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Transformation of alkali and alkaline earth metals during the preparation of activated carbon from Zhundong high-alkali coal
RSC Advances ( IF 3.9 ) Pub Date : 2021-1-20 , DOI: 10.1039/d0ra09518d Dingcheng Liang 1 , Qiang Xie 1 , Jinchang Liu 1 , Deqian Liu 1 , Chaoran Wan 1 , Shuai Yang 1
RSC Advances ( IF 3.9 ) Pub Date : 2021-1-20 , DOI: 10.1039/d0ra09518d Dingcheng Liang 1 , Qiang Xie 1 , Jinchang Liu 1 , Deqian Liu 1 , Chaoran Wan 1 , Shuai Yang 1
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The preparation of activated carbon (AC) is a promising approach for the efficient utilization of Zhundong high-alkali coal. The volatilization and release of alkali and alkaline earth metal (AAEM) species can be effectively inhibited by using a lower operating temperature and a carbon matrix. However, the long time of the pyrolysis and activation process may promote the release of the AAEM from the coal during the process. Therefore, it is necessary to explore the transformation of AAEM during the preparation of AC from Zhundong high-alkali coal, and the cleanness of this process is evaluated accurately. In this study, the evolution of AAEM, distribution, and chemical speciation is characterized before and after the preparation of AC from the coal, and then thermodynamic calculations were performed using FactSage to simulate the transformation of AAEM in the coupled process of pyrolysis and activation. The results showed that in the process of AC preparation, the AAEM species inside the carbon matrix moved towards the surface of the AC with the aid of released volatiles and the activation reaction. Some Na and K species were released due to their weak binding with the carbon matrix and this resulted in the loss of Na and K content, whereas Mg and Ca were closely combined with the carbon matrix and were enriched in the AC. Furthermore, the defects and amorphous structure of the AC prepared with H2O activation were more than that of the AC prepared with CO2 activation, which meant that more of the AAEM species were exposed to the high temperature environment. As a result, the loss of AAEM content in the AC with H2O activation was higher than that in the AC with CO2 activation. In this process, a small amount of highly volatile and corrosive AAEM was produced, and the release of volatile matter and the consumption of the carbon matrix were the main factors for the AAEM loss. Therefore, the preparation of AC from Zhundong high-alkali coal is a viable method for its clean use.
中文翻译：
准东高碱煤制备活性炭过程中碱金属和碱土金属的转化
制备活性炭（AC）是准东高碱煤高效利用的一种有前景的方法。通过使用较低的操作温度和碳基质，可以有效地抑制碱金属和碱土金属（AAEM）物质的挥发和释放。然而，长时间的热解和活化过程可能会促进煤中AAEM的释放。因此，有必要探索准东高碱煤制备活性炭过程中AAEM的改造，并准确评价该过程的清洁度。本研究描述了煤制备活性炭前后AAEM的演变、分布和化学形态，然后使用FactSage进行热力学计算，模拟热解和活化耦合过程中AAEM的转变。结果表明，在AC制备过程中，碳基体内的AAEM物质借助释放的挥发物和活化反应向AC表面移动。一些Na和K物质由于与碳基质的结合较弱而被释放，这导致Na和K含量的损失，而Mg和Ca与碳基质紧密结合并在AC中富集。此外，H 2 O活化制备的AC的缺陷和非晶结构比CO 2活化制备的AC更多，这意味着更多的AAEM物种暴露于高温环境。 结果，H 2 O活化的AC中AAEM含量的损失高于CO 2活化的AC中的AAEM含量损失。在此过程中，产生少量高挥发性和腐蚀性的AAEM，挥发物的释放和碳基体的消耗是AAEM损失的主要因素。因此，以准东高碱煤为原料制备活性炭是清洁利用活性炭的可行方法。
更新日期：2021-01-20
中文翻译：
准东高碱煤制备活性炭过程中碱金属和碱土金属的转化
制备活性炭（AC）是准东高碱煤高效利用的一种有前景的方法。通过使用较低的操作温度和碳基质，可以有效地抑制碱金属和碱土金属（AAEM）物质的挥发和释放。然而，长时间的热解和活化过程可能会促进煤中AAEM的释放。因此，有必要探索准东高碱煤制备活性炭过程中AAEM的改造，并准确评价该过程的清洁度。本研究描述了煤制备活性炭前后AAEM的演变、分布和化学形态，然后使用FactSage进行热力学计算，模拟热解和活化耦合过程中AAEM的转变。结果表明，在AC制备过程中，碳基体内的AAEM物质借助释放的挥发物和活化反应向AC表面移动。一些Na和K物质由于与碳基质的结合较弱而被释放，这导致Na和K含量的损失，而Mg和Ca与碳基质紧密结合并在AC中富集。此外，H 2 O活化制备的AC的缺陷和非晶结构比CO 2活化制备的AC更多，这意味着更多的AAEM物种暴露于高温环境。 结果，H 2 O活化的AC中AAEM含量的损失高于CO 2活化的AC中的AAEM含量损失。在此过程中，产生少量高挥发性和腐蚀性的AAEM，挥发物的释放和碳基体的消耗是AAEM损失的主要因素。因此，以准东高碱煤为原料制备活性炭是清洁利用活性炭的可行方法。
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