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- Author or Editor: L.-J. Chen x
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Abstract
In our invention, FCC (fluid catalytic cracking) dry gas could be used to react with benzene without any special purification, and more than 90% ethylene was converted to ethylbenzene. The phenomenon of carbon deposition over catalyst surface was obvious and leads to a deactivation of catalyst, so it is important to study the behavior of carbon deposition of catalyst during alkylation of benzene. The influence of several factors such as temperature, reaction time, reactant concentration of the amount and the kinetics of carbon deposition were investigated, during which carbon depositing rate equations were obtained for different reactant.
CuO nanocrystals in thermal decomposition of ammonium perchlorate
Stabilization, structural characterization and catalytic activities
Abstract
CuO nanocrystals of different surface areas were prepared. All samples were characterized by X-ray diffraction, transition electron microscope, thermogravimetry, Brunauer-Emmett-Teller technique, Fourier transform infrared spectroscopy, and Raman spectroscopy. CuO nanocrystals showed a stable monoclinic structure. With increasing surface areas, the surface hydration became significant, which is followed by shifts in infrared frequencies and Raman phonon modes. CuO nanocrystals were explored as an additive to catalytic decomposition of ammonium perchlorate (AP). AP decomposition underwent a two-stage process. Addition of CuO nanocrystals led to a downshift of high-temperature stage towards lower temperatures.
Abstract
Aluminum (Al) nanopowders with mean diameter of about 50 nm and passivated by alumina (Al2O3) coatings were prepared by an evaporation route: laser heating evaporation. Thermal properties of the nanopowders were investigated by simultaneous thermogravimetric-differential thermal analysis (TG-DTA) in dry oxygen environment, using a series of heating rates (5, 10, 20, 30, 50 and 90°C min−1) from room temperature to 1200°C. With the heating rates rise, the onset and peak temperatures of the oxidation rise, and the conversion degree of Al to Al2O3 varies. However, the specific heat release keeps relatively invariant and has an average value of 18.1 kJ g−1. So the specific heat release is the intrinsic characteristic of Al nanopowders, which can represent the ability of energy release.
Abstract
Excess molar enthalpies of binary mixtures for tributyl phosphate (TBP)+methanol/ethanol were measured with a TAM air Isothermal calorimeter at 298.15 K and ambient. The results for xTBP+(1–x)CH3OH are negative in the whole range of composition, while the values for xTBP+(1–x)C2H5OH change from positive values at low x to small negative values at high x. The experimental results have been correlated with the Redlich–Kister polynomial. IR spectra of the mixtures were measured to investigate the effect of hydrogen bonding in the mixture.
Abstract
The thermal decomposition of Zn[NFA]2 5H2O (NFA=C16H18FN3O3, norfloxacin) and its kinetics were studied under non-isothermal conditions in air by TG-DTG and DTA methods. The intermediate and residue for each decomposition were identified from the TG curve. The non-isothermal kinetic data were analyzed by means of the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The possible reaction mechanisms were investigated by comparing the kinetic parameters. The kinetic equation for the second stage can be expressed as d/dt=Aexp(–E/RT)(1–).
Summary
Electronic stopping power of 19F in Ni, Pd and Gd was measured and compared to Mstar and SRIM calculation as well as experimental results published in literature. It turns out that the present electronic stopping power agrees reasonably well with them.
Abstract
Di-tert-butyl peroxide (DTBP) is an organic peroxide (OP) which has widespread use in the various chemical industries. In the past, thermal runaway reactions of OPs have been caused by their general thermal instability or by reactive incompatibility in storage or operation, which can create potential for thermal decomposition reaction. In this study, differential scanning calorimetry was applied to measure the heat of decomposition reactions, which can contribute to understand the reaction characteristics of DTBP. Vent sizing package 2 was also employed to evaluate rates of increase for temperature and pressure in decomposition reactions, and then the thermokinetic parameters of DTBP were estimated. Finally, hazard characteristics of the gassy system containing DTBP, specifically with respect to thermal criticality, were clearly identified.
In this study, the cDNA of homocysteine S-methyltransferase was isolated from Aegilops tauschii Coss., with the gene accordingly designated as AetHMT1. Similar to other methyltransferases, AetHMT1 contains a GGCCR consensus sequence for a possible zinc-binding motif near the C-terminal and a conserved cysteine residue upstream of the zinc-binding motif. Analysis of AetHMT1 uncovered no obvious chloroplast or mitochondrial targeting sequences. We functionally expressed AetHMT1 in Escherichia coli and confirmed its biological activity, as evidenced by a positive HMT enzyme activity of 164.516 ± 17.378 nmol min−1 mg−1 protein when catalyzing the transformation of L-homocysteine. Compared with the bacterium containing the empty vector, E. coli harboring the recombinant AetHMT1 plasmid showed much higher tolerance to selenate and selenite. AetHMT1 transcript amounts in different organs were increased by Na2SeO4 treatment, with roots accumulating higher amounts than stems, old leaves and new leaves. We have therefore successfully isolated HMT1 from Ae. tauschii and characterized the biochemical and physiological functions of the corresponding protein.
Abstract
The heat capacities of LiNH2 and Li2MgN2H2 were measured by a modulated differential scanning calorimetry (MDSC) over the temperature range from 223 to 473 K for the first time. The value of heat capacity of LiNH2 is bigger than that of Li2MgN2H2 from 223 to 473 K. The thermodynamic parameters such as enthalpy (H–H 298.15) and entropy (S–S 298.15) versus 298.15 K were calculated based on the above heat capacities. The thermal stabilities of them were investigated by thermogravimetric analysis (TG) at a heating rate of 10 K min−1 with Ar gas flow rate of 30 mL min−1 from room temperature to 1,080 K. TG curves showed that the thermal decomposition of them occurred in two stages. The order of thermal stability of them is: Li2MgN2H2 > LiNH2. The results indicate that addition of Mg increases the thermal stability of Li–N–H system and decrease the value of heat capacities of Li–N–H system.