【作者】 张峰；

【导师】 黄海凤；

【作者基本信息】 浙江工业大学 ， 环境工程， 2010， 硕士

【摘要】 氮氧化物（NOx）是主要的大气污染物之一,也是形成光化学烟雾的主要前驱物,控制和治理氮氧化物的污染越来越受到国内外环保领域的关注。在处理电厂烟气NOx的工艺中,选择性催化还原（SCR）脱硝技术由于其高效率、高选择性和高经济性,是主流的脱硝技术。其中催化剂是SCR脱硝技术的核心,工艺中催化剂要承受大风量烟气以及烟尘、SO₂的冲击,因此提高催化剂抗硫性能及开发整体化制备技术是SCR脱硝催化剂工业化应用需解决的关键问题。本文针对不同SCR脱硝技术的特点,对低温SCR的Mn₁Fe_1-xCe_x/TiO₂催化剂的抗硫再生性能和高温SCR的V₂O₅-WO3/TiO₂（-SiO2）催化剂的整体化制备技术进行了研究。以MnOx为活性组分,Fe、Ce的氧化物为助剂,制备了新型的Mn₁Fe_1-xCe_x/TiO₂低温SCR脱硝催化剂。通过抗硫再生性能研究,结果表明,Mn₁Fe_0.9Ce_0.1/TiO₂表现出最佳的脱硝活性,在140℃时NO转化率可达到100%。Mn₁Fe_0.9Ce_0.1/TiO₂同样也表现出优良的抗硫性能,在SO₂浓度小于0.002vol%时,催化剂只发生可逆中毒,当SO₂浓度大于0.002vol%时,催化剂表面会生成硝酸盐及硫酸盐导致不可逆失活,但中毒失活催化剂在经水洗后可实现再生,催化活性可基本恢复至新鲜催化剂水平。通过添加助剂整体挤压和以堇青石为载体表面原位负载合成两种方法对V₂O₅-WO₃/TiO₂（-SiO2）进行整体化制备技术研究。整体挤压成型研究结果表明水粉比为1:2,以磷酸为助剂与制备好的V₂O₅-WO₃/TiO₂-SiO2催化剂直接揉捏时较易成型。活性测试在320℃时NO转化率达到90%以上,可达到商业成型催化剂的活性效果。以TiO₂（-SiO2）为涂层,原位浸渍法制备的菁青石蜂窝陶瓷整体型V₂O₅-WO₃催化剂,V₂O₅与WO₃最佳负载量为2%,340℃时NO转化率均可达90%。涂层的负载可明显提高催化剂的活性。在不同空速下催化剂活性表现差异大,在空速为30000h^-1,300℃时NO转化率便可达到100%。催化剂的脱落率均在1%以下,牢固度好。更多还原

【Abstract】 NOx is one of the most prominent air pollutants. It is also the main precursor of photochemistry fog. It has been a hot spot in environmental field at home and abroad to control and deal with NOX pollution. Due to high efficiency, selective and economic value, selective catalytic reduction （SCR） is the major technology for treating NOx emissions from power plant. The catalyst is the key of SCR technology. According to the catalyst could be eroded by large air flow, dust and SO₂ in the SCR technology, to improve performance of sulfur tolerance and exploit the technology to prepare monolithic catalyst become important factors for industrial application. In this paper, for different NOx SCR technology characteristics, we studied the sulfur tolerance and regeneration of Mn₁Fe_1-xCe_x/TiO₂ for the low-temperature SCR, and the technology to prepare monolithic V₂O₅-WO₃/TiO₂ （ -SiO2 ） catalyst for the high- temperature SCR also have been studied. Using MnOx as the active components, the oxides of Fe and Ce as auxiliary agent to prepare Mn₁Fe_1-xCe_x/TiO₂ catalyst for low-temperature SCR, sulfur tolerance and regeneration of Catalyst have been studied. The results showed the catalytic behavior of Mn₁Fe_0.9Ce_0.1/TiO₂ performed best, the conversion of NO was up to 100% at the temperature of 140℃. It also performed well on the sulfur tolerance, the catalytic behavior was reversible when the concentration of SO₂ was lower than 0.002vol%; when the concentration of SO₂ was more than 0.002vol%, the catalyst was poisoned irreversibly because of nitrate and sulfate formed on the surface. But the poisoned catalyst could regenerate after washed by water, the NO conversion could return to the catalytic behavior of fresh catalyst.Molding monolithic catalyst of V₂O₅-WO₃/TiO₂（-SiO2） have been studied by two methods. One is that the catalyst was squeezed by adding auxiliary agent, and the other is that the monolithic catalyst was originally prepared by impregnation method on honeycomb-shaped cordierite support. The results showed it is easy to mold catalyst by adding phosphoric acid to the finished power catalyst when the proportion of water and power is 1:2. The NO conversion could get to 90% at 320℃, it could satisfy to the catalytic activity of commercial moiding catalyst. The monolithic V₂O₅-WO₃ catalyst was originally prepared by impregnation method on honeycomb-shaped cordierite support with the coating as TiO₂（-SiO2）, the best loading of V₂O₅-WO₃ was 2%, NO conversion could get to more than 90% at 340℃. Adding coating on honeycomb-shaped cordierite support could obviously improve the activity of catalyst. And the catalytic activity performed different at different space velocity. When space velocity was 30000 h^-1, NO conversion could get to 100% at 300℃. The rate of catalyst desquamation was lower than 1%, so the catalyst well combined to the honeycomb-shaped cordierite support.更多还原