Changes in OH-Cr-montmorillonite after heating in air and nitrogen atmospheres

Montmorillonite materials before and after intercalation of OH-Cr(III) species were analyzed thermically up to 1000 °C in air and nitrogen atmospheres. The thermal treatments were obtained by using thermal analysis equipment and the structural changes were followed by X-ray diffraction. Compared to the original montmorillonite, the montmorillonite treated with OH-Cr species showed differences in both thermal processes. The 450 °C thermal treatment on OH-Cr-montmorillonite in air and N2 produced different interlayer spacing. The 1000 °C thermal treatment, where clay has already collapsed, also present differences in the obtained products: eskolaite (Cr2O3) in air and Mg-Cr-spinel in nitrogen.