Thermogravimetry-differential Scanning Calorimeter Research Articles

Cu metallization of Al2O3 ceramics via CuO reduction: Role of SiO2 additive and sintering atmosphere

A Cu-coated Al2O3 substrates which can be used for power modules are prepared via sintering and reduction of CuO–SiO2 film onto the surface of Al2O3 ceramic without precious metal brazing filler or high-vacuum equipment. This method has a significant cost advantage over the existing technology. Effects of oxygen partial pressure from sintering atmosphere and SiO2 content on microstructure and mechanical properties of Cu/Al2O3 interface are systematically investigated. Phase compositions and morphologies of sintered Cu2O layer, reduced Cu layer and reactive layer are characterized via X-ray diffraction and scanning electron microscopy. In addition, physicochemical changes within CuO–SiO2 during sintering are characterized by thermogravimetry-differential scanning calorimeter. It is found that oxygen and SiO2 can promote the generation of Cu2O–CuO–SiO2 eutectic phase with low melting point upon sintering, which increases the thickness of reaction layer and the densification of Cu layer. The shear strength between the Cu layer and the Al2O3 substrate is enhanced with the increase in Cu layer densification degree, while varying in irregular manner with the thickness of reaction layer. In particular, the highest shear strength of 62.70 MPa is obtained at oxygen partial pressure of 0.02 atm and SiO2 content of 1.5 wt%.

Preparation of YbVO4 by Sol-Gel Method and Its Photocatalytic Activity

Using ytterbium nitrate pentahydrate (Yb(NO3)3·5H2O), ammonium metavanadate (NH4VO3) and citric acid monohydrate (C6H8O7·H2O) as main raw materials, the YbVO4 was prepared by sol-gel method. The samples were characterized by thermogravimetry differential scanning calorimeter (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflection spectrometer (DRS) and Fourier infrared spectrometer (FT-IR). The photocatalytic activity of YbVO4 was studied by using 10 mg/L methyl orange as simulated wastewater. The results show that pure YbVO4 can be prepared by calcining at 500 °C to 900 °C. The surface of YbVO4 sample prepared at different temperatures is porous and irregular. The forbidden band width of YbVO4 sample calcined at 700 °C is about 3.04 eV. Under ultraviolet light conditions, the degradation rate of methyl orange was over 95% after illumination for 30 min with YbVO4 sample calcined at 700 °C. YbVO4 show excellent photocatalytic activity for degradation of methyl orange. This indicates that YbVO4 is a new photocatalyst with wide application prospect in the field of photocatalysis.

The role of HMX particle size in the combustion and agglomeration of HTPB-based propellant

Cyclotetramethylene tetranitramine (HMX) is usually added to solid propellants, but the inclusion of HMX significantly affects the propellant combustion characteristics, especially by yielding more condensed combustion products (CCPs). The effect of HMX size on aluminum agglomeration and CCPs of hydroxyl-terminated polybutadiene (HTPB)-based propellant is evaluated experimentally in this paper. Using a thermogravimetry–differential scanning calorimeter, laser ignition setup, and high-pressure combustion bomb, we have examined the propellants' thermal reactivity, ignition behavior, combustion characteristics, agglomeration, and CCPs with 10–200 μm virgin HMX particles. The results indicate that HMX in propellant suppresses the pyrolysis reaction of ammonium perchlorate. Meanwhile, the exothermic peak temperature of 200 μm HMX increases by 17.8°C compared to 10 μm HMX. With the increase of HMX size from 10 μm to 200 μm, the combustion intensity of the propellant increases, and the ignition delay time of aluminum particles decreases from 580.6 ms to 498.3 ms. Increasing HMX size leads to an increased burning rate, while the pressure exponent decreases from 0.34 to 0.23. Including HMX in propellants also promotes aluminum agglomeration during propellant combustion. With HMX size expanding from 10 μm to 200 μm, the mean agglomerate size in the CCPs decreases from 221.9 μm to 124.5 μm, and the fraction of aluminum involved in agglomeration decreases from 0.206 to 0.104. The unburned aluminum content in agglomerated particles increases monotonically with increasing agglomerates size. Overall, HMX size has a significant impact on the ignition, combustion, and agglomeration characteristics of aluminized propellant. The conclusions of the paper can be used as a guidance for optimizing the propellant formulation

