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

Abstract

Abstract The harmless treatment of SF6 waste gas is currently a highly concerned focus in the power industry. This article used a new supported catalyst, TiO2/SiC, to study the thermocatalytic conversion of SF6 waste gas. Firstly, the catalytic activity of TiO2/SiC was tested, and it was found that the catalytic efficiency of TiO2/SiC was 3.73 times that of TiO2 at 700 °C; Subsequently, the optimal catalytic conditions for TiO2/SiC were figured out by experiments, which were conducted under different initial pressures and oxygen concentrations. It was found that the catalytic efficiency of TiO2/SiC was highest when the initial pressure was 0.16 MPa and the concentration rate of SF6 and O2 was 1:4. Under these conditions, the total conversion of SF6 by TiO2/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 SF6 reached 110–130 ml, the catalytic activity of TiO2/SiC decreased; the oxygen concentration has a significant influence on the products: the higher the oxygen concentration is, the higher the production of SO2F2 rate in the product, while the lower that of SO2 rate. Finally, in order to know the catalytic mechanism of TiO2/SiC, XPS tests were conducted on the catalysts before and after the experiment. According to the XPS spectrum, gaseous products would react with TiO2 and generate TiF4 and Ti(SO4)2. According to the test results, the catalytic mechanism of TiO2/SiC was summarized in this article. It explained the catalytic effect of TiO2/SiC from two aspects: promoting the defluorination of SF6 and consuming low-fluorinated sulfides. The empirical conclusions of this article provide a theoretical reference for the harmless treatment of SF6 waste gas.