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Showing papers on "Thermal decomposition published in 2008"


Journal ArticleDOI
TL;DR: In this article, a dynamic TG analysis under nitrogen was used to investigate the thermal decomposition processes of 10 types of natural fibers commonly used in the polymer composite industry, including wood, bamboo, agricultural residue, and bast fibers.

713 citations


Journal ArticleDOI
TL;DR: Dynamic surface rearrangement and thermal stability of N-functional groups on carbon nanotubes, obtained by functionalization of pristine CNTs with NH(3), were studied by temperature-programmed XPS and MS and a conversion into graphitic nitrogen was observed.

320 citations


Journal ArticleDOI
TL;DR: Based on annealing experiments with natural and synthetic raw materials of known grain size and impurity level as well as single crystals, the temperature of thermal dissociation of ZrSiO 4 was assessed at 1673±10°C as discussed by the authors.
Abstract: Based on annealing experiments with natural and synthetic raw materials of known grain size and impurity level as well as single crystals the temperature of thermal dissociation of ZrSiO 4 was assessed at 1673 ± 10 °C. ZrSiO 4 decomposes by a solid-state reaction releasing SiO 2 in form of discrete metastable intermediate phases with superstoichiometric Si-content. The eutectic temperature in the ZrO 2 –SiO 2 system was set to 1687 ± 10 °C. The thermodynamic dataset for the ZrO 2 –SiO 2 system was optimised and the quasi-binary phase diagram was re-calculated. The significant influence of even small amounts of impurities on the decomposition temperature and kinetics is explained by the formation of low melting liquid phases resulting in the favoured dissolution of solid silica immediately after release from the zircon structure.

309 citations


Journal ArticleDOI
TL;DR: In this paper, the mesoporous Co3O4 nano-needles with a 3D single-crystalline framework were synthesized based on controlled thermal oxidative decomposition.
Abstract: In this work, we report the simple solid-state formation of mesoporous Co3O4 nano-needles with a 3D single-crystalline framework. The synthesis is based on controlled thermal oxidative decomposition and re-crystallization of precursor β-Co(OH)2 nano-needles. Importantly, after thermal treatment, the needle-like morphology can be completely preserved, despite the fact that there is a large volume contraction accompanying the process: β-Co(OH)2 → Co3O4. Because of the intrinsic crystal contraction, a highly mesoporous structure with high specific surface area has been simultaneously created. The textual properties can be easily tailored by varying the annealing temperature between 200–400 °C. Interestingly, thermal re-crystallization at higher temperatures leads to the formation of a perfect 3D single-crystalline framework. Thus derived mesoporous Co3O4 nano-needles serve as a good model system for the study of lithium storage properties. The optimized sample manifests very low initial irreversible loss (21%), ultrahigh capacity, and excellent cycling performance. For example, a reversible capacity of 1079 mA h g−1 can be maintained after 50 cycles. The superior electrochemical performance and ease of synthesis may suggest their practical use in lithium-ion batteries.

308 citations


Journal ArticleDOI
TL;DR: In this article, the authors used X-ray diffraction (XRD), thermogravimetric (TG) analysis coupled with differential thermal analysis (DTA), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) technique, and Fourier transformation infrared spectroscopy (FTIR) for ammonium perchlorate (AP) decomposition.

245 citations


Journal ArticleDOI
TL;DR: In this paper, the glass phase transition in cellulose was studied using the differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermal gravimetry.
Abstract: Cellulose powder and cellulose pellets obtained by pressing the microcrystalline powder were studied using differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermal gravimetry (TG). The TG method enabled the assessment of water content in the investigated samples. The glass phase transition in cellulose was studied using the DSC method, both in heating and cooling runs, in a wide temperature range from −100 to 180 °C. It is shown that the DSC cooling runs are more suitable for the glass phase transition visualisation than the heating runs. The discrepancy between glass phase transition temperature T g found using DSC and predictions by Kaelbe’s approach are observed for “dry” (7 and 5.3% water content) cellulose. This could be explained by strong interactions between cellulose chains appearing when the water concentration decreases. The T g measurements vs. moisture content may be used for cellulose crystallinity index determination.

