Ni,Co掺杂对Mn-Ce/TiO_2催化剂脱硝活性的影响

以Ti O_2为载体,采用浸渍法制备Ni或Co掺杂的Mn-Ce/Ti O_2催化剂,用于烟气的选择性催化还原法低温脱硝。考察Ni或Co的掺加对Mn-Ce/Ti O_2催化剂活性的影响,并对各催化剂进行了BET,XRD,H_2-TPR,XPS表征。实验结果表明:在NO,NH_3,O_2的体积分数分别为6×10~(-4),6×10~(-4),6×10~(-2),空速为16 000 h~(-1)的条件下,Mn-Ce/Ti O_2、Mn-Ce-Ni_(0.4)/Ti O_2和Mn-Ce-Co_(0.2)/Ti O_2催化剂的NO去除率在120℃时分别为38%,68%,74%,在150℃时分别为64%,92%,近100%,这表明掺加Ni或Co后Mn-Ce/Ti O_2催化剂的脱硝活性明显提高;在进气中加入体积分数为1×10~(-4)的SO_2后,Mn-Ce/Ti O_2催化剂的NO去除率在300 min内从98.2%下降至57.2%,而Mn-CeCo_(0.2)/Ti O_2和Mn-Ce-Ni_(0.4)/Ti O_2催化剂的NO去除率分别为73.9%和69.8%,这表明Ni或Co的掺加有助于提高催化剂的抗硫性能。表征结果表明:Ni或Co的掺加基本不影响Mn和Ce在载体Ti O_2上的分散;Ce元素以Ce~(3+)和Ce~(4+)价态存在,且主要为Ce~(4+);催化剂的比表面积变化不大;Mn O_x与Ce O_x的结晶度降低,催化剂的氧化还原能力增强。

Effects of doped Ni,Co on denitrification activity of Mn-Ce/TiO2 catalyst

Ni or Co doped Mn-Ce/TiO₂ catalysts for low temperature denitration of flue gas by selective catalytic reduction （SCR） were prepared by impregnation method using TiO₂ as carrier. The effects of doped Ni or Co on catalytic activity of Mn-Ce/TiO₂ catalysts were investigated,and the catalysts were characterized by BET,XRD,H₂-TPR and XPS. The experimental results show thatWhen the volume fraction of NO,NH₃,O₂ is 6×10^-4,6×10^-4,6×10^-2 and the space velocity is 16 0000 h^-1,the NO removal rates on Mn-Ce/TiO₂,Mn-Ce-Ni_0.4/TiO₂ and Mn-Ce-Co_0.2/TiO₂ are 38%,68% ,74% at 120 ℃ and 64%,92% and nearly 100% at 150 ℃ respectively,which indicates that the denitration activities of Ni or Co doped Mn-Ce/TiO₂ catalysts are increased;When SO₂ with 1×10^-4 of volume fraction is added into the inlet gas,the NO removal rate on Mn-Ce/TiO₂ catalyst is decreased from 98.2% to 57.2% in 300 min,while those on Mn-Ce-Co_0.2/TiO₂ and Mn-Ce-Ni_0.4/TiO₂ catalysts are 73.9% and 69.8% respectively,which indicates that the doped Ni or Co helps to improve the sulfur-resistance performance of the catalyst. The characterization results show that the doped Ni or Co has no effect on dispersion of Mn,Ce on TiO₂;The existing forms of Ce are Ce³⁺ and Ce⁴⁺,and mainly Ce⁴⁺;The specific surface area of the catalyst changes little;The crystallinities of MnO_x and CeO_x are reduced,which cause the improving of redox ability of the catalyst.