烟气脱硫中亚硫酸钙铁锰复合催化氧化优化

Optimization for Fe-Mn catalyzed sulfite oxidation in flue gas desulfurization

亚硫酸钙氧化是湿法石灰石/石膏法脱硫中十分重要的一个环节,优化亚硫酸钙氧化过程有助于降低湿法脱硫能耗和物耗。以Ca SO_3氧化速率(SOR)为研究对象,对比了Fe和Mn单独催化和复合催化的氧化效果,通过单因素和响应面法考察了p H、Fe/Mn比例和起始Ca SO_3浓度对SOR的单独和联合效应。结果表明,Fe和Mn复合催化的SOR明显高于单独催化。对SOR的影响大小依次为起始Ca SO_3浓度>p H>Fe/Mn,Fe/Mn和起始Ca SO_3浓度的交互作用显著。Ca SO_3氧化的最佳条件为p H 4.5,Fe/Mn为0.37,起始浓度为17.83 mmol·L^(-1),优化的SOR为4.22 mmol·(L·min)^(-1)。结构表征结果表明,亚硫酸钙氧化首先生成Ca SO_4·2H_2O的(020)、(021)和(041)晶面,产物为Ca SO_4·2H_2O。

Oxidation of calcium sulfite is a very important part of wet limestone/gypsum flue gas desulfurization （FGD） process. Optimization of the oxidation process will help reduce energy consumption and cost. We studied standard oxidation rate （SOR） of calcium sulfite by Fe catalyst, Mn catalyst and Fe/Mn combined catalyst. Single factor analysis and response surface methodology were employed to study separate and joint effects of pH, Fe/Mn ratio and initial CaSO3 concentration （ICS） on SOR. The results showed that combined catalyst resulted in a higher SOR than only Fe or Mn. ICS had the most impact on SOR, followed by pH and Fe/Mn ratio. Fe/Mn ratio and ICS had the most significant interaction. Optimum conditions for CaSO3 oxidation were：pH of 4.5, Fe/Mn ratio of 0.37 and ICS of 17.83 mmol·L-1. Under the optimum conditions, SOR reached 4.22 mmol·（L·min）-1. The results from structural analysis indicated that the （020）, （021） and （041） faces of the product CaSO4·2H2O were first formed in the oxidation process.