(400c) Thermally Stabilized Ferrite Nanoparticles for Hydrogen Generation From Thermochemical Water-Splitting Reaction

Thermally Stabilized Ferrite Nanoparticles for Hydrogen Generation
from Thermochemical Water-Splitting Reaction

X. Pasala, R.R. Bhosale,
J. A. Puszynski, R. V. Shende*

Chemical and Biological Engineering,

South Dakota School of Mines and Technology,

Rapid City, SD 57701. Rajesh.Shende@sdsmt.edu

    Among several redox materials, ferrites
show higher H₂ volume generation at lower temperatures. Nominally
phase pure ferrite materials were synthesized using sol-gel method and
investigated for H₂ generation from water-splitting reaction. Using
sol-gel derived Ni-ferrite material, about 125 thermochemical cycles were
performed for hydrogen generation where water-splitting and regeneration were
performed at 700^o-900^oC and 1100^oC,
respectively. After performing 125 cycles, significant grain growth was
observed during SEM analysis and this material exhibited very low specific
surface area, <1 m²/g. As heterogeneous grain growth was observed
after water-splitting reaction, it was considered important to investigate
thermal stability of ferrite materials and mitigate their grain growth using
ZrO₂, Al₂O₃, Y₂O₃ and
yttria-stabilized zirconia (YSZ) inhibitors. These inhibitors were mixed with
Ni-ferrite nanoparticles (10-25 wt %) using vortex mixing and sonication. The
materials thus obtained were analyzed using scanning electron microscopy (SEM),
X-ray Diffraction (XRD) and BET (Brunauer-Emmett-Teller) surface area analyzer.
The H₂ generation ability of these ferrite nanomaterials was
investigated by performing ten consecutive thermochemical cycles in the Inconel
packed-bed reactor where water-splitting and regeneration were carried out at
700-900^oC and 1100^oC, respectively. In addition, during the
regeneration step, oxygen was continuously monitored to understand the reaction
stoichiometry. The results obtained on hydrogen generation using thermally
stabilized ferrite materials in multiple thermochemical water-splitting cycles will
be presented in detail.