On the geometric trajectories of pores during the thermal sintering of relevant catalyst supports

The thermal events typically encountered during the reactivation of inorganic catalytic supports have been investigated. For this, two relevant inorganic materials were studied; an amorphous silica and a gamma (γ) alumina. The materials were thermally treated in air at temperatures ranging 700 up to 1100 °C and the structural and textural changes were assessed. The crystallinity was enhanced and the textural parameters decreased, but the most remarkable effect was the pore trajectory. This varies depending on the sintering mechanism, contractive sintering (silica) or coarsening (alumina), which was detected by high-resolution physisorption. The reduction in the surface area is not a good indicator of the pore changes; in addition to pore changes, the material can also suffer densification, and both effects determine the surface area. Finally, the study shows that thermal treatment is an easy way to modify the pore size of the studied materials; the γ-alumina showing more controllability.