TiO₂/SiC supported catalyst for efficient thermocatalytic conversion of SF₆ waste gas

Abstract

Abstract The harmless treatment of SF 6 waste gas is currently a highly concerned focus in the power industry. This article used a new supported catalyst, TiO 2 /SiC, to study the thermocatalytic conversion of SF 6 waste gas. Firstly, the catalytic activity of TiO 2 /SiC was tested, and it was found that the catalytic efficiency of TiO 2 /SiC was 3.73 times that of TiO 2 at 700 °C; Subsequently, the optimal catalytic conditions for TiO 2 /SiC were figured out by experiments, which were conducted under different initial pressures and oxygen concentrations. It was found that the catalytic efficiency of TiO 2 /SiC was highest when the initial pressure was 0.16 MPa and the concentration rate of SF 6 and O 2 was 1:4. Under these conditions, the total conversion of SF 6 by TiO 2 /SiC reached 288 ml in 6 h, and the average catalytic conversion efficiency reached 33 ml g −1 h −1 . It was also found that when the conversion of SF 6 reached 110–130 ml, the catalytic activity of TiO 2 /SiC decreased; the oxygen concentration has a significant influence on the products: the higher the oxygen concentration is, the higher the production of SO 2 F 2 rate in the product, while the lower that of SO 2 rate. Finally, in order to know the catalytic mechanism of TiO 2 /SiC, XPS tests were conducted on the catalysts before and after the experiment. According to the XPS spectrum, gaseous products would react with TiO 2 and generate TiF 4 and Ti(SO 4 ) 2 . According to the test results, the catalytic mechanism of TiO 2 /SiC was summarized in this article. It explained the catalytic effect of TiO 2 /SiC from two aspects: promoting the defluorination of SF 6 and consuming low-fluorinated sulfides. The empirical conclusions of this article provide a theoretical reference for the harmless treatment of SF 6 waste gas.