2.0 μm independent of the weight ratio of primary nanoparticles. When the nanocomposite particles containing nanoparticles with the size of 200 nm are prepared at 80 °C, no decomposition into nanoparticles was observed in water. Fine particle values, FPF, of the nanocomposite particles were not affected by the weight ratio of primary nanoparticles when they were prepared at optimum inlet temperature. 相似文献
16.
The interaction between ganglioside G M1 (GM1) and
--dipalmitoylphosphatidylcholine (DPPC) in mixed monolayers was investigated using surface pressure measurements and atomic force microscopy (AFM), and the effects of GM1, surface pressure and temperature on the properties of the membranes were examined. Mixed GM1/DPPC monolayers were deposited on mica using the Langmuir–Blodgett (LB) technique for AFM. GM1 and DPPC were miscible below the 0.2 mole fraction of GM1 and there was attractive interaction between GM1 and DPPC. The AFM images for the GM1/DPPC monolayers ( XGM1 < 0.2) at 30 mN m −1 and 25 °C indicated a percolation pattern which means a micro phase separation: namely, the mixed film composed of GM1 and DPPC phase-separated from the DPPC liquid-condensed film. The AFM images for the mixed monolayers at 33 mN m −1 indicated a specific morphology when the surface pressure was varied from 30 to 40 mN m −1. The percolation pattern in the AFM image at 25 °C came to be destroyed with increasing temperature and completely disappeared at 45 °C. The change in the morphology of mixed GM1/DPPC monolayers on varying the surface pressure and temperature is thought to be related to signal transduction and a preventive mechanism against viral infections in the human body. 相似文献
17.
Sintering behavior and bioactivity of diopside, CaMgSi 2O 6, prepared by a coprecipitation process were examined for its biomedical applicability. As-prepared powder was synthesized by adding aqueous ammonia to an ethanol solution containing Ca(NO 3) 2·4H 2O, Mg(NO 3) 2·6H 2O, and Si(OC 2H 5) 4 and characterized by means of TG–DTA, XRD, and TG–MS. The dried powder was X-ray amorphous and crystallized into diopside at 845.5 °C. The glass network formation by SiO 4 tetrahedra was almost completed below 800 °C. The bioactivity of the diopside prepared by sintering the compressed powder at 1100 °C for 2 h was evaluated by immersion of the sintered body in a simulated body fluid (SBF) at 36.5 °C. Leaf-like apatite particles were found to be formed on the surface of the sintered body and grew with passage of soaking time. This apatite-forming behavior in the SBF is related to the dissolution of Ca(II) ions from the sintered body in the early stage of immersion. Thus, diopside prepared by the coprecipitation process using the metal alkoxide and the metal salts was found to have an apatite-forming ability. 相似文献
18.
Ag nanoparticles were synthetized in the interlamellar space of a layered kaolinite clay mineral. Disaggregation of the lamellae of non-swelling kaolinite was achieved by intercalation of dimethyl sulfoxide. The kaolinite was suspended in aqueous AgNO 3 solution and, after adsorption of Ag +, the ions were reduced with NaBH 4. The interlamellar space limits particle growth ( dave=3.8–4.2 nm); however, larger silver particles may be formed on the exterior surface of kaolinite with dave=5.6–10.5 nm diameter. The diameter of the particles prepared in this way is depending on the initial AgNO 3 concentration. The silver nanoparticles prepared were characterized by UV–vis spectroscopy, X-ray diffraction (XRD), Small angle X-ray scattering (SAXS), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM). 相似文献
19.
Hydrogen production by steam reforming of methane using catalytic membrane reactors was investigated first by simulation, then by experimentation. The membrane reactor simulation, using an isothermal and plug-flow model with selective permeation from reactant stream to permeate stream, was conducted to evaluate the effect of permselectivity on membrane reactor performance – such as methane conversion and hydrogen yield – at pressures as high as 1000 kPa. The simulation study, with a target for methane conversion of 0.8, showed that hydrogen yield and production rate have approximately the same dependency on operating conditions, such as reaction pressure, if the permeance ratio of hydrogen over nitrogen ( (H 2/N 2)) is larger than 100 and of H 2 over H 2O is larger than 15. Catalytic membrane reactors, consisting of a microporous Ni-doped SiO 2 top layer and a catalytic support, were prepared and applied experimentally for steam reforming of methane at 500 °C. A bimodal catalytic support, which allows large diffusivity and high dispersion of the metal catalyst, was prepared for the enhancement of membrane catalytic activity. Catalytic membranes having H 2 permeances in the range of 2–5 × 10 −6 m 3 m −2 s −1 kPa −1, with H 2/N 2 of 25–500 and H 2/H 2O of 6–15, were examined for steam reforming of methane. Increased performance for the production of hydrogen was experimentally obtained with an increase in reaction-side pressure (as high as 500 kPa), which agreed with the theoretical simulation with no fitting parameters. 相似文献
20.
The perovskite CaCu 3Ti 4O 12 (CCT) has been obtained after calcination of oxalate precursors at 900–1000 °C in air. Those precursors are prepared using a soft chemistry method, the coprecipitation. The oxalate powders consist of disk-like particles of 2–3 μm diameter and 300–400 nm thickness. By varying the ratio of the initial amounts of metal chlorides, additional phases (CaTiO 3, TiO 2 and CuO) could be obtained besides CCT. The corresponding multiphased ceramics present improved dielectric properties. 相似文献
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