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Calorimetric measurements of the heat of adsorption of CO2 on zeolites with variable content of mono- and divalent cations lead to common conclusions. High initial heats (up to 120 kJ·mol−1 for NaA), generally associated with a slow and activated rate of adsorption, are found for high contents of Na+, Li+ or Ca2+. They are attributed to a limited number of chemisorption sites (0.3 per α cage in NaA).

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mA). Nitrogen physisorption measurements were carried out at 77 K using Quantachrome NOVA Automated Gas Sorption Instrument. The pore-size distributions were calculated from the desorption isotherms with the BJH method. The

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develop an improved low-temperature Pd/FeAlPO-5 zeolite for N 2 O reduction. The developed catalysts will be characterized by N 2 physisorption, XRD and H 2 -TPR and tested in catalytic reduction of N 2 O with methane. Experimental

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Reaction Kinetics, Mechanisms and Catalysis
Authors: Natpakan Srisawad, Wasu Chaitree, Okorn Mekasuwandumrong, Artiwan Shotipruk, Bunjerd Jongsomjit, and Joongjai Panpranot

characterization techniques were employed including N 2 physisorption, X-ray diffraction (XRD), temperature programmed reduction of H 2 (H 2 -TPR), and X-ray photoelectron spectroscopy (XPS). Experimental Catalysts

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XRD and nitrogen physisorption characterization, were studied by ammonia and carbon dioxide adsorption microcalorimetry, as well as by catalytic testing for 4-methylpentan-2-ol conversion in long-lasting runs under both mild and stressed conditions

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4000–500 cm −1 region. BET surface areas of the zeolite catalyst were measured with an automatic physisorption-chemisorption apparatus (NOVA 2000). The surface area was calculated with the BET equation (Brunauer–Emmett–Teller). The XPS analysis of the

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Abstract  

The physisorption of trichloroethylene and tetrachloroethylene on ZSM-5 (Si/Al = 339) zeolite was investigated at 298 K using thermogravimetry, differential microcalorimetry and X-ray diffraction. The zeolite always undergoes a monoclinic-orthorhombic structural change during the adsorption of the first molecules. An alignment of the polar trichloroethylene molecules inside all the channels of the zeolite is proposed to account for the experimental results. A phase transition of the non-polar tetrachloroethylene is suggested to produce the stepped isotherm, the steep rise in the heat curve and the high increase in the mobility of the molecules for the loading of 4 molecules per unit cell.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Valenzuela, P. Bosch, B. Zapata, G. Aguilar-Ríos, V. Lara, E. García-Figueroa, and I. Schifter

Abstract  

ZnAl2O4 and Sn−ZnAl2O4 were synthesized by coprecipitation, sol-gel and impregnation methods. These materials were calcined and treated in H2 at 1073 K. Thermal analysis (DTA and TG), nitrogen physisorption (BET method), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used as characterization techniques. H2 treatment promoted AlxZny crystallization in the coprecipitated and impregnated samples. When tin was added to zinc aluminate, the tin acted as a protective shell against high-temperature reduction, independently of the preparation technique.

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Abstract  

In this paper we present a brief review of the current state of positron annihilation research into the phase behaviour of fluids confined within restricted boundaries. We summarise, in the form of selected examples, the work done so far on: (1) fluids confined in the nanometer-size pores of VYCOR glass, with particular emphasis on the confined phase diagram and the mechanisms behind phase transitions compared to bulk. (2) The adsorption/physisorption of gases on internal surfaces of grafoil and the potential of positron technique for revealing physical properties, such as the intricate molecular arrangements during phase transitions of the layered fluid.

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Abstract  

This paper presents possible applications of thermal analysis and sorptomatic methods to study physico-chemical properties of the high-T csuperconductor Y1Ba2Cu3O7-x and perovskite LaCoO3. It is shown that both Y1Ba2Cu3O7-x and perovskite phase are highly sensitive to water vapour. Mechanism of adsorption of water on LaCoO3depends largely on time activation (t act). When the time of water vapour saturation was 0<t act<180 s, physisorption process was observed. In the case of longer times water vapour action, t act>180 s, chemical decomposition was observed.

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