Abstract:

H₂O₂ low-temperature catalytic oxidative desulfurization and denitrification technology can be applied to low-temperature flue gas in the deep peaking process of coal-fired power stations. In this work, a pilot hot state experimental system was built, industrial honeycomb TiO₂ catalysts were selected with characterizations by XRD, XRF and SEM, and an integrated experimental study of desulfurization and denitrification was carried out to investigate the influence of various factors on the efficiency of low-temperature catalytic oxidative denitrification of H₂O₂. The results showed that the nano-TiO₂ particles were uniformly distributed, well dispersed and highly pure under microscopic conditions. In separate denitrification experiment, temperature had minor effect on the NO oxidation and removal efficiency. When the catalyst was not used, the oxidative removal of NO mainly relied on the oxidizing property of H₂O₂ itself and a small amount of ‧HO₂ generated by the decomposition of H₂O₂, which is less effective. With the increase of H₂O₂/NO molar ratio after the adoption of catalyst, the efficiency of NO oxidation and removal was greatly improved compared with that without catalyst. In the desulfurization and denitrification experiments, the oxidation and removal efficiency of NO was significantly promoted by SO₂ under the uncatalyzed condition. While under the catalyzed condition, there was a competitive effect between NO and SO₂ on the utilization of ‧OH when the molar ratio of H₂O₂/(NO+SO₂) was 0.5, and the oxidation and removal efficiency of NO was gradually enhanced and that of SO₂ was gradually reduced with the increase of SO₂ concentration. With the introduction of honeycomb TiO₂ catalyst, when the H₂O₂/NO molar ratio was 8, the NO oxidation efficiency reached 90.4%, the NO _x removal efficiency reached 63.7%, and the SO₂ removal efficiency could reach 100%.

Key words: oxidation, catalyst, flue gas, denitrification, removal efficiency

摘要：

H₂O₂低温催化氧化法脱硫脱硝技术在燃煤电站深度调峰过程中可以应用于低温烟气。本文搭建中试热态实验系统，选取工业蜂窝状TiO₂催化剂，通过X射线衍射（XRD）、X射线荧光光谱（XRF）和扫描电子显微镜（SEM）等对其进行表征，进行脱硫脱硝一体化实验研究，探究各因素对H₂O₂低温催化氧化脱硝效率的影响规律。结果表明：微观下纳米TiO₂颗粒分布均匀、分散性好、纯度高。在单独脱硝实验中，温度对NO氧化和脱除效率影响较小；不采用催化剂时，NO的氧化脱除主要依靠H₂O₂自身的氧化性以及少量H₂O₂分解生成的‧HO₂，效果较差。采用催化剂后，随着H₂O₂/NO摩尔比增加，NO氧化及脱除效率与无催化剂时相比大幅提升。在脱硫脱硝实验中，无催化剂条件下SO₂对NO的氧化和脱除效率有明显促进作用；有催化剂条件下，当H₂O₂/(NO+SO₂)摩尔比为0.5时，NO与SO₂对‧OH的利用存在竞争效应，随着SO₂浓度的增加，NO氧化及脱除效率逐渐提升，SO₂脱除效率逐渐降低。采用蜂窝TiO₂催化剂，当H₂O₂/NO摩尔比为8时，NO氧化效率达90.4%，NO _x 脱除效率达63.7%，SO₂脱除效率可达到100%。

关键词: 氧化, 催化剂, 烟道气, 脱硝, 脱除效率