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1.
Copper forms of synthetic zeolite ZSM5 containing ethylenediamine (en) were characterised by methods of thermal analyses - TG, DTA and DTG in the temperature range 20-1000°C, in air and in argon atmosphere. Mass spectroscopy was used for the study of the released gas products of thermal decomposition. The results of thermal analyses of three Cu(en)xZSM5 zeolitic products with different composition (x depends on the mode of preparation) checked their different thermal properties. The main part of the decomposition process occurs at considerably higher temperatures than the boiling point of ethylenediamine of all three products, it proves strong bond and irreversibility of en-zeolite interaction. According to the results of the mass spectroscopy method the decomposition process in inert atmosphere is characterised by the development of a large spectrum of products with atomic mass from 28 to 178 atomic mass units, and there is a correlation between the mode of sample preparation and the spectrum of the released products. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

2.
New zinc(II) 4-hydroxybenzoate complex compounds with general formula [Zn(4-OHbenz)2LnxH2O, where 4-OHbenz = 4-hydroxybenzoate; L = isonicotinamide, N-methylnicotinamide, N,N-diethylnicotinamide, thiourea, urea, phenazone, theophylline, methyl-3-pyridylcarbamate; n = 2, 3; x = 0–3, 5, were synthesized and characterised by elemental analysis, thermal analysis and IR spectroscopy. The thermal behaviour of the prepared compounds was studied by TG/DTG and DTA methods in argon atmosphere. The thermal decomposition of hydrated compounds started with dehydration. During the thermal decomposition, organic ligand, carbon monoxide, carbon dioxide and phenol were evolved. The final solid product of the thermal decomposition was zinc or zinc oxide. The volatile gaseous product, solid intermediate products and the final product of thermal decomposition were identified by IR spectroscopy, mass spectrometry, qualitative chemical analyses and X-ray powder diffraction method. The antimicrobial activity of zinc(II) carboxylate compounds was tested against various strains of bacteria, yeasts and filamentous fungi (S. aureus, E. coli, C. parapsilosis, R. oryzae, A. alternata, M. gypseum). The presence of zinc in complexes led to the increase in their antimicrobial activity in comparison with free 4-hydroxybenzoic acid.  相似文献   

3.
New adducts of ethylenediamine (en), N,N-dimethylethylenediamine (ndmen) and N,N′-dimethylethylenediamine (dmen) with squarate as counter-ions were synthesized and characterized by physico-chemical methods (IR and UV/vis spectroscopy, magnetic susceptibility and thermoanalytical measurements). The crystal structure of tris(ethylenediamine)cobalt(III) 1.5 squarate hexahydrate, [Co(en)3](sq)1.5 · 6H2O, was determined by single crystal X-ray diffraction. Co(III), Ni(II) and Cu(II) ions in the monomeric octahedral tris(ethylenediamine)cobalt(III) 1.5 squarate hexahydrate (1), tris(ethylenediamine)nickel(II) squarate 0.5 hydrate (2) and diaquabis(ethylenediamine)copper(II) squarate dihydrate (3) are chelated by ethylenediamines through two amine nitrogen atoms. Cu(II) atoms in the diaquabis(ndmen)copper(II) squarate (4) and diaquabis(dmen)copper(II) squarate (5) monomeric octahedral complexes are coordinated by ndmen and dmen molecules through two amine nitrogen atoms in a bidentate chelating manner. Water molecules complete the octahedral coordination. The orange (1), violet (4) and violet (5) complexes upon heating transform to claret, green and green species on dehydration, respectively, which revert immediately after cooling in the open atmosphere. The violet (3) complex upon heating loses water molecules yielding a deep blue dehydrated species, which on further heating undergoes an exothermic phase transition accompanied by thermochromism, deep blue to brown in the solid state. The decomposition mechanism and thermal stability of the solid complexes are interpreted in terms of their structures. The final decomposition products – the respective metal oxides – were identified by IR spectroscopy.  相似文献   

