Novel process for facile preparation of mesoporous silica-based materials with controllable pore structure from coal fly ash--颗粒学报PARTICUOLOGY

Gao, J.-m., Li, Z., Ma, S., Zhang, Y., & Cheng, F. (2024). Novel process for facile preparation of mesoporous silica-based materials with controllable pore structure from coal fly ash. Particuology, 91, 128-137. https://doi.org/10.1016/j.partic.2024.03.001

Novel process for facile preparation of mesoporous silica-based materials with controllable pore structure from coal fly ash

Jian-ming Gao^*, Zhen Li, Shujia Ma, Yuanyuan Zhang, Fangqin Cheng^*

Institute of Resources and Environment Engineering, State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources, Shanxi Collaborative Innovation Center of High Value-added Utilization of Coal-related Wastes, Shanxi University, Taiyuan 030006, China

10.1016/j.partic.2024.03.001

Volume 91, August 2024, Pages 128-137

Received 22 September 2023, Revised 9 February 2024, Accepted 4 March 2024, Available online 14 March 2024, Version of Record 21 March 2024.

E-mail: gaojianming@sxu.edu.cn; cfangqin@sxu.edu.cn

Highlights

• Mesoporous silica materials were successfully produced from fly ash by the template-free process.

• Under the calcination with K₂CO₃, mullite gradually transforms into kaliophilite and KAlSiO₄–O1 phase.

• With the increase of etching degree, the pore structure of the obtained silica-based materials is different.

• Mesoporous silica with specific surface area of 475.93 and 642.57 m²/g could be synthesized from activated fly ash.

• A cost-effective and large-scale process for mesoporous silica materials preparation from fly ash is provided.

Abstract

Extraction of silica from fly ash to produce mesoporous silica materials is one of the most important utilization approaches. Mesoporous silica could not be synthesized on a large-scale by conventional sol-gel method. In this paper, facile preparation of mesoporous silica with controllable pore structure from fly ash by the template-free process via two steps of mineral phase transformation and selective acid etching was proposed. The influence of crystalline structure and acid etching degree on structure of as-synthesized mesoporous silica materials was revealed, as well as mechanism of crystalline structure transformation and pore structure formation. The results show that mullite and quartz could be transformed into acid-soluble kaliophilite when fly ash reacted with K₂CO₃ at temperature of 800–1100 °C. The hexagonal kaliophilite would be transformed into orthorhombic KAlSiO₄–O1 phase when the temperature is controlled at 1100 °C. Mesoporous silica with specific surface area of 475.93 m²/g and 642.57 m²/g could be synthesized from activated fly ash with kaliophilite and KAlSiO₄–O1 phase crystalline structure. By controlling the degree of acid etching, mesoporous silica materials with different pore structures can be obtained. This paper provides a cost-effective and large-scale process for the preparation of mesoporous silica materials with controllable pore structure from solid waste fly ash.

Graphical abstract

Keywords

Fly ash; Mesoporous silica; Crystal transformation; Acid etching; Controllable pore structure

文章导读