242 citations


Journal ArticleDOI
TL;DR: In this article, a facile method has been developed to synthesize nanoporous manganese and nickel oxides with polyhedron particle morphologies, high surface areas and narrow pore distributions by controlled thermal decomposition of the oxalate precursors.
Abstract: A facile method has been developed to synthesize nanoporous manganese and nickel oxides with polyhedron particle morphologies, high surface areas and narrow pore distributions by controlled thermal decomposition of the oxalate precursors. This method can be extended to using other kinds of salt precursors to prepare a series of nanoporous metal oxides. The heating rate, calcination temperature and controlled particle size of the oxalate precursors are important factors to get well-defined pore structures. XRD, TG-DTA, TEM, SEM, XPS, wet chemical titration and N2 sorption isotherm techniques are employed for morphology and structure characterizations. High surface area microporous manganese oxide (283 m2 g−1) and mesoporous nickel oxide (179 m2 g−1) with narrow pore distribution at around 1.0 nm and 6.0 nm, respectively, are obtained. Especially, we can tune the pore size of manganese oxides from microscope to mesoscope by controlling the thermal procedure. Electrochemical properties of manganese and nickel oxides are studied by cyclic voltammetry measurements in a mild aqueous electrolyte, which shows a high specific capacitance of 309 F g−1 of microporous manganese oxide and a moderately high specific capacitance of 165 F g−1 of mesoporous NiO due to their nanoporous structure, presenting the promising candidates for super capacitors (SC).

241 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the influence of potassium on the pyrolysis behavior of cellulose and lignin, and showed that the effect of the addition of 1% of potassium in the form of potassium acetate has a huge influence on the char formation stage and increases the char yields.

240 citations


Journal ArticleDOI
01 Apr 2008-Fuel
TL;DR: In this paper, a double-bed micro-reactor was used for wood (Cedar) biomass gasification using a specially designed flow-type double beds micro reactor in a two-step process: temperature programmed non-catalytic steam gasification of biomass was performed in the first bed at 200-850°C followed by catalytic decomposition of volatile matters (including tars) in the second bed at a constant temperature, mainly 600°C.

225 citations


Journal ArticleDOI
TL;DR: A chemical synthesis process for the fabrication of NiO is described in this paper, where a chemical route for preparation of nickel hydroxide thin films on the glass substrate from solution containing Ni (2+) ions and ammonia is reported.

224 citations


Journal ArticleDOI
TL;DR: In this article, X-ray diffraction (XRD) analysis revealed broad pattern for fcc crystal structure of copper metal and particle size by use of Debye-Scherrer's equation was calculated to be about 40nm.

Journal ArticleDOI
TL;DR: In this article, the effects of three nitrogen additives (urea, guanidine carbonate, and melamine formaldehyde) on the flame retardant action of cotton cellulose treated with tributyl phosphate (TBP) were investigated.

Journal ArticleDOI
TL;DR: The ammonia complex of magnesium borohydride Mg(BH4)2.2NH3 (I), which contains 16.0 wt % hydrogen, is a potentially promising material for hydrogen storage, and the structure of I that crystallizes in the orthorhombic space group Pcab is solved.
Abstract: The ammonia complex of magnesium borohydride Mg(BH4)2·2NH3 (I), which contains 16.0 wt % hydrogen, is a potentially promising material for hydrogen storage. This complex was synthesized by thermal decomposition of a hexaaammine complex Mg(BH4)2·6NH3 (II), which crystallizes in the cubic space group Fm3m with unit cell parameter a = 10.82(1) A and is isostructural to Mg(NH3)6Cl2. We solved the structure of I that crystallizes in the orthorhombic space group Pcab with unit cell parameters a = 17.4872(4) A, b = 9.4132(2) A, c = 8.7304(2) A, and Z = 8. This structure is built from individual pseudotetrahedral molecules Mg(BH4)2·2NH3 containing one bidentate BH4 group and one tridentate BH4 group that pack into a layered crystal structure mediated by N−H···H−B dihydrogen bonds. Complex I decomposes endothermically starting at 150 °C, with a maximum hydrogen release rate at 205 °C, which makes it competitive with ammonia borane BH3NH3 as a hydrogen storage material.

