Mo对平板式V-Mo/Ti脱硝催化剂活性及SO_(2)氧化性能的影响

Effect of molybdenum on activity and SO_(2) oxidation of plate-type V-Mo/Ti De-NO_(x) catalyst

在工业脱硝催化剂生产线上制备不同MoO_(3)含量的V-Mo/Ti脱硝催化剂,通过XRF、XRD、N_(2)吸附-脱附、Raman、H_(2)-TPR、NH_(3)-TPD、SO_(2)-TPD、TG和耐磨强度对催化剂物化性质进行分析。在固定床反应器中考察催化剂的脱硝活性,并研究MoO_(3)含量对催化剂SO_(2)氧化性能的影响。结果表明,提高催化剂中MoO_(3)含量,对催化剂的晶型、孔结构影响较小,对催化剂单板的机械性能有一定的负面影响。相比V-Mo(3)/Ti催化剂,V-Mo(5)/Ti催化剂的酸性变化不大,还原性能提升,具有更好的脱硝活性。当MoO_(3)含量达到质量分数6.98%时,催化剂的总酸量明显降低,导致脱硝活性下降。提高催化剂中MoO_(3)含量造成脱硝反应过程中副产物N_(2) O生成量的增加,但较高的MoO_(3)含量可以有效减少催化剂对SO_(2)的吸附,减少脱硝反应过程中硫酸氢铵的生成。综合来看,V-Mo(5)/Ti催化剂显示了最佳的反应性能。

A serious of V-Mo/Ti De-NO_(x) catalysts with different amount of MoO_(3) were prepared on the industrial production line.XRF,XRD,N_(2)-adsorption,abrasion strength,Raman,H_(2)-TPR,NH_(3)-TPD,SO_(2)-TPD,and TG were used to characterize the physicochemical properties of the different catalysts.The catalytic activities of catalysts were tested in a fixed-bed micro-reactor.Besides,the effect of MoO_(3) on the SO_(2)oxidation activity of different catalysts was investigated by stability tests.The results showed that the amount of MoO_(3) had little impact on the crystal structure and pore structure of V-Mo/Ti catalyst,but could lead to the decrease of mechanical property of V-Mo/Ti catalyst.V-Mo(5)/Ti catalyst exhibited similar acidity and better reducibility than that of V-Mo(3)/Ti catalyst.As a result,V-Mo(5)/Ti catalyst possessed higher catalytic activity.When mass fraction of MoO_(3) reached to 6.98%,catalyst acidity decreased obviously,leading to the decline of catalytic performance.The increase of MoO_(3) could increase the N_(2) O generation during the SCR reaction process,and decrease the SO_(2)adsorption ability of the catalyst,which was benefit to decrease the generation of ammonium bisulfate.Overall,V-Mo(5)/Ti catalyst revealed the best catalytic performance among the investigated catalysts.