SusChemE 2015
International Conference on Sustainable Chemistry & Engineering
October 8-9, 2015, Hotel Lalit, Mumbai
Fe2O3 Dispersed on TiO2, ZrO2 and CeO2 as Catalyst for Sulfuric Acid Decomposition
Reaction: Effect of Support on Catalytic Properties
Ashish Nadar, A. M. Banerjee*, M. R. Pai, A. K. Tripathi and S.R. Bharadwaj
Chemistry Division, Bhabha Atomic Research Centre, Mumbai - 400085, India
*-Corresponding Author e-mail: atinmb@barc.gov.in; atinmb@gmail.com
1. Introduction:
Sulfuric acid decomposition is the thermal to chemical energy conversion step in the sulfur based thermochemical
cycles [1] for hydrogen production by water splitting. This reaction is driven by solar thermal heat at temperatures of 800-900
°C in a solar furnace. But due to slow kinetics a catalyst is required to achieve higher efficiencies at such operating
temperatures. Previously, we have explored Fe2O3 based catalyst [2, 3] for the sulfuric acid decomposition reaction but we
observed sintering and grain growth during long term operation at 800 °C. To overcome this agglomeration phenomenon we
studied the catalytic performance of Fe2O3 dispersed on several supports viz. TiO2, ZrO2 and CeO2 which is reported in this
article. The metal oxide (15 wt. % Fe2O3) was dispersed in nanometer range over various supports to achieve higher catalytic
activities and also envisaged to increase thermal stability by decreasing sintering rates.
2. Materials and Methods:
Fe2O3(15 wt. %) dispersed on TiO2, ZrO2 and CeO2 were prepared by an equilibrium-adsorption method. Briefly, 5 wt.
% Fe2O3 dispersed on each support was prepared by calcining at 500 °C (4 h) the powders obtained by adding iron acetyl
acetonate (required amount) to the respective supports dispersed in 50% 1-propanol at 0°C and pH=10 (by adding NH4OH). 15
wt. % Fe2O3 was obtained by repeating the above process couple of times but using the 5 and 10 wt. % products obtained in the
previous method instead of using the bare support. The final products Fe2O3(15 wt. %)/TiO2, Fe2O3(15 wt. %)/ZrO2 and
Fe2O3(15 wt. %)/CeO2 were further calcined at 1000 °C in air for 5 h and will be henceforth abbreviated as FTO15, FZO15 and
FCO15 respectively. The samples were characterized by XRD, FTIR and Mossbauer spectroscopy and the catalytic activity for
sulfuric acid decomposition reaction was evaluated with 20-44 mesh fraction of the catalyst in the temperature range 500-900°C
in a flow through quartz catalytic reactor as described elsewhere [1].
3. Significant Results:
Powder XRD patterns in the 2 range of 10-70 degrees of all the supports and that of the synthesized samples calcined
at 1000 °C i.e. FTO15, FZO15 and FCO15 were measured and analyzed. TiO2, ZrO2 and CeO2 were having anatase (JCPDS-211272), baddeleyite (JCPDS-37-1484) and fluorite (JCPDS-34-0394) phases respectively. Weak reflection due to Fe2O3 were
also visible in the powder XRD patterns of FZO15 and FCO15 in addition to the support phase. 100 % peak of both -Fe2O3
and -Fe2O3 was present on FZO15 and FCO15, while no peaks due to Fe2O3 was observed in FTO15. The reason for this
phenomenon was found out from the Mossbauer spectra of the samples which revealed the presence of superparamagnetic
nanoparticle of Fe2O3 dispersed on TiO2, and thus the absence of any long range ordering. Therefore, the phase evolution of
Fe2O3 on different supports was found to be highly dependent on nature and type of support. All the dispersed samples were
SusChemE 2015
International Conference on Sustainable Chemistry & Engineering
October 8-9, 2015, Hotel Lalit, Mumbai
found to be active in the 500-900 °C temperature range. The order of activity was found to be: FTO15 ~ FZO15 > FCO15 below
850 °C. At 900 °C the SO2 yield of all the samples were found to be comparable. Proper metal oxide-support interaction is
proposed to be the possible cause for the enhanced activity of FTO15 and FZO15.
Figure 1: Effect of temperature on the catalytic activity of FZO15, FTO15 and FCO15 for sulfuric acid decomposition reaction.
Conclusion: Fe2O3 has been successfully dispersed on TiO2, ZrO2 and CeO2 by equilibrium adsorption method. The catalytic
activity for the sulfuric acid decomposition was of the order as FZO15 ~ FTO15 > FCO15 at 850°C.
References:
1. A. M. Banerjee, M. R. Pai, S. S. Meena , A. K. Tripathi and S. R. Bharadwaj, Int. J. Hydrog. Energ. 36 (2011) 4768.
2. A. M. Banerjee, A. R. Shirole, M. R. Pai, A. K. Tripathi, S. R. Bharadwaj, D. Das and P. K. Sinha, Appl. Catal. B: Environ.
127 (2012) 36–46.
3. A. M. Banerjee, M. R. Pai, K. Bhattacharya, A. K. Tripathi, V. S. Kamble, S. R. Bharadwaj, S. K. Kulshreshtha, Int. J.
Hydrog. Energ. 33 (2008) 319-326.