Journal ArticleDOI
TL;DR: The thermal decomposition of ammonia borane (AB) in the absence and presence of chemical additives was investigated to develop an approach for reducing the induction period for hydrogen release in the solid state as mentioned in this paper.
Abstract: The thermal decomposition of ammonia borane (AB) in the absence and presence of chemical additives was investigated to develop an approach for reducing the induction period for hydrogen release in the solid state. Gas chromatography techniques were used to measure the yield of hydrogen as a function of time under isothermal conditions between 75 and 90 °C to set the baseline. Solid-state 11B-NMR spectroscopy of the products produced after 1 mol equiv of hydrogen had been desorbed from AB (i.e., polyaminoborane) showed a complex mixture of sp3 boron species. Raman microscopy was used to follow the transformation of crystalline AB to amorphous AB upon heating and the subsequent formation of the diammoniate of diborane (DADB). A gas buret was used to monitor the time-dependent release of hydrogen from AB in the presence of chemical additives. The combination of these approaches provides insight into the mechanism of hydrogen release from solid AB. The release of molecular hydrogen is described by a process i...

Journal ArticleDOI
TL;DR: This communication describes the Pd(OAc)2-catalyzed ethoxycarbonylation reactions of aromatic C−H bonds using diethyl azodicarboxylate (DEAD) together with Oxone or K2S2O8.
Abstract: This communication describes the Pd(OAc)2-catalyzed ethoxycarbonylation reactions of aromatic C−H bonds using diethyl azodicarboxylate (DEAD) together with Oxone or K2S2O8. Substrates such as 2-arylpyridines, pyrrolidinone, acetylindoline, quinoline, and oximes were ethoxycarbonylated with excellent chemo- and regioselectivities. The catalytic reaction is probably initiated by chelation-assisted cyclopalladation of the ortho-C−H bond. Preliminary studies suggested that reactive ethoxyacyl radicals generated from thermal decomposition of DEAD were involved in the ester formation.

Journal ArticleDOI
TL;DR: In this paper, nanorods and octahedrons of α-Fe 2 O 3 were selectively synthesized through one-step hydrothermal treatment of iron(III) chloride in aqueous formamide solution for different time.

