MnO_x-CeO_2 catalysts were synthesized to investigate the active sites for NO oxidation by varying the calcination temperature. XRD and TEM results showed that cubic CeO_2 and amorphous MnO_x existed in MnO_x-CeO_2 ca...MnO_x-CeO_2 catalysts were synthesized to investigate the active sites for NO oxidation by varying the calcination temperature. XRD and TEM results showed that cubic CeO_2 and amorphous MnO_x existed in MnO_x-CeO_2 catalysts. High temperature calcination caused the sintering of amorphous MnO_x and transforming to bulk crystalline Mn_2O_3, H_2-TPR and XPS results suggested the valence of Mn in MnO_x-CeO_2 was higher than pure MnO_x, and decreased with the increasing calcination temperature, The turnover frequency（TOF） was calculated based on the initial reducibility according to H_2-TPR quantitation and kinetic study. The TOF results indicated that the initial reducibility of amorphous MnO_x with high valence manganese ions was equivalent to the active sites for NO oxidation. It can be inferred that the amorphous MnO_x plays a key role in low-temperature NO oxidation.展开更多
MnOx-CeO2 mixed oxide catalysts for methane combustion were prepared with co-precipitation me-thod.With the same content of Mn,the modified catalysts were gained via adding KMnO4.These catalysts were characterized wit...MnOx-CeO2 mixed oxide catalysts for methane combustion were prepared with co-precipitation me-thod.With the same content of Mn,the modified catalysts were gained via adding KMnO4.These catalysts were characterized with XRD,LRS,XPS and TPR techniques,respectively.It was found that the solid solution structures of the catalysts were reserved,while the low-temperature activities were promoted remarkably duo to more Mn4+ species and easier reductions through properly changing the adding amounts of Mn(NO3)2 and KMnO4.With a molar ratio of 1:4,the MnOx-CeO2 catalyst exhibited the highest activity,over which methane conversion reached 90% at a temperature as low as 390 ℃,and a better stability.展开更多
为更有效脱除空气中甲醛污染物,分别将CeO_2、MnO_x-CeO_2和Ag/MnO_x-CeO_2催化剂与介质阻挡放电等离子体结合,在大气压及35℃下脱除空气中甲醛,选取脱除效果最好的Ag/MnO_xCeO_2为催化剂,研究放电电压和HCHO初始体积分数以及空速对HCH...为更有效脱除空气中甲醛污染物,分别将CeO_2、MnO_x-CeO_2和Ag/MnO_x-CeO_2催化剂与介质阻挡放电等离子体结合,在大气压及35℃下脱除空气中甲醛,选取脱除效果最好的Ag/MnO_xCeO_2为催化剂,研究放电电压和HCHO初始体积分数以及空速对HCHO脱除率的影响。结果表明,当空气中甲醛的体积分数为2.0×10-4、水的体积分数为1.0%、空速为16 364 h-1、放电电压为18 k V时,Ag/MnO_x-CeO_2与等离子体结合的甲醛脱除率达99.0%,高出单纯等离子体和单纯Ag/MnO_x-CeO_2催化氧化(不放电)脱除率之和23.9%。实验证明,在脱除空气中HCHO的过程中,Ag/MnO_x-CeO_2与等离子体结合产生了很强的协同作用,且等离子体中的活性物种是协同作用的关键。展开更多
基金Project supported by the National key research and development program(2016YFC0204901)the National Natural Science Foundation of China(21576207)the introduction of talent and technology cooperation plan of Tianjin(14RCGFGX00849)
文摘MnO_x-CeO_2 catalysts were synthesized to investigate the active sites for NO oxidation by varying the calcination temperature. XRD and TEM results showed that cubic CeO_2 and amorphous MnO_x existed in MnO_x-CeO_2 catalysts. High temperature calcination caused the sintering of amorphous MnO_x and transforming to bulk crystalline Mn_2O_3, H_2-TPR and XPS results suggested the valence of Mn in MnO_x-CeO_2 was higher than pure MnO_x, and decreased with the increasing calcination temperature, The turnover frequency（TOF） was calculated based on the initial reducibility according to H_2-TPR quantitation and kinetic study. The TOF results indicated that the initial reducibility of amorphous MnO_x with high valence manganese ions was equivalent to the active sites for NO oxidation. It can be inferred that the amorphous MnO_x plays a key role in low-temperature NO oxidation.
文摘MnOx-CeO2 mixed oxide catalysts for methane combustion were prepared with co-precipitation me-thod.With the same content of Mn,the modified catalysts were gained via adding KMnO4.These catalysts were characterized with XRD,LRS,XPS and TPR techniques,respectively.It was found that the solid solution structures of the catalysts were reserved,while the low-temperature activities were promoted remarkably duo to more Mn4+ species and easier reductions through properly changing the adding amounts of Mn(NO3)2 and KMnO4.With a molar ratio of 1:4,the MnOx-CeO2 catalyst exhibited the highest activity,over which methane conversion reached 90% at a temperature as low as 390 ℃,and a better stability.
基金supported by the National High Technology Research and Development Program of China(863 Program,2013AA065304)the Open Object for Green Catalysis and Key Laboratory of Sichuan Provincial University(2013LF3004)~~
文摘为更有效脱除空气中甲醛污染物,分别将CeO_2、MnO_x-CeO_2和Ag/MnO_x-CeO_2催化剂与介质阻挡放电等离子体结合,在大气压及35℃下脱除空气中甲醛,选取脱除效果最好的Ag/MnO_xCeO_2为催化剂,研究放电电压和HCHO初始体积分数以及空速对HCHO脱除率的影响。结果表明,当空气中甲醛的体积分数为2.0×10-4、水的体积分数为1.0%、空速为16 364 h-1、放电电压为18 k V时,Ag/MnO_x-CeO_2与等离子体结合的甲醛脱除率达99.0%,高出单纯等离子体和单纯Ag/MnO_x-CeO_2催化氧化(不放电)脱除率之和23.9%。实验证明,在脱除空气中HCHO的过程中,Ag/MnO_x-CeO_2与等离子体结合产生了很强的协同作用,且等离子体中的活性物种是协同作用的关键。
