Oxidative destruction of anionite AV-17×8 using the Fenton reaction

The kinetic studies of AV-17×8 strongly basic anionite’s oxidative destruction using the Fenton reaction have been carried out. The effect of the process’s temperature and the concentration of catalysts of iron(II) sulfate or copper(II) sulfate on the oxidation of anion-exchange resin with hydrogen peroxide is estimated. With an increase in temperature in the range of 323–348 K, a regular increase in the effective rate constant of oxidative anionite destruction is observed when using iron(II) sulfate by 1.5 times, and when using copper(II) sulfate – by 22 times. It was found that the obtained values of the activation energy of the anion exchanger’s oxidation with the addition of copper(II) sulfate are 124.3–115.7 kJ/mol and are characteristic of the process proceeding in the kinetic region. The nature of the change in the surface morphology of the anionite granules in the process of oxidative decomposition has been revealed.

Determination of Kinetic Parameters for the Oxygen Reduction Reaction on Platinum in an AEMFC

To promote the development of anion exchange membrane fuel cells (AEMFC), an understanding of the oxygen reduction reaction (ORR) kinetics in porous gas diffusion electrodes is essential. In this work, experimental polarisation curves for electrodes with different platinum catalyst loadings and oxygen partial pressures at the cathode are fitted to a physics-based porous electrode model in the voltage range from open circuit voltage (OCV) to 0.7 V. The model is verified against polarisation curves with different anode platinum catalyst loading, and hydrogen partial pressures. The reactions are described using a two-step Tafel-Volmer pathway at the anode and concentration-dependent Butler-Volmer kinetics at the cathode. The model shows a good fit to the kinetic region with an exchange current density of 1.0e-8 A/cm2, for oxygen humidified to 95 % RH at 50 °C, a charge transfer coefficient of 0.8 and a first order dependence on oxygen partial pressure. For lower oxygen partial pressure, hydrogen crossover is needed for explaining the downward shift of the polarisation curves in the kinetic region. In the experimental data, the polarisation curves show an apparent limitation at lower hydrogen partial pressures, which can be explained by the lower rate of the Tafel step at these conditions.

SOME ISSUES OF THE MECHANISM OF DEEP OXIDATION OF ETHANOL ON THE SURFACE OF THE CATALYST OF A THERMOCATALYTIC SENSOR

In this work, the effect of the partial pressures of the starting materials and reaction products on the patterns of deep oxidation of ethanol on the surface of the catalyst of the thermocatalytic sensor was studied experimentally. At the same time, the regularities of the oxidation of combustible substances on selected catalysts have been established and the optimal conditions have been identified that ensure the flow of the process under study in the kinetic region. It is shown that the reaction on the sensor catalyst surface proceeds along two kinetically independent (basic) routes. Taking into account the above, a more detailed scheme of the heterogeneous catalytic oxidation of ethanol in the presence of a sensor catalyst is proposed.

Research of the process of obtaining potassium fertilizers from carnallite ore

To providedomestic and foreign markets with potash fertilizers Kazakhstan has begun to create own production of these products. But at the moment enterprises engaged in mining potash salts did not reach a practical stage. The Chelkarcarnallite ore deposit is auniqueone in solving these urgent problems. The article presents results of the study of processing Chelkar potash ore washed from sodium chloride to obtain a potassium fertilizer containing potassium and magnesium sulfates. The kinetics of nitric acid decomposition of carnallite ore has been investigated. The calculated value of reaction activation energy of potassium sulfate and nitric acid inter-action characterizes the kinetic region of the process behavior.Optimal conditions for decomposition of washed calcined ore with 30%nitric acid solution at 50°C were determined. It has been found that to ensure better filtration properties and high rate of suspension separation, washed non-calcined ore should be used to exclude gypsum dehydration, which causes its phase conversion into anhydrite. The double salt of potassium-magne-sium sulfate was separated by crystallization from nitric acid extract and an ammoniated mother liquor drying allowed to obtain a salt, which is ballast-free chlorine-free complex nitrogen-potassium-magnesium fertilizer.

Kinetic and MD modelling of automotive fuel droplets heating and evaporation: recent results

Recent results of the investigation of kinetic and molecular dynamics (MD) models for automotive fuel droplet heating and evaporation are summarised. The kinetic model is based on the consideration of the kinetic region in the close vicinity of the surface of the heated and evaporating droplets, where the motion of molecules is described in terms of the Boltzmann equations for vapour components and air, and the hydrodynamic region away from this surface. The effects of finite thermal conductivity and species diffusivity inside the droplets and inelastic collisions in the kinetic region are taken into account. A new self-consistent kinetic model for heating and evaporation of Diesel fuel droplets is briefly described. The values of temperature and vapour densities at the outer boundary of the kinetic region are inferred from the requirement that both heat flux and mass flux of vapour components in the kinetic and hydrodynamic regions in the vicinity of the interface between these regions are equal. At first, the heat and mass fluxes in the hydrodynamic region are calculated based on the values of temperature and vapour density at the surface of the droplet. Then the values of temperature and vapour density at the outer boundary of the kinetic region, obtained following this procedure, are used to calculate the corrected values of hydrodynamic heat and species mass fluxes. The latter in their turn lead to new corrected values of temperature and vapour density at the outer boundary of the kinetic region. It is shown that this process quickly converges and leads to self-consistent values for both heat and mass fluxes. Boundary conditions at the surface of the droplet for kinetic calculations are inferred from the MD calculations. These calculations are based on the observation that methyl (CH3 ) or methylene (CH2 ) groups in n-dodecane (approximation of Diesel fuel) molecules can be regarded as separate atom-like structures in a relatively simple United Atom Model. Some results of the application of quantum chemical methods to the estimation of the evaporation/condensation coefficient are discussed.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4593

Electrolytes For Intermediate Temperature Solid Oxide Fuel Cells

Solid electrolytes for construction of the intermediate-temperature solid oxide fuel cells, IT-SOFC, have been reviewed. Yttrium stabilized tetragonal zirconia polycrystals, YTZP, as a potential electrolyte of IT-SOFC have been highlighted. The experimental results involving structural, microstructural, electrical properties based on our own studies were presented. In order to study aluminum diffusion in YTZP, aluminum oxide was deposited on the surface of 3 mol.% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP). The samples were annealed at temperatures from 1523 to 1773 K. Diffusion profiles of Al in the form of mean concentration vs. depth in B-type kinetic region were investigated by secondary ion mass spectroscopy (SIMS). Both the lattice (DB) and grain boundary (DGB) diffusion were determined.