The catalytic decomposition of CHF3 over ZrO2-SO4

The destruction of CHF3 over ZrO2 and ZrO2-SO4 was studied in a fixed bed catalytic reactor system in dry and humid air streams. The addition of sulfate to the zirconia greatly improved the catalytic activity, decreasing the light-off temperature by approximately 40 degrees C. The destruction of CHF3 proceeded according to a catalyzed hydrolysis reaction, rather than an oxidation reaction, thereby necessitating that water be present in the feed stream. The presence of water in the feed stream had a significant effect on the stability of the catalyst. In dry air, the catalyst rapidly deactivated. Deactivation is attributed to the fluorination of the zirconium, which results in a loss of oxygen and sulfur from the catalyst and a significant decrease in surface area. The addition of 2.5% water to the feed stream greatly improves the catalyst's stability; however, some deactivation was observed. Deactivation in humid air was attributed to a gradual accumulation of fluorine on the catalyst, which resulted in a loss of sulfate and oxygen from the zirconia, and a decrease in the surface area of the catalyst. (C) 1999 Elsevier Science B.V. All rights reserved.