4.
New zinc(II) 4- and 5-chlorosalicylate complexes of general formula [Zn(X-sal)2(L) n (H2O) x ] (where X-sal?=?4-Clsalicylate, 5-Clsalicylate; L?=?N,N-diethylnicotinamide, isonicotinamide, theophylline; n?=?1, 2; x?=?0, 1, 2, 4) were prepared. The complexes were determined by elemental analysis and characterised by infrared spectroscopy. The thermal behaviour of the complexes was studied by simultaneous TG, DTG and DTA methods under dynamic air conditions. The thermal decomposition is a multi-step process. In the first step of the thermal decomposition, water is released in hydrated compounds. The anhydrous compounds start to decompose by the release of organic ligand, followed by chlorosalicylic acid, chlorophenol and carbon monoxide. The final solid product of the thermal decomposition is zinc oxide. The volatile products of the thermal decomposition were determined by mass spectrometry. The antimicrobial activities of the complexes were evaluated against selected pathogen and probiotic bacteria, yeasts and fungi strains. Bioactivities of the tested compounds are different against bacteria, yeasts and filamentous fungi. It was found that bacteria were more sensitive to the studied zinc(II) complex compounds than yeasts or filamentous fungi.  相似文献   

5.
Violet crystals of [Cu(en)2][Pt(CN)4] and blue crystals of [Cu(dmen)2][Pt(CN)4] were crystallized from the water-methanol solution containing CuCl2·2H2O, ethylenediamine (en) or N,N-dimethylethylenediamine (dmen) and K2[Pt(CN)4]·3H2O. Both compounds were characterized using elemental analysis, infrared and UV-VIS spectroscopy, magnetic measurements, specific heat measurements and thermal analysis. X-ray structure analysis revealed chain-like structure in both compounds. The covalent chains are built of Cu(II) ions linked by [Pt(CN)4]2− anions in the [111] and [101] direction, respectively. The Cu(II) atoms are hexacoordinated by four nitrogen atoms in the equatorial plane from two molecules of bidentate ligands L with average Cu-N distance of 2.022(2) and 2.049(4) Å, respectively. Axial positions are occupied by two nitrogen atoms from bridging [Pt(CN)4]2− anions at longer Cu-N distance of 2.537(2) and 2.600(5) Å, respectively. Both materials are characterized by the presence of weak antiferromagnetic exchange coupling. Despite the one-dimensional (1D) character of the structure, the analysis of magnetic properties and specific heat at very low temperatures shows that [Cu(en)2][Pt(CN)4] behaves as two-dimensional (2D) spatially anisotropic square lattice Heisenberg magnet, while more pronounced influence of interlayer coupling is observed in [Cu(dmen)2][Pt(CN)4].  相似文献   

6.
New zinc(II) 4-bromobenzoate complex compounds with general formula [Zn(4-BrC6H4COO)2L2xH2O (where L?=?urea, nicotinamide, phenazone or thiourea, x?=?0?C2) were prepared and characterized by elemental analysis, IR spectroscopy and thermal analysis. The thermal decomposition of hydrated compounds started with dehydration process. During the thermal decomposition, the neutral organic ligand, bis(4-bromophenyl)methanone and carbon dioxide were evolved. The solid intermediates and volatile products of thermal decomposition were proved by IR spectroscopy and mass spectrometry. The final solid product of the thermal decomposition heated up to 800?°C was zinc oxide, which was confirmed by X-ray powder diffractometry. Antimicrobial activity of the prepared compounds was tested against various strains of bacteria, yeasts and filamentous fungi (E. coli, S. aureus, C. albicans, R. oryzae, A. alternata and M. gypseum). It was found that bacterium S. aureus and fungi A. alternata are the most sensitive to the studied compounds.  相似文献   

