Showing papers on "Thermal decomposition published in 2018"
TL;DR: In this paper, a hybrid chemistry approach to model the high-temperature oxidation of real, distillate fuels is presented, in which the kinetics of thermal and oxidative pyrolysis of the fuel are modeled using lumped kinetic parameters derived from experiments.
286 citations
TL;DR: Eight of the 20 standard amino acids decompose at well-defined, characteristic temperatures, in contrast to commonly accepted knowledge, and the novel quantitative results emphasize the impact of water and cyclic condensates with peptide bonds.
Abstract: The pathways of thermal instability of amino acids have been unknown. New mass spectrometric data allow unequivocal quantitative identification of the decomposition products. Calorimetry, thermogravimetry and mass spectrometry were used to follow the thermal decomposition of the eight amino acids G, C, D, N, E, Q, R and H between 185 °C and 280 °C. Endothermic heats of decomposition between 72 and 151 kJ/mol are needed to form 12 to 70% volatile products. This process is neither melting nor sublimation. With exception of cysteine they emit mainly H2O, some NH3 and no CO2. Cysteine produces CO2 and little else. The reactions are described by polynomials, AA→a NH3+b H2O+c CO2+d H2S+e residue, with integer or half integer coefficients. The solid monomolecular residues are rich in peptide bonds. Eight of the 20 standard amino acids decompose at well-defined, characteristic temperatures, in contrast to commonly accepted knowledge. Products of decomposition are simple. The novel quantitative results emphasize the impact of water and cyclic condensates with peptide bonds and put constraints on hypotheses of the origin, state and stability of amino acids in the range between 200 °C and 300 °C.
195 citations
06 Nov 2018
TL;DR: Catalytic behavior of the fabricated spinel NPs revealed that the samples containing metallic Ni are active catalysts for the degradation of 4-nitrophenol in aqueous medium.
Abstract: Here, we present the low-temperature (∼600 °C) solution combustion method for the fabrication of CoFe2O4, NiFe2O4, and Co0.5Ni0.5Fe2O4 nanoparticles (NPs) of 12–64 nm range in pure cubic spinel structure, by adjusting the oxidant (nitrate ions)/reductant (glycine) ratio in the reaction mixture. Although nitrate ions/glycine (N/G) ratios of 3 and 6 were used for the synthesis, phase-pure NPs could be obtained only for the N/G ratio of 6. For the N/G ratio 3, certain amount of Ni2+ cations was reduced to metallic nickel. The NH3 gas generated during the thermal decomposition of the amino acid (glycine, H2NCH2COOH) induced the reduction reaction. X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometry, and X-ray photoelectron spectroscopy techniques were utilized to characterize the synthesized materials. XRD analyses of the samples indicate that the Co0.5Ni0.5Fe2O4 NPs have lattice parameter larger than that of NiFe2O4, but smaller than that of CoFe2O4 NPs. Although the saturation magneti...
179 citations
TL;DR: The role of thermodynamics in assessing the intrinsic instability of the CH3NH3PbX3 perovskites (X = Cl,Br,I) is outlined on the basis of the available experimental information, with emphasis on the discrepant results presently available.
Abstract: The role of thermodynamics in assessing the intrinsic instability of the CH3NH3PbX3 perovskites (X = Cl,Br,I) is outlined on the basis of the available experimental information. Possible decomposition/degradation pathways driven by the inherent instability of the material are considered. The decomposition to precursors CH3NH3X(s) and PbX2(s) is first analyzed, pointing out the importance of both the enthalpic and the entropic factor, the latter playing a stabilizing role making the stability higher than often asserted. For CH3NH3PbI3, the disagreement between the available calorimetric results makes the stability prediction uncertain. Subsequently, the gas-releasing decomposition paths are discussed, with emphasis on the discrepant results presently available, probably reflecting the predominance of thermodynamic or kinetic control. The competition between the formation of NH3(g) + CH3X(g), CH3NH2(g) + HX(g) or CH3NH3X(g) is analyzed, in comparison with the thermal decomposition of methylammonium halides....
