钾盐负载Ce_(0.5)Mn_(0.5)O_(2)催化氧化碳烟的活性及稳定性分析

Analysis of activity and stability of K-supported Ce_(0.5)Mn_(0.5)O_(2)catalyst on soot oxidation

为了降低柴油机碳烟的氧化温度,采用柠檬酸溶胶凝胶法制备了KNO_(3)和KOH负载的nK-Ce_(0.5)Mn_(0.5)O_(2)(n=0.05、0.20、0.50)催化剂.利用热重(thermogravimetric,TG)、程序升温氧化(temperature programmed oxidation,TPO)等试验来研究其对柴油机碳烟催化氧化活性和稳定性的影响.利用X射线衍射仪(X-ray diffractometer,XRD)对TPO试验前后的催化剂进行了表征.结果表明:钾盐负载催化剂使得柴油机碳烟的起燃温度都有不同程度的降低,其中0.50KOH-Ce_(0.5)Mn_(0.5)O_(2)在NO环境下对碳烟的氧化活性最好;在10次TPO循环试验之后,0.20KNO_(3)-Ce_(0.5)Mn_(0.5)O_(2)催化剂保持着高催化活性和良好的稳定性;KNO_(3)的衍射峰基本保持不变,而KOH的衍射峰消失,KNO_(3)负载的催化剂稳定性能优异;通过制备性能合适的催化剂,可以有效降低柴油机颗粒捕集器(diesel particulate filter,DPF)对温度的需求,进一步降低排放.

To reduce the oxidation temperature of diesel soot,the KNO_(3)and KOH supported n K-Ce_(0.5)Mn_(0.5)O_(2)(n=0.05,0.20 and 0.50)catalysts were prepared by citric acid sol-gel method.Thermogravimetric(TG)and temperature programmed oxidation(TPO)were used to investigate the effects of catalysts on the catalytic oxidation activity and stability of diesel soot.X-ray diffractometer(XRD)was used to characterize the catalyst before and after the TPO experiment.The results show that the K-supported catalyst can reduce the ignition temperature of diesel soot.The 0.50KOH-Ce_(0.5)Mn_(0.5)O_(2)has the best oxidation activity for soot under NO atmosphere among all catalysts.After TPO experiments for 10 times,the 0.20KNO_(3)-Ce_(0.5)Mn_(0.5)O_(2)catalyst still maintains high catalytic activity with good stability.The diffraction peak of KNO_(3)does not change,while the diffraction peak of KOH is disappeared,which proves the KNO_(3)-supported catalyst has excellent stability.By preparing a catalyst with suitable performance,the temperature required for diesel particulate filter(DPF)regeneration can be effectively reduced with decreased emissions.