N2O活化的Fe/ZSM-5表面活性氧的表征(英)

Temperature-programmed reduction (H₂-TPR) was employed to quantitatively characterize the active oxygen species generated from a high Fe-loading Fe/ZSM-5 catalyst exposed to N₂O at 250 ℃. [Fe-O-Fe]²⁺ dimer was determined as the active iron complex for N₂O decomposition to produce the active oxygen. Reduction of Fe³⁺ to Fe²⁺ by H₂ in the dimer and removal of OH^- groups from Fe²⁺ dimer by heating Fe/ZSM-5 to 700 ℃ were the prerequisites for the formation of this active Fe complex. A linear correlation with a slope of 1.0 between the amount of [Fe-O-Fe]²⁺ and that of active oxygen species was observed. Maximum amount of active oxygen species can be generated by reducing Fe/ZSM-5 catalyst with H₂ at the temperatures over 500 ℃ and then heating the resulting product in Ar to 700 ℃, followed by N₂O exposure at 250 ℃. The ratio of the total number of oxygen atoms (Ode) deposited by interaction of [Fe-O-Fe]²⁺ with N₂O to the amount of [Fe-O-Fe]²⁺ was 2. However, not all the deposited oxygen atoms were active oxygen (O_a); the ratio of O_a and O_de was 0.5. The iron dimer complex composing active oxygen is a five-atom ion [Fe₂O₃]²⁺; the most probable structure is as follows:     

由镁、铝醇盐配合物合成纳米粒子MgAl2O4尖晶石

Mg and Al alkoxide complex was synthesized in a cell without battery separator by electrochemical dissolution of aluminum for 6 h and magnesium for 1.8 h at 45 ℃ in ethanol solution of 0.04 mol·dm^-3 (Bu₄N)Br with a current density of 100 mA·cm^-2. IR and Raman spectroscopy were used to characterize the structure of the precursor of MgAl₂O₄. The results show that the current efficiency attains 98.4% and the precursor is MgAl₂(OCH₂CH₃)₅(acac)₃. The acac^- group-containing precursor could prevent it from agglomeration. The xerogel was obtained by drying in vacuum for 24 h and hydrolysis under pH≈8.5 of the precursor, which was heated at 350 ℃ for 2 h to obtain the nano-MgAl₂O₄ powder. XRD and TEM were used to investigate the structure of nano-MgAl₂O₄. The result suggests that the xerogel with an average particle size of 10 nm and the Nano-sized Spinel MgAl₂O₄ Particle of 12 nm thus obtained are with high purity.     

配位聚合物{[Zn(TSC)(MAL)]·H2O}n的制备及结构表征

The novel Zn^Ⅱ complex, {[Zn(TSC)(MAL)]·H₂O}_n (1), where TSC is thiosemicarbazide and MAL is malonate radicle, was synthesized by self-assembling from the reaction of stoichiometric zinc chloride, thiosemicarbazide and malonic acid in solution at pH 4.5~5.0. The structural and physicochemical properties were characterized by X-ray diffraction, infrared spectroscopy, electronic spectra and thermal analysis. The crystal data for the title coordination polymer: Monoclinic, P2₁/c, β=107.808(1)°, a=0.937 59(1) nm, b=1.110 83(1) nm, c=0.921 00(2) nm, Z=2, μ=2.919 mm^-1, R₁=0.039 0, wR₂=0.099 4. The structure feature is that the bridging dicarboxylates effectively link the zinc centers to form polymeric chain in a zig-zag way, which is stabilized by N-H…O, N-H…S and O-H…O hydrogen bonds. CCDC: 231861.     