7.
The sol-gel process is a useful method for preparing two series of organically and co-ordinately modified xerogels of the types [CuN n N 5–n ·5xSiO4/2 (n < 4) and [Cu(N–N)n]·(N–N)2–n ·2x SiO4/2(n 2), where N = NH2(CH2)3 SiO3/2, N–N = NH2(CH2)2NH·(CH2)3SiO3/2 and x = [SiO4/2]/[N] or [SiO4/2]/[N–N]. The amino groups in the materials are coordinately active and participate partly in the coordination sphere of Cu(II) ions. The composition of the coordination sphere can be varied with the SiO4/2 content and also as a result of the thermal decomposition of the organic residues at higher temperatures.Because the xerogel materials are considered to be catalyst precursors, this study is focused on their coordination and thermal properties. The prepared xerogels, such as silica, aminated silicates with N and N–N, as well as those entities complexed with Cu(II), were characterised by FT-IR spectroscopy. During gelation and thermal decomposition the materials were analysed by electron paramagnetic resonance (EPR) spectroscopy. The xerogels were additionally studied by UV-Vis absorption spectroscopy. The gaseous products of the thermal decomposition of these materials in an Ar atmosphere were investigated by the use of FT-IR spectroscopy coupled with TG and DTG thermal analysis. These data were complemented by temperature-programmed decomposition (TPDec) in a 2% O2 + 98% Ar stream coupled with quadrupole mass spectroscopy.  相似文献   

8.
The N-pyrrolidine-N??-(2-chlorobenzoyl)thiourea, HL, and their Ni(II), Cu(II), and Co(III) complexes (NiL2, CuL2, and CoL3) have been synthesized and characterized. The thermal decomposition reactions of all the compounds have been investigated by DTA/TG combined systems. The mass spectroscopy technique has been used to identify the products during pyrolytic decomposition. The pyrolytic final products have been analyzed by X-ray powder diffraction method. After comparison of thermogravimetric and mass results of HL, NiL2, CuL2, and CoL3, the decomposition mechanism of these compounds have been suggested. The thermal stability of the Ni(II) and Cu(II) complexes according to the thermogravimetric curves follows the sequence: NiL2?<?CuL2. The values of the activation energy, E a, have been obtained using model-free (Kissenger?CAkahira?CSunose, KAS, Flyn?CWall?COzawa, FWO, and Isoconversional) methods for all decomposition stages. The E a versus the extent of conversion, ??, plots show that the values of E a varies as ??. Thirteen kinetic model equations have been tested for selecting correct reaction models. The optimized value of E a and Arrhenius factor, A, have been obtained using the best model equation. The thermodynamic functions (??H*, ??S*, and ??G*) have been calculated using these values.  相似文献   

9.
The thermal degradation and corresponding decomposition products of fresh and heat-treated soybean oil were investigated by synchronous thermal analyzer combined with Fourier transform infrared spectrometry and quadrupole mass spectrometry (STA–FTIR–QMS). Two longtime heat-treated soybean oil samples were aforehand prepared by consistently heating the fresh soybean oil for 50 and 100 h, respectively. N2 and simulative air (N2/O2 = 4:1, volume) were used as the thermal reaction gas atmosphere. The results showed that one stage of mass loss appeared in analysis of the all oil samples under N2 atmosphere condition and longtime heat pre-treatment had no effect on the thermal behavior of the soybean oil under N2 atmosphere condition. However, four stages occurred in analysis of both untreated and heat-treated oil samples under the simulative air atmosphere condition. Longtime heat pre-treatment influenced the thermal behavior of the soybean oil in certain extent, which was reflected in the different mass loss values of the four stages. According to the infrared absorption profiles and MS spectra of the released compounds in vapor phase, H2O, CO, CO2, hydrocarbons (such as CH4), and hydroxyl, carbonyl, and carboxyl-contained compounds have been confirmed. Therefore, STA–FTIR–QMS can be suggested as a promising technique for investigating of thermal degradation and monitoring the decomposition products of the evolving substances in edible oils.  相似文献   