Combustion studies of Agnihotra Yajnya

Agnihotra is a traditional domestic solemnity, performed to maintain harmony between living beings and nature, without harming and by giving respect. Agnihotra, the simplest forms of yajnya performed at sunset/ sunrise in which cow dung is burnt in the copper pot by using cow ghee (clarified butter) and brown rice as oblations along with chanting of mantras of sun and fire. Combustion studies of Agnihotra raw material was done with the analysis of fuel gases using Orsat Analyzer, proximate analysis by Proximate Analyzer, ultimate analysis by CHONS Analyzer and calorific value estimation by using Bomb Calorimeter. Combustion rate was analyzed of by Thermogravimetry Differential Scanning Calorimeter. The fuel analysis of Agnihotra raw material shows incomplete combustion with low calorific value. As raw material is mainly lignocellulosic, combustion takes place with four major steps. Initially Moisture and Volatile Matter get combusted then Cellulose and Hemicellulose material then Lignin compounds and finally Char.

Alkali‐dissolving hydrothermal synthesis of zeolite P from fly ash

Zeolite P with the pseudo-spherical form was successfully synthesised from low-grade fly ash via alkali-dissolving hydrothermal synthesis method. These samples were characterised by X-ray diffraction, scanning electron microscope, X-ray fluorescence, Fourier-transform infrared spectroscopy, thermogravimetry-differential scanning calorimeter (TG-DSC) and Brunauer–Emmett–Teller. The textural properties of zeolite P were further studied by N2 adsorption–desorption technique. In addition, the TG-DSC study confirmed that the bound water content of zeolite P is 19.7% and the phase transition temperature of zeolite P is 400°C. Moreover, this thermal stability study approach not only extends the application of zeolite P but can be further extended to other zeolite materials as well.

The effects of temperature and Ce-dopant concentration on the synthesis of zirconolite glass-ceramic

Abstract Zirconolite based glass-ceramic has been deemed as a promising waste form for high-level waste (HLW). In this study, the zirconolite (nominally CaZrTi2O7) glass-ceramic based on a SiO2-B2O3-Na2O-CaO-ZrO2-TiO2-Al2O3 system was sought to be synthesized by two-step thermal treatment. The temperature effects such as nucleation temperature and cooling rate were studied. The influence of the Ce-dopant concentration on crystallization behavior was also investigated. For characterization, powder X-ray diffraction (XRD), thermogravimetry-differential scanning calorimeter (TG-DSC) and scanning electron microscopy (SEM) were applied. Our results illustrate that homogeneous zirconolite with the particle size of 1.8 μm can be the target phase when the glass matrix underwent a rapid cooling process and the nucleation temperature was controlled at around 860 °C. Besides, the results also indicate that the distribution of the zirconolite along with its lattice parameters change regularly as the increase of CeO2 concentration. A larger crystal size of zirconolite phase and some trace amounts of precipitated phases are observed when the CeO2 concentration exceed 3 wt%. This work emphasizes the synthesis of zirconolite glass-ceramic in a SiO2-B2O3-Na2O-CaO-ZrO2-TiO2-Al2O3 system, which is expected to provide basic technical data for underground disposal of HLW.

Direct Modification of Microcrystalline Cellulose with Ethylenediamine for use as Adsorbent for Removal Amitriptyline Drug from Environment.

Cellulose derivatives have been widely used as adsorbents for the removal of micropollutants such as drugs, dyes, and metals, due to their abundance, low cost and non-contaminating nature. In this context, several studies have been performed searching for new adsorbents (cellulose derivatives) efficient at contaminant removal from aqueous solutions. Thus, a new adsorbent was synthesized by chemical modification of cellulose with ethylenediamine in the absence of solvent and applied to the adsorption of amitriptyline (AMI) in aqueous solution. The modification reaction was confirmed by X-ray Diffraction (XRD), elemental analysis, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry/Differential Scanning Calorimeter (TG/DSC), solid state Nuclear Magnetic Resonance of 1H and 13C (1H-NMR and 13C-NMR). Moreover, the effectiveness of reaction was confirmed by computational calculations using Density Functional Theory (DFT) at level B3LYP/6-31G(d). This adsorption process was influenced by pH, time, concentration, temperature and did not show significant changes due to the ionic strength variation. Through these experiments, it was observed that the maximum adsorption capacity of AMI by CN polymer at 298 K, 300 min, and pH 7 was 87.66 ± 0.60 mg·g−1.

