Green synthesis of mesoporous γ-Al2O3 from coal fly ash with simultaneous on-site utilization of CO2

• Published in: Journal of hazardous materials 2018-10, Vol.359, p.535-543
• Main Authors: Yan, Feng, Jiang, Jianguo, Liu, Nuo, Gao, Yuchen, Meng, Yuan, Li, Kaimin, Chen, Xuejing
• Format: Article
• Language: English
• Subjects: Aluminum recovery; CO2-assistant precipitation; Coal fly ash; Lime-sinter method; Mesoporous γ-Al2O3
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2018.07.104

[Display omitted] •Facile conversion of coal fly ash into highly ordered mesoporous γ-Al2O3.•Practical extraction technique and high extraction efficiency of aluminum.•Green and rapid synthesis of γ-Al2O3 through the CO2-assistant precipitation.•Synthetic product shows crystalline framework walls and ordered mesostructure. Mesoporous Al2O3 with crystalline framework walls has expanded all over the world due to the various potential applications especially in catalysis. Here, we develop a green and facile approach for the conversion of coal fly ash (CFA) into ordered mesoporous γ-Al2O3. The practical and promising lime-sinter method was comprehensively studied for the extraction of aluminum from CFA as a first step. The extraction efficiency of aluminum could reach up to 87.42%, through calcining with CaCO3 at 1390°C for 1 h and then dissolving in Na2CO3 solution at 70°C for 0.5 h. Combined with the urgent demand for CO2 emission reduction, simulated purified flue gas was introduced to precipitate the Al(OH)3 precursors without structure-directing agents for just 1 h, followed by calcining at only 400°C or 550°C. A series of characterizations were conducted to discuss the effect of precipitation temperature and calcination temperature, resulting the superior product (Al2O3-65/550) with high surface area (230.3 m2 g−1), crystalline γ-Al2O3 phase and ordered mesostructure. This proposed strategy, integrating the on-site recycling of CFA and utilization of CO2, appears to be promising for scalable production of mesoporous γ-Al2O3.