The Research Of Pluse Discharge Plasma Combined With Compound Catalysts Decomposition Of Formaldehyde

Atomospheric pollution serious affect the health of environment and human beings, the formaldehyde is one of the typical volatile organic compounds, which has harmful of toxic, cancer and pollution time is long. Therefore, adopt new technology and method to remove formaldehyde has very important practical significance and application value. Pulsed discharge plasma combine with catalyst technology is one of the most promising to remove formaldehyde method, but it has two problems: high energy consumption and difficult to control by-products, preparation of effective catalyst is the key to the technology.With formaldehyde as treatment object, this research adopted method of pulse discharge plasma combined with catalyst. The experiment first for the catalyst carrier and active component screening, then used molecular sieve as carrier, prepared three catalysts: Mn/Ti O2-molecular sieve, Ag-Mn/Ti O2-molecular sieve and Ce-Ag-Mn/Ti O2-molecular sieve catalysts which would be characterized by methods of 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 molecular sieve is the best carrier of catalyst, loading Mn active component has the best effect. 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. While the impulse voltage was 20 k V, the frequency was 40 Hz and the gas flow rate was 0.5L/min, 5%Mn/Ti O2-molecular sieve calalyst its formaldehyde removal efficiency achieves 94.4%, ozone concentration is 105.4mg/m3 and carbon dioxide selectivity is 42.2%.The activity of catalyst 4%Ag-Mn/Ti O2-molecular sieve is much higher than catalyst 5%Mn/Ti O2-molecular sieve, its formaldehyde removal efficiency achieves 97.6%, ozone concentration is 99.4mg/m3 and carbon dioxide selectivity is 50.2%. The activity of catalyst 3%Ce-Ag-Mn/Ti O2-molecular sieve is much higher than catalyst 4%Ag-Mn/Ti O2-molecular sieve, its formaldehyde removal efficiency achieves 99.4%, ozone concentration is 60.7mg/m3 and carbon dioxide selectivity is 58.8%. Pulsed discharge plasma combined with CeAg-Mn/Ti O2-molecular sieve catalyst for removing formaldehyde has the best synergistic effect. Meanwhile, the mechanism of degrading formaldehyde in pulse discharge plasma combined with catalysts was also discussed. The research of pulsed discharge plasma combined with catalyst for removing formaldehyde provides some guidance for the selection of the compound catalyst.