平板式V_2O_5-MoO_3/TiO_2型SCR催化剂的中低温脱硝和抗中毒性能研究

针对中低温锅炉烟气脱硝技术需求的特点,采用等体积浸渍法,以V_2O_5为活性组分、MoO_3为助剂,制备了高钒高钼含量的V_2O_5-MoO_3/TiO_2型粉末和平板式SCR脱硝催化剂,考察了活性组分和助剂含量对催化剂活性以及抗SO_2和H_2O中毒性能的影响,对反应前后的催化剂进行了微观表征,并针对最优催化剂研究了其在不同烟气工况下催化剂的脱硝性能。结果表明,提升V_2O_5负载量可以有效提高催化剂的脱硝活性;MoO_3助剂的添加也可以提高催化剂的脱硝活性。XPS、XRF、FTIR等表征结果表明,MoO_3的含量会影响催化剂中V~(4+)/V~(5+)的比值,其相对含量的增加有利于催化剂中非化学计量钒物种的形成以及化学吸附氧比例的增加,钼与钒物种间的交互作用是抑制SO_2和H_2O对催化剂的毒化作用的关键。3V_2O_5-10MoO_3/TiO_2平板式催化剂在温度为200℃、空速为3 500 h~(-1)含SO_2和H_2O烟气条件下,经30 d连续反应,脱硝效率稳定维持在82%左右,该催化剂在中低温下具有优异的抗SO_2和H_2O中毒性能以及稳定性。

Research on the middle-low temperature denitration and anti-poisoning properties of plate V2O5-MoO3/TiO2 SCR catalysts

Considering the technical requirements for middle-low temperature denitration of flue gas, a series of powder and plate type V₂O₅-MoO₃/TiO₂ SCR catalysts were prepared using incipient wetness impregnation method with V₂O₅ as the active component and with MoO₃ as the promoter. Experiments were performed to investigate the effects of active component and promoter contents of the catalysts on the activities and the resistance to deactivation by SO₂ and H₂O. The characterization of the fresh and used catalysts was conducted, and the optimal catalyst was further studied to reveal the denitration performance under different flue gas conditions. The results indicate that the activities of the catalysts are enhanced with the increase of V₂O₅ loadings. Also, the addition of MoO₃ can promote the catalytic activity. The characterization results from XRF, XPS, FT-IR and other analysis suggest that the MoO₃ content could affect the V⁴⁺/V⁵⁺ ratio in the catalyst. The increase in relative MoO₃ content is favorable for the formation of non-stoichiometry vanadium species as well as the rise of chemical adsorption oxygen. Therefore, the interactions between molybdenum and vanadium species might be an essential reason for the resistance to the deactivation by SO₂ and H₂O. The denitrification efficiency of 3V₂O₅-10MoO₃/TiO₂ plate catalyst keeps steady around 82% after 30 days test in the presence of SO₂ and H₂O at temperature of 200℃ and space velocity of 3 500 h^-1. The catalyst is identified to have an excellent resistance to the deactivation by SO₂ and H₂O under middle-low temperatures.