整体式Pt基催化剂上CH4选择性催化还原NO的研究

以La-Al2O3(La稳定的γ-Al2O3)、Ce0.63Zr0.37O2(OSM1)及Ce0.5Zr0.3Mn0.2O2(OSM2)为载体, Pt为活性组分, 制备了Pt质量分数为1%的整体式催化剂. 研究了不同载体负载的催化剂对CH4选择催化还原NO反应的性能, 并利用XRD、H2-TPR和XPS对催化剂进行了表征. 结果表明, Pt/OSM1和Pt/OSM2催化剂在氧含量为0.8%时对CH4催化还原NO具有优异的净化性能, Pt/OSM1催化剂上500 ℃时, CH4和NO均达到100%转化; Pt/OSM2催化剂上500 ℃时, CH4和NO的转化率分别达到73%和100%; 而 Pt/ La-Al2O3催化剂只在O2含量较低时(0.4%以下)具有较好活性, 500 ℃以上才可使CH4和NO完全转化. H2-TPR结果表明, Pt与OSM1和OSM2存在的相互作用导致低温还原物相生成. Pt与OSM的相互作用及OSM的储氧性能使催化剂在过量氧存在下对CH4催化还原NO具有优异性能.

Selective Catalytic Reduction of NO by CH4 on Platinum-based Monolithic Catalysts

La-Al2O3, Ce0.63Zr0.37O2 (OSM1) and Ce0.5Zr0.3Mn0.2O2(OSM2) were prepared by co-precipitation method. The catalysts of Pt/La-Al2O3 and Pt/OSM were prepared by impregnation with platinum loading of 1%(w). The monolithic catalysts were investigated for the selective catalytic reduction of NO by methane and were characterized by XRD, H2-TPR and XPS. The results reveal that Pt/OSM1 and Pt/OSM2 have excellent purification properties for the catalytic reduction of NO by methane in the condition of 0.8% O2. Both CH4 and NO reach 100% conversion at 500 ℃ over Pt/OSM1, while over Pt/OSM2 the conversions of CH4 and NO are 73% and 100%, respectively. Over Pt/La-Al2O3, CH4 and NO reach almost 100% conversions only when O2 content is below 0.4% at 500 ℃. As O2 is excessive, the activity of Pt/La-Al2O3 decreases sharply. The results of H2-TPR reveal that the interaction of Pt and OSM leads to the formation of reduction phase at low temperature. The high activity of NO reduction by methane in the excessive presence of O2 is due to the interaction of Pt and OSM and the oxygen storage capacity of OSM.