关键词: 脉冲放电等离子体, TiO₂-分子筛, 催化剂, 甲醛, 协同作用

Abstract: In order to further improve formaldehyde removal efficiency,increase carbon dioxide selectivity,and decrease the generation concentration of ozone in pulse discharge plasma,a method of discharge plasma combined with catalysts was adopted in this research. Molecular sieve was used as carrier,then three catalysts were prepared,i.e. Mn/TiO₂-molecular sieve,Fe/TiO₂-molecular sieve and Cu/TiO₂-molecular sieve catalysts,which were characterized by XRD,SEM,EDS and FT-IR. Decomposition of formaldehyde in pulse discharge plasma combined with three catalysts was studied. Effects of plasma combined with different catalysts on formaldehyde removal efficiency,carbon dioxide selectivity and generation concentration of ozone were compared. The results showed that catalysts have synergistic effects on pulse discharge plasma. It could improve formaldehyde removal efficiency,increase carbon dioxide selectivity,and decrease generation concentration of ozone efficiently. Mn/TiO₂-molecular sieve catalyst has the best synergistic effect with the impulse voltage of 20kV,the frequency of 40Hz and the gas flow rate of 0.5L/min,i.e. its formaldehyde removal efficiency achieved 94.4% and carbon dioxide selectivity achieved 42.2%. Characterization results showed that Mn/TiO₂-molecular sieve catalyst uniform dispersion of active ingredients is as well as the existence of anatase TiO₂,and microcrystalline state MnO_x increased the oxidation of formaldehyde decomposition. Meanwhile,the mechanism of degrading formaldehyde in discharge plasma combined with Mn/TiO₂-molecular sieve catalyst was also discussed.

Key words: pulse discharge plasma, TiO₂-molecular sieve, catalyst, formaldehyde, synergistic effect