纳米氧化物对钙基材料在高温燃煤中除砷脱硫的促进机理研究

Study on the enhancement mechanism of dearsenic and desulfurization with the calcium-based materials containing-nano-oxides during high temperature coal combustion

将纳米MgO、Al2O3和ZnO分别添加于CaCO3中制备出钙基纳米氧化物复合吸附剂,进行了燃煤过程中除砷脱硫的实验研究;对燃煤灰渣进行了比表面积及孔隙度分析、X-射线衍射分析和扫描电镜观察,探讨了纳米MgO对CaCO3除砷脱硫的促进机理。结果表明,添加了纳米MgO的复合吸附剂除砷脱硫性能最好,比单一的CaCO3除砷率和脱硫率分别高出了28.73%和37.21%,表现出同时除砷脱硫的良好性能;其促进机理是纳米MgO的加入改变了灰样的微观结构促进了气相间的流动使得灰渣孔隙明显扩大,提高了CaO与As2O3和SO2反应的能力;在除砷的反应中生成了新的物质Ca3 Mg2(AsO4)2,在一定程度上抑制了除砷产物的分解。

A series of calcium-based containing-nano-oxides compound sorbents were prepared by doping nano-MgO, Al2O3 , and ZnO into CaCO3 , respectively, which the characteristics of dearsenic and desulfurization researched during coal combustion. The ashes from burning different coal samples were tested and observed re- spectively with surface area and porosity, X-ray diffraction and scanning electron microscopy. Meanwhile, the enhancement mechanism of dearsenic and desulfurization with the CaCO3 containing-nano-MgO was discussed. The results showed that the efficiency of dearsenic and desulfurization increased by 28.73% and 37.21% with calcium-based containing-nano-MgO compound sorbent than single CaCO3 sorbent,the compound sorbent of calci- um-based containing-nano-MgO could be applied to dearsenic and desulfurization simultaneously during coal combustion. The enhancement mechanism in promoting CaCO3 to dearsenic and desulfurization is considered that Nano-MgO changes the micro-structure of CaCO3 at high temperatures and makes a marked widening of ash pore, thereby contributing to response capabilities of CaO with SO2 and As2O3. A new kind of Ca3Mg2 （AsO4）2 is formed, which inhibits the decomposition of the to a certain extent.