A Potential Hydrogen Sources from Milled Silicon Powder Activated by Lithium, and Aluminum Chloride

A potential hydrogen source generated from milled Li-Si-AlCl3 composite was evaluated in this paper. The composite exhibits good hydrogen generation performance in water at 313–343 K, whereas pure silicon powder cannot continuously react with water under similar conditions. The hydrogen yield reaches 1300 mL hydrogen/g within 20 min, and the highest hydrogen generation rate is higher than 1200 mL hydrogen/g min within the first minute of hydrolysis. The hydrogen generation performance increases with increasing concentrations of lithium and aluminum chloride. Microstructure analysis indicates that silicon activity increases due to decreased particle size and distribution of lithium and aluminum chloride into silicon matrix during milling. The hydrolysis of the additives generates heat and alkaline hydrolysis byproducts, thereby stimulating the hydrolysis rate of silicon in the micro area. Therefore, the hydrolysis of silicon in water may act as a potential hydrogen source for portable micro fuel cells.

HIGH-TEMPERATURE STUDIES OF METALLURGICAL PROCESSES: PART II. THE THERMAL REDUCTION OF CALCINED DOLOMITE WITH SILICON

The production of magnesium by the following reaction has been studied:[Formula: see text]The rate of reaction (a) was followed by continuous weight loss measurements of the reactants. Keeping the particle size of the reactants and size and shape of the charge constant, the following factors which affect the yield of magnesium were investigated: (1) temperature, from 1050–1560 °C; (2) pressure, from less than 1 µ to 261 mm of Hg; (3) catalysts, CaF2, BaF2, and MgF2; and (4) ferrosilicon grade, from 18.7% to 96.7% Si.It was found that the yield increased by a factor 1.55 for a 50° increase in temperature over the temperature range investigated. At temperatures below 1300 °C the yield falls linearly with increase in pressure, while at temperatures above 1300 °C the yield remains relatively constant until the pressure exceeds the equilibrium magnesium pressure. All fluoride additions were found to increase the yield, CaF2 being the most effective. The rate of the reaction was also found to have a direct relationship with the silicon activity.