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首页> 外文期刊>RSC Advances >Mechanism of the evolution of pore structure during the preparation of activated carbon from Zhundong high-alkali coal based on gas–solid diffusion and activation reactions
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Mechanism of the evolution of pore structure during the preparation of activated carbon from Zhundong high-alkali coal based on gas–solid diffusion and activation reactions

机译：基于气固扩散和活化反应的抗隆高碱煤的活性炭在制备活性炭过程中的机制

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Zhundong coal can significantly reduce the preparation temperature of activated carbon (AC) due to the high contents of alkali and alkaline earth metals (AAEMs) present in it. Moreover, because of its lower operating temperature and the presence of carbon matrix, Zhundong coal can effectively inhibit the release of AAEM during the preparation of AC. For these reasons, the preparation of AC from Zhundong coal is a promising approach for the clean utilization of Zhundong coal. Accordingly, this study was aimed to investigate optimum conditions for the preparation of AC from Zhundong coal. For this purpose, at first, Raman spectroscopy was used to determine the conditions for an optimal carbonization process using a coal sample; then, the evolution of the pore structure of AC under different conditions was examined by small-angle X-ray scattering (SAXS) and the N _(2) adsorption analyser. Furthermore, environmental scanning electron microscopy (ESEM) was performed to analyze the surface morphology of AC. Finally, by dividing the activation process into gas–solid diffusion and activation reactions, a mechanism for the evolution of pore structure during the preparation of AC was proposed. The results showed that the char with an amorphous structure and less graphite-like carbon, which was obtained by heating Zhundong coal from room temperature to 600 °C at 5 °C min ~(?1) under the protection of N _(2) and then maintaining it at this temperature for 60 min, is suitable for the subsequent activation process. At low temperatures, the diffusion of H _(2) O was dominant in the activation process, and the weak gas–solid reaction resulted in poor development of the pore structure; on the other hand, the CO _(2) activation reaction mainly occurred on the surface of the char due to the poor diffusion of CO _(2) , and then, the produced pores could improve the diffusion of CO _(2) ; this led to significant development of the pore structure. With an increase in temperature, the H _(2) O diffusion reaction was enhanced, and the pore structure of AC was completely developed; however, the diffusion of CO _(2) reduced with an enhancement in the CO _(2) activation reaction, leading to the consumption of carbon matrix by CO _(2) gasification instead of pore formation by the CO _(2) activation reaction. Therefore, proper utilization of the unique characteristics of H _(2) O and CO _(2) during pore formation is important to control the activation process.
机译：由于其中存在的碱和碱土金属（AAEMs）的高含量，抗谐煤可以显着降低活性炭（AC）的制备温度。此外，由于其较低的工作温度和碳基质的存在，抗煤煤可以有效地抑制AAEM在AC的制备过程中释放AAEM。出于这些原因，逆东煤炭的编制是抗煤炭清洁利用的有希望的方法。因此，本研究旨在调查从振冬煤制备AC的最佳条件。为此目的，首先，使用拉曼光谱法测定使用煤样的最佳碳化过程的条件;然后，通过小角X射线散射（SAX）和N _（2）吸附分析仪检查不同条件下AC的孔结构的演变。此外，进行环境扫描电子显微镜（ESEM）以分析AC的表面形态。最后，通过将活化过程划分为气体固体扩散和活化反应，提出了一种在AC制备过程中孔隙结构演变的机制。结果表明，通过在5℃的5℃min〜（2）下，通过从室温从室温加热到600℃，通过将Zhundong煤从室温〜600℃加热至600℃而获得的焦炭和较少的石墨碳。（2）然后在该温度下保持60分钟，适用于随后的活化过程。在低温下，H _（2）o的扩散在活化过程中占主导地位，弱气体固体反应导致孔结构的发育不佳;另一方面，由于Co _（2）的扩散差，CO _（2）激活反应主要发生在COL的表面上，然后，所产生的孔可以改善CO _（2）的扩散;这导致了孔隙结构的显着发展。随着温度的增加，H _（2）o扩散反应增强，AC的孔隙结构完全开发;然而，CO _（2）的扩散随CO _（2）激活反应的增强，导致CO _（2）气化的碳基质消耗而不是CO _（2）激活而不是孔形成反应。因此，在孔隙形成期间适当利用H _（2）O和CO_（2）的独特特征对于控制激活过程是重要的。

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