Regeneration Catalysts Of Wet Ammonia Denox Process

Nitric oxide(NO) can be effectively complexed from flue gas into solution by hexaaminecobalt(Ⅱ) ion and then oxidized to nitrate, however, the hexaaminecobalt(Ⅱ) ion is then oxidized to hexaaminecobalt(Ⅲ) ion, the oxidization product cannot complex NO. As catalyst, activated carbon is introduced into the process to catalyze the trivalue complex to be divalue.Acetic acid, oxalic acid and tartaric acid are used to modify coconut shell activated carbon respectively and modified carbons are investigated in the regeneration or NO removal coupled with regeneration experiment. The results showed three modification methods are effective.The optimum modification conditions and experimental results are listed as follows:(1) Acetic acid:impregnation concentration 2mol/L and time 20h; calcination temperature 600 ℃ and time 4h. Compared to original activated carbon, the conversion efficiency of hexaaminecobalt(III) catalyzed by carbon modified by acetic acid improved 8% and long time running NO removal efficiency improved 21%.(2) Oxalic acid:impregnation concentration 0.7mol/L and time 24h; calcination temperature 600 ℃ and time 5h. Compared to original activated carbon, the conversion efficiency of hexaaminecobalt(III) catalyzed by carbon modified by oxalic acid improved 15% and long time running NO removal efficiency improved 12%;(3) Tartaric acid:impregnation concentration 1.5 mol/L and time 20h; calcination temperature 600 ℃ and time 4h. Compared to original activated carbon, the conversion efficiency of hexaaminecobalt(III) catalyzed by carbon modified by tartaric acid improved 10% and long time running NO removal efficiency improved 26%;Charaterizations of modified activated carbon and unmodified activated carbon showed modification can improve the specific surface area, acetic acid 10%, oxalic acid 9%, tartaric acid 25%, compared to original activated carbon. Micropore number are mainly improved after modification of three kinds of organic acid. Oxygen-containing functional group of carbon increased sharply after modification, acetic acid, tartaric acid and oxalic acid as increasing sequence. The catalysis effect of ester group of activated carbon on is much more stronger than that of carboxyl and hydroxyl group.