基于碳烟颗粒催化氧化的三维有序大孔催化剂制备及性能

Preparation of three-dimensionally ordered macroporous spinel-type catalysts and their performance for catalytic oxidation of soot

三维有序大孔钴锰尖晶石催化剂(3DOMCoMn_2O_4)以及三维有序大孔镧、铈掺杂的钴锰尖晶石催化剂(3DOMR_xCo_(1-x)Mn_2O_4(R=Ce, La))由胶晶模板法成功合成。通过对所得的催化剂在NO_x协助下的碳烟催化氧化活性评价,优化了Ce/Co和La/Co的配比。此外,还对目标催化剂进行了XRD、N2吸脱附、Raman、H_2-TPR、SEM、XPS等表征。结果表明:3DOM结构增强了催化剂与碳烟颗粒之间的接触,对碳烟氧化等"固-固-气"非均相催化反应具有明显的提升作用。此外,铈和镧的掺杂增大了活性氧物种的浓度,从而增强了钴锰尖晶石催化剂的催化氧化能力。在松散接触工况下,3DOM Ce_(0.9)Co_(0.1)Mn_2O_4的Tig(起燃温度)和T_m(CO_2出口浓度最大时的温度)分别为285℃和377℃,3DOM La_(0.3)Co_(0.7)Mn_2O_4的T_(ig)和T_m分别为287℃和376℃。

Three-dimensionally ordered macroporous（3DOM） CoMn2O4 and 3DOM RxCo（1-x）Mn2O4（R=Ce, La） spinel were successfully synthesized with the colloidal crystal template method. The catalytic activities of these catalysts for NOx-assisted soot combustion were evaluated, and the optimum ratios of Ce/Co and La/Co were determined. XRD, SEM,N2 adsorption-desorption, XPS, Raman and H2-TPR were employed to characterize the prepared samples. It was found that 3DOM structure provides better contact between soot and catalysts compared to other structures, thus promoting the heterogeneous catalytic soot oxidations in solid-solid-gas interfaces. In addition, the doping of cerium or lanthanum improved the catalytic oxidation capability of spinels by increasing the concentrations of active oxygen species. And under loose contact, Tig= 285 ℃ and Tm= 377 ℃ were achieved for 3 DOM Ce（0.9）Co（0.1）Mn2O4 catalysts, while T（ig）= 287 ℃ and Tm= 376 ℃ were achieved for 3 DOM La（0.3）Co（0.7）Mn2O4, both of which are the enhanced catalytic activities.