Regeneration Treatment Technology of Deactivated Vanadium Tungsten and Titanium Denitration Catalysts

The regeneration of cleaning process of the deactivated commercial V2O5-WO3/TiO2 SCR catalysts used for 3 years at a power station was investigated by different cleaning regeneration techniques. Three kinds of cleaning fluids used were cleaning fluid C1 with deionized water, cleaning fluid C2: 0.01 mol/L ethylene diamine tetraacetic acid (EDTA)+0.5 mol/L sulphuric acid(H2SO4)+0.5% dodecylbenzene sulfonic acid (LAS) and cleaning fluid C3: 0.5% 2, 4, 6-trimercaptotriazine (TMT103). The cleaning processes used involved cleaning process A - cleaned by a mixed cleaning fluid (i.e., a volume ratio of cleaning fluid C2 to cleaning fluid C3 of 1:1), cleaning process B - cleaned by cleaning fluid C2 and then cleaning fluid C3, and cleaning process C - cleaned by cleaning fluid C3 and then cleaning fluid C2. The results show that with deionized water, the optimum cleaning time of cleaning fluid C2 and C3 are 30 min and 1 h at ultrasonic cleaning frequency of 50 kHz, leading to NOx conversion to 77% and 79%, respectively. NOx conversion can be 85% as using cleaning process C. NOx conversion can return to the fresh catalyst level at 300-450 °C when the active components are added after cleaning by cleaning process C. It is revealed that cleaning process C can effectively remove the toxic elements (i.e., arsenic), restore the surface pore structure of the catalyst (i.e., micropore structure), enhance the amount and strength of the surface Brönsted and Lewis acid sites, and improve the reducibility as well. © 2019, Editorial Department of Journal of the Chinese Ceramic Society. All right reserved.