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rounded corners, which amounts to a total of 56 cm 2 geometric surface area. The illumination was achieved either by means of a Philips UV-C lamp TUV 4 W/G4 T5 (4 W), emitting monochromatic light at the wavelength of 253.7 nm or by a Tungsram K1R7s linear

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Abstract  

This work reported on the thermal decomposition of ammonium perchlorate activated by addition of NiO nanocrystals with different surface areas. NiO samples were characterized by X-ray diffraction (XRD), transition electron microscope (TEM), Brunauer-Emmett-Teller (BET) technique, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. With increasing annealing temperature, the surface areas of NiO samples reduced from 108.6 to 0.9 m2 g−1. The catalytic activities of NiO nanocrystals on the thermal decomposition of ammonium perchlorate were investigated by thermogravimetric analysis (TG) coupled with differential thermal analysis (DTA). With addition of NiO nanocrystals, thermal decomposition temperature of AP decreased greatly. Larger surface areas of NiO nanocrystals promoted the thermal decomposition of AP.

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Char particle combustion is the slowest step in the combustion of coal, therefore char reactivity and texture have an important influence on this process. In this work, two coals were devolatilised in an entrained flow reactor and the chars obtained were burned under different experimental conditions in order to achieve various degrees of burnoff. Char reactivity was determined by means of non-isothermal thermogravimetric analysis, and the conversion-time data were evaluated by the random pore model proposed by Bhatia and Perlmutter. Char texture was characterised by means of N2 and CO2 adsorption isotherms. The surface areas obtained were used to calculate intrinsic reaction rate parameters. It was found that under chemical controlled conditions, the available surface area during combustion is best represented by the N2 surface area.

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The photocatalytic properties of MoS2 samples including nano-ball, nano-slice and bulk 2H-MoS2 were evaluated and compared with that of the anatase TiO2 using the degradation reaction of methyl orange under visible light. The catalytic behaviors of the samples were also characterized using transmission electron microscopy, Brunauer-Emmett-Teller (BET) surface area, ultraviolet-visible spectroscopy, and FTIR spectroscopy. The results show that the bulk MoS2 and the anatase TiO2 were almost inactive under visible light. The nano-slice presented the most positive catalytic effect because it has a wide absorption at 400–700 nm and a high BET surface area. Though the BET surface area of the nano-ball was lower than that of the nano-slice, it has an active curved basal surface and presented a catalytic activity close to that of the nano-slice. Moreover, the MoS2 nano-slice catalyst could be conveniently regenerated after filtration and drying.

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Preparations were characterized by specific surface area, thermogravimetry, and X-ray diffractometry. Thermal effects observed were (a) sulfur loss, (b) sintering, (c) crystallization and transformation of the crystalline phase(s). Thermoanalytical curves indicate that decomposition of the sulfate occurs in two distinct steps. Decrease of surface area due to (b) and (c) is concomitant to decomposition of sulfate. Sulfate was found to hinder sintering, crystallization and phase transformations of ZrO2 and TiO2. In low-titania and -zirconia sulfated TiO2-ZrO2 the minor component enhances the effect of sulfate. In equimolar TiO2-ZrO2 sulfate decomposition is accompanied by rapid formation of crystalline TiZrO4.

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CuO nanocrystals in thermal decomposition of ammonium perchlorate

Stabilization, structural characterization and catalytic activities

Journal of Thermal Analysis and Calorimetry
Authors: L.-J. Chen, G.-S. Li, and L.-P. Li

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.

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Decomposition and removal of carbonizate was performed over platinum catalysts supported on two types of alumina differing in the surface area: low surface area one (LSA) and high surface one (HSA). For the sake of comparison, the performance of platinum catalyst supported on silica and bimetallic platinum-rhenium catalysts was analyzed. It has been shown that all platinum catalysts examined caused an increase in the removal of carbonizate. The activity of these catalysts was independent of the kind of support applied or addition of rhenium as a second component.

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Decomposition and removal of carbonizate was performed over platinum catalysts supported on two types of alumina differing in the surface area: low surface area one (LSA) and high surface one (HSA). For the sake of comparison, the performance of platinum catalyst supported on silica and bimetallic platinum-rhenium catalysts was analyzed. It has been shown that all platinum catalysts examined caused an increase in the removal of carbonizate. The activity of these catalysts was independent of the kind of support applied or addition of rhenium as a second component.

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We propose to install a balance at the surface of Mars. In this paper we present a survey on tasks which could be accomplished by means of a balance. The determination of the specific surface area and porosity of Martian soil and other sorption experiments are discussed. Criteria for the choice of a suitable balance type are given.

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Journal of Thermal Analysis and Calorimetry
Authors: V. Yanishpolskii, A. Pavlenko, V. Tertykh, V. Il'in, R. Leboda, and J. Skubiszewska-Zieba

Abstract  

Mesoporous titanium-containing silicas with TiO2 contents from 1 up to 70 mol% were prepared. The obtained samples have been characterized by the powder X-ray diffraction data, the diffuse reflectance infrared Fourier transform method, and nitrogen adsorption at 77 K. Specific surface area, total pore volume, distribution pore volume on pore sizes were determined from nitrogen adsorption isotherm for synthesized titanosilicas.

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