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Evolution of the crystallographic structure and physicochemical aspects of rectorite upon calcination
Applied Clay Science ( IF 5.3 ) Pub Date : 2020-02-01 , DOI: 10.1016/j.clay.2019.105374
Weimin Xie , Jie Wang , Liangjie Fu , Qi Tan , Xiumin Tan , Huaming Yang

Abstract Rectorite (Rec) with exchangeable cations has a wide range of potential applications, including adsorbents, catalyst supports, high-temperature binders, and flame retardant additives. The understanding of the variation of rectorite upon thermal treatment is vital for exploiting its application potential. This paper reports on the thermal decomposition and structural evolution of Rec in the temperature range of 25–1200 °C. Thermogravimetric (TG) analysis, in-situ X-ray diffraction (XRD), and in-situ Fourier transform infrared (FTIR) spectroscopy were used to trace real-time variations in rectorite upon calcination. Then, pristine rectorite and its calcined samples were systematically characterized by 29Si and 27Al magic-angle sample spinning nuclear magnetic resonance (MAS NMR), Brunauer-Emmet-Teller (BET), Zeta potential, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The results showed that Rec went through the following four stages after thermal treatment: dehydration at room temperature (RT) to 300 °C, dehydroxylation at 500–700 °C, structural collapse at 1000 °C, and formation of a new phase above 1100 °C. Furthermore, SiO4 tetrahedral units and AlO6 octahedral units in Rec were distorted around 1000 °C, so that the maximum contents of active SiO2 and Al2O3 could be simultaneously obtained. The atomic-level structural evolution mechanism of Rec upon calcination is proposed.

中文翻译:

煅烧后蒙脱石的晶体结构和物理化学方面的演变

摘要 具有可交换阳离子的 Rectorite (Rec) 具有广泛的潜在应用,包括吸附剂、催化剂载体、高温粘合剂和阻燃添加剂。了解热处理后雷托石的变化对于开发其应用潜力至关重要。本文报道了 Rec 在 25-1200 °C 温度范围内的热分解和结构演变。使用热重 (TG) 分析、原位 X 射线衍射 (XRD) 和原位傅里叶变换红外 (FTIR) 光谱来追踪煅烧后蒙脱石的实时变化。然后,通过 29Si 和 27Al 魔角样品旋转核磁共振 (MAS NMR)、Brunauer-Emmet-Teller (BET)、Zeta 电位、扫描电子显微镜 (SEM) 和透射电子显微镜 (TEM) 技术。结果表明,Rec经过热处理后经历了以下四个阶段:室温(RT)至300°C脱水,500-700°C脱羟基,1000°C结构坍塌,1100°C以上形成新相。 ℃。此外,Rec 中的 SiO4 四面体单元和 AlO6 八面体单元在 1000°C 左右发生畸变,从而可以同时获得最大的活性 SiO2 和 Al2O3 含量。提出了焙烧后Rec的原子级结构演化机制。1000 °C 时结构坍塌,并在 1100 °C 以上形成新相。此外,Rec 中的 SiO4 四面体单元和 AlO6 八面体单元在 1000°C 左右发生畸变,从而可以同时获得最大的活性 SiO2 和 Al2O3 含量。提出了焙烧后Rec的原子级结构演化机制。1000 °C 时结构坍塌,并在 1100 °C 以上形成新相。此外,Rec 中的 SiO4 四面体单元和 AlO6 八面体单元在 1000°C 左右发生畸变,从而可以同时获得最大的活性 SiO2 和 Al2O3 含量。提出了焙烧后Rec的原子级结构演化机制。
更新日期:2020-02-01
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