我们采用柠檬酸配合法制备了Ce基复合氧化物催化剂,分别在热重分析仪(TG)和管式反应器中测试了其氧化碳烟及同时脱除NOx的催化活性;并利用XRD、BET、H2-TPR、XPS表征手段考察其结构.其中,Co0.1/C e La0.05复合氧化物同时催化去除碳烟和NOx的性能最佳,碳烟脱除率为50%的反应温度为301℃,N2产率为41.4%.实验结果表明,Co主要以氧化物形式均匀分散在Ce-La固溶体表面,Co3+与Co2+价态共存,离子间的变价有利于提高催化剂的氧化还原性能,有效降低了碳烟的起燃温度.La的引入增大了催化剂的比表面积,抑制了Ce O2晶粒长大,进而提高了N2产率.部分La和Co形成了微量的La Co O3,形成了更多氧空位,有利于提高催化氧化碳烟的活性.
A 0.5 wt.% Pt/TiO2 catalyst was prepared and used for the low-temperature selective catalytic reduction （SCR） of NO with C3H6 in the presence of excess oxygen. The effects of Pt loading and 02 concentration on Pt/TiO2 catalytic performance for low-temperature SCR were investigated. It was found that optimal Pt loading was 0.5 wt.% and excess 02 favored low-temperature SCR of NOx. The mechanism of low-temperature SCR of NO with C3H6 was investigated with respect to the behavior of adsorbed species over Pt/TiO2 at 150~C using in situ DRIFTS. The results indicated that surface nitrosyl species （Pt~＋-NO and Ti3＋-NO） and pt2＋-CO are main reaction intermediates during the interactions of NO, C3H6 and 02. A simplified NO decomposition mechanism for the low-temperature SCR of NO with C3H6 was proposed.
Zhixiang Zhang,Mingxia Chen,Zhi Jiang,Wenfeng Shangguan Research Center for Combustion and Environmental Technology,Shanghai Jiao Tong University,Shanghai 200240,China.
Pt supported on mesoporous silica SBA-15 was investigated as a catalyst for low temperature selective catalytic reduction（SCR） of NO by C 3 H 6 in the presence of excess oxygen.The prepared catalysts were characterized by means of XRD,BET surface area,TEM,NO-TPD,NO/C 3 H 6-TPO,NH 3-TPD,XPS and 27 Al MAS NMR.The effects of Pt loading amount,O 2 /C 3 H 6 concentration,and incorporation of Al into SBA-15 have been studied.It was found that the removal efficiency increased significantly after Pt loading,but an optimal loading amount was observed.In particular,under an atmosphere of 150 ppm NO,150 ppm C 3 H 6,and 18 vol.% O 2,0.5% Pt/SBA-15 showed remarkably high catalytic performance giving 80.1% NOx reduction and 87.04% C 3 H 6 conversion simultaneously at 140°C.The enhanced SCR activity of Pt/SBA-15 is associated with its outstanding oxidation activities of NO to NO 2 and C 3 H 6 to CO 2 in low temperature range.The research results also suggested that higher concentration of O 2 and higher concentration of C 3 H 6 favored NO removal.The incorporation of Al into SBA-15 improved catalytic performance,which could be ascribed to the enhancement of catalyst surface acidity caused by tetrahedrally coordinated AlO 4.Moreover,the catalysts could be easily reused and possessed good stability.