131 citations
TL;DR: In this paper, a series of temperature programmed reduction-temperature programmed oxidation (TPR-TPO) thermal cycling studies were conducted to understand the interactions between three assigned copper species (α, β, and γ) with CeO2 support and the corresponding catalytic performance of the catalysts.
122 citations
TL;DR: In this article, the economic feasibility of hydrogen production by thermal decomposition of methane was compared to two other technologies, namely steam methane reforming and water electrolysis, in current and potential future market environments.
121 citations
TL;DR: In this article, the relationship between ionic mobility and viscosity in organosolv and chemically modified kraft lignin has been studied and the rheological results have been interpreted in terms of the competitive processes of thermal plasticisation and stiffening through crosslinking.
120 citations
TL;DR: In this paper, a thermal decomposition route with different sintering temperatures was employed to prepare non-stoichiometric nickel oxide (Ni1−δO) from Ni(NO3)2·6H2O as a precursor.
Abstract: A thermal decomposition route with different sintering temperatures was employed to prepare non-stoichiometric nickel oxide (Ni1−δO) from Ni(NO3)2·6H2O as a precursor. The non-stoichiometry of samples was then studied chemically by iodometric titration, wherein the concentration of Ni3+ determined by chemical analysis, which is increasing with increasing excess of oxygen or reducing the sintering temperature from the stoichiometric NiO; it decreases as sintering temperature increases. These results were corroborated by the excess oxygen obtained from the thermo-gravimetric analysis (TGA). X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) techniques indicate the crystalline nature, Ni–O bond vibrations and cubic structural phase of Ni1−δO. The change in oxidation state of nickel from Ni3+ to Ni2+ were seen in the X-ray photoelectron spectroscopy (XPS) analysis and found to be completely saturated in Ni2+ as the sintering temperature reaches 700 °C. This analysis accounts for the implication of non-stoichiometric on the magnetization data, which indicate a shift in antiferromagnetic ordering temperature (TN) due to associated increased magnetic disorder. A sharp transition in the specific heat capacity at TN and a shift towards lower temperature are also evidenced with respect to the non-stoichiometry of the system.
116 citations
TL;DR: The thermal stability in air of the mixed cation organic-inorganic lead halide perovskites is studied, which suggests that the first stage mainly involves reaction of MA+ and the second stage mainly FA+.
Abstract: We study the thermal stability in air of the mixed cation organic–inorganic lead halide perovskites Cs0.17FA0.83Pb(I0.83Br0.17)3 and Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3. For the latter compound, containing both MA+ and FA+ ions, thermal decomposition of the perovskite phase was observed to occur in two stages. The first stage of decomposition occurs at a faster rate compared to the second stage and is only observed at relatively low temperatures (T < 150 °C). For the second stage, we find that both decomposition rate and the activation energy have similar values for Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3 and Cs0.17FA0.83Pb(I0.83Br0.17)3, which suggests that the first stage mainly involves reaction of MA+ and the second stage mainly FA+.
113 citations
TL;DR: In this paper, hydrotalcite-derived catalysts promoted with Zr species were prepared via co-precipitation method, resulting in materials with various Zr loading.
Abstract: Hydrotalcite-derived catalysts promoted with Zr species were prepared via co-precipitation method, resulting in materials with various Zr loading. Physicochemical properties of catalysts precursors and final catalysts were investigated via XRF, XRD, low temperature N2 sorption, H2-TPR, CO2-TPD, TG, SEM and TEM techniques. So characterized catalysts were subsequently tested in the dry methane reforming reaction at 550 °C. Zr-loading introduced into brucite-like layers influenced the process of thermal decomposition of HTs and, as a result, their properties and performance in DRM. Although Zr promotion decreased activity, it strongly increased the stability and selectivity of the catalysts. The catalyst with Zr species present in the framework of periclase-like mixed oxide exhibited high resistance to coking due to the rearrangement of Ni particles upon DRM reaction.
