Na及矿物类型对高碱煤快速热解焦油及BTEXN产物分配的影响

Effect of sodium and mineral types on distribution of tar and BTEXN under high alkali coal fast pyrolysis

轻质芳烃(BTEXN)如苯、甲苯、乙苯、二甲苯和萘作为高价值化学原料,在工业中具有广泛应用。煤干馏焦油的精制是BTEXN重要生产方法之一。本文分别选用红沙泉和将军庙两种典型新疆高碱煤,通过逐级萃取及外源添加Na两种预处理方式,利用Py-GC/MS半定量研究了高碱煤中钠形态和含量,以及矿物组分类型对煤快速热解焦油及BTEXN产物分布的影响。结果表明,两种高碱煤中固有矿物质均可提高焦油及BTEXN析出量,水溶性矿物质(Na)对此起关键作用。内源性水溶性矿物及醋酸铵溶性矿物使红沙泉煤焦油析出量提高22%和55%;而外源添加的水溶性NaCl和醋酸铵溶性CH3COONa降低了将军庙煤焦油析出量。水溶性矿物及1.0%(质量)的NaCl和CH3COONa分别使煤焦油中的BTEXN析出量提高45%、42%和62%,醋酸铵溶性物质及低含量[0.4%(质量)]Na则会抑制BTEXN的析出。

Light aromatic hydrocarbons(BTEXN)such as benzene,toluene,ethylbenzene,xylene and naphthalene are used as high-value chemical raw materials and are widely used in industry.Refining of coal retorting tar is one of the important production methods of BTEXN.In this paper,we carry out fast pyrolysis research on Xinjiang highalkali coal in order to expand the applications of Xinjiang high-alkali coal in chemical industry.Two typical highalkali coals from Xinjiang which called Hongshaquan and Jiangjunmiao,which were prepeared through the two pretreatment methods of sequential extraction and external addition of sodium,were used to semi-quantitatively study the effect of sodium form and content in high alkali coal,as well as the types of mineral components on the fast pyrolysis tar and BTEXN precipitation characteristics by Py-GC/MS.The results show that the inherent minerals in both high-alkali coals could increase the precipitation of tar and BTEXN for which the water-soluble(Na,Ca)minerals played a key role.Endogenous water-soluble minerals and ammonium acetate-soluble minerals which mainly based on sodium and calcium both increased the precipitation of Hongshaquan coal tar by 22%and 55%.However,the addition of water-soluble NaCl and ammonium acetate-soluble CH3COONa from external sources reduced the precipitation of Jiangjunmiao coal tar.Water-soluble minerals,1.0%(mass)NaCl and CH3COONa respectively increased the precipitation of BTEXN in coal tar by 45%,42%and 62%.However,the ammonium acetate soluble substance and low content(0.4%(mass))Na will inhibit the precipitation of BTEXN.