Na-Containing Mineral Transformation Behaviors during Na2CO3-Catalyzed CO2 Gasification of High-Alumina Coal

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• 作者：Yangang Mei ; Zhiqing WangHuibin Fang ; Yongwei Wang ; Jiejie Huang ; Yitian Fang
• 刊名：Energy & Fuels
• 出版年：2017
• 出版时间：February 16, 2017
• 年：2017
• 卷：31
• 期：2
• 页码：1235-1242
• 全文大小：436K
• ISSN：1520-5029

文摘

Interactions between alkali metals in catalysts and silicon or aluminum minerals in coal are closely related to gasification reactivity, deactivation, and recovery of alkali catalysts during coal catalytic gasification, and alkali-containing minerals and their transformation behaviors are key issues for understanding these interactions. In this paper, Na-containing mineral transformation behaviors and their influences on the catalytic performance during Na₂CO₃-catalyzed CO₂ gasification of high-alumina coal were comprehensively investigated by thermogravimetry, inductively coupled plasma, X-ray diffraction, and Fourier transform infrared spectroscopy. Moreover, to have a better understanding of the mineral transformation during catalytic gasification, model compounds, i.e., kaolinite (Al₂O₃·2SiO₂·2H₂O) and boehmite (AlOOH), the main Al-containing minerals in high-alumina coal, were chosen as model compounds to investigate the mineral transformation behaviors. The results show that Na₂CO₃ first deactivates to generate inert sodium aluminum silicate (Na_1.55Al_1.55Si_0.45O₄) at 700 °C, which contributes to the deactivation of catalysts, and then various kinds of sodium aluminum silicates are formed with increasing temperature and Na₂CO₃ addition. Among them, sodium aluminum silicate [(Na₂O)_0.33NaAlSiO₄] has been testified as the most stable mineral during gasification. In addition, Na-containing mineral transformation and its resulting products are helpful to the recovery of Al from the ash of catalytic gasification, and 94% recovery rate can be obtained, which is considered to be a method to extract Al from gasification ash. Model kaolinite and boehmite can well explain the mineral transformation during Na₂CO₃-catalyzed CO₂ gasification of high-alumina coal.