砷(As)及其他杂质元素是导致燃煤电厂废弃SCR脱硝催化剂失活的主要原因,借助Fenton反应对废弃SCR脱硝催化剂中的有害杂质元素As及Fe、Al进行氧化酸洗脱除,探究了酸洗液种类、酸浓度、氧化剂浓度、反应温度、反应时间、液固比等因素对杂质浸出率的影响。结果表明,最佳的杂质浸出条件为:反应温度为50℃、H₂SO₄浓度为1.5 mol/L、H₂O₂浓度为 1.5 mol/L、转速为500 r/min、反应时间为240 min、液固比为20 mL/g,此时As、Fe、Al的浸出率分别为99.58%、41.80%、39.60%。废弃催化剂杂质元素浸出机理为过氧化氢与被硫酸浸出的Fe²⁺形成了芬顿试剂,将As³⁺氧化为As⁵⁺,使其氧化溶出,提高了As元素的脱除效率。

Arsenic (As) and other impurity elements are the main causes for deactivation of SCR denitrification catalysts used in coal-fired power plants.The impurity elements such as As,Fe and Al in spent SCR catalyst are leached and removed by means of Fenton reaction,and the influences of factors such as the type of acid washing solution,acid concentration,oxidizer concentration,reaction temperature,reaction time,liquid-solid ratio on the leaching rate of impurities are explored.The optimal impurity leaching conditions are determined as follows:50℃,the concentration of H₂SO₄ is 1.5 mol·L^-1,the concentration of H₂O₂ is 1.5 mol·L^-1,the rotating speed is 500 rpm,the reaction lasts for 240 min,and the liquid-solid ratio is 20 mL·g^-1.Under the optimal conditions,the leaching rates of As,Fe and Al are 99.58%,41.80% and 39.60%,respectively.The leaching mechanism of impurity elements in spent SCR catalyst is that hydrogen peroxide and Fe²⁺ leached by sulfuric acid form Fenton reagent,which oxidizes trivalent As³⁺ to pentavalent As⁵⁺,and hence improves the removal efficiency of As.

朱媛霏(1995-),女,硕士研究生,研究方向为固废处理,zhuyuanfei0607@163.com。