中毒脱硝催化剂氟法洗涤再利用及其活化机制

Reutilization of toxic denitration selective catalytic reduction catalyst by fluoride washing and its activation mechanism

为解决常规再生或资源化方法对于中毒脱硝选择性催化还原(SCR)催化剂洗涤效果不好、难以达到新鲜催化剂性能水平的问题,利用氟试剂对中毒SCR催化剂进行清洗,并通过扫描电镜(SEM)、能谱仪(EDS)、NH3程序升温脱附(NH3-TPD)、H2程序升温还原(H2-TPR)、原位红外(in situ-FTIR)等方法对催化剂性能进行分析。结果表明:氟洗效果优于水洗或碱洗,洗涤后有效组分纯度可达99.0%;氟洗后可以恢复催化剂300℃以上中高温段活性至新鲜催化剂水平,300℃以下中低温段活性优于新鲜催化剂;氟试剂可以有效洗除孔道堵塞物,从而深度清洗脱钙,复活催化剂酸中心,以恢复中高温催化活性;氟试剂还可以活化氧化还原位点,促进NH3摘氢形成NH2中间体,从而提高中低温催化活性。

In order to solve the problem that the washing effect of conventional regeneration or recycling methods for toxic denitration selective catalytic reduction(SCR)catalyst is not good,and it is difficult to reach the performance level of fresh catalyst,fluorine reagent was used to clean the toxic SCR catalyst,and scanning electron microscope(SEM),energy dispersive spectrometer(EDS),NH3 temperature programmed desorption(NH3-TPD),H2 temperature programmed reduction(H2-TPR),hydrogen peroxide temperature programmed desorption(NH3-TPD),hydrogen peroxide temperature programmed reduction(H2-TPR),and in situ FTIR were used to analyze the performance of the catalyst.The results show that the effect of fluoride washing is better than that of water washing or alkali washing,and the purity of effective components can reach 99.0%.The catalyst can be recovered after fluoride washing.The activity of medium and high temperature section above 300℃reaches the level of fresh catalyst.The activity of the catalyst below 300℃is better than that of the fresh catalyst.Fluorine reagent can effectively remove the blockage in the pore channel,so as to deeply clean the decalcification and reactivate the acid center of the catalyst to restore the catalytic activity at medium and high temperature.Fluorine reagent can also activate redox sites and promote the dehydrogenation of NH3 to form NH2 intermediates,thus improving the catalytic activity at medium and low temperatures.