锌对捣固焦和顶装焦气化反应的催化作用

采用液相吸附法研究了不同温度、富锌量等条件对捣固焦和顶装焦气化反应的影响,并结合XRD、扫描电子显微镜和光学显微镜对比分析了锌对2种焦炭气化反应后的微晶结构、显微结构、孔结构的影响。研究结果表明,升高温度和增大富锌量均能使焦炭反应性增大,反应后焦炭强度减小。反应温度低于1 000℃时,锌对焦炭气化反应的影响较小,而在1 100℃时,2种焦炭的反应率随富锌浓度的增大快速增大,且富锌后顶装焦的反应率比捣固焦高约1%~2%。XRD分析表明,锌对焦炭有序化微晶气化反应的催化作用大于无序化微晶,从而导致气化反应后焦炭微晶片层的堆积高度减小,石墨化程度降低。结合扫描电子显微镜和光学显微全景图发现,锌在催化焦炭气化反应过程中孔壁变薄甚至消失,孔面积和孔直径增大,孔的贯穿连通程度加大,为锌蒸气的渗透和气化反应的动力学提供有利条件,导致反应进一步被加剧,但捣固焦较致密的孔结构使其在气化反应中具有优于顶装焦的抗锌催化能力。

Catalysis behavior of zinc on gasification reaction of top charged coke and stamp charged coke

The influences of temperature and zinc content on the gasification reaction of top charged coke and stamp charged coke were investigated by liquid phase adsorption method.The effects of zinc on microcrystalline structure,microstructure,pore structure of two kinds of reacted coke were compared and analyzed by X-Ray diffraction (XRD),scanning electron microscopy (SEM) and optical microscopy.The results show that the gasification reaction can be enhanced by rising the reaction temperature or enriching zinc content,resulting in the increase of coke reactivity index and the decrease of coke strength after reaction.Furthermore,when the reaction temperature is lower than 1000 C,zinc has little effect on the gasification reaction.However,the reactivity of two kinds of coke increases rapidly with the increase of zinc content at 1 100 ℃,and the reactivity of Zn-enriched top charged coke is about 1 ％-2 ％ higher than that of Zn-enriched stamp charged coke.XRD analysis reveal that catalytic effect of zinc on gasification reaction of ordered microcrystals of coke is larger than that of the disordered microcrystals,and resulting in a decrease in the stacking height of crystallite,and a decrease in degree of graphitization of coke.The combination of SEM and optical panorama show that under the condition of catalysis effect of zinc on gasification reaction,pore walls become thinner even disappear,surface area and diameter of pores increase,as well as expansion and incorporation of coke pores enhance,which provides favorable conditions for the permeation of zinc vapor and the kinetics of gasification reaction,thereby the reaction is intensified.Moreover,the resistance to zinc catalysis on gasification reaction of stamp charged coke is better than that of top charged coke because of the dense pore structure of stamp charged coke.