Hydrogen storage in Mg using Sulphur encapsulation: Investigating sorption kinetics and air resistance

Hydrogen storage in Mg using Sulphur encapsulation: Investigating sorption kinetics and air resistance

Valk, R.

Mulder, F.M. (mentor)

Mechanical, Maritime and Materials Engineering

Materials Science & Engineering

2015-05-29

Magnesium hydride (MgH2) is a well known hydrogen storage material. It has a low weight, high abundance and low cost. It is also characterised by slow kinetics and corrosive properties. To improve this, MgH2 is ball milled (bm) to create nanoparticles and is encapsulated with sulphur (S). MgH2 samples with S are compared to samples without S. The samples are bm and tested inside HYDRA a temperature programmed desorption (TPD) setup. From the peak temperatures (Tp), which result from this method, an activation energy (Ea) can be calculated. Also the wt% H desorbed can be deduced with this setup. The TPD results show that there is not much difference in Ea of the samples with or without S. All fall within the margin of error. The wt% H desorbed shows the T during absorption was too low to get MgH2 back completely, there was still ?Mg present. The samples with S performed marginally better. The air resistance of the samples is tested by exposure to atmospheric conditions. The encapsulation of S is a protective layer against both the creation of MgO and Mg(OH)2. The results are measured using X-ray diffraction is performed and analysed using Rietveld refinement. The encapsulation of MgH2 nanoparticles using S did show good results protect against corrosion during air exposure. The samples with S showed less oxidation and slowed it down. The method should be improved to get better results. A good layer of S should protect better against oxidation and might even avoid it from occurring. More structural details are provided by SEM and to get more details on the elements present EDX is used. A layer was found on the outside of the particles and it shows the presence of S after the high temperature of desorption.

hydrogen
MgH2
encapsulation

http://resolver.tudelft.nl/uuid:f01dae50-fcee-43c0-be69-1e3c2ef24a1a

Student theses

master thesis

(c) 2015 Valk, R.