钒和钨负载量对V2O5-WO3/TiO2表面形态及催化性能的影响

采用浸渍法制备了一系列不同钒和钨负载量的V₂O₅-WO₃/TiO₂催化剂样品,对样品NH₃选择性催化还原NO性能进行了评价,并用BET、XRD、XPS等手段对催化剂样品的表面形态进行了表征.研究发现,钒的负载量对催化剂的比表面积和催化活性有显著影响,当钒负载量从1％升高到8％时,催化剂比表面积下降了16 m²/g,最高活性温度降低了约100℃.钨起到稳定剂和助剂的双重作用,当钒负载量为1％时,钨负载量从0升高到6％,催化剂比表面积仅下降了3 m²/g,而活性温度窗口向高温和低温各拓宽了约50℃.研究表明钒和钨负载量都能影响催化剂表面的VO_x物种,但对催化剂的表面晶型没有明显影响.

Effect of Vanadium and Tungsten Loadings on the Surface Characteristics and Catalytic Activities of V2O5-WO3/TiO2 Catalysts

V2O5-WO3/TiO2 catalysts with different vanadium and tungsten loadings were prepared by impregnation method. The activities of selective catalytic reduction (SCR) of NO with NH3 were measured and surface characteristics of those samples were characterized. It is found that both the surface areas and catalytic activities are influenced by vanadium loadings. When the vanadium loadings increased from 1% to 8%, the catalyst surface areas decreased by 16 m2/g, while the highest activity temperature was reduced by about 100 degrees C. Tungsten acts as stabilizer and promoter of the SCR catalyst. When the vanadium loading was 1%, an increase of tungsten loadings from 0 to 6% resulted in the decrease of the catalyst surface areas by only 3 m2/g, while the activity window was expanded to both high and low temperature range each by about 50 degrees C. Vanadium and tungsten loadings have an effect on the surface VOx, but do not change the surface crystal structure of the catalysts.