ACF负载金属氧化物及尿素低温去除NO

以活性炭纤维(ACF)负载NiO以及NiO-CeO2制备了一系列催化剂,并在催化剂上负载尿素作为还原剂,研究其在30～120℃范围内的催化还原NO的活性.通过SEM、BET、XRD等表征实验选择性地对催化剂进行了理化特征研究.结果表明,3种不同质量分数的NiO催化剂中,5%NiO/ACF效率较低,10%NiO的催化剂活性以及活性稳定性较好,在90℃即可达到50%左右的NO净化效率,15%NiO/ACF的催化活性稳定性较差.在3种不同质量分数的NiO-CeO2/ACF催化剂中,5%NiO-5%CeO2/ACF的活性以及活性稳定性最好,在110℃可达到55%以上的NO净化效率.10%CeO2-5%NiO/ACF活性高于5%CeO2-10%NiO/ACF;活性金属的最佳负载量为10%,过多的负载量会引起催化剂比表面积的减少从而导致催化剂活性下降;金属氧化物是催化反应的活性中心.对10%CeO2/ACF、10%NiO/ACF和5%CeO2-5%NiO/ACF的研究显示,5%CeO2-5%NiO/ACF的催化活性最好,CeO2和NiO的协同作用使催化剂的活性优于2种单独负载的催化剂.本研究还对催化剂的低温催化机制进行了分析和讨论.

Reaction of NO with Metal Oxides and Urea Supported on Activated Carbons at Low Temperature

The catalysts were prepared by activated carbon fiber (ACF) loaded different contents of NiO and NiO-CeO2, Urea was loaded on the prepared catalysts as reductant. The experiments of selective catalytic reductions (SCR) of NO were carried out from 30 to 120 degrees C. The experiments of SEM, BET and XRD of the samples were also carried out selectively to study the catalysts properties, respectively. The experimental results showed that the loaded mass fraction of NiO could greatly affect the catalytic activity of the catalysts. 10% NiO catalyst activity and activity stability were both higher than that of the others, and it could yield about 50% removal efficiency of NO at 90 degrees C. With the loaded mass increasing, the catalytic activity was obviously decreased. And furthermore, the catalyst of 5% NiO-5% CeO2/ACF had the best catalytic activities on SCR NO and stability among the prepared NiO-CeO2/ACF catalysts, and its NO removal efficiency was over 55% at 110 degrees C. When the loaded mass increased, the similar phenomenon was observed, which was due to the decreasing of specific surface area of the catalysts. The metal oxides, loaded on ACF, were the catalytic centers in this study. Moreover, 5% CeO2-5% NiO/ACF had the highest catalytic activity than 10% CeO2/ACF and 10% NiO/ ACF. Therefore, there should be synergistic effect between CeO2 and NiO. Finally, the catalytic mechanism of SCR on NO at low temperature was discussed.