铈掺杂纳米ZnO结构与室温脱硫性能的相关性研究

Nano-ZnO desulfurizer doped with cerium was prepared by homogeneous precipitation. The bulk and surface structures were characterized by TG-DTA, XRD, XPS and TEM. The desulfurizing performance at ambient temperature was studied. The results show that at ambient temperature the desulfurizing activities of nano-Ce-ZnO desulfurizer are closely related to the particle size, the electron density on desulfurizer surface and the quantity of active sites. Compared with nano-ZnO, nano-Ce-ZnO desulfurizer calcined at 270 ℃ showed smaller particle size and higher surface electron density, which favored the adsorption and reaction of H₂S, resulting in improved desulfurizing activity at ambient temperature since the quantity of Zn^(2-δ)+ became greater by electron gain of zinc ion from cerium ion. The tendency for zinc and cerium to be separated out as individual oxide from Ce-ZnO desulfurizer would increase as the calcination temperature was raised. The enrichment of cerium on the surface of ZnO made decrease the active sites for H₂S adsorption, which led to the decrease in desulfurization activity at ambient temperature.     

由乙氧基铅配合物制备纳米PbO

Lead complex was directly synthesized by electrochemical dissolution of lead in a cell without separating the cathode and anode. The product was characterized by FTIR, Raman spectra and ¹H NMR. The xerogel was prepared by a direct sol-gel of the electrolyte solution and then dryness of it. The xerogel was heated at 450 ℃ for 2 h to obtain the nano-PbO powder. FTIR, XRD, and TEM were used to investigate the structure of nano-PbO. The results show that the lead complex is Pb(OEt)₂(acac)₂, which contains acac- group and could prevent the precursor from hydrolysis and sintering during the calcinations process. The nano-PbO of 20～30 nm was thus obtained in a high purity by drying at 450 ℃.     

有机体系中纳米TiO2 / ZrO2修饰电极的制备及电催化活性

The complexes Ti(OCH₂CH₂O)₂ and Zr(OCH₂CH₂O)₂ were directly synthesized by using HOCH₂CH₂OH dissolution in 50 mL flask. The nano-ZrO₂ / TiO₂ powders were prepared by a direct sol-gel synthesis using the above solution and followed by drying at 400 ℃ for 2 h. The complexes were characterized by FTIR and ¹H NMR. XRD and TEM were used to investigate the structure of nano-ZrO₂ / TiO₂. The results show that the complexes containing ^-OCH₂CH₂O^- group could prevent the precursor from agglomeration and sintering during the hydrolysis and calcination process. The ZrO₂ / TiO₂ powders of 20～35 nm was thus obtained in a high purity. The highly active nano-ZrO₂ / TiO₂ modified electrode was prepared by using daubing and calcination. The electro-catalytic activities of this electrode in (COOH)₂ were investigated. The discharge current of nano-ZrO₂ / TiO₂ electrode increased obviously. In preparative electrolysis under optimal conditions, the average yield and current efficiency for HOOC-CHO were 84.7% and 91.6 %, respectively.     

溶剂热-热解法制备具有纳米孔结构的Co3O4

Nanoporous rhombohedral Co₃O₄ was synthesized by thermal decomposition of the precursor obtained via a solvothermal method in the presence of Co(CH₃COO)₂·4H₂O, urea, sodium dodecyl sulfate (SDS), ethanol and water. The calcined sample was characterized by XRD, FTIR, SEM, TG-DTA, Nitrogen adsorption-desorption, cyclic voltammetry and galvanostatic charge/discharge measurements. The results show that the calcined sample at 400 ℃ is rhombohedral structure Co₃O₄ with nano-porosity assembled by uniform nanosheets. The BET surface area is 49 m²·g^-1 and its specific capacitance as single electrode is up to 233.4 F·g^-1 at 5 mA·cm^-2 current density.     

有机溶液中电化学制备纳米MgTiO3

In a cell without separating the cathode and anode spaces, the precursor MgTi(OCH₂CH₃)_(6-y)(acac)_y of the mixed oxide MgTiO₃ was directly synthesized by electrochemical dissolution of titanium for 4 hours and then of magnesium for 1 hour 40 minutes at the current of 0.2 A in ethanol and acetyl-acetone solution. The nano- MgTiO₃ powder was prepared by a direct sol-gel process of the electrolyte solution under pH≈8.5 followed by washing, drying in vacuum for 24 h, and calcination at 500 ℃ for 2 h. IR and Raman spectroscopy, XRD, and TEM were used to investigate the structure of nano-MgTiO₃ and its precursor. The result suggested that it was more appropriate to control the temperature between 35～40 ℃ and the concentration of conductive additive (Bu₄N)Br at 0.04 mol·L^-1. The xerogel with an average particle size of 12 nm and the nano-MgTiO₃ of 20 nm was thus obtained in a high purity.     

