Calcination effects on meta-forms of kaolin and halloysite: Role of Al-Si spinel crystallization in zeolite synthesis

IF 4.8 3区材料科学 Q1 CHEMISTRY, APPLIED

Microporous and Mesoporous Materials Pub Date : 2025-04-05 DOI:10.1016/j.micromeso.2025.113626

Pelin Pasabeyoglu , Burcu Akata

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Abstract

The role of Al-Si spinel crystallization during high-temperature calcination of kaolin and halloysite was investigated to optimize the direct synthesis of zeolites 4A and 13X without additional silica or structure-directing agents. Differential thermogravimetry (DTG) and in situ synchrotron X-ray diffraction (SR-XRD) tracked dehydroxylation and Al-Si spinel crystallization, revealing complete dehydroxylation at 575 °C for kaolin and 500 °C for halloysite, with spinel crystallization occurring in a range of 900–940 °C for both clays. Calcination promoted the formation of Al-Si spinel and amorphous silica, increasing the Si/Al ratio and enabling control of zeolite composition and porosity. Calcination conditions determined the zeolite type, evolving from pure 4A to a mixture of 4A/13X, and finally pure 13X. The presence of Al-Si spinel in 13X enhanced mesoporosity, introducing voids and channels between micropores and contributing to high BET surface areas (>500 m²/g) with a dual micro/mesoporous structure. This study establishes a direct link between calcination parameters and zeolite properties, highlighting Al-Si spinel's role in phase transitions and porosity development. These findings provide valuable insights for optimizing industrial applications such as adsorption and catalysis.

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来源期刊

Microporous and Mesoporous Materials 化学-材料科学：综合

CiteScore

10.70

自引率

5.80%

发文量

649

审稿时长

26 days

期刊介绍： Microporous and Mesoporous Materials covers novel and significant aspects of porous solids classified as either microporous (pore size up to 2 nm) or mesoporous (pore size 2 to 50 nm). The porosity should have a specific impact on the material properties or application. Typical examples are zeolites and zeolite-like materials, pillared materials, clathrasils and clathrates, carbon molecular sieves, ordered mesoporous materials, organic/inorganic porous hybrid materials, or porous metal oxides. Both natural and synthetic porous materials are within the scope of the journal. Topics which are particularly of interest include: All aspects of natural microporous and mesoporous solids The synthesis of crystalline or amorphous porous materials The physico-chemical characterization of microporous and mesoporous solids, especially spectroscopic and microscopic The modification of microporous and mesoporous solids, for example by ion exchange or solid-state reactions All topics related to diffusion of mobile species in the pores of microporous and mesoporous materials Adsorption (and other separation techniques) using microporous or mesoporous adsorbents Catalysis by microporous and mesoporous materials Host/guest interactions Theoretical chemistry and modelling of host/guest interactions All topics related to the application of microporous and mesoporous materials in industrial catalysis, separation technology, environmental protection, electrochemistry, membranes, sensors, optical devices, etc.