低温等离子体改性对Fe_2O_3/ACF低温选择性催化还原NO的影响

Effect of Fe_2O_3/ACF catalysts modified by non-thermal plasma on the selective catalytic reduction of NO at low temperature

利用N2低温等离子体对过量溶液浸渍法制备的Fe2O3/ACF(活性炭纤维)催化剂进行了改性,运用BET比表面积、扫描电子显微镜(SEM)、X射线衍射光谱(XRD)和傅立叶变换红外光谱(FT-IR)对催化剂进行表征.同时,对催化剂的NH3选择性催化还原(SCR)NO的催化性能进行了研究.结果表明,活性组分最佳负载量的质量分数为10.3%;N2等离子体改性最优改性电压为6kV,改性时间为3min;随着反应温度的升高,空白ACF上NO转化率先升高再下降,而催化剂上NO转化率呈上升趋势.在NO体积分数1000×10-6、NH3体积分数1000×10-6、O2体积分数5%、空速10040h-1和反应温度240℃的条件下,催化剂3.7%Fe2O3/ACF和10.3%Fe2O3/ACF经N2等离子体改性后,其NO转化率(相对于未改性的)分别提高了16.43%和6.84%.N2等离子体改性催化剂提高了活性组分在ACF上的分散度,增加了ACF表面的含氮官能团,从而提高了催化剂的SCR低温活性.

A series of Fe2O3/ACF （activated carbon fiber） catalysts were prepared by excess solution impregnation and then modified with a non-thermal N2 plasma at atmospheric pressure in a self-made wire-plate dielectric barrier discharge （DBD） apparatus. The relationship between the catalytic performance and the structure of the Fe2O3/ACF catalysts was explored using BET surface area measurement,scanning electron microscopy （SEM）,X-ray powder diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR）. The catalytic activity for the selective catalytic reduction （SCR） of NO with NH3 in O2 at temperatures between 120℃ and 240℃ was studied. The optimal catalyst preparation conditions were active component （Fe2O3 ） loading of 10.3% followed by non-thermal N2 plasma treatment at 6 kV for 3 rain. The NO conversion on blank ACF initially increased between 120℃ and 150℃ and then decreased above 150℃ , while the NO conversion on Fe2O3/ACF catalysts continued to increase. Under the reaction conditions of NO volume fraction 1000 ×10^-6, NH3 volume fraction 1000 × 10^-6, O2 5% , GHSV （gas hourly space velocity） = 10040 h^-1 and reaction temperature 240℃ , the NO conversion on 3.7% and 10.3% Fe2O3/ACF modified with the N2 plasma increased by 16.43% and 6.84% , respectively. After N2 plasma treatment, the catalytic activity of Fe2O3/ACF was enhanced because of an increased number of nitrogen-containing functional groups on ACF and improved dispersion of the active component （ Fe2O3 ）.