Investigation of Photoinduced Sensitized Chemiluminescence by Sulfonated Phthalocyanines Using Flow Injection Technology

This paper reports the photoinduced chemiluminescence (PCL) of a methyl cypridina luciferin analogue (MCLA) in a flow injection system using phthalocyanine derivatives as photosensitizers. The photoexcited phthalocyanine produces singlet molecular oxygen (¹O₂) in air-saturated solutions. Subsequently ¹O₂ reacts with MCLA to initiate chemiluminescence. The MCLA-dependent chemiluminescence method would thus potentially provide an easy way for determination of ¹O₂. Under the optimum conditions, the increase in PCL intensity was proportional to the MCLA concentration ranging from 0.1 to 1.0 μM. The assay was sensitive and reproducible (the relative standard deviation was 6.3%, n = 10). The method has successfully been applied to compare the ability of ¹O₂ generation of tetra(potassium) salt and tetra(tetrabutylammonium) salt of tetra sulfonated phthalocyanine zinc, which have similar structures and spectra.     

梯度材料LiNi0.8Co0.2O2的合成与表征

The gradient composite LiNi_0.8Co_0.2O₂ was synthesized using spherical Ni(OH)₂ particle coated by a sol-gel containing cobalt and lithium. The precursor was examined by DSC-TG. The gradient composite was characterized by SEM, EDS, XPS, XRD and ICP-AES. The XPS, EDS and ICP-AES results show that content of cobalt in the surface is higher than in the center of the spherical particle of the gradient composite. The first discharge specific capacity of the gradient composite sintered at 700 ℃ is 187.3 mAh·g^-1.     

预氧化固气法合成LiNiO2的研究

LiNiO₂ was prepared by reaction of stoichiometric amounts of thoroughly-mixed LiOH·H₂O and preoxidation nanometer-scale Ni₃O₂(OH)₄ powders in O₂ at the temperature of 700℃ for 6h. The products were tested by XRD， XPS， SEM and electrochemistry methods. It was shown that product was LiNiO₂ single-phase， and the valence of nickel was +3; the average size of it was 40nm; its initial charge specific capacity is 168mAh·g^-1 and the coulomb efficiency is 90%; the second charge specific capacity is 160mAh·g^-1 and the coulomb efficiency is 96%.     

纳米晶构筑一维多孔氧化锌的合成与表征

One-dimensional porous zinc oxide was prepared via the calcination of zinc oxalate precursor obtained by solvothermal method. The products were characterized by XRD, SEM, TEM, photoluminescence (PL) spectrum and nitrogen adsorption-desorption. The results show that the obtained zinc oxide sample is porous and constructed by nanoparticles about 30 nm in size. The specific surface area and total pore volume are 126 m²·g^-1 and 0.13 cm³·g^-1, respectively． The PL properties related with defects in ZnO nanoparticles were discussed for porous zinc oxide samples.     

锐钛矿型TiO2水溶胶的低温制备及其表征

Anatase titanium dioxide hydrosol was prepared at low temperature by a simple method. The title material was characterized by TEM, XRD, FTIR and BET, respectively. The photocatalytic activity of the as-prepared TiO₂ was evaluated by the degradation of methyl orange solution under sunlight and the photocatalytic oxidation of acetone in air. The results showed that the titanium dioxide hydrosol was composed of anatase phase with average grain size of about 7 nm, and the crystallinity became more perfect with the increase of temperature. The BET surface areas were more than 220 m²·g^-1 for these samples. It is found that the photocatalytic activity was much better for the higher heat processing temperature. Especially, the photocatalytic activity of the sample with a heat treatment of 110 ℃ was better than that of P25. In addition, TiO₂ hydrosol also possessed good photocatalytic activity under the sunlight illumination.     

