制备条件对Ce/AC催化剂低温C_3H_6选择性催化还原NO的影响

Infulence of the Preparation Conditions in the Low-temperature SCR of NO with C_3H_6 over CeO_x/AC

采用浸渍法制备了一系列的Ce/AC催化剂,以C3H6为还原剂,通过程序升温反应考察其选择性催化还原NO的催化性能。着重探讨Ce含量以及焙烧温度对催化剂催化性能的影响,并用BET、XRD、XPS和SEM对催化剂进行了表征。结果表明,Ce的氧化物能在载体表面呈现出高度分散状态;随着Ce含量的增加,催化剂的比表面积逐渐降低,而NO转化率却得到提高;Ce(0.07)/AC-400的催化剂能在270℃到330℃的温度区间内保持70%以上的NO转化率;过高的焙烧温度则会对催化剂载体结构造成严重破坏,在400℃焙烧制得的催化剂具有较宽的反应温度适应范围。

Catalysts with the loading of cerium oxide on activated carbon prepared by impregnation were used for the selective catalytic reduction（SCR） of NO with C3H6 by temperature programmed reaction（TPR）.The different loading of cerium oxides and calcination temperature was investigated,respectively.The catalysts were characterized by N2-specific surface area measurement（BET）,X-ray diffraction（XRD）,X-ray photoelectron spectra（XPS）,scanning electron microscope（SEM）.The results indicated that cerium oxide supported on activated carbon is highly dispersed.The specific surface area of activated carbon decreases with the increase of the loading of cerium oxide,but the NO conversion increases with the increase of the loading of cerium oxide.Ce（0.07）/AC-400 can keep the NO conversion above 70% between 270 ℃ to 330 ℃.It is benefit to NO reduction by getting a better balance between the loading amount and dispersion of cerium oxides on AC.The calcination temperature is important to the conversion of precursor,but the higher temperature may destroy the structure of AC.It was indicated that the catalyst which is calcined at 400 ℃ can achieve wider temperature window.