LAUSR

Abstract Transformation of natural clay minerals is an interesting way to design new microporous solids with potential applications as adsorbents or heterogeneous catalysts. Particularly, kaolinite is a widely commercialized 1:1 clay mineral of promising modifiable structure. This paper reports the preparation of microporous solids with high surface areas and increased acidity by thermal-acid treatments of a natural kaolinite. Previous heating (700 °C and 900 °C) was used to activate the kaolinite (23 m2/g surface area) and produce metakaolinite. Then, aluminum extraction with 3 M HCl solution yielded solids with 320 m2/g and 526 m2/g micropore surface areas. The successful dissolution of Al3+ ions from the kaolinite octahedral sheets produces strong dealuminized solids with superior acidity (Bronsted and Lewis). The remarkable characteristics of these solids (high thermal stability, high porosity and enhanced acidity) allow considering them as important catalytic supports.