铜基铈钴镧复合氧化物催化剂制备及其选择催化还原NO

采用改进的共沉淀法制备铈钴镧复合氧化物(Ce-Co-La-O)载体,等体积浸渍负载活性组分Cu,制得铜基铈钴镧复合氧化物(Cu/Ce-Co-La-O)催化剂。考察该催化剂在富氧条件下对C₃H₆选择性还原NO反应(C₃H₆-SCR)的催化性能,并且利用BET、XRD、H₂-TPR、Py-IR、TG和SEM等方法,研究催化剂结构与性能的关系。实验结果表明,Co能显著增加B(Brφnsted)酸的酸量并有效提高还原能力;La能进一步增加B酸的酸量并明显提高热稳定性;Ce-Co-La-O能够形成固溶体结构,发生良好的相互协同作用。因此,Cu/Ce-Co-La-O催化剂具有良好的低温催化活性和热稳定性,最佳催化活性温度为250 ℃,NO转化率高达81.6%,600 ℃时NO转化率仍可达52.5%。

Preparation of Ce-Co-La-O composite oxide supported Cu-based catalyst and its performance for selective catalytic reduction of NO

Ce-Co-La-O composite oxide support was prepared by a modified coprecipitation method and the Cu-based catalyst (Cu/Ce-Co-La-O) was then obtained through incipient impregnation; the performance of the Cu/Ce-Co-La-O catalyst in the selective reduction of NO with propylene in excess oxygen was investigated and the relationship between the catalyst structure and performance was explored by means of surface area measurement, X-ray diffraction (XRD), temperature-programmed reduction (H₂-TPR), pyridine absorption infrared spectrum (Py-IR), thermal gravimetric analysis (TG) and scanning electron microscope (SEM). The results indicated that Co promoter can increase the amount of Brnsted acidic sites of the Cu-based catalyst and enhance its reducibility. La promoter can further increase the amount of Brnsted acidic sites and the catalyst thermal stability. Meanwhile, Ce-Co-La-O may form a sosoloid and have a synergistic effect on the catalytic performance of Cu/Ce-Co-La-O. Consequently, the Cu/Ce-Co-La-O catalyst exhibits excellent low-temperature activity and thermal stability in the selective reduction of NO; the conversion of NO reaches a maximum of 81.6% at 250 ℃ and is still 52.5% even at 600 ℃.