脉冲放电等离子体协同Mn/TiO2-分子筛、Fe/TiO2-分子筛、Cu/TiO2-分子筛催化剂降解甲醛

摘要

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 MnOx 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.%为进一步提高脉冲放电等离子降解甲醛的效率,增加CO2选择性,降低O3产生量,研究采用放电等离子体和催化剂协同技术.实验以分子筛为载体,分别制备了Mn/TiO2-分子筛、Fe/TiO2-分子筛和Cu/TiO2-分子筛3种催化剂,并利用 XRD、SEM、EDS、FT-IR 方法对催化剂进行表征分析.进行了脉冲放电等离子体协同 3 种催化剂降解甲醛的研究,比较了不同催化剂协同等离子体对甲醛去除率、CO2选择性、O3产生量的影响.结果表明,3 种催化剂与脉冲放电等离子体都存在协同作用,并能有效地提高甲醛去除率,增加 CO2选择性,降低O3产生量.当脉冲电压为20kV、放电频率为40Hz、气体流量为0.5L/min时,Mn/TiO2-分子筛催化剂协同效果最佳,甲醛去除率为94.4%,CO2选择性为42.2%.催化剂表征结果显示Mn/TiO2-分子筛的活性组分颗粒分布均匀,锐钛矿相的 TiO2 和微晶状态的 MnOx 的存在有效促进了甲醛的氧化分解.研究还对放电等离子体协同Mn/TiO2-分子筛催化剂降解甲醛的机理进行了探讨.