"Fast SCR" reaction over Sm-modified MnOx-TiO2 for promoting reduction of NOx with NH3
"Fast SCR" reaction over Sm-modified MnOx-TiO2 for promoting reduction of NOx with NH3
复制标题
DOI：
10.1016/j.apcata.2018.07.017
复制
发表时间：
2018-08-25
影响因子：
5.5
通讯作者：
Niu, Chunming
中科院分区：
文献类型：
--
作者：
Gao, Chen;Shi, Jian-Wen;Niu, Chunming
制备了一系列Sm改性的MnOx-TiO 2（SMT）催化剂，并对其进行了表征。结果表明，Sm的引入能有效抑制MnOx和TiO 2的晶化过程，提高比表面积，增加表面化学吸附氧物种浓度和表面强酸性中心数量，降低Mn 4+的表面浓度。通过NH3选择性催化还原（SCR）NOx反应评价了SMT催化剂的催化性能。结果表明，SMT-0.3催化剂（Sm/Mn摩尔比为0.3）在180 ~ 390 ℃的宽操作温度范围内具有100% N-x转化率，在36,000 h-1的GHSV下，在120 ~ 390 ℃的宽操作温度范围内具有100%N-2选择性，明显优于未添加Sm的MnOx TiO 2。原位DRIFT谱表明，在低温（低于200 ℃）下，MnOx-TiO 2催化剂上吸附的NH3物种与气相NO的反应遵循Eley-Rideal（E-R）机理，而SMT-0. 3催化剂上NH3-SCR反应遵循E-R和Langmuir-Hinshelwood（L-H）机理。然而，在高温（高于200摄氏度）下，MnOx-TiO 2上的SCR反应是通过“标准SCR”过程，而SMT-0.3上的SCR反应是通过“快速SCR”反应。
A series of Sm-modified MnOx-TiO2 (SMT) catalysts are prepared and characterized. The results show that the introduction of Sm can effectively restrain the crystallization process of MnOx and TiO2, enhance the specific surface area, increase the surface concentration of chemisorbed oxygen species and the amount of strong surface acid sites, and reduce the surface concentration of Mn4+. The catalytic performances of the SMT catalysts are evaluated by the selective catalytic reduction (SCR) of NOx with NH3. It is found that SMT-0.3 catalyst (a 0.3 mol rate of Sm/Mn) exhibits a 100% N-x conversion in a wide operating temperature window from 180 to 390 degrees C, and a 100% N-2 selectivity from 120 to 390 degrees C under a GHSV of 36,000 h(-1), which is obviously better than MnOx TiO2 without Sm addition. In-situ DRIFT spectra reveal that, at low temperature (below 200 degrees C), absorbed NH3 species can react with gas-phase NO over MnOx-TiO2 catalyst following Eley-Rideal (E-R) mechanism, while the NH3-SCR of NO over SMT-0.3 follows both E-R and Langmuir-Hinshelwood (L-H) mechanisms. However, at high temperature (above 200 degrees C), the SCR reaction over MnOx-TiO2 is via "standard SCR" process, but the SCR reaction over SMT-0.3 is through "fast SCR" reaction.