Physical and chemical properties and thermogravimetric performance of hydrogenated biodiesel

ABSTRACTThe partially hydrogenated soybean methyl ester (PHSME) is produced from soybean methyl ester (SME) via catalytic transfer hydrogenation. It is revealed that after the catalytic transfer hydrogenation of SME, the high unsaturated components are selectively converted to low unsaturated or saturated components by Gas Chromatography-Mass Spectrometer (GC-MS) analysis. Although the kinematic viscosity of PHSME is increased slightly, its oxidation stability is improved significantly, and the cetane number of PHSME rises to a desirable level as well. Based on the analysis of thermogravimetry-differential scanning calorimeter (TG-DSC), it is found that PHSME has a greater average oxidation rate. In summary, the hydrogenated biodiesel has excellent ignition characteristic.

Synthesis and Characterization of CoMn<sub>2</sub>O<sub>4</sub> Nanopowders by a Reverse Micelle Processing

CoMn2O4 nanoparticles were synthesized by reverse micelle processing from the mixed precursor (consisting of Co (NO3)2 ·6H2O and MnCl2·4H2O). The CoMn2O4 was prepared by mixing the aqueous solution at a molar ratio of Co : Mn = 1 : 2. The synthesized powders were calcined at 600°C for 2h. The average size and distribution of synthesized powders were in the range of 10-20nm and narrow, respectively. The average size of the synthesized powders increased with increasing water to surfactant molar ratio. The XRD diffraction patterns show that the phase of CoMn2O4 was spinel (JCPDS no.77-0471). The synthesized and calcined powders were characterized by thermogravimetry-differential scanning calorimeter (TG-DSC), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The magnetic property of the powder was measured by Vibrating Sample Magneto-meter (VSM) at 298K. The effect of synthesis parameter, such as the molar ratio of water to surfactant, is discussed.

Hydrogenation of CO2 to CH3OH over CuO/ZnO/Al2O3 catalysts prepared via a solvent-free routine

A series of CuO/ZnO/Al2O3 catalysts were prepared via a direct combustion of Cu nitrate, Zn and Al acetate with citric acid, oxalic acid or urea as fuel. The combustion processes were monitored by thermogravimetry differential scanning calorimeter. Characterizations disclosed that the physicochemical properties of these catalysts depended strongly on the type and amount of fuel. CuO/ZnO/Al2O3 catalyst using citric acid as fuel has a larger surface area, higher CuO dispersion, and the exposed Cu surface area increased with the increasing molar ratio of citric acid/salts in feed. The performances of these catalysts for CO2 hydrogenation to methanol were compared and discussed with their structure.

Study of Hg0 removal characteristics on Fe2O3 with H2S

A series of elemental mercury removal experiments were performed at different temperatures to explore the elemental mercury oxidation efficiency on α-Fe2O3 and γ-Fe2O3 in the presence of H2S. Our experimental results indicated that the α-Fe2O3 and γ-Fe2O3 similarly played important roles in removing elemental mercury. The reaction temperature around 230°C is a critical turning point in effectively capturing elemental mercury, above which the Hg0 removal efficiency would decrease. According to our previous researches, H2S will preferentially adsorb on the Fe2O3 surface, forming active sulfur sites to react with Hg0. In this paper, we analyzed the contrastive samples before and after removing Hg0 to further investigate the probable products by the Hg0 re-release experiments, as well as thermogravimetry–differential scanning calorimeter (TG–DSC) and X-ray photoelectron spectroscopy (XPS) analysis. The test results of morphological characterization showed that mercury compounds and new substances generated in the Fe2O3 samples after adsorbing Hg0. At the same time, the detection results showed that Hg2+, sulfur, S2−, S− and Fe2+ had appeared, which demonstrated the probable mercury products, and the H2S pre-adsorption and Hg0 oxidation could be confirmed as well by the different groups of comparative tests. In conclusion, our experimental results are in good agreement with our previous experiments and computational results.

