Abstract: This paper studied the distribution and occurrence of elements in fresh and deactivated catalysts with operational time of 35000 h, which were used in flue gas denitration process in thermal power plant. At gas hourly space velocity of 30000 h?1, NH3 to NO volume ratio of 0.8, and 5 vol% O2, NO conversion rate was only 41% at 200 °C using the deactivated catalyst, and it decreased 8% compared with the fresh catalyst at the temperature of 250 to 400°C. The main phase of deactivated catalyst remained the anatase TiO2, but the honeycomb structure of deactivated catalyst was destoried. Due to the surface chemical erosion, the size of TiO2 particles decreased to 37.2 nm. The impurity elements, such as Fe, K, Al, and As, have heterogeneously deposited on the surface of the catalyst. It results in 10.44% decreasing of total pore volume. Compared with the fresh catalyst, the distribution of anatase TiO2 becomes heterogeneous in the deactivated catalyst. The atomic ratio of V/Ti reduced by 29.53%, and the valence ratio of V4+/(V4++V5+) also reduced by 25.89%. It leads to the decreasing of the acid site on the surface, and the activity of catalyst obviously decreased at low temperatures.

Key words: selective catalytic reduction denitration catalyst, deactivated, element, occurrence characterization, spectral analysis

摘要： 研究了火电厂烟气脱硝过程中新催化剂和运行35000 h后不可直接再生失活催化剂的元素分布规律和表面结合方式等特征. 结果表明，在气体体积空速为30000 h?1、NH3/NO体积比为0.8及O2体积含量为5%条件下，失活催化剂脱硝率在200℃仅为41%，在250~400℃比新催化剂下降8%. 失活催化剂晶型仍为锐钛型TiO2，但整体蜂窝状结构塌陷，化学磨损导致晶体粒径降至37.2 nm. 催化剂表面Fe, K, Al, As等杂质元素非均匀沉积，使孔容减小10.44%. 对比新催化剂，失活催化剂中锐钛型TiO2载体呈现非均匀分布，且表面V/Ti原子比降低29.53%, V4+/(V4++V5+)价态比降低25.89%，使表层酸性位减少，导致催化剂低温活性明显降低.

关键词: 选择性催化还原脱硝催化剂, 失活, 元素, 赋存特征, 光谱分析