Regeneration of alkali metal K deactivation in low-temperature manganese-based SCR catalyst

Based on the MnO_x/TiO₂ catalyst prepared by the sol–gel method as the substrate, the impregnation method was used to simulate the deactivation process of the alkali metal K of the MnO_x/TiO₂ catalyst, and the regeneration experiment of the deactivated K–MnO_x/TiO₂ catalyst was carried out by water washing and acid washing. The effects of methods and process conditions on the regeneration effect of deactivated catalysts were discussed emphatically. The results show that the regeneration effect of acid washing on the deactivated catalyst is obviously better than that of water washing. Under the conditions of ultrasonic frequency of 30 kHz, HNO₃ concentration of 0.3 mol l^–1, acid washing for 45 min and calcination at 400°C for 4 h, the removal rate of NO by the catalyst can be recovered from 35 to 89%. Using Brunauer–Emmett–Teller and Barren–Johner–Halendar analysis, X-ray fluorescence analysis, and NH₃ temperature-programmed desorption analysis, it was found that acid washing can better restore the specific surface area and surface acid content of the deactivated catalyst, and has a strong ability to remove alkali metal K.