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Boundary Reactions (boundary + reaction)
Selected AbstractsEvaluation of the Limiting Regime in Iron Ore Fines Reduction with H2 -Rich Gases in Fluidized Beds: Fe2O3 to Fe3O4CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2009J. Sturn Abstract In metallurgical processes, fluidized-bed technology is gaining more importance because of its advantages. Processes with H2 -rich and CO-rich reducing gases were developed for the reduction of iron ore fines (e.g. FINEX®). For improvement of these new technologies, greater knowledge about the chemical kinetics of iron ore reduction in fluidized beds is necessary. The scope of this work is to evaluate the limiting regime of the iron ore fines reduction. Therefore, experimental results of reduction tests were compared with theoretically investigated reduction rates. These reduction rates were based on a limitation either of mass transfer through the external gas film to the particle surface, diffusion in a porous product layer (pore diffusion and Knudsen diffusion), diffusion in a dense product layer (solid diffusion) or the phase boundary reaction. The phase boundary reaction was found to be the most likely limiting reaction regime. [source] Two-phase flow electrosynthesis: Comparing N -octyl-2-pyrrolidone,aqueous and acetonitrile,aqueous three-phase boundary reactionsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 1 2009Stuart M. MacDonald Abstract A microfluidic double channel device is employed to study reactions at flowing liquid,liquid junctions in contact with a boron-doped diamond (BDD) working electrode. The rectangular flow cell is calibrated for both single-phase liquid flow and biphasic liquid,liquid flow for the case of (i) the immiscible N -octyl-2-pyrrolidone (NOP),aqueous electrolyte system and (ii) the immiscible acetonitrile,aqueous electrolyte system. The influence of flow speed and liquid viscosity on the position of the phase boundary and mass transport-controlled limiting currents are examined. In contrast to the NOP,aqueous electrolyte case, the acetonitrile,aqueous electrolyte system is shown to behave close to ideal without ,undercutting' of the organic phase under the aqueous phase. The limiting current for three-phase boundary reactions is only weakly dependent on flow rate but directly proportional to the concentration and the diffusion coefficient in the organic phase. Acetonitrile as a commonly employed synthetic solvent is shown here to allow effective three-phase boundary processes to occur due to a lower viscosity enabling faster diffusion. N -butylferrocene is shown to be oxidised at the acetonitrile,aqueous electrolyte interface about 12 times faster when compared with the same process at the NOP,aqueous electrolyte interface. Conditions suitable for clean two-phase electrosynthetic processes without intentionally added supporting electrolyte in the organic phase are proposed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Layer solutions in a half-space for boundary reactionsCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 12 2005Xavier Cabré First page of article [source] | ||||||||||