煤热解过程中碱金属对碳黑形成的影响

Effect of Alkali Metals on the Formation of Soot During Coal Pyrolysis

通过分析担载碱金属Na的酸洗煤热解产物的浓度分布、化学结构与微观结构,研究碱金属对煤衍生碳黑形成的影响.结果表明煤热解产物的粒数与质量浓度分布分别在0.12μm与0.20μm附近存在峰值,无Na酸洗煤超细颗粒生成量较多;随着煤中含量增加,热解使Na先赋存于半焦中,抑制焦油的释放;之后过量的Na气化并抑制焦油向碳黑转化;Na可增加样品中含氧官能团含量,减少脂肪族化合物尤其是短链或支链化程度较高脂肪族化合物含量、增加芳香族化合物含量并降低芳香环稠化度;气化的Na可以造成碳黑微晶体晶格缺陷,形成一些嵌套或类晶体特异结构.

In order to study the effect of alkali metals on the formation of soot during coal pyrolysis,the concentration distribution,chemical structure and microstructure of the pyrolysis products of acid-washed coal carrying alkali metal Na were analyzed.The results showed that the number and mass concentration distributions of particles generated by coal pyrolysis reached the peaks near 0.12μm and 0.2μm,respectively,and there were more ultra-fine particles of acid-washed coal without Na generated.With the increase of loading,Na first occurred in semi-coke,which inhibited the release of tar;afterwards,excessive Na vaporized and inhibited the conversion of tar to soot;loading Na increased the content of oxygen-containing functional groups in the sample,reduced aliphatic compounds,especially short-chain or branched-chained aliphatic compounds,increased aromatics content and reduced aromatic ring densification;vaporized Na caused soot microcrystal lattice defects and formed some nested or crystal-like specific structures.