Bi-metallic and tri-metallic Pt-Sn/C, Pt-Ir/C, Pt-Ir-Sn/C catalysts for electro-oxidation of ethanol in direct ethanol fuel cell

In the present work, combination of bi-metallic and tri-metallic Pt, Ir, Sn electro-catalysts was prepared by impregnation reduction method on carbon Vulcan XC-72 to improve upon electro-oxidation of ethanol in direct ethanol fuel cell. The prepared electro-catalysts were characterized by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analyses. XRD and TEM analyses reveal that the prepared catalysts are of nano size (6-10 nm) range. It is shown that Pt lattice parameter decreases with the addition of Ir, and increases with the addition of Sn in Pt-Ir-Sn/C catalyst. The electro-catalytic activities characterized by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) techniques reveal that the addition of small amount of Ir in Pt-Sn/C electro-catalyst exhibits higher activity towards ethanol oxidation than the Pt-Sn/C (20% Pt and 20% Sn by wt) electro-catalyst. The single direct ethanol fuel cell (DEFC) test at 90 °C, 1 bar with catalyst loading of 1 mg/cm² and 2 M ethanol as anode feed showed an enhancement of catalytic activity in following order: Pt-Ir-Sn/C (20% Pt, 5% Ir and 15% Sn by wt) > Pt-Ir-Sn/C (20% Pt, 10% Ir and 10% Sn by wt) > Pt-Sn/C (20% Pt and 20% Sn by wt) > Pt-Ir-Sn/C (10% Pt, 15% Ir and 15% Sn by wt) > Pt-Ir/C (20% Pt and 20% Ir by wt) >    Pt/C (40% Pt by wt). Pt-Ir-Sn/C (20% Pt, 5% Ir and 15% Sn by wt) exhibited highest performance among all the catalysts prepared with power density of 29 mW/cm² in DEFC operating at 90 °C.     

Structural, magnetic and electrical properties of Fe/Cu/Fe films

A set of sandwich films in the configurations, Fe(200 nm)/Cu(t)/Fe(200 nm); t = 20 nm, 40 nm, 60 nm, 80 nm, 100 nm and 200 nm have been grown using thermal and electron beam gun evaporation techniques at a temperature of 473 K, under high vacuum conditions. The structure and crystallite sizes of the films were investigated by grazing incidence X-ray diffraction (GIXRD). The microstructure was examined by scanning electron microscope (SEM) studies. Average grain size and surface roughness were determined by atomic force microscope (AFM). The room temperature magnetization as a function of field has been measured using the vibrating sample magnetometer (VSM). The results revealed the existence of antiferromagnetic (AF) coupling between Fe layers through an interfacer Cu layer. The strength of AF coupling was observed to be increasing with increasing t and became maximum for t = 60 nm and, decreases for further increase in t. The behavior of coercive field with t indicated softness of the films. The low temperature electrical resistivity in the range from 4.2 K to 300 K has been measured. The residual resistance ratio, RRR and the temperature coefficient, TCR were determined. The power laws for the resistivity variation with temperature have been established. This is for the first time that a set of sandwich films in the present configurations were investigated for structural, magnetic and electrical properties and, the power laws for resistivity variation at low temperature have been established.     

Synthesis and Characterization of Thermochemical Storage Material Combining Porous Zeolite and Inorganic Salts

Thermal energy storage has the potential to decarbonize the heating sector, facilitating the use of renewable energy sources, in particular solar thermal energy. In this paper we present a study on thermochemical storage material composed of inorganic salts hosted in the porous matrix of zeolite 13X; we prepared a series of composites containing different amounts of inorganic salts – MgCl₂, MgSO₄ by impregnation method and we characterized them by multiple experimental techniques: energy storage and adsorption/desorption rates were assessed using simultaneous thermal analysis by coupling thermogravimetric and differential scanning calorimetry, microstructure, and composition were assessed through scanning electron microscopy and energy-dispersive X-ray spectroscopy. Finally, thermal conductivity was measured by laser flash analysis. With our composite material, we achieved an energy density of 400 kJ/kg across the temperature range 30–150°C and a 35% increase in thermal conductivity by adding 1% of multiwall carbon nanotubes. These features make the material an interesting option for thermal storage in buildings. We attribute the behavior of the material to the combination of large zeolite-specific area coupled with the heat of water sorption/hydration of MgCl₂, MgSO₄.     

Synthesis and study of thermal and electrical behaviour of some polyaromatic amines

Samples of polyaromatic amines were synthesised by chemical and electrochemical methods, using different amounts of electrolytes for the purpose of doping the polymer. These polymers were found to show electrical conductivity in the range 10^?12–10^?6 S/cm. A study of conductivity at various temperatures indicates the semiconducting behaviour of these polymers. Thermal analysis shows that these polymers have high thermal stability.     

Studies on the extraction of aromatics with sulpholane and its combination with thiodiglycol

Liquid—liquid equilibria for the systems: toluene—heptane—sulpholane, toluene—heptane—sulpholane plus thiodiglycol at 40°C, and benzene—heptane—sulpholane plus thiodiglycol and benzene—heptane—sulpholane plus 9% water at 110°C have been studied. The results of the combined solvents have been compared with those obtained with sulpholane containing up to 9% water. Several advantages of combined solvents are discussed. The selectivities of the mixed solvents for different hydrocarbon types have been calculated from the limiting activity coefficients determined by gas chromatography.     

Liquid-liquid equilibria for toluene-heptane-N-methyl pyrrolidone and benzene-heptane solvents

The liquid-liquid equilibria for toluene-n-heptane-N-methyl pyrrolidone containing 10 and 20% water at 298 and 313 K, and of benzene-n-heptane with N-methyl pyrrolidone-ethylene glycol and γ-butyrolactone-ethylene glycol, which is a new solvent combination, have been determined at 303 K.     

Radiation induced polymerisation of trioxane: A study of the effects of variables

Polymerisation of trioxane in the solid state induced by γ-radiation is mainly affected by three variables: radiation dose, post-polymerisation temperature and its duration. In order to optimise the process parameters and study the effects and interactions of these three variables on the conversion of trioxane to polyacetal investigations were carried out by a series of statistically designed experiments. The relationship between the variables and yield was correlated by a least square fit polynomial equation. Applying this relationship, contours of yields were plotted against the variables in the range of interest. The effects of these process variables and the optimum conditions are discussed.     

Permeation of benzene through liquid surfactant membranes

The effect of time on the permeation of benzene through aqueous surfactant membranes formed with two non-ionic surfactants has been studied on a batch scale under two different conditions of surfactant concentration and hydrocarbon: water ratio in the emulsions. The data have been correlated by an equation based on Casamatta's model of hydrocarbon permeation from an emulsion drop. The results indicate that the correlation can be used to treat the data until the onset of membrane rupture. The membrane thickness depends on the hydrocarbon: water ratio in the emulsion, and varies from about 1.57 to 5.10 μm.