超声波辅助氧化改性钙基吸收剂的制备及性能研究

Preparation of Ultrasonic Impregnated Oxidized Calcium-based Absorbent and Its Desulfurization and Denitrification Properties

通过超声波辅助溶液浸渍的方法,将K_(2)S_(2)O_(8)、Ca(ClO)_(2)、(NH_(4))_(4)Ce(SO_(4))_(4)及K_(2)Cr_(2)O_(7)等氧化剂分别浸渍在钙基吸收剂表面,形成具有氧化性的活性位点,即氧化位点,改善钙基吸收剂脱除NOx的效果。通过正交实验,在不同超声波功率、浸渍时间和浸渍温度下,按照一定掺杂比例,利用氧化剂对钙基吸收剂进行化学调质。将改性后钙基吸收剂在固定床反应器上进行了同时脱硫脱硝实验,选择污染物的平均脱除率作为评价指标。正交实验结果表明:以Ca(ClO)_(2)作为氧化剂进行超声波浸渍改性效果最好,最优改性工艺参数为氧化剂掺杂比例20%(质量分数,下同)、超声波功率100%、浸渍时间1.5 h、浸渍温度70℃。同时,基于晶相结构(XRD)分析和扫描电镜(SEM)显微形貌观测,可知超声波辅助氧化改性的方法能有效改善钙基吸收剂表面形貌,表面上形成了氧化位点,该氧化位点不仅能够增大吸收剂与SO2和NOx的接触,还能促进NO氧化为NO2,进一步提高SO2和NOx的脱除率。

In this work,the oxidants such as K_(2)S_(2)O_(8),Ca(ClO)_(2),(NH_(4))_(4)Ce(SO_(4))_(4)and K_(2)Cr_(2)O_(7) were impregnated on the surface of calcium-based absorbent by ultrasonic-assisted solution impregnation method,and the active sites with oxidation were formed to improve the effect of cal-cium-based absorbent on NO_(x) removal.Through orthogonal experiment,under different ultrasonic power,impregnation time and impregnation temperature,the calcium-based absorbent was chemically modified by oxidant according to a certain doping ratio.The simultaneous desulfurization and denitrification experiments of modified calcium-based absorbent were carried out in a fixed bed reactor,and the average removal rate of pollutants was selected as the evaluation index.The orthogonal experiment results showed that Ca(ClO)2 was the best oxidant for ultrasonic impregnation modification.The optimal modification process parameters were as follows:the oxidant doping ratio of 20%,the ultrasonic power of 100%,the impregnation time of 1.5 h,and the impregnation temperature of 70℃.At the same time,based on the crystal structure(XRD)analysis and scanning electron microscopy(SEM),it can be seen that the ultrasonic-assisted oxidation modification method can effectively improve the surface morphology of calcium-based absorbent,and the oxidation sites are formed on the surface.On the one hand,it can increase the contact between the absorbent and SO2 and NOx,on the other hand,it can promote the oxidation of NO to NO2,and further improve the removal rate of both.