10.
Sorption of hazardous pyridine derivates by copper forms of synthetic zeolite ZSM5 and natural zeolite of the clinoptilolite type (CT) has been investigated. Sorption of 2-chloropyridine (clpy) and 2-ethylpyridine (ethylpy) from liquid and gas phase by copper forms of zeolites (Cu-ZSM5 and Cu-CT) has been studied by CHN analysis, thermal (TG, DTG and DTA) analysis, FTIR spectroscopy, X-ray powder diffractometry and determination of the surface areas and the pore volumes by low-temperature adsorption of nitrogen. The results of thermal analyses of Cu-ZSM5, Cu-(clpy) x -ZSM5, Cu-(ethylpy) x -ZSM5, Cu-CT, Cu-(clpy) x -CT and Cu-(ethylpy) x -CT zeolitic products with different composition (x depends on the experimental conditions of sorption of pyridine derivates) clearly confirmed their different thermal properties and the sorption of pyridine derivates. The main part of the decomposition process of zeolitic samples containing pyridine derivates occurs at considerably higher temperatures than the boiling point of pyridine derivates proving strong bond and irreversibility of clpy- and/or ethylpy–zeolite interaction. FTIR spectra showed well-resolved bands for pyridine derivates in the Cu-(clpy) x -zeolite and Cu-(ethylpy) x -zeolite. Surface area and pore volumes of the samples Cu-clpy-ZSM5, Cu-ethylpy-ZSM5, Cu-clpy-CT and Cu-ethylpy-CT in comparison with Cu-ZSM5 and Cu-CT decreased due to the adsorption of pyridine derivates.  相似文献   

11.
Summary Prediction of the thermal decomposition pathway of the metal complexes is very important from the theoretical and experimental point of view to determine the properties and structural differences of complexes. In the prediction of the decomposition pathways of complexes, besides the thermal analysis techniques, some ancillary techniques e.g. mass spectroscopy is also used in recent years. In the light of the molecular structures and fragmentation components, it is believed that the thermal decomposition pathway of most molecules is similar to the ionisation mechanism occurring in the mass spectrometer ionisation process. In this study, the thermal decomposition pathway of [Ni(dmen)2(H2O)2](acs)2 complex have been predicted by the help of thermal analysis data (TG, DTG and DTA) and mass spectroscopic fragmentation pattern. The complex was decomposed in four stages: a) dehydration between 84-132°C, b) loss of N,N'-dimethylethylenediamine (dmen) ligand, c) decomposition of remained dmen and acesulfamato (acs) by releasing SO2, d) burning of the organic residue to resulting in NiO. The volatile products observed in the thermal decomposition process were also observed in the mass spectrometer ionisation process except molecular peak and it was concluded that the ionisation and thermal decomposition pathway of the complex resembles each other.  相似文献   

12.
The thermal decomposition of rare-earth trioxalatocobaltates LnCo(C2O4)3 · x H2O, where Ln  La, Pr, Nd, has been studied in flowing atmospheres of air/oxygen, argon/ nitrogen, carbon dioxide and a vacuum. The compounds decompose through three major steps, viz. dehydration, decomposition of the oxalate to an intermediate carbonate, which further decomposes to yield rare-earth cobaltite as the final product. The formation of the final product is influenced by the surrounding gas atmosphere. Studies on the thermal decomposition of photodecomposed lanthanum trioxalatocobaltate and a mechanical mixture of lanthanum oxalate and cobalt oxalate in 1 : 2 molar ratio reveal that the decomposition behaviour of the two samples is different. The drawbacks of the decomposition scheme proposed earlier have been pointed out, and logical schemes based on results obtained by TG, DTA, DTG, supplemented by various physico-chemical techniques such as gas and chemical analyses, IR and mass spectroscopy, surface area and magnetic susceptibility measurements and X-ray powder diffraction methods, have been proposed for the decomposition in air of rare-earth trioxalatocobaltates as well as for the photoreduced lanthanum salt and a mechanical mixture of lanthanum and cobalt oxalates.  相似文献   

