摘要
采用溶胶凝胶法和浸渍法制备10%Mn/Al_2O_3-TiO_2催化剂,借助TPO、XRD、O_2-TPD、Raman、XPS等手段,考察焙烧温度(450~650℃)对催化剂结构以及氧化NO性能的影响。TPO结果表明催化剂活性随焙烧温度的升高先增后减,其中焙烧温度为550℃时催化剂活性最好。XPS结果显示随着焙烧温度的升高(450~550℃),催化剂表面Mn^(3+)的含量逐渐升高,与催化剂活性的强弱成对应关系,并且催化剂晶格氧含量下降,而表面化学吸附氧从40.9%增加到64.8%。Raman分析显示550℃焙烧时,催化剂表面存在丰富的Mn_2O_3活性物种,并且O_2-TPD分析也表明随着焙烧温度的升高,晶格氧向表面化学吸附氧流动,提高了化学吸附态氧物种的含量。这些结果表明Mn_2O_3可能是NO氧化起主要作用的活性Mn物种,释放更多的表面化学吸附氧物种,将有助于促进NO的催化氧化。
The catalysts were prepared to study the effect of calcination temperature on the structure and performance of 10% Mn/Al2O3-TiO2 catalyst in the catalytic oxidation of NO using the sol-gel method and impregnation method. The catalysts were characterized by using TPO, XRD, O2-TPD, Raman and XPS. The TPO results show that the performance of catalyst shows a trend of incline and then decline as calcination temperature increases and the performance of 10% Mn/Al2O3-TiO2（550 ℃） is the best. The results of XPS indicate that the content of Mn^3＋ gradually increases with the exaltation of calcination temperature（450 -550 ℃） and the performance of corresponding catalyst gradually enhances. At the same time, the content of lattice oxygen decreases, while chemisorption oxygen on the surface of catalyst increases from 40.9% to 64.8%. Raman analysis show that there are in rich of Mn2O3 on the surface of catalyst when the calcination temperature is 550 ℃. And O2-TPD analysis also show that the lattice oxygen flows to chemisorption oxygen to improve the content of chemisorption oxygen species with the exaltation of calcination temperature. These results suggest that Mn2O3 may be the main Mn species and releasing more surface chemisorption oxygen will help to promote the catalytic oxidation of NO.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2016年第4期602-608,共7页
Chinese Journal of Inorganic Chemistry
基金
国家自然科学基金(No.21576058)资助项目
