溶胶-凝胶原位合成钒钨钛催化剂及NH_3-SCR性能

In situ preparation of mesoporous V_2O_5-WO_3/TiO_2 catalyst by sol-gel method and its performance for NH_3-SCR reaction

利用溶胶-凝胶技术原位合成V_2O_5-WO_3/TiO_2介孔结构脱硝催化剂。通过XRD、BET、SEM和XPS等手段对催化剂结构与组成进行表征,发现结构导向剂CTAB促进催化剂的比表面积和孔容的增加,促进催化剂活性组分的分散与裸露的V活性组分数量增加;且随CTAB含量的增加,V4^+/V5^+的比值降低,即降低了催化剂表面钒物种的氧化能力,有利于提高催化剂的低温脱硝活性与高温选择性。催化活性评价结果表明,CTAB对催化剂的脱硝活性有显著促进作用,当CTAB的添加量为0.01(质量)时,催化剂的脱硝活性大于90%的温度窗口最宽为212~393℃,200℃时脱硝效率达85.6%。

A series of V2Os-WO3/TiO2 catalysts were prepared by the in situ sol-gel method with different amounts of cetyl trimethyl ammonium bromide（CTAB） as structure-directing agent. The XRD, BET, SEM and XPS were performed to characterize the catalysts. The results demonstrated that the introduction of CTAB facilitated the formation of mesoporous structure with increased specific surface area and pore volume, resulting in the high dispersion of active components and thus more bared V2O5 on the surface of support. Moreover, the ratios of V^4＋/V^5＋ decrease with the increase of CTAB content, which reduce the oxidation capacity of the surface vanadium species and enhance the low-temperature activity together with the high-temperature selectivity. The results of activity evaluation indicate that the introduction of CTAB obviously promote the catalytic performance, and CTAB-0.01 catalyst has the highest low-temperature denitration activity （85.6% NO conversion at 200℃） and the widest temperature window （above 90% NO conversion from 212 ℃ to 393 ℃）.