SCR废催化剂中钒和钨常温常压浸出新工艺

Novel Leaching Process of Vanadium and Tungsten from Spent SCR Catalyst at Normal Temperature and Pressure

基于SEM-EDS,XPS,获得常温常压下SCR废催化剂二段式浸出新工艺,采用Box-Behnken试验设计(BBD)方法分段研究了各因素及其交互作用对钒和钨浸出影响,得到了最佳工艺参数,并分析了浸出机理.结果表明,采用二段式浸出工艺,各因素影响顺序为:第一阶段提钒,反应温度>浸出时间>浸出剂浓度;第二阶段提钨,反应温度>浸出剂浓度>浸出时间.第一段当NaOH浓度0.5 mol·L^(-1),60℃下反应10 min时,钒浸出率为(61.40±0.24)%;第二段当NaOH浓度2.5 mol·L^(-1),90℃下反应50 min时,钨浸出率为(55.73±0.22)%.废催化剂中钒以V_(2)O_(3),VOSO_(4)和V_(2)O_(5)形式存在,与NaOH反应生成可溶性钒酸盐,少部分V_(2)O_(3)和V_(2)O_(5)在反应过程中生成VOSO_(4)后溶解.

Based on SEM-EDS and XPS,a novel two-stage leaching process of spent SCR(selective catalytic reduction)catalyst under normal temperature and pressure was proposed.Box-Behnken design(BBD)was used to study the effects of various factors and their interactions on the leaching of vanadium and tungsten,then,the optimal process parameters were obtained and the leaching mechanism was studied.The results showed that:during the two-stage leaching process,the order of influence factors on the leaching rate is temperature>time>leaching agent concentration in the first stage(vanadium extraction process)and temperature>leaching agent concentration>time in the second stage(tungsten extraction process).In the first stage,when the NaOH concentration is 0.5 mol·L^(-1) and reacts at 60℃for 10 min,the vanadium leaching rate is(61.40±0.24)%.In the second stage,when the NaOH concentration is 2.5 mol·L^(-1) and reacts at 90℃ for 50 min,the tungsten leaching rate is(55.73±0.22)%.Vanadium in the spent catalyst exists in the form of V_(2)O_(3),VOSO_(4) and V_(2)O_(5),and reacts with NaOH to form soluble vanadate.A small part of V_(2)O_(3) and V_(2)O_(5) are dissolved after forming VOSO_(4).