13.
Solid-state M–L compounds, where M stands for bivalent Mn, Co, Ni, Cu and Zn and L is folate (C19H17N7O6), have been synthesized. Simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), X-ray powder diffractometry, infrared spectroscopy (FTIR), TG–DSC coupled to FTIR, elemental analysis and high-resolution continuum source flame atomic absorption spectrometry technique (HR-CS FAAS) were used to characterize and to study the thermal behaviour of these compounds. The results provided information concerning the composition, dehydration, thermal stability and thermal decomposition.  相似文献   

14.
In this article, the influences of temperature and atmosphere on thermal stability of BaCrO4 were investigated. BaCrO4 powders with an orthorhombic structure were synthesized by a facile aqueous solution route. The synthesized BaCrO4 products were then heat treated at different atmospheres to evaluate their thermal stability by differential thermal analysis–thermogravimetry (DTA–TG), X-ray photoelectron spectroscopy and X-ray diffraction. BaCrO4 has a good thermal stability and does not decompose in air up to 1,400 °C. However, the decomposition of BaCrO4 in vacuum depends mainly upon a two-stage chemical reaction. BaCrO4 is finally decomposed into BaCr2O4 with trivalent Cr3+ cations and Ba3(Cr6+ Cr5+)2O9?x with both pentavalent Cr5+ and hexavalent Cr6+ cations after heat treatments in vacuum.  相似文献   

15.
The non-isothermal decomposition of cobalt acetate tetrahydrate was studied up to 500°C by means of TG, DTG, DTA and DSC techniques in different atmospheres of N2, H2 and in air. The complete course of the decomposition is described on the basis of six thermal events. Two intermediate compounds (i.e. acetyl cobalt acetate and cobalt acetate hydroxide) were found to participate in the decomposition reaction. IR spectroscopy, mass spectrometry and X-ray diffraction analysis were used to identify the solid products of calcination at different temperatures and in different atmospheres. CoO was identified as the final solid product in N2, and Co3O4 was produced in air. A hydrogen atmosphere, on the other hand, produces cobalt metal. Scanning electron microscopy was used to investigate the solid decomposition products at different stages of the reaction. Identification of the volatile gaseous products (in nitrogen and in oxygen) was performed using gas chromatography. The main products were: acetone, acetic acid, CO2 and acetaldehyde. The proportions of these products varied with the decomposition temperature and the prevailing atmosphere. Kinetic parameters (e.g.E and lnA) together with thermodynamic functions (e.g. °H, C p and °S) were calculated for the different decomposition steps. In celebration of the 60th birthday of Dr. Andrew K. Galwey  相似文献   

16.
Pyridine adducts of Co, Ni, Cu and Zn sulfate were obtained by refluxing the corresponding sulfate with pyridine in chloroform. The compounds were characterized by elemental analysis, X-ray powder diffraction and FTIR spectroscopy. The thermal decompositions (TG/DTG/DTA) of the complexes in the interval 20–1000°C were also studied. The elemental and thermal analysis results revealed that the formulae of the complexes are M2(SO4)2 xC5H5NyH2O, where x=2, 3, 2 and 1 and y=6, 4, 6 and 4 for the Co, Ni, Cu and Zn compound, respectively. The complexes were not found to be isostructural, but certain structural similarities were observed between the Zn and Co compounds. Although the thermal decomposition pathways of the various compounds were quite different and each consisted of several steps, in all cases the dehydration preceded the depyridination. Metal oxide was always obtained as final product. The spectral data are discussed with regard to the thermal behaviour. Appreciably stronghydrogen-bonding and pronounced structural differences relating to the sulfate ions were presumed for the Cu compound. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

