化学链气化中准东煤灰对CaSO_(4)载氧体改性及其作用机理

Modification of CaSO_(4)oxygen carrier by Zhundong coal ash in chemical looping gasification and its mechanism

以CaSO_(4)为载氧体,采用机械混合法制备了将军庙煤灰修饰的CaSO_(4)-Ash复合载氧体。借助TG-MS考察复合载氧体CaSO_(4)-Ash与将军庙煤的化学链气化反应特性,并对将军庙煤灰改性CaSO_(4)载氧体的作用机理进行了研究。结果表明:将军庙煤灰对CaSO_(4)载氧体有一定的改性作用。900℃时,与纯CaSO_(4)载氧体相比,CaSO_(4)-Ash复合载氧体表现出良好的反应活性和稳定性,CaSO_(4)-Ash复合载氧体化学链气化产生的CO量明显增多,产率也更加稳定。X射线衍射分析表明,CaSO_(4)-Ash复合载氧体中存在少量的Ca_(2)Fe_(2)O_(5)和Fe_(2)O_(3),它们附着在CaSO_(4)表面,作为CaSO_(4)晶格氧传输的中介,起到促进CaSO_(4)晶格氧迁移的效果。通过Jade软件计算纯CaSO_(4)载氧体和改性后的CaSO_(4)载氧体的晶格常数和晶格体积,并结合拉曼光谱和电子顺磁共振光谱表征,证明了煤灰中Na+改性CaSO_(4)载氧体的机理。通过扫描电子显微镜测试,发现改性后的CaSO_(4)载氧体表面孔径结构更加清晰。

Using CaSO_(4)as the oxygen carrier,the CaSO_(4)-Ash composite oxygen carrier modified by Jiangjunmiao coal ash was prepared by mechanical mixing method.With the TG-MS device,the chemical looping gasification reaction characteristics of composite oxygen carrier CaSO_(4)-Ash and Jiangjunmiao coal were investigated,and the action mechanism of Jiangjunmiao coal ash-modified CaSO_(4)oxygen carrier was studied.The results showed that Jiangjunmiao coal ash had a certain modification effect on CaSO_(4)oxygen carrier.At 900℃,the CaSO_(4)-Ash composite oxygen carrier showed good reactivity and stability compared with the pure CaSO_(4)oxygen carrier.The amount of CO produced by the chemical chain gasification of the CaSO_(4)-Ash composite oxygen carrier increased significantly,and the yield also more stable.X-ray diffraction(XRD)analysis showed that there were a small amount of Ca_(2)Fe_(2)O_(5)and Fe_(2)O_(3)in the CaSO_(4)-Ash composite oxygen carrier,which were attached to the surface of CaSO_(4)and promoted the effect of CaSO_(4)lattice oxygen migration as an intermediary for the transport of CaSO_(4)lattice oxygen.The lattice constant and lattice volume of pure CaSO_(4)oxygen carrier and modified CaSO_(4)oxygen carrier were calculated by Jade software,and combined with Raman and Electron Paramagnetic Resonance(EPR)characterization,the mechanism for Na+to modify CaSO_(4)oxygen carrier in coal ash was proved.Through Scanning Electron Microscope(SEM)test,it was found that the surface pore structure of the modified CaSO_(4)oxygen carrier was clearer.