磁性凹凸棒土制备及其脱汞性能研究

对自然界中广泛存在的凹凸棒土(Atp)进行磁改性,通过沉积-沉淀法制备出磁性氧化铁改性的磁性凹凸棒土(MAtp),采用BET、VSM、XRD以及SEM等手段对其理化性质加以分析,并在固定床实验台上进行模拟烟气脱汞性能测试,研究了铁氧化物含量、反应温度和烟气成分对其除汞能力的影响。结果表明,Atp与磁性物质的复合提高了其对Hg~0的脱除能力,并且随铁氧化物含量升高,MAtp脱汞能力逐渐增强;在实验温度区间内,脱汞能力随温度的升高逐渐增强,MAtp对Hg~0以化学吸附为主;O_2、NO的添加有利于Hg~0的脱除,但Hg~0穿透率随浓度变化不显著;SO_2抑制汞的脱除,并且随浓度的增加,其抑制效果更加明显,但是当NO和SO_2共同存在时,NO能明显削弱SO_2对脱汞的抑制作用。

Study on the preparation of magnetic attapulgite and its mercury removal performance

The attapulgite (Atp) widely existed in nature could be modified by magnetism, and a magnetic attapulgite (MAtp) modified by magnetic iron oxide was prepared by deposition-precipitation method. The physical and chemical properties of the magnetic attapulgite were analyzed by BET, VSM, XRD and SEM, and the effects of iron oxide content, reaction temperature and flue gas composition on the mercury removal capacity were studied. The results show that the removal ability for Hg⁰ is enhanced by the combination of Atp and magnetic materials, and the removal ability of MAtp is gradually improved with the increase in iron oxide content. Moreover, the removal ability of Hg⁰ is enhanced with the increase of temperature in the test temperature range, and the chemical adsorption of Hg⁰ is a main factor for MAtp. The addition of O₂ and NO is beneficial to the removal of Hg⁰, but the Hg⁰ penetration rate does not change significantly with the concentration; while SO₂ inhibits the removal of mercury, and the inhibition effect is more obvious with the increase of concentration. However, when NO and SO₂ coexist, NO can greatly weaken the inhibition effect of SO₂ on mercury removal.