Abstract The main aim of this investigation is to present a comprehensive analysis of carbothermal reactions with tobelite at high temperatures under N2. The mixtures with mass ratios of demineralized coal: tobelite = 1:3, 1:5, 1:7, 1:9 were subjected to thermogravimetric analysis (TGA) up to 1500 °C, the mineral composition and morphology of the product after carbothermal reaction were evaluated by X-ray diffraction (XRD) and scanning electron microscope with energy dispersive spectroscopy (SEM-EDS). FactSage equilibrium calculations also used for predicting mineral transformation process. It was found that thermal transformation of the tobelite in demineralized coal includes four stages: stage I (0–200 °C), stage II (200–900 °C), stage III (900–1200 °C), stage IV (1200–1500 °C). The processes of coal devolatilization and tobelite decomposition are independent processes when the temperature is below 1000 °C, the contact mode among minerals and coal matrix affect the thermal behavior of minerals. The carbothermal reactions start at 1200 °C. When coal: tobelite = 3:7, the products include incompletely reacted Al6Si2O13 (mullite), Al2O3, SiC, β-Si3N4 and Al6Si6N8O9; When coal: tobelite = 5:5, the reaction products include SiAl6O2N, Al2O3 and SiC, Al2O3 and SiC are the main phases; When coal: tobelite = 7:3, the composition is Si6AlO6N5, AlN, SiC and SiO2, SiC and AlN are the main phases. Carbon structure may strongly influence the carbothermal reaction. In addition, the formation and disappearance of SiC could releases CO by reaction with carbon during the carbothermal reaction, thus promoting char gasification.

中文翻译：

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在 N2 气氛下高温碳热反应与碳热反应

摘要 本研究的主要目的是全面分析在 N2 下高温下与甲苯沸石的碳热反应。将脱矿煤：tobelite = 1:3, 1:5, 1:7, 1:9 的混合物进行高达 1500 °C 的热重分析 (TGA)，碳热后产物的矿物组成和形貌通过X射线衍射（XRD）和具有能量色散光谱的扫描电子显微镜（SEM-EDS）评估反应。FactSage 平衡计算也用于预测矿物转化过程。研究发现脱矿煤中妥贝石的热转变包括四个阶段：I阶段（0-200℃）、II阶段（200-900℃）、III阶段（900-1200℃）、IV阶段（1200℃） –1500 °C）。当温度低于 1000 ℃时，煤的脱挥发分和甲苯沸石分解过程是独立的过程，矿物与煤基体的接触方式影响矿物的热行为。碳热反应开始于 1200 °C。当煤：tobelite = 3:7时，产物包括不完全反应的Al6Si2O13（莫来石）、Al2O3、SiC、β-Si3N4和Al6Si6N8O9；当煤：tobelite=5：5时，反应产物为SiAl6O2N、Al2O3和SiC，Al2O3和SiC为主要相；当煤：tobelite = 7:3时，成分为Si6AlO6N5、AlN、SiC和SiO2，主要相为SiC和AlN。碳结构可能强烈影响碳热反应。此外，在碳热反应过程中，SiC 的形成和消失可以通过与碳反应释放 CO，从而促进炭气化。