涂层组分对堇青石脱硝催化剂性能的影响

Performance of structured cordierite catalysts with different coatings for NH_3-SCR

为了探究涂层组分对整体式低温选择性催化还原(SCR)脱硝催化剂性能的影响,本文使用锰氧化物(MnO_x)、氧化物涂层(TiO_2、SiO_2及Al_2O_3)、堇青石(CC)基体制备整体式涂层催化剂,考察催化剂牢固度以及脱硝活性。结果表明:在200℃时,对于MnO_x/Al_2O_3/CC催化剂,MnO_x负载率为6%(质量分数)时脱硝效率最高为95%;对于MnO_x/TiO_2/CC,负载率为6%～12%时脱硝效率相差不大,为75%左右;对于MnO_x/SiO_2/CC,负载率12%时脱硝效率80%。样品牢固度排列顺序如下:MnO_x/Al_2O_3/CC> MnO_x/SiO_2/CC> MnO_x/TiO_2/CC。通过BET、SEM、TG、Raman、H_2-TPR等测试与分析方法发现:影响催化剂性能的因素主要为活性组分MnO_x状态以及载体性能的差异。Al_2O_3涂层比表面积适中,作为载体活性好;SiO_2涂层虽然比表面积大、牢固度好,但作为载体活性差;TiO_2作为涂层比表面积较小,溶胶中溶剂挥发快使得涂层表面不均匀。

In order to explore the influence of coating components on the performance of monolithic SCR denitration catalysts, manganese oxide (MnOx), oxides (TiO2, SiO2, and Al2O3) coatings and Honeycomb Cordierite (CC) substrate were selected to prepare structured coating catalysts, and the firmness and the denitrification activity of the catalysts were investigated. The denitration results showed that, for MnOx / Al2O3/CC catalysts, the denitrification efficiency at 200℃ was up to 95% when MnOx loading amount was 6%. The efficiency was about 75% for MnOx/TiO2/CC as the loading was from 6% to 12% and it was 80% with 12% loading for the MnOx /SiO2/CC. The sample firmness was in the order: MnOx /Al2O3/CC>MnOx / SiO2 /CC>MnOx /TiO2 /CC. Through BET, SEM, TG, Raman, H2-TPR and other analysis methods, it was found that the differences between the state of active component MnOx and the performance of the carrier were the main influence factors on the performance of catalysts. The Al2O3 coating had moderate specific surface area, and showed good activity as carrier. SiO2 coating had high specific surface area and good firmness, but it acted poorly as carrier. TiO2 had relatively small specific surface area, and the solvent evaporation in the sol was fast, resulting in an uneven coating surface uneven.