Abstract Victorian Morwell coal’s physico-chemical properties were modified through densification with Ca(OH)2, KOH, NH4OH and NaOH, in order to compare the effects of varying alkali metals addition on self-heating behaviour. The wire basket results showed that densification of brown coal with alkali hydroxides increased the critical ignition temperature in the order Ca(OH)2 Fourier transform infrared spectroscopy (FTIR) results suggested a catalytic role for cations (K > NH4 > Na > Ca) in the formation of quinones during kneading of brown coal under alkaline conditions. The results revealed that the addition of alkalis to brown coal at basic pH improves the oxidation tolerance of the carboxylic/carboxylate groups and also enhances the polymerization and aromatization reactions during the thermal oxidation of coal, generating aromatic ether and/or ketone substituted polymers with higher thermal stability toward oxidation. Using NaCl as additive, at coal’s natural acidic pH, resulted in a very brittle densified product, with higher macro and mesopore volumes than the coal densified prepared without additive. However, the Tcr value increased, probably due to its lower micropore volume.

中文翻译：

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碱金属氢氧化物致密化对褐煤自热行为和理化性质的影响

摘要 为了比较不同碱金属添加对自热行为的影响，Victorian Morwell 煤的物理化学性质通过用 Ca(OH)2、KOH、NH4OH 和 NaOH 致密化进行了改进。网篮结果表明，用碱金属氢氧化物对褐煤进行致密化后，临界点火温度按 Ca(OH)2 傅里叶变换红外光谱 (FTIR) 的顺序升高，结果表明阳离子 (K > NH4 > Na > Ca) 在褐煤在碱性条件下捏合过程中醌的形成。结果表明，在碱性 pH 值条件下，向褐煤中加入碱提高了羧基/羧酸酯基团的氧化耐受性，并增强了煤热氧化过程中的聚合和芳构化反应，生成对氧化具有更高热稳定性的芳香醚和/或酮取代聚合物。使用 NaCl 作为添加剂，在煤的天然酸性 pH 值下，会产生非常脆的致密产品，与没有添加剂制备的致密煤相比，具有更高的宏观和中孔体积。然而，Tcr 值增加，可能是由于其较低的微孔体积。