负载复合金属催化剂的活性半焦脱除烟气中NO的非等温动力学研究

Reaction Kinetics of NO with Carbon Catalyzed by Activated-char-supported Composite Metals During Flue Gas Cleaning

对负载复合金属催化剂的活性半焦脱除烟气中NO进行了非等温动力学研究,并对其反应机制进行了探讨.使用热重分析仪进行程序升温脱硝实验,采用Flynn-Wall-Ozawa(FWO),Kissinger-Akahira-Sunose(KAS)和Coats-Redfen(CR)非等温动力学方法,计算纯活性半焦和负载金属催化剂的活性半焦脱硝的表观活化能.使用X射线衍射仪(XRD)对催化剂脱硝前后的金属活性相进行了分析.结果表明:在活性半焦上负载铜铁复合金属催化剂后,降低了脱硝反应的表观活化能、反应所需温度和反应能耗;当活性半焦的碳转化率≤0.3时,脱硝过程主要由化学反应控制,当碳转化率>0.3时,脱硝过程转向扩散控制为主;通过XRD结果分析可知,金属催化剂的低价态活性相具有较高的催化活性,随着脱硝反应的进行,金属活性相被氧化成为活性较低的高价态;复合金属氧化物铁酸铜能在反应过程中分解成为活性更高的金属活性相,提高了脱硝性能.

The kinetics of reaction between NO and carbon during flue gas denitrification catalyzed by activated-char-supported composite metals were investigated under non-isothermal conditions.The apparent activation energy of the catalytic denitrification reaction by activatedchar was calculated using Flynn-Wall-Ozawa（FWO）,Kissinger-Akahira-Sunose（KAS）and Coats-Redfern（CR）methods using TGA data.The catalyst phases before and after denitrification reaction were analyzed using X-ray diffraction（XRD）.The results show that the apparent activation energy of the denitrification reaction and the reaction temperature decrease after loading of copper and iron composite metal catalysts onto chars.When the carbon conversion of the activated char is less than 0.3,the denitrification process is limited by chemical reaction rate.When the carbon conversion is higher than 0.3,the denitrification process turns to diffusion controll.During the denitrification process,the deactivation of the catalysts is caused by the oxidation of the active metal phases.