Journal ArticleDOI
TL;DR: The first synthesis and crystal structure determination of a mixed alkali metal borohydride, LiK(BH4)2, offers the real prospect of chemical control of Tdec by the manipulation of multication combinations.
Abstract: Metal borohydrides continue to attract considerable interest as potential hydrogen storage materials owing to their very large gravimetric hydrogen densities. In terms of the equally important performance parameter, the thermal decomposition temperature Tdec, it has emerged [1–3] that the degree of charge transfer between the metal cation and the BH4 anion is a key component for any ultimate materials design. Although manipulation of Tdec in single-cation borohydrides is clearly limited by the intrinsic properties of the individual metal (its characteristic electronegativity, for example), double and multiple cation substitution allows more extensive and precise control of Tdec. Although this approach is supported by bulk thermochemical studies, there are few X-ray structural investigations of double cation substitutions in these important materials. Such structural information is key to assessing whether genuine new multinary compounds are formed, or whether microscopic segregation of constituent phases takes place. Herein we report the first synthesis and crystal structure determination of a mixed alkali metal borohydride, LiK(BH4)2. Importantly in this new material, the observed decomposition temperature lies between that of the constituent phases. This finding of a genuine, dual-cation single-phase material offers the real prospect of chemical control of Tdec by the manipulation of multication combinations. X-ray diffraction data of thirteen samples with varying initial ratio LiBH4:KBH4 were collected. LiK(BH4)2 (see Figure 1) was identified from the data as having the space group Pnma and approximate lattice parameters a= 7.9134 4, b= 4.4907 4, and c= 13.8440 4. The b-axis lattice parameter is very similar to that of orthorhombic LiBH4 (4.43686(2) 4), suggesting a degree of structural similarity between the phases. The BH4 units in LiK(BH4)2 form an approximately tetrahedral coordination around the lithium ion, which is similar to that found in orthorhombic LiBH4. The Li B bonds are greater in LiK(BH4)2 than in LiBH4 but with a narrower range of angles (see Supporting Information). The larger Li···B separations observed in the new phase may originate from the presence of potassium cations in the structure, which are considerably larger than their lithium counterparts (Li ionic radius 0.59 4, K ionic radius 1.38 4 in tetrahedral coordination). The arrangement of the BH4 units in LiK(BH4)2 and KBH4 differs considerably. KBH4 has an octahedral arrangement of BH4 units, whereas those in LiK(BH4)2 might be best described as monocapped trigonal prisms (see Supporting Information). The K···B distances in KBH4 are 3.364 4, [8] whereas in LiK(BH4)2 the (seven) distances are 3.404(3)(18) 4 (twice), 3.409(3) 4 (twice), 3.431(3) 4 (twice), and 3.475(3) 4 (once). It is thought that these larger separations arise because of the greater number of BH4 units present around the potassium cation. The BH4 units in LiK(BH4)2 appear to be distorted in a similar manner to those reported in the orthorhombic structure of LiBH4 by Soulie et al. [6] (see Supporting Information). Specifically, while KBH4 has all equivalent B H bonds, those in orthorhombic LiBH4 [6] and LiK(BH4)2 are separated into two equivalent pairs. LiK(BH4)2 was found to have a narrower range of B H bond lengths than LiBH4 Figure 1. A schematic diagram of a) the proposed LiK(BH4)2 structure and b) that of orthorhombic LiBH4. K crimson, Li yellow, B green, H gray.

Journal ArticleDOI
01 Jan 2008-Carbon
TL;DR: In this paper, the authors investigated the hydrogen sorption properties of MgH2 and carbon materials, including graphite, activated carbon, multi-walled carbon nanotubes (MWCNTs), carbon nanofibres (CNFs) and activated carbon fibres.

Journal ArticleDOI
TL;DR: Kinetic simulation results for a high temperature pyrolysis environment show that MB radicals are mainly produced through hydrogen abstraction reactions by H atoms, and the C(O)OCH(3) = CO + CH( 3)O reaction is found to be the main source of CO formation.
Abstract: In this paper, we report a detailed analysis of the breakdown kinetic mechanism for methyl butanoate (MB) using theoretical approaches. Electronic structures and structure-related molecular properties of reactants, intermediates, products, and transition states were explored at the BH&HLYP/cc-pVTZ level of theory. Rate constants for the unimolecular and bimolecular reactions in the temperature range of 300−2500 K were calculated using Rice−Ramsperger−Kassel−Marcus and transition state theories, respectively. Thirteen pathways were identified leading to the formation of small compounds such as CH3, C2H3, CO, CO2, and H2CO. For the initial formation of MB radicals, H, CH3, and OH were considered as reactive radicals participating in hydrogen abstraction reactions. Kinetic simulation results for a high temperature pyrolysis environment show that MB radicals are mainly produced through hydrogen abstraction reactions by H atoms. In addition, the C(O)OCH3 = CO + CH3O reaction is found to be the main source of C...

Journal ArticleDOI
TL;DR: In this paper, the photoluminescence of ZnO nanoparticles was studied by exciting the sample with an ArF laser (193nm) and a strong blue-shift of the emission band was observed, suggesting a strong quantum size effect.

