Characterization of the pore architecture created by alkaline treatment of HMCM-22 using 129Xe NMR spectroscopy

Sol–Gel Synthesis of Microporous Carbon Using Resorcinol and Formaldehyde

Microporous carbon materials were prepared by thermal decomposition of a xerogel. The xerogel was synthesised through polycondensation of resorcinol and formaldehyde using an acid-catalysed sol–gel method. Acetic acid (1 M) was used as a catalyst. The effect of the molar ratio of resorcinol/catalyst (10/3, 5, 10, 20) on the obtained hydrogel was studied. The temperature range 25–110 °C was used to convert the hydrogel into a solid resorcinol/formaldehyde xerogel. The optimum molar ratio of resorcinol/catalyst was found to be 10/3. The dried xerogels were pyrolysed under an argon atmosphere at 800 °C to obtain microporous carbon materials with a uniform structure consisting of hollow particles and a specific surface area of 650 m2 g−1.

Hