酒石酸改性活性炭对烟气脱硝钴氨吸收液中Co~(3+)的催化还原

废气中的NO和SO2可通过钴氨吸收液去除,但钴氨吸收液中的Co~(2+)易被氧化成Co~(3+)而失去脱硝能力。为了实现Co~(2+)的再生,采用酒石酸溶液对活性炭进行改性,提高其对Co~(3+)的催化还原能力,考察了活性炭催化剂改性及活化条件对钴氨吸收液Co~(3+)还原率及NO去除率的影响。实验结果表明:在酒石酸溶液浓度为1.5 mol/L、改性时间为18 h、活化温度为400℃、活化时间为4 h的条件下,改性活性炭的催化性能最佳;Co~(3+)还原率为67.5%,比原炭提高了11.9百分点;对应的钴氨吸收液的NO去除率为86.0%,比原炭提高了26.0百分点。pHpzc测定、Boehm滴定和BET表征结果表明,与原炭相比,改性活性炭酸性增强,羧基和内酯基含量增加,微孔数目增加,比表面积增大。这些表面特性的改变使改性活性炭的催化性能得到改善。

Catalytic reduction of Co3+ in Co-NH3 absorption solution for flue-gas denitration using activated carbon modified by tartaric acid

NO and SO₂ can be removed from waste gas using Co-NH₃ absorption solution. But the Co-NH₃ absorption solution may lose its denitration ability due to oxidation of Co²⁺ to Co³⁺. In order to regenerate Co²⁺,activated carbon was modified by tartaric acid solution to improve its catalytic ability. The effects of activated carbon modification conditions and activation conditions on Co³⁺ reduction rate and NO removal rate were investigated. The experimental results indicated that：Under the conditions of tartaric acid solution concentration 1.5 mol/L,modification time 18 h,activation temperature 400 ℃ and activation time 4 h,the catalytic ability of the modified activated carbon was the best;The reduction rate by the modified activated carbon was 67.5%,which was 11.9 percentage higher than that by activated carbon;The NO removal rate by the modified activated carbon system was 86.0%,which was 26.0 percentage higher than that by activated carbon system. The characterization results by pHpzc determination,Boehm titration and BET show that the acidity,carboxyl and lactone group number,micropore number and specific surface area of the modified activated carbon were all more than activated carbon. These surface property changes make the improvement of catalytic ability of the modified activated carbon.