羧酸钠对五彩湾煤热解及煤焦热反应性的影响

Effect of Sodium Carboxylate on Pyrolysis and Coal Char Reactivity of Wucaiwan Coal

针对准东煤中高含量有机钠对煤热解燃烧会产生不利影响的问题,通过向酸洗脱除碱金属后的五彩湾煤定向加载羧酸钠的方法,对比分析加钠煤和再次脱钠二次酸洗煤的热重曲线、气体产物及不同温度热解焦在低温下的热反应性,研究羧酸钠对五彩湾煤热解和焦反应活性的影响。结果表明:羧酸钠会显著促进五彩湾煤热解挥发分的释放及煤羧基官能团的热分解,在600℃以下抑制CO的生成,600℃以上时则相反,同时高温下会抑制脂肪侧链的分解及煤的缩聚反应;羧酸钠对煤焦的热反应性具有催化作用,主要由两条路径实现:在煤焦表面形成"C-O-Na"基团或钠团簇进行催化。

The high content of organic sodium in Zhundong coal has certain disadvantageous effects on coal pyrolysis and combustion.In this paper, the effect of sodium carboxylate on coal pyrolysis and char reactivity was studied by loading sodium carboxylate in Wucaiwan coal whose alkali metal species were removed and making a comparative analysis between NFC(Na-Form Coal) and HFC-2(H-Form-Coal, prepared from the acid-washing of NFC).In this study, the TGA lines, gas products and char reactivity at low temperature were compared.The results show that sodium carboxylate significantly promotes the release of volatiles during pyrolysis and the thermal decomposition of coal carboxyl functional groups, and inhibits the formation of CO below 600 ℃,while it works the opposite when the temperature is higher than 600 ℃,and it also inhibits the decomposition of aliphatic side chains and poly-condensation reaction at high temperature.Sodium carboxylate catalyzes the thermal reactivity of coal char, mainly by forming "C-O-Na" group or sodium cluster on the surface of coal char.