A series of Sm modified Mn/TiO₂ catalysts were proposed for selective catalytic reduction of NO with NH₃ and their catalytic activity was evaluated at low temperature. The effect of Sm on the catalytic activity of Mn-Sm/TiO₂ was comprehensively studied using XRD, low-temperature N₂ adsorption, XPS, NH₃-TPD and H₂-TPR. The results showed that the 20Mn-10Sm/TiO₂ catalyst, prepared by ultrasonic impregnation, exhibited NO_x conversion of higher than 80% at the temperature range of 110-250 °C with a gas hourly space velocity of 80000 h^-1. The weak Lewis acid site and redox ability may be crucial properties for catalytic performance as a result of the increase of Mn⁴⁺ and surface chemisorption oxygen as well as weak acid sites due to the enhanced interaction among Mn, Sm and Ti after addition of Sm. The in situ DRIFTS experiments were conducted to investigate the adsorption of NH₃ and NO with their surface reaction. The results revealed that the SCR reactions on the surface of Mn/TiO₂ catalyst follow both Langmuir-Hinshelwood and Eley-Rideal mechanism and bridging nitrate is the important intermediate. While, that on surface of 20Mn-10Sm/TiO₂ catalyst comply with only Eley-Rideal mechanism, as the introduction of Sm changes the reaction path by inhibiting the adsorption of NO in the presence of NH₃. Besides, SCR reaction rate over 20Mn-10Sm/TiO₂ catalyst is fast as a result of large amount of -NH₂ species formed on the surface of 20Mn-10Sm/TiO₂ catalyst for the breaking of N-H bonds become easier over the Sm modified catalyst, which is beneficial for SCR activity of 20Mn-10Sm/TiO₂ catalyst at low temperature. The TG-DSC-MS results revealed that the addition of Sm reduce the sulfation of Mn/TiO₂ catalyst.

提出了一系列Sm改性的Mn / TiO ₂催化剂用于NH ₃选择性催化还原NO，并在低温下对其催化活性进行了评价。利用XRD，低温N ₂吸附，XPS，NH ₃ -TPD和H ₂ -TPR全面研究了Sm对Mn-Sm / TiO ₂催化活性的影响。该结果表明，20MN-10SM /二氧化钛₂催化剂，通过超声波浸渍制备，表现出NO _X的高于80％的转化率在温度范围110-250的℃下以80000 h的气时空速^-1。由于Mn ⁴⁺和表面化学吸附氧的增加以及弱酸位，弱的Lewis酸位和氧化还原能力可能对催化性能至关重要，这是由于添加Sm后Mn，Sm和Ti之间的相互作用增强了弱酸位。进行了原位DRIFTS实验，以研究NH ₃和NO的表面反应吸附。结果表明，Mn / TiO ₂催化剂表面的SCR反应既遵循Langmuir-Hinshelwood方法，又遵循Eley-Rideal机理，而桥接硝酸盐是重要的中间体。而在20Mn-10Sm / TiO ₂表面催化剂仅符合Eley-Rideal机理，因为Sm的引入通过在NH ₃的存在下抑制NO的吸附来改变反应路径。此外，过20MN-10SM /氧化钛SCR反应速率₂催化剂是快大量的-NH的结果₂形成20MN-10SM / TiO 2的表面上的物质₂为NH键的断裂催化剂变得更容易在钐改性催化剂，有利于20Mn-10Sm / TiO ₂催化剂在低温下的SCR活性。TG-DSC-MS结果表明，Sm的加入减少了Mn / TiO ₂催化剂的硫酸化。