基于铅在中国燃煤和MSW焚烧烟气中的特点,采用静态N_2物理吸附、NH_3化学吸附、程序升温表面反应、傅里叶变换红外光谱和催化剂活性评价的方法,研究了PbO对1 wt.%V_2O_5/TiO_2催化剂NH_3选择性催化还原NO的影响.结果表明,PbO使SCR催化剂活性降低.对于燃煤锅炉,PbO对V_2O_5/TiO_2催化剂的影响可以忽略不计;对于MSW焚烧炉,PbO是使V_2O_5/TiO_2催化剂失活的重要铅化合物.Pb覆盖在TiO_2表面上,与V活性位覆盖在TiO_2表面上的方式类似.催化剂的失活主要是由于PbO中和了催化剂表面Brφnsted酸性位的酸性,Brφnsted酸性位对于NH_3的吸附和活化起重要作用.
Based on the characteristics of lead in flue gas from Chinese coal and MSW-fired plants,the effect of PbO on 1 wt.%V_2O_5/TiO_2 catalyst for selective catalytic reduction of NO with NH_3is studied using static N_2 physical adsorption,NH_3 chemisorption,temperature-programmed dutface reaction.Fourier transform infrared spectroscopy and activity measurement.The results show that PbO deactivates the V_2O_5/TiO_2 catalysts.For the V_2O_5/TiO_2 catalysts used in coal-fired plants,the effect of PbO can be neglected,while PbO is an important poison for V_2O_s/TiO_2 catalysts in MSW-fired applications.Pb covers the surface of TiO_2 sites,similar to active V sites.The deactivation is mainly caused by neutralization of the BrCnsted acid sites on the surface of a V_2O_5/TiO_2 catalyst,which plays a key role on the absorption and activation of NH_3.
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