Catalytic reduction of sulfuric acid to sulfur dioxide

Abstract

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.

Electrochemical Noise Analysis of the Corrosion of Titanium Alloys in NaCl and H2SO4 Solutions

“…Factors that permit a non-uniform current distribution on the Ti surface is the inhomogeneity of the alloy according to Yang et al [88]; however, a passive film is formed, and this reduces the corrosion kinetic of alloys and increases material life [89].…”

“…This converges with the results from PSD, where Ti CP2 dissolution presents a value of −104 dBi in H 2 SO 4 , while in NaCl, the value is −122 dBi. This occurs due to the aggressiveness of redox reaction of H 2 SO 4 shown in the next equations, parting from water dissociation [87][88][89][90]:…”

Corrosion Behavior of Titanium Alloys (Ti CP2, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-4V and Ti Beta-C) with Anodized and Exposed in NaCl and H2SO4 Solutions

“…This phenomenon occurs in cathodic reactions where hydrogen reacts. On the other hand, the growth of a passive layer in electrochemical conditions is represented by the next equations [59][60][61]:…”