Elucidating the process of hydrogen generation from the reaction of sodium hydroxide solution and ferrosilicon
journal contributionposted on 25.04.2017, 13:59 by Paul Brack, Sandie DannSandie Dann, Upul Wijayantha-Kahagala-GamageUpul Wijayantha-Kahagala-Gamage, Paul L. Adcock, Simon E. Foster
For the first time, the process of hydrogen evolution from ferrosilicon 75 using sodium hydroxide solution has been investigated as a function of temperature using a combination of X-ray photoelectron spectroscopy, X-ray diffraction and physical measurements. Ferrosilicon 75, a mixture of silicon (~50wt.%) and iron disilicide (~50wt.%), has been shown to produce hydrogen by the action of sodium hydroxide solution on the silicon only, with the iron disilicide acting in the role of spectator/protector species for the silicon. Neither iron disilicide alone nor ferrosilicon 45, which does not contain a pure metallic silicon phase, was found to generate hydrogen under similar reaction conditions, further indicating that the presence of a pure metallic silicon phase is essential for hydrogen generation. As the iron disilicide acts as a diluent for the active silicon, it is hypothesized that this would result in a slower release of hydrogen than that which would be obtained from the reaction of silicon alone, which may be useful for applications which require a long-term, sustained release of hydrogen. A hydrogen yield of 462.5mL/g and a maximum hydrogen generation rate of 83mL/min g were obtained within 10min of reaction with 40wt.% NaOH at 348K.
The authors would like to thank the EPSRC and Intelligent Energy for funding this project.