Ce(x)Mn/TiO2-y催化剂低温NH3-SCR脱硝性能
Ce(x)Mn/TiO2-y catalysts for NH3-SCR of NO at low temperature
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摘要: 以锐钛矿TiO2（P25）为载体采用原位生长法负载锰氧化物制备了Mn/TiO2催化剂，再以等体积浸渍-煅烧法对该催化剂掺杂氧化铈制备Ce （x） Mn/TiO2-y催化剂用以烟气低温SCR脱硝.在固定锰负载量（质量分数为8%）的基础上，考察了铈掺杂量（铈锰摩尔比）、煅烧温度对催化剂SCR脱硝性能的影响.采用TEM、BET、XRD和XPS等手段表征了催化剂的理化结构特性.结果发现，当Ce/Mn的摩尔比例为1.0，煅烧温度为300℃时，Ce （1.0） Mn/TiO2-300催化剂在150—300℃温度范围内、10500—27000 h-1的空速范围内，能够保持90%以上的NO转化率.理化性能分析结果表明，煅烧温度对催化剂的微观形貌影响显著，随着煅烧温度的升高，Ce （1.0） Mn/TiO2-500催化剂活性物种颗粒集聚明显、比表面积降低，且锰氧化物价态分布偏向于低价态；铈的掺杂有助于Ce （1.0） Mn/TiO2-300催化剂活性物种在载体表面的均匀分散，可以促进产生更多的Mn4+物种和更多的吸附氧，有利于催化剂低温SCR脱硝性能的提升.Abstract: The Mn/TiO2 catalyst was prepared by in-situ growth method loading manganese oxide with anatase TiO2 (P25) as carrier. Then the Mn/TiO2 catalyst was doped with cerium oxide by the pore volume impregnation-calcination method to prepare Ce(x)Mn/TiO2-y catalyst to control NOx emission. Based on the manganese loading (mass percentage 8%), the effects of cerium loading (the molar ratio of Ce/Mn) and calcination temperature on the catalytic performance of the catalyst were investigated. The physicochemical properties of the catalysts were characterized by TEM, BET, XRD and XPS. The results showed that the optimal ratio (Ce/Mn=1.0) and the optimum calcination temperature (300 ℃), the Ce(1.0)Mn/TiO2-300 catalyst can maintain more than 90% NO conversion in a wide temperature window (150—300 ℃) under gas hourly space velocity range of 10500—27000 h-1. The results of physical and chemical properties showed that the calcination temperature possessed a significant effect on the micro-morphology of the catalyst. With the higher calcination temperature, the active species particles of Ce(1.0)Mn/TiO2-500 catalyst were more aggregated, the reduction of its surface area was greater, and the number of its Mn4+ species was less. The doped cerium contributed to the uniform dispersion of the active species of the Ce(1.0)Mn/TiO2-300 catalyst on the surface of the carrier, which can promote the production of more Mn4+ species and more adsorbed oxygen, which were beneficial to the improvement of the low-temperature SCR catalytic performance.
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Key words:
- manganese-based SCR catalyst /
- in-situ deposition method /
- NH3-SCR /
- CeOx
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