Journal ArticleDOI
TL;DR: The data on nanoflower-like nanostructures are generalized for several groups of inorganic compounds (carbon, elemental metals, their alloys and compounds with the elements of V and VI Groups of the Periodic Table), as well as for a few coordination and organic compounds.
Abstract: The data on nanoflower-like nanostructures are generalized for several groups of inorganic compounds (carbon, elemental metals, their alloys and compounds with the elements of V and VI Groups of the Periodic Table), as well as for a few coordination and organic compounds. Their synthetic techniques include oxidation of elemental metals, reduction of metal salts, thermal decomposition of relatively unstable compounds, or electrochemical route. Some current and possible applications of nanoflowers are noted.

Journal ArticleDOI
TL;DR: In this paper, porous nanocrystalline ZnFe2O4 "timber-like" superstructures were synthesized through the thermal decomposition of zinc ferrioxalate precursor prepared from metal sulfates and sodium.
Abstract: In this paper, porous nanocrystalline ZnFe2O4 “timber-like” superstructures were synthesized through the thermal decomposition of zinc ferrioxalate precursor prepared from metal sulfates and sodium...

Journal ArticleDOI
TL;DR: In this paper, the H2 release from the thermal decomposition reaction of sodium tetrahydroboride (NaBH4) in the solid state has been investigated using a first-principles approach.

Journal ArticleDOI
TL;DR: The variations of photoluminescence spectra and catalytic roles in ammonium perchlorate decomposition were discussed in terms of the defect structure of ZnO twin-cones.
Abstract: ZnO twin-cones, a new member to the ZnO family, were prepared directly by a solvothermal method using a mixed solution of zinc nitrate and ethanol. The reaction and growth mechanisms of ZnO twin-cones were investigated by X-ray diffraction, UV-visible spectra, infrared and ion trap mass spectra, and transmission electron microscopy. All as-prepared ZnO cones consisted of tiny single crystals with lengths of several micrometers. With prolonging of the reaction time from 1.5 h to 7 days, the twin-cone shape did not change at all, while the lattice parameters increased slightly and the emission peak of photoluminescence shifted from the green region to the near orange region. ZnO twin-cones are also explored as an additive to promote the thermal decomposition of ammonium perchlorate. The variations of photoluminescence spectra and catalytic roles in ammonium perchlorate decomposition were discussed in terms of the defect structure of ZnO twin-cones.

Journal ArticleDOI
TL;DR: In this article, the effect of the Ni2+ and Ce3+ incorporation methods in the hydrotalcite-type structure was studied, and the results demonstrate the formation of solids with mixed crystalline phases of NiO−MgO (periclase) type and CeO2 (fluorite) as well as other types of reducible species.

Journal ArticleDOI
TL;DR: In this article, the same combination of triphenylphosphine and oleylamine were added as surfactants to control the particle size to depict the phase and morphology.

Journal ArticleDOI
TL;DR: In this paper, the performance of nanometer copper ferrite on the thermal decomposition of ammonium perchlorate (AP) was investigated by DTA and the results showed that the nanometer CuFe 2 O 4 has high a catalytic activity, and the temperature of AP shift 105 ˚C downward with the effect of nano-copper ferrite.

Journal ArticleDOI
TL;DR: In this paper, a DSC study of the thermal decomposition of starch kept at constant moisture content (0-50%) in a sealed system comprising a high-pressure stainless steel pan with a gold-plated copper seal was performed.

Journal ArticleDOI
TL;DR: In this paper, the authors reported on the synthesis of Mn 3 O 4 nanoparticles using thermal decomposition and their physicochemical characterization using [bis(salicylidiminato)manganese(II)] as a precursor.

Journal ArticleDOI
Li Jie1, Liu Yuwen1, Shi Jingyan1, Wang Zhiyong1, Hu Ling1, Yang Xi1, Wang Cunxin1 
TL;DR: In this article, an online-coupled TG-FTIR evolved gas analysis (EGA) instrument was used to identify and monitor the evolution of gaseous products during the thermal decomposition of phenylalanine and tyrosine in flowing N 2 atmosphere up to 800°C.