In contrast to precious metals (e.g., Pt), which possess their electro catalytic activities due to their surface electronic structure, the activity of the Ni-based electrocatalysts depends on formation of an electroactive surface area (ESA) from the oxyhydroxide layer (NiOOH). In this study, the influences of Sn content, nanostructural morphology, and synthesis temperature on the ESA of Sn-incorporated Ni/C nanostructures were studied. To investigate the effect of the nanostructural, Sn-incorporated Ni/C nanostructures, nanofibers were synthesized by electrospinning a tin chloride/nickel acetate/poly (vinyl alcohol) solution, followed by calcination under inert atmosphere at high temperatures (700, 850, and 1000 °C). On the other hand, the same composite was formulated in nanoparticulate form by a sol-gel procedure. The electrochemical measurements indicated that the nanofibrous morphology strongly enhanced formation of the ESA. Investigation of the tin content concluded that the optimum co-catalyst content depends on the synthesis temperature. Typically, the maximum ESA was observed at 10 and 15 wt % of the co-catalyst for the nanofibers prepared at 700 and 850 °C, respectively. Study of the effect of synthesis temperature concluded that at the same tin content, 850 °C calcination temperature reveals the best activity compared to 700 and 1000 °C. Practical verification was achieved by investigation of the electrocatalytic activity toward methanol and urea oxidation. The results confirmed that the activity is directly proportionate to the ESA, especially in the case of urea oxidation. Moreover, beside the distinct increase in the current density, at the optimum calcination temperature and co-catalyst content, a distinguished decrease in the onset potential of both urea and methanol oxidation was observed.

The present study investigates the discharge rates of ultrafine and superfine powders from a semi-batch circulating fluidized bed (CFB) using a binary mixture of fine Al(OH)₃ powders (mean size 0.5 and 8.0 µm, Geldart-C) and coarse fluidized catalytic cracker (FCC) particles (mean size 6 µm, Geldart-A). Discharge rates of fine powders were measured at the top of the cyclone. Effects of the equilibrium water content of coarse FCC particles on the performance of the CFB, in terms of discharge rates of fine powders, were investigated at a starting loading of fine powders of 5 wt%. The discharge rates of the cohesive ultrafine powders were much smaller than the discharge rates of the less cohesive superfine powders, irrespective of the water content of FCC particles. In the presence of 8.0 µm superfine powders, the discharge rates decreased with decreasing the loading of superfines in the bed. At a certain loading of superfines, specifically at high equilibrium water contents in the range of 0.061 and 0.067 kg-water/kg-dry FCC, discharge rates decreased with decreasing the equilibrium water content of FCC particles. For FCC particles of low equilibrium water content as 0.038 kg-water/kg-dry FCC, discharge rates were low at the beginning then increased to maximum, within a few minutes, then decreased again with decreasing the loading of superfines in the bed. In the presence of 0.5 µm ultrafine powders, at high water equilibrium content of FCC particles as 0.067 kg-water/kg-dry FCC, the discharge rates decreased with decreasing the loading of ultrafines in the bed. However, at the two relatively low equilibrium water contents of FCC particles of 0.038 and 0.061 kg-water/kg-dry FCC, the discharge rates were almost constant. The cohesive property of ultrafine powders prevailed. Copyright © 2013 John Wiley & Sons, Ltd.

The technological pathway to extract fuels from oil shale is still in a stage of development. The present study is an attempt to examine the factors affecting the pyrolysis of oil- shale of Quseir-Safaga in Egypt. Investigations were carried out on samples of different particle sizes using a thermo gravimetric technique at different temperatures. The process is summarized as an empirical formula in terms of temperature, time, and particle size. The model showed a good agreement between the calculated and measured weight losses. The topographic evaluations revealed the kerogen layers, which are subsequently released after subjecting the oil-shale to pyrolysis. Graphical Abstract