Doping effect of Al2O3 and CeO2 on Fe2O3 support for gold catalyst in CO oxidation at low-temperature

Al2O3/CeO2 doped Fe2O3 support was synthesized by co-precipitation method, based on which gold was loaded by deposition–precipitation. Both the catalytic activity and thermal stability of the gold catalyst were enhanced significantly by Al2O3/CeO2 doping. The catalyst loaded with 1.0% Au and calcined at 180°C converted CO completely at −8.9°C, while the sample modified by Al2O3/CeO2 showed a 100% CO conversion at −20.1°C. Characterization techniques, such as N2 adsorption–desorption, X-ray diffraction (XRD), transmission electron microscopic (TEM), thermogravimetry–differential scanning calorimeter (TG–DSC) and CO2 temperature programmed desorption (CO2-TPD) were employed to investigate the structure and surface morphology of the catalysts. Al2O3/CeO2 doping retarded the mesoporous structures of the catalysts from collapse during the calcination at high temperature, which thus maintained higher specific surface area and lower pore size. After being calcined at 500°C, the average diameter of the gold particles in Au/Fe2O3 was 7.0nm and the sizes of support grains ranged from 50 to 100nm. However, the average diameter of the gold particles in Au/Al2O3/CeO2/Fe2O3 was only 5.1nm and the sizes of support grains ranged from 10 to 30nm. Gold loaded on the Fe2O3 support by the doping of Al2O3/CeO2 have better catalytic activity for CO oxidation.

Fluorescent drug-containing hydrotalcite-like compound for monitoring drug release

A novel fluorescent drug-containing layered double hydroxide (MgAlZn-Asp-LDH) was prepared for the first time by the coprecipitation method with aspirin (Asp) used as the model drug. Magnesium (II) was partially replaced by zinc (II) in the hydrotalcite-like layers, and the drug, aspirin (Asp), was dispersed into the interlayer region; Zn 2+ ion in the layers was coordinated with the acetylsalicylate among the interlayer region, making a blue-fluorescent aspirin-containing layered double hydroxide. The obtained sample was tested as a drug carrier by investigating its drug-storage/release properties. X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR spectroscopy, X-ray photo-electron spectroscopy (XPS), thermogravimetry, differential-scanning calorimeter (TG-DSC), and photoluminescence (PL) spectra were used to characterize the structural, morphological, and optical properties of the resulting sample. The Asp-loaded layered double hydroxide system shows blue luminescence of zinc acetylsalicylate under UV irradiation and controlled release of Asp. In addition, the emission intensity of the system varies with the released amount of Asp, and thus drug release can be easily tracked and monitored by the change in luminescence intensity. The system provides a promising candidate for application in the drug delivery and disease therapy fields.

High thermal stable gold catalyst supported on La 2O 3 doped Fe 2O 3 for low-temperature CO oxidation

La 2O 3 doped Fe 2O 3 support was prepared by co-precipitation method, and gold was loaded by deposition-precipitation. Thermal stability of gold catalyst was enhanced considerably by La 2O 3 doping. Even when calcined at 500 °C for 12 h, the catalyst doped with La 2O 3 could convert 90% of CO at 28.9 °C, while the catalyst without La 2O 3 doping achieved 90% CO conversion at 43.5 °C. Characterization techniques, such as N 2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopic (TEM) and thermogravimetry-differential scanning calorimeter (TG-DSC), were employed to investigate the structure and surface morphology of the catalysts. La 2O 3 doping retarded the collapse of mesoporous structure of catalysts during the calcination at high temperature, keeping higher specific surface area, smaller pore size and narrower pore distribution. After calcination at 500 °C, the size of gold particles in Au/Fe 2O 3 was in the range of 6–10 nm and the size of support grains was 50–100 nm. However, the sizes of gold particles and support grains in Au/La 2O 3//Fe 2O 3 were remained in the ranges of 4–8 nm and 25–50 nm, respectively. The results of X-ray diffraction and thermal analysis also proved that La 2O 3 doping not only restrained the growth of gold particles, but also retarded the crystallization of support.

SYNTHESIS AND CHARACTERIZATION OF Y2SiO5:Ce3+ PHOSPHOR MATERIALS BY SOL–GEL PROCESS

Y 2 SiO 5: Ce 3+ particles was synthesized by sol–gel process. In all samples treated at 1100°C, monoclinic X 1 phase for all cerium concentration. Luminescence spectra shows broad Ce 3+ luminescence in Y 2 SiO 5 host, which picks around 450 nm. The synthesized and calcined powders were characterized by thermogravimetry-differential scanning calorimeter (TG-DSC), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and photoluminescence spectra (PL).

