MnαTi1-α催化剂NH3选择性催化还原NO的中低温活性及机理研究

Study on the activity and mechanism of selective catalytic reduction of NO with NH3 over MnαTi1-α catalyst at medium-low temperatures

  • 摘要: 采用浸渍法制备了不同MnOx负载量的SCR催化剂,检测其在中低温下的脱硝活性和抗SO2中毒性能,并分析影响MnαTi1-α催化剂中低温活性的机理。采用BET、XRD、XPS、NH3-TPD和H2-TPR对催化剂表征。研究表明,随着MnOx负载量的增加,MnαTi1-α催化剂最高脱硝活性温度区间向低温区移动,Mn0.1Ti0.9催化剂在200-385 ℃脱硝效率达80%以上。SO2会造成MnαTi1-α催化剂脱硝活性显著下降,且不可逆。当MnOx负载量增加时,催化剂比表面积先增大后略微减小、H2-TPR中Mn4+峰面积增大、表面化学吸附氧增加,有利于NH3-SCR反应在低温下的进行。MnαTi1-α催化剂的酸性位点随MnOx含量增加而增多,H2还原峰出现温度较低,表明MnαTi1-α催化剂具有良好的中低温氧化还原性。

     

    Abstract: MnαTi1-α catalysts for selective catalytic reduction (SCR) of NO were prepared with impregnation method and their denitration activity and SO2 resistance at medium-low temperature were evaluated. The catalysts were characterized using BET, XRD, XPS, NH3-TPD and H2-TPR. The results showed that the temperature range of the highest denitration activity of MnαTi1-α catalyst shifted to the lower temperature zone along with the increase of MnOx loading. The denitration efficiency of Mn0.1Ti0.9 catalyst reached over 80% at 200-385 ℃. SO2 could bring down denitration activity of MnαTi1-α catalyst greatly and resulted in irreversible deactivation. The specific surface area of the catalyst first increased then slightly decreased with the increase of Mnx loading. Both Mn4+ peak area in H2-TPR and surface chemical adsorbed oxygen increased along with the increase of MnOx loading. All these factors were beneficial to the proceeding of NH3-SCR reaction at low temperature. With the increase of MnOx loading, the acid sites of MnαTi1-α catalyst increased and the reduction peak at low temperature appeared, indicating that MnαTi1-α catalyst had good redox performance at medium and low temperature.

     

/

返回文章
返回