The reduction of H2SO4 to SO2 occurs with a relatively good efficiency only at high temperatures, in the presence of catalysts. Some experimental results, regarding conversion of sulfuric acid (96 wt.%) to sulfur dioxide and oxygen, are reported. The reduction has been performed at 800 – 900°C and atmospheric pressure, in a tubular quartz reactor. The following commercial catalysts were tested: Pd/Al2O3 (5 wt.% and 0.5 wt.% Pd), Pt/Al2O3 (0.1 wt.% Pt) and α-Fe2O3. The fresh and spent catalysts were characterized by X-Ray diffraction and BET method. The highest catalytic activity was determined for 5 wt.% Pd/Al2O3, a conversion of 80% being obtained for 5 hours time on stream, at 9 mL h−1 flow rate of 96 wt.% H2SO4. A conversion of 64% was determined for 0.5 wt.% Pd/Al2O3 and 0.1 wt.% Pt/Al2O3. For α-Fe2O3, a less expensive catalyst, a conversion of 61% for about 60 hours was obtained.
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 S. Brutti, L. Bencivenni, V. Barbarossa, S. Sau, G. De Maria, J. Chem. Thermodynamics 38, 1292 (2006) http://dx.doi.org/10.1016/j.jct.2006.02.009
 D. Schwartz, R. Gadiou, J.F. Brilhac, G. Prado, G. Martinez, Ind. Eng. Chem. Res. 39, 2183 (2000) http://dx.doi.org/10.1021/ie990801e
 L.E. Brecher, S. Spewock, C.J. Warde, Int. J. Hydrogen Energy 2, 7 (1977) http://dx.doi.org/10.1016/0360-3199(77)90061-1
 G.H. Farbman, Int. J. Hydrogen Energy 4, 111 (1979) http://dx.doi.org/10.1016/0360-3199(79)90045-4
 G.E. Beghi, Int. J. Hydrogen Energy 11, 761 (1986) http://dx.doi.org/10.1016/0360-3199(86)90172-2
 J.H. Norman, G.E. Besenbruch, L.C. Brown, D.R. O’Keefe, C.L. Allen, General Atomics Report GA-A16713, DOE Report DOE/ET/26225-1, May 1982. Available on-line at http://www.osti.gov/bridge/servlets/purl/5063416-Hhmrtj/5063416.pdf
 R. Buckingham, B. Russ, L. Brown, G.E. Besenbruch, General Atomics Annual Report, November 2004. Available on-line at http://www.osti.gov/bridge/servlets/purl/834680-0cKoDQ/native/834680.pdf
 J.F. Pierre, R.L. Ammon, in: Proceedings of the 4th World Hydrogen Energy Conference 2, 703 (1982)
 M. Dokiya, T. Kameyama, K. Fukuda, Y. Kotera, Bull. Chem. Soc. Jap. 50, 2657 (1977) http://dx.doi.org/10.1246/bcsj.50.2657
 J.H. Norman, K.J. Mysels, R. Sharp, D. Williamson, Int. J. Hydrogen Energy 7, 545 (1982) http://dx.doi.org/10.1016/0360-3199(82)90035-0
 L.N. Yannopoulos, J.F. Pierre, Int. J. Hydrogen Energy 9, 383 (1984) http://dx.doi.org/10.1016/0360-3199(84)90058-2
 G. Karagiannakis, C.C. Agrafiotis, A. Zygogianni, C. Pagkoura, A.G. Konstandopoulos, Int. J. Hydrogen Energy 36, 2831 (2011) http://dx.doi.org/10.1016/j.ijhydene.2010.11.083
 A. Giaconia, S. Sau, C. Felici, P. Tarquini, G. Karagiannakis, C. Pagkoura, C. Agrafiotis, A.G. Konstandopoulos, D. Thomey, L. de Oliveira, M. Roeb, C. Sattler, Int. J. Hydrogen Energy 36, 6496 (2011) http://dx.doi.org/10.1016/j.ijhydene.2011.02.137
 D.M. Ginosar, L.M. Petkovic, A.W. Glenn, K.C. Burch, Int. J. Hydrogen Energy 32, 482 (2007) http://dx.doi.org/10.1016/j.ijhydene.2006.06.053