Ce0.8Y0.2O1.9-Ca3(PO4)2-K3PO4复合电解质在中温区的质子导电性及在常压合成氨中的应用

A precursor of Ce_0.8Y_0.2O_1.9(YDC) solid electrolyte was synthesized by the gol-gel method. YDC and phosphates powders were prepared by mixing the YDC and phosphates according to different weight ratios. The mixtures of the YDC and binary phosphates were ground and sintered at 1 400 ℃. The proton conductivity in solid electrolyte of the sintered samples was examined using electrochemical methods at 400～800 ℃. Ammonia was synthesized from nitrogen and hydrogen at atmospheric pressure in the solid state proton conducting cell reactor. The optimal condition for the ammonia production was determined. The result indicated that composite electrolyte of 80wt% YDC: 20wt% binary phosphates as proton conductor could obtain the highest ionic conductivity and ammonia production rate among the four samples, the rate of evolution of ammonia was up to 9.5 × 10^-9 mol·s^-1·cm^-2.     

石墨负载Pt催化剂的制备、表征及活性研究

Pt/graphite catalyst was prepared by incipient wetness impregnation using H₂PtCl₆·6H₂O as precursor. The catalyst was characterized by SEM, XRD, XPS and its degradation ability for oxalic acid was evaluated. The preparation parameters, including the reduction temperature, Pt loading and pyrolysis were studied. The optimal preparation conditions were 350 ℃ with Pt loading of 1.0%. Results show that the loading of Pt can significantly enhance catalytic activity of graphite and that Pt/graphite catalytic ozonation can effectively remove oxalic acid in aqueous solution. The BET surface area of graphite is much smaller than that of activated carbon, however, the catalytic activity of Pt/graphite towards oxalic acid degradation is higher than that of Pt/AC. The XPS results indicate that the active phase at catalyst surface is in the form of Pt⁰. Compared with that of reduction process in hydrogen, the activity of Pt/graphite catalyst decreases when it is prepared by pyrolysis in air due to the lower Pt dispersion on graphite surface.     

一个新的双核锌配合物Zn2(dhaash)2(py)4的合成及晶体结构

The crystal of binuclear zinc complex Zn₂(dhaash)₂(py)₄ was obtained in DMF and pyridine, where H₂dhaash is 2,4-dihydroxy-5-acetylacetophenone-N-salicylhydrazone. It has been characterized by IR, UV, element analysis and X-ray single crystal diffraction. The crystallographic data were as follows: monoclinic system, space group P2₁/c, a=1.108 98(11) nm, b=1.640 84(16) nm, c=1.445 14(14) nm, β=108.617(2)°, Z=2, V=2.492 1(4) nm³, D_c=1.466 g·cm^-3, M_r=1 099.74, μ=1.031 mm^-1, F(000)=1 136 and the final R=0.044 8 and wR=0.105 8 for 4 143 observed reflections with I≥2σ(I), respectively. The X-ray crystal structure analysis revealed that, in the centrosymmetric binuclear complex molecule, two zinc(Ⅱ) centers are linked by two oxygen atoms (O(3) and O(3A)), respectively. Zn(1)…Zn(1A) distance is 0.314 81(6) nm, O(3)…O(3A) distance is 0.270 4(2) nm. Every zinc(Ⅱ) ion has an elongated octahedral coordination. For example, the two pyridine nitrogen atoms, one oxygen atom and one nitrogen atom from salicylhydrazone, one oxygen atom from 2,4-dihydroxy-5-acetylacetophenone in one dhaash^2- ligand and one oxygen atom from 2,4-dihydroxy-5-acetylacetophenone in another dhaash^2- ligand coordinated to zinc(Ⅱ) ion, respectively. Two zinc(Ⅱ) ions and all the 72 non-hydrogen atoms in the two dhaash^2- ligands are in the same plane. CCDC: 261929.     

