Co对工业V-Mo/Ti脱硝催化剂的影响

Effect of cobalt on the catalytic performance of industrial V-Mo/Ti de-NO_(x) catalyst

为提升工业V-Mo/Ti脱硝催化剂的低温活性,拓展催化剂的活性温度窗口,对催化剂进行过渡金属元素Co改性。通过浸渍法制备了一系列不同CoO负载量的V-Mo/Ti脱硝催化剂。采用XRF、N_(2)-吸附脱附、H_(2)-TPR、拉曼光谱和NH_(3)-TPD对不同催化剂进行表征,分析了CoO对催化剂物理化学性质的影响。通过固定床微型反应评价装置,对不同催化剂的脱硝性能和抗SO_(2)、H_(2)O性能进行测试。研究表明:CoO负载对V-Mo/Ti催化剂的孔结构、晶型影响较小。V-Mo-Co/Ti催化剂上VO_(x)、MoO_(x)物种的结构也与V-Mo/Ti催化剂基本一致。向V-Mo/Ti催化剂上负载适量CoO(质量分数0.28%)后,催化剂的酸性性能提升,还原性能基本不变,催化剂的脱硝活性增加。负载CoO质量分数0.28%的CO-2催化剂在烟温280℃时,脱硝效率达80%以上。继续增加CoO负载量,尽管催化剂的酸性进一步增加,但催化剂的活性组分被CoO覆盖,减少了与反应气体的接触,催化剂脱硝活性下降。研究还发现,负载一定量CoO后,能有效增强催化剂的抗SO_(2)、H_(2)O性能。

In order to enhance the catalytic performance at low flue gas temperature and broad its catalytic activity temperature,cobalt modified industrial V-Mo/Ti De-NO_(x) catalysts were prepared by impregnation method.XRF,N_(2)-adsorption desorption,H_(2)-TPR,Raman spectrum and NH_(3)-TPD were used to characterize the catalysts.The denitrification performance and resistance to SO_(2) and H_(2)O of the different catalysts were tested by a fixed-bed micro-reactor.The results show that the loading of CoO has little impact on the pore structure and crystal structure of V-Mo/Ti catalyst.The structures of VO_(x) and MoO_(x) species of V-Mo-Co/Ti catalysts are similar to that of the V-Mo/Ti catalyst.Suitable amount of CoO(0.28%) can lead to the enhancement of acidity of the catalyst,without decreasing the reducibility of the catalyst.As a result,the catalyst activity is improved.When the flus gas temperature is 280 ℃,the NO_(x) conversion of CO-2 catalyst with 0.28% CoO is above 80%.However,excessive loading of CoO might results in the coverage of active sites by CoO,which reduces the chances of contact between VO_(x) species and the reaction gas.Consequently,the catalytic activity of the catalyst decreases.Besides,this study also finds that the SO_(2) and H_(2)O resistance of the catalyst can be effectively enhanced by Co modification.