暴露CeO2不同晶面的VOx-MnOx/CeO2催化剂低温NH3-SCR脱硝的原位红外研究

为实现低温(200-250℃) NH_3-SCR烟气脱硝,开发出了一种高分散暴露CeO_2不同晶面的VO_x-MnO_x/CeO_2低温脱硝催化剂。脱硝性能评价实验结果表明,暴露{110}晶面的VO_x-MnO_x/CeO_2-R催化剂在很宽的温度范围内(220-330℃)都保持了95%的脱硝效率。原位漫反射红外分析结果可知,暴露{110}晶面的VO_x-MnO_x/CeO_2-R催化剂表面更易发生NH_3和NO吸附,进而提高NO的转化效率。气态NH_3在VO_x-MnO_x/CeO_2-R催化剂上吸附生成NH_3(L)和NH_4~+(B),该中间体与NO吸附的中间体桥联硝酸盐和双齿硝酸盐反应生成N_2和H_2O,并遵循Langmuir-Hinshelwood机理。

In-situ DRIFTs study on different exposed facets of VOx-MnOx/CeO2 catalysts for low-temperature NH3-SCR

In order to achieve the low-temperature (200-250℃) NH₃-SCR, highly dispersed VO_x-MnO_x/CeO₂ catalysts with different exposed facets were produced. The NH₃-SCR performance results indicate that the NO conversion over VO_x-MnO_x/CeO₂-R with preferentially exposed {110} facets can achieve NO conversion >95% over a wide temperature span of 220-330℃. From the in-situ DRIFTs, gaseous NH₃ and NO are favorable to be absorbed on the surface of the VO_x-MnO_x/CeO₂-R catalyst with preferentially exposed {110} facets, which improves the efficiency of NO conversion. The mechanism study via in situ DRIFTs demonstrates that the well dispersed vanadium species on CeO₂ {110} absorb NH₃ to generate NH₃(L) and NH₄⁺(B) species, which in turn become highly reactive toward bridging nitrate and bidentate nitrate species to form N₂ and H₂O according to the Langmuir-Hinshelwood mechanism.