Mechanistic Investigations of Oxidation of Some Dipeptides by Sodium N‐chloro‐p‐toluenesulfonamide in Alkaline Medium:A Kinetic Study

The kinetics of oxidation of five dipeptides (DPP) viz., glycylglycine (Gly-Gly), L-alanyl-L-alanine (Ala-Ala), L-valyl-L-valine (Val-Val), L-leucyl-L-leucine (Leu-Leu) and phenylglycyl-phenylglycine (Phg-Phg) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in NaOH medium was studied at 308 K. The reactions follow identical kinetics for all the dipeptides, being first-order dependence each on [CAT]_o, [DPP]_o and fractional-order on [OH^－]. Addition of p-toluenesulfonamide or halide ions (Cl^－ or Br^－) has no significant effect on the rate of reaction. The reaction rate was found to increase with increase in ionic strength of the medium. The solvent isotope effect was studied using D₂O. The activation parameters for the reaction were computed from Arrhenius plots. Equilibrium and decomposition constants were evaluated. The oxidation products of the dipeptides were identified as their corresponding aldehydes. An isokinetic relationship was observed with β＝352 K, indicating that enthalpy factors control the reaction rate. CH₃C₆H₄SO₂NCl^－ of the oxidant has been postulated as the reactive oxidizing species. Under comparable experimental conditions, the rate of oxidation of the dipeptides increases in the order: Phg-Phg＞Ala-Ala＞Val-Val＞Leu-Leu＞Gly-Gly. The kinetics of oxidation of the dipeptides have also been compared with those of their corresponding monomer amino acids. The observed results have been explained by a plausible mechanism and the related rate law has been deduced.     

La0.9Sr0.1Al0.9Mg0.1O3-δ-Ca3(PO4)2-K3PO4复合电解质的合成及在常压天然气合成氨中的应用

La_0.9Sr_0.1Al_0.9Mg_0.1O_0.9(LSAM) was synthesized by the sol-gel method, an oxide-salt composite electrolyte LSAM-Ca₃(PO₄)₂-K₃PO₄ was prepared by mixing the LSAM and phosphates. The mixture was ground and sintered at 1 400 ℃. Using the LSAM electrolyte and its oxide-salt composite as solid electrolytes and silver-palladium alloy as electrodes, electrical conductivity was measured at different conditions. Ammonia was synthesized from wet natural gas and nitrogen at atmospheric pressure in the solid state proton conducting cell reactor and the optimal conditions for ammonia production were determined. The oxide-salt composite exhibited much higher ionic conductivity and ammonia production rate than that of the LSAM electrolyte at 400～800 ℃, the rate of evolution of ammonia was up to 5.30 × 10^-9 mol·cm^-2·s^-1.     

纳米SnO2的非水溶剂溶胶-凝胶法制备与表征

Nanometer SnO₂ powders were successfully prepared by non-hydrolytic sol-gel approach combined with heat treatments using tin tetrachloride as starting material and ethylene glycol as solvent. The reaction mechanism of the sol-gel process is proposed. Results indicate that the -OHCH₂CH₂OH- prevent Cl^- ion from accessing to tin Sn⁴⁺ due to steric effect, and hence increaseing the stability of the sol solution. Ethylene glycol functions not only as a complextion agent to form a polymer network but also as a “spacer” to modulate the distance between metal ions, preventing metal oxide particles from aggregation during desiccation of the sol. The effects of heat treatments on the evolution of structure and morphology of nanosized SnO₂ powders were studied. The powders with narrow size distribution around 15～20 nm could be obtained at 500 ℃ for 4 h.     

[COH(NH2)2]2[Cu(pic)2(ClO4)2]的合成与晶体结构

The title compound was synthesized by reaction of Cu(ClO₄)₂， picolinic acid and carbamide in C₂H₅OH/CH₃CN solution， and characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system， space group Pbca with a=14.0481(8)， b=9.0130(5)， c=18.626(1)?， V=2358.3(2)?³， Z=4， D_x=1.771g·cm^-3， μ=1.235mm^-1 and F(000)=1276. The final R factor is 0.0440 for 1434 observed reflections. The X-ray analysis revealed that the copper(Ⅱ) atom is coordinated by two picolinic ligands in the equatorial plane， while the two oxygen atoms of perchlorate occupy the axial positions of octahedron with lengthened Cu-O distances， resulting in a 4+2 elongated octahedral environment. In the compound， there also exist two protonated carbamide cations for charge balance. CCDC： 195354.