山西大学程芳琴团队报道了粉煤灰制备可控孔结构介孔硅基材料的新工艺。相关研究成果发表在2024年3月14日出版的《颗粒学报》。

从粉煤灰中提取二氧化硅制备介孔二氧化硅材料是最重要的利用途径之一。传统的溶胶-凝胶法无法大规模合成中孔二氧化硅。

该文提出了以粉煤灰为原料，采用无模板法，通过矿物相变和选择性酸蚀两步，制备孔径可控的介孔二氧化硅。揭示了晶体结构和酸蚀程度对合成的介孔二氧化硅材料结构的影响，以及晶体结构转变和孔结构形成的机理。结果表明，当粉煤灰与K₂CO₃在800–1100°C的温度下反应时，莫来石和石英可以转化为酸溶性钾长石。

当温度控制在1100°C时，六方亲钾岩将转变为正交的KAlSiO₄–O1相。以钾长石和KAlSiO4–O1相晶体结构的活性粉煤灰为原料，可以合成比表面积分别为475.93m²/g和642.57m²/g的介孔二氧化硅。通过控制酸蚀刻的程度，可以获得具有不同孔结构的介孔二氧化硅材料。

该文提供了一种从固体废粉煤灰中制备，具有可控孔结构介孔二氧化硅材料的经济高效的大规模工艺。

附：英文原文

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

Author: Jian-ming Gao, Zhen Li, Shujia Ma, Yuanyuan Zhang, Fangqin Cheng

Issue&Volume: 2024/03/14

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 475.93m2/g and 642.57m2/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.

DOI: 10.1016/j.partic.2024.03.001

Source: https://www.sciencedirect.com/science/article/abs/pii/S1674200124000336