Adsorption Monitoring of Hydrothermal and Thermal Stability of Polymer-Templated Mesoporous Materials

Abstract

The thermal and hydrothermal stability of FDU-1 silica with ordered, large (~10 nm), cage-like mesopores was studied using nitrogen and argon adsorption at −196∘C. It was confirmed that FDU-1 silica retains uniform mesoporosity even after heating for 5 hours at 950–1000∘C. Although typical FDU-1 silicas and other polymeric-templated silicas with large cage-like mesopores tend to be significantly microporous, the FDU-1 sample calcined at 1000∘C appeared to be essentially free from microporosity, as can be inferred from the relation between its surface area, pore volume and pore diameter. This result suggests that high-temperature calcination can be used to synthesize model mesoporous adsorbents with large cage-like (spherical) mesopores. Evidence of the concomitant decrease in the pore diameter and the pore entrance size with an increase in the calcination temperature is presented. The structural stability of FDU-1 during heating in water at 100∘C for 2, 4, and 8 days is additionally demonstrated.