17.
Spinel ferrites of the composition Ni1−xCuxFe2O4 (x = 0.0-1.0) have been prepared through the thermal decomposition of their respective impregnated oxalates. The oxalate decomposition process was followed using differential thermal analysis-thermogravimetry techniques (DTA-TG). The synthesized nanocrystallites were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). The formation of single-phase ferrite is confirmed by XRD. Tetragonal deformation is observed for samples with composition x ? 0.7. The increase in the lattice parameter with increasing Cu content can be explained based on the relative ionic radius. The TEM image shows spherically non-agglomerated particles with an average crystallite size that agrees well with that obtained from XRD. FT-IR studies show two absorption bands (ν1 and ν2) near to 600 and 400 cm−1 for the tetrahedral and octahedral sites, respectively. The hysteresis measurements were done using a vibrating sample magnetometer (VSM). The cation distribution in these compositions is calculated from the magnetization data. With increasing Cu content, the saturation magnetization (Ms) was observed to decrease while the coercivity (Hc) increases. The possible reasons responsible for the composition dependence of the magnetic properties were discussed. The Curie temperature, measured through the temperature dependence of the dc-molar magnetic susceptibility, was found to decrease with increasing Cu content.  相似文献   

18.
Manganese–copper bimetal oxide catalysts supported on ZSM5 and acid-treated multi-walled carbon nanotubes (MWCNTs) were produced by incipient wetness impregnation for selective catalytic reduction of NO with dielectric barrier discharge plasma. Plasma can activate molecules even at ambient temperature, generating active oxygen species such as O, O3, and HO2 radicals, which can oxidize NO to NO2 effectively. The SCR activity of Mn–Cu/MWCNTs was studied and compared to that of the Mn–Cu/ZSM5. The obtained samples were characterized by XRD, SEM, TEM, ICP, H2-TPR, Raman spectroscopy, and XPS. The results show that MnCu/MWCNTs catalyst possesses NO removal activity superior to that of the MnCu/ZSM5 catalyst. MWCNTs-based catalyst attains NO removal efficiency of 88% at 480 J/L, while the ZSM5-supported catalyst achieves NO removal efficiency of 82% at the same energy density. The oxygen content increased from 3.33 to 19.07% on the nanotube surface after introducing Mn and Cu, which almost remained unchanged on ZSM5. The oxygen-containing functionalities are important for NOx adsorption and removal. Moreover, the characterization revealed that CuO is the main phase of copper oxide, but copper dispersion decreases on MnCu/ZSM5 surface because of the formation of copper dimer species. The manganese is well-dispersed on the catalysts, MnO2 and Mn2O3 contents of MnCu/MWCNTs are larger than that of MnCu/ZSM5, MnO2 is the predominant phase of manganese oxide.  相似文献   

19.
The Mössbauer spectra of Sm2Fe17Nx, prepared by the nitrogenation of Sm2Fe17 powders in an ammonia and hydrogen atmosphere, were observed at elevated temperatures to shed light on the thermal behavior of nitrogen in the compounds Sm2Fe17Nx. It was found that there were large differences in thermal behavior between the starting Sm2Fe17, crystalline Sm2Fe17Nx (x≈1.7) and amorphous Sm2Fe17Nx(x~7). The thermal decomposition behavior of Sm2Fe17N3.2, developed as one of the most promising hard magnetic materials, was found to be different under different atmospheres.  相似文献   

20.
Oxynitrides of the general composition SrMoO3−xNx (x>1) were synthesized by thermal ammonolysis of crystalline SrMoO4. According to neutron and X-ray diffraction experiments, the materials crystallize in the cubic perovskite structure (space group Pmm). X-ray absorption spectroscopy (XAS) shows evidence of local distortions of the Mo(O,N)6 octahedra. The oxidation states of Mo determined by X-ray absorption near edge structure (XANES) spectroscopy are slightly lower than that calculated from the oxygen/nitrogen(O/N) content. The disagreement arises from the higher covalence of the Mo-N bonding when compared to the Mo-O bonding (“chemical shift”). The electrical transport properties of the samples are strongly different from SrMoO3. It was found that the conductivity of the samples decreases with increasing nitrogen content. The Seebeck coefficient values are up to three times higher than those of SrMoO3.  相似文献   

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