New Insights Into Oxidation Behaviours of Crude Oils

Abstract Systematic studies are performed to investigate oxidation behaviour of three different types of crude oils (light oil, medium oil and Athabasca bitumen) by using two thermal analysis techniques: Thermogravimetry and Pressurized Differential Scanning Calorimetry. This study is also to look at the effect of pressure on energy generation associated with oxidation reactions in different temperature ranges. It is observed that oxidation behaviours for light and medium oils are substantially different from those of Athabasca bitumen. The difference is seen in the temperature ranges where significant oxidation reactions occur. The experimental data in this work provide further evidence and addresses the difference in the oxidation behaviour of light oil and heavy oil. Introduction It is important to distinguish air injection applied to a light oil reservoir from the same process for heavy oil. Generally, the former is called air injection for light oil and the latter is termed in situ combustion. In both processes, various oxidation reactions take place(1). However, the main objective of air injection for light oil is to produce flue gas though oxidation reactions and to sweep the oil with the flue gas given that light oil is mobile under reservoir conditions(2), whereas in the heavy oil case, a thermal effect is desired for reducing the viscosity of heavy oil and to mobilize it. Moore et al. (2) reported that for both light oil and heavy oil, effective displacement requires the oxidation kinetics to be in the bond scission or combustion mode, i.e., effective displacement for both light and heavy oil needs a vigorous high temperature oxidation front to be maintained. There is some controversy about the application process for light oils. Some researchers state that light oil can be displaced without the need to generate higher temperatures. Ren et al.(3) point out that air injection in a light oil reservoir could be viewed as a conventional gasflooding process, as long as the oxygen in the injected air is removed in the oil bearing zones. Kisler and Shallcross(4), Moore et al.(2) and Ferguson(5) have addressed the different oxidation behaviours between light and heavy oils that might occur in the different temperature intervals. Because of the lack of a full understanding of light oil oxidation at reservoir conditions, people simply apply the concept of oxidation behaviour from heavy oil onto the case of light oil, which creates misleading information regarding the oxidation behaviour of light oils. Therefore, the principle objective of this study is to provide experimental information about the effect of pressure on the oxidation behaviour of crude oils and the difference between the oxidation behaviours of light oils and heavy oils. Instruments and Test Conditions Two different thermoanalyzers are used to conduct this study: Pressurized Differential Scanning Calorimeter (Q10P TA Instrument, US) and Thermogravimetry Differential Scanning Calorimeter (TG/DSC 111 Setaram, France). Pressurized Differential Scanning Calorimeter (PDSC) Experiment The test pressure is up to 7 MPa (1,000 psig) and the temperature range is from 20 to 650 °C.

Preparation and characterization of mesoporous indium oxide

Indium oxide nanocrystals with mesoporous structure were successfully synthesized by using triblock copolymer as a template, and characterized by thermogravimetry-differential scanning calorimeter (TG-DSC), X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and N2 adsorption. A high EO/PO ratio is thought to be the key point to prepare mesoporous In2O3. The results show that the average pore diameter of the products is 6 nm, the BET surface area is 54.78 m2/g, and the adsorbing pore volume is 0.345 cm3/g. After comparing with normal indium oxide nanoparticles by BET test, mesoporous indium oxide demonstrates a large difference in adsorbing pore volume and average pore diameters from normal ones.

Synthesis of ultrafine spherical YAG:Eu 3+ phosphors by MOCVD

Ultrafine Europium-doped yttrium aluminum garnet (YAG:Eu 3+) phosphor powders, with uniform diameters of about 1 μm, have been prepared by metallorganic chemical vapor deposition (MOCVD). The metal–organic precursors have been characterized by thermogravimetry–differential scanning calorimeter (TG–DSC). The phosphor powders have been identified by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence measurements. It shows that the YAG:Eu 3+ particles annealed at 1473 K for 3 h are nonaggregated and spherical, the diameter of particles is in the range of 1–2 μm. Phase-pure YAG which is of spherical shaped particles have been obtained and observed good luminescence property. Three major emission peaks were observed at 589, 594, and 607 nm.