Preparation and characterization of hollow glass microspheres (HGMs) for hydrogen storage using urea as a blowing agent

• HGMs with and without urea were synthesized using flame spheroidization.
• Effect of urea concentration on HGMs for hydrogen adsorption was investigated.
• The blowing agent like urea loading in HGMs results in enhanced hydrogen storage capacity.
• The hydrogen storage capacity was found to be 2.3 wt.% on HAU2, whereas on HA it was only 1.23 wt.%.

Hollow glass microspheres (HGMs) are unique class of porous material that can be used for hydrogen storage. They are finely dispersed and free flowing powder having microsphere diameter, 10–200 μm and wall thickness, 0.5–2 μm. In this report, we present the preparation of HGMs from glass frits using air-acetylene flame spheroidisation method. Urea was incorporated in the feed glass as a blowing agent to get porous walled HGMs. Effect of concentration of urea in the feed glass on the development of pores on HGMs wall was investigated. It was observed that, the porosity of the HGMS walls increased with the increase in urea content in the feed glass. Characterization of HGMs prepared was done using FE–SEM, ESEM, FTIR and XRD techniques. The spherical nature and the morphology of the HGMs samples prepared were confirmed using FE–SEM, while the pore diameter and the porosity of the samples was observed in the ESEM images. Hydrogen adsorption experiments were carried out at room temperature (RT) and 200 °C at 10 bar pressure, for 5 h for all the HGMs samples prepared. The HGMs prepared with 2% urea showed large number of micro/nano pores and it showed a hydrogen storage capacity of 2.3 wt.% at 200 °C and 10 bar pressure. The hydrogen adsorption on HGMs at RT and 10 bar pressure was lower than that observed at 200 °C and 10 bar pressure.

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