104 citations
TL;DR: In this paper, the effect of burning rate suppressants on the thermal behavior and decomposition kinetics of composite solid propellants was investigated, and it was found that oxamide played an inhibition effect on both stages, whereas the ADA acts as a catalyst in the first stage and as coolant in the second one.
Abstract: The employment of burning rate suppressants in the solid rocket propellant formulation is long known. Different research activities have been conducted to well understand the mechanism of suppression, but literature about the action of oxamide (OXA) and azodicarbonamide (ADA) on the thermal decomposition of composite propellant is still scarce. The focus of this study is on investigating the effect of burning rate suppressants on the thermal behavior and decomposition kinetics of composite solid propellants. Thermogravimetric analysis (TG) and differential thermal analysis have been used to identify the changes in the thermal and kinetic behaviors of coolant-based propellants. Two main decomposition stages were observed. It was found that OXA played an inhibition effect on both stages, whereas the ADA acts as a catalyst in the first stage and as coolant in the second one. The activation energy dependent on the conversion rate was estimated by two model-free integral methods: Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) based on the TG data obtained at different heating rates. The mechanism of action of coolants on the decomposition of solid propellants was confirmed by the kinetic investigation as well.
TL;DR: The experiments reveal the decomposition route for the CsPbX3 perovskites in high vacuum, with a much higher stability than their hybrid organic-inorganic MAPb X3 counterparts.
Abstract: We present the growth, phase transitions, and thermal decomposition of CsPbX3 (X = I, Br) thin films monitored by in situ X-ray diffraction (XRD). The perovskite films are prepared in vacuum via co-evaporation of PbX2 and CsX (X = I, Br) onto glass substrates. In situ X-ray diffraction allows the observation of phase transitions and decomposition while the samples are heated with a linear temperature ramp. Our experiments reveal the decomposition route for the CsPbX3 perovskites in high vacuum, with a much higher stability than their hybrid organic–inorganic MAPbX3 counterparts. We also observe the response of a black CsPbI3 thin film to exposure to ambient air at room temperature using the same XRD system. Exposing the black CsPbI3 to ambient air leads to the formation of yellow orthorhombic δ-CsPbI3, whose crystal structure could be identified by its X-ray diffraction pattern. Additionally, the linear coefficients of expansion are determined for δ-CsPbI3 and the (020)-orientation of CsPbBr3.
TL;DR: In this paper, a co-precipitation method was used to obtain Ni-containing and Ni-La promoted catalysts, which showed very high activity in CO2 methanation, which is an efficient way of carbon dioxide conversion into methane.
Abstract: Hydrotalcite-derived Ni-containing and Ni-La promoted catalysts showed very high activity in CO2 methanation, which is an efficient way of carbon dioxide conversion into methane – a valuable product. The catalysts were obtained by co-precipitation method followed by thermal decomposition and characterized by elemental analysis, low temperature nitrogen sorption, XRD, H2-TPR, CO2-TPD and TEM. The obtained results confirmed the formation of periclase-like structure materials, with nickel present as NiO nanoparticles and suggested successful incorporation of lanthanum into the catalytic system. The addition of lanthanum changed the interaction between nickel and periclase matrix (H2-TPR) and changed the distribution of basic sites, especially medium strength ones (CO2-TPD). Moreover, the catalysts were studied by complementary HERFD-XANES and XES spectroscopy under model operando conditions. The results uncovered that the presence of lanthanum strongly influenced the chemical nature and oxidation state of nickel species and its crucial role in catalyst activity enhancement in CO2 methanation reaction.
TL;DR: In this study, a ε-CL-20 supercell was constructed and ReaxFF-lg reactive molecular dynamics simulations were performed to investigate thermal decomposition ofε- CL-20 at various temperatures (2000, 2500, 2750, 3000, 3250, and 3500 K).
Abstract: Hexanitrohexaazaisowurtzitane (CL-20) has a high detonation velocity and pressure, but its sensitivity is also high, which somewhat limits its applications. Therefore, it is important to understand the mechanism and characteristics of thermal decomposition of CL-20. In this study, a e-CL-20 supercell was constructed and ReaxFF-lg reactive molecular dynamics simulations were performed to investigate thermal decomposition of e-CL-20 at various temperatures (2000, 2500, 2750, 3000, 3250, and 3500 K). The mechanism of thermal decomposition of CL-20 was analyzed from the aspects of potential energy evolution, the primary reactions, and the intermediate and final product species. The effect of temperature on thermal decomposition of CL-20 is also discussed. The initial reaction path of thermal decomposition of CL-20 is N–NO2 cleavage to form NO2, followed by C–N cleavage, leading to the destruction of the cage structure. A small number of clusters appear in the early reactions and disappear at the end of the re...
TL;DR: In this paper, pressure-assisted thermal decomposition of graphene oxide films by hot pressing at different temperatures (i.e., 300°C, 1000°C or 2000°C) was discussed.
TL;DR: In this article, the authors identified temperature ranges on the phases in actual cementitious systems (portland cement (OPC) pastes, blended pastes of ground granulated blast furnace slag (GGBFS) with OPC, and Ca(OH)2-activated GGBFS), by simultaneously using thermogravimetry (TG) and high-temperature X-ray diffraction (HT-XRD).
TL;DR: This work paved a feasible method to prepare well-dispersed carbides@Co-Ni LDH nanocomposites with a more environmentally friendly method.
Abstract: This work proposed an idea of recycling in preparing Co-Ni layered double hydroxide (LDH)-derived flame retardants. A novel and feasible method was developed to synthesize CO-Ni LDH-decorated graphene oxide (GO) and carbon nanotubes (CNTs), by sacrificing bimetal zeolitic imidazolate frameworks (ZIFs). Organic ligands that departed from ZIFs were recyclable and can be reused to synthesize ZIFs. ZIFs, as transitional objects, in situ synthesized on the surfaces of GO or CNTs directly suppressed the re-stacking of the carbides and facilitated the preparation of GO@LDHs and CNTs@LDHs. As-prepared hybrids catalytically reduced toxic CO yield during the thermal decomposition of unsaturated polyester resin (UPR). What is more, the release behaviors of aromatic compounds were also suppressed during the pyrolysis process of UPR composites. The addition of GO@LDHs and CNTs@LDHs obviously inhibited the heat release and smoke emission behaviors of the UPR matrix during combustion. Mechanical properties of the UPR matrix also improved by inclusion of the carbides derivatives. This work paved a feasible method to prepare well-dispersed carbides@Co-Ni LDH nanocomposites with a more environmentally friendly method.
TL;DR: In this paper, the synergistic catalytic effect of the SrTiO3 and Ni on the improvement of the hydrogen storage properties of the MgH2 system has been carried out.
TL;DR: In this article, three different kinds of hierarchical MoS2 microspheres are successfully synthesized by a simple hydrothermal route, and their morphology, thermal stability and electrochemical performance in thermal battery are characterized.
TL;DR: In this article, NiO nanoparticles were synthesized at different annealing temperatures via a thermal decomposition process and characterized using X-ray diffraction, scanning electron microscopy, and UV-vis spectroscopy.
Abstract: NiO nanoparticles (NPs) were synthesized at different annealing temperatures via a thermal decomposition process and characterized using X-ray diffraction, scanning electron microscopy, and UV-vis spectroscopy. The NiO NPs prepared at higher annealing temperature (400 °C) were shown excellent adsorption and photocatalytic activity toward textile dyes reactive black 5 (RB-5) and methylene blue (MB). About 87.2% of RB-5 in 60 min and 70.2% of MB in 5 h was removed using NiO NPs synthesized at 400 °C. The photocatalytic degradation of MB was found to increase with an increase in the annealing temperature of the catalyst. Moreover, the kinetic study revealed that the adsorption and photocatalytic activity of NiO NPs followed the second and first-order kinetics, respectively. The enhanced performance of NiO NPs toward dye removal might be related to its optical and structural properties.
TL;DR: The co-pyrolysis of MSS and hazelnut shell blend was analyzed by a method of multi-heating rates and different blend ratios with TG-DTG-MS under N2 atmosphere and showed there were four thermal decomposition stages.
TL;DR: In this paper, a facile thermal decomposition of metal oxide nanomaterials was carried out by employing [Fe(C32H22N4O2)]·2H2O and [Co(C16H11N3O4] as new precursors.
TL;DR: In this paper, the lignin-based carbon (LC) samples activated by different potassium compounds using EHL as a raw material were characterized by TG, EA, FT-IR, BET, TEM, XRD and Raman spectroscopy.
TL;DR: This review examined pragmatically thermal decomposition as one of the best ways to synthesize monodispersed metal nanoparticles which are stable and of small particle sizes.
Abstract: Monodispersed forms of metal nanoparticles are significant to overcome frightening threat of cancer. This review examined pragmatically thermal decomposition as one of the best ways to synthesize monodispersed metal nanoparticles which are stable and of small particle sizes. Controlled morphology for delivery of anticancer agent to specific cells can also be obtained with thermal decomposition. In addition to thermal decomposition, the study also looked into processes of characterization techniques, biological evaluation, toxicity of nanoparticles, and future perspectives.
TL;DR: Results indicated that MgH2, Mg2NiH4, and Mg1CuH3 can decrease the thermal decomposition peak temperature and increase the total released heat of decomposition and improve the effect of thermal decomposing of the propellant.
TL;DR: In this article, thermal and catalytic analysis of virgin low-density polyethylene (LDPE), high density polyethylenes (HDPE, polypropylene (PP), and mixtures of LDPE/PP were carried out in a 200 mL laboratory scale batch reactor at 460 °C in a nitrogen atmosphere.
Abstract: Thermal and catalytic pyrolysis of virgin low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP) and mixtures of LDPE/PP were carried out in a 200 mL laboratory scale batch reactor at 460 °C in a nitrogen atmosphere. Thermogravimetric analysis (TGA) was carried out to study the thermal and catalytic degradation of the polymers at a heating rate of 10 °C/min. The amount of PP was varied in the LDPE/PP mixture to explore its effect on the reaction. In thermal degradation (TGA) of LDPE/PP blends, a lower decomposition temperature was observed for LDPE/PP mixtures compared to pure LDPE, indicating interaction between the two polymer types. In the presence of a catalyst (CAT-2), the degradation temperatures for the pure polymers were reduced. The TGA results were validated in a batch reactor using PP and LDPE, respectively. The result from thermal pyrolysis showed that the oil product contained significant amounts of hydrocarbons in the ranges of C7–C12 (gasoline range) and C13–C20 (diesel range). The catalyst enhanced cracking at lower temperatures and narrowed the hydrocarbon distribution in the oil towards the lower molecular weight range (C7–C12). The result suggests that the oil produced from catalytic pyrolysis of waste plastics has a potential as an alternative fuel.
TL;DR: In this article, a synergistic hybrid structure of two fillers with different dimensions had been designed and prepared by taking hexagonal born nitride (h-BN) platelets and ammine carbon nanotubes (CNT-NH2) into the flexible polymer matrix.
Abstract: High thermal conductive filler (hexagonal boron nitride and carbon nanotube) reinforced polymer composites have obtained a growing attention in the microelectronic industry for their good thermal conductivity but electrical insulating. In this work, a synergistic hybrid structure of two fillers with different dimensions had been designed and prepared by taking hexagonal born nitride (h-BN) platelets and ammine carbon nanotubes (CNT-NH2) into the flexible polymer matrix. Using cycloaliphatic epoxy resin (CER) as the polymer matrix, a serious of (a) h-BN/CER based, (b) hybrid filler h-BN@CNT-NH2/CER based, and (c) mixed filler CNT-NH2 and h-BN/CER based composites were prepared. In this structure, h-BN (and h-BN@CNT-NH2) platelets stacked along the horizontal direction under the assistance of gravity force and interactivity between the fillers. The orientation of the h-BN platelets was investigated by scanning electron microscope (SEM) of the cracked cross-section of the composite film and XRD measurement via calculating the orientation function (f). The CNT-NH2 was embedded within the network to improve the filler-filler contact or network-density. Due to the anisotropic properties of h-BN platelets and dispersion states of CNT-NH2, the composites with different structures presented different and special properties, including thermal/electrical conductivity properties, mechanical properties, and thermal decomposition properties. The analysis of structure and mechanism of thermal decomposition were then proposed to explain those interesting properties. The incorporation and dispersion states of CNT-NH2 in the composites played an important effect on the enhancement of the thermal conductivity properties both included in-plane (∼1.76 W/m·K) and through-plane (∼1.09 W/m·K) thermal conductivity. Additionally, the good electrical insulating properties and mechanical properties of the composites provided a potential application in the thermal management areas. The solvent-free procedure was environment friendly, easy operation, and suitable for the practical application in large scale.
TL;DR: Co 3 O 4 nanowires (NWs) arrays were successfully fabricated via a facile hydrothermal-annealing method as discussed by the authors, which exhibited an excellent catalytic performance on the thermal decomposition of ammonium perchlorate (AP).
TL;DR: In this paper, a tung-oil-derived renewable plasticizer, tungmaleic triglycidyl esters (TMTE), was prepared and incorporated into polyvinyl chloride (PVC) for the first time.
Abstract: A tung-oil-derived renewable plasticizer, tung-maleic triglycidyl esters (TMTE), was prepared and incorporated into poly(vinyl chloride) (PVC) for the first time. The chemical structure was studied by Fourier transform infrared (FTIR), 1H nuclear magnetic resonance (NMR), and 13C NMR. The plasticizing effects of TMTE replacement of dioctyl phthalate (DOP) in soft PVC films were researched. Thermal stability, thermal degradation performance, dynamic mechanical property, and mechanical properties of pure PVC and PVC films were investigated with thermogravimetric analysis (TGA), TGA-FTIR, TGA-mass spectrometry, dynamic mechanical analysis, and mechanical test. The results showed that PVC films plasticized with the TMTE exhibited increased thermal stability, plasticizing effect, compatibility, and flexibility. When 30 phr (parts per hundred parts of resin) DOP was substituted with TMTE in PVC blends, glass transition temperature (Tg) dropped from 41.46 to 40.18 °C, the initial decomposition temperature (Ti), ...
TL;DR: Temperature-programmed electrospray-differential mobility analysis (TP-ES-DMA) provides the characterization of temperature-dependent morphological change directly in the gas phase, and the results are shown to be highly correlated with the structural thermal stability of MOFs determined by the traditional measurements of porosity and crystallinity.
Abstract: We report an aerosol-based approach to study the thermal stability of metal–organic frameworks (MOFs) for gas-phase synthesis of MOF-based hybrid nanostructures used for highly active catalysis. Temperature-programmed electrospray-differential mobility analysis (TP-ES-DMA) provides the characterization of temperature-dependent morphological change directly in the gas phase, and the results are shown to be highly correlated with the structural thermal stability of MOFs determined by the traditional measurements of porosity and crystallinity. The results show that MOFs underwent thermal decomposition via simultaneous disassembly and deaggregation. Trimeric Cr-based MIL-88B-NH2 exhibited a higher temperature of decomposition (Td), 350 °C, than trimeric Fe-based MIL-88B-NH2, 250 °C. For UiO-66, a significant decrease of Td by ≈100 °C was observed by using amine-functionalized ligands in the MOF structure. Copper oxide nanocrystals were successfully encapsulated in the UiO-66 crystal (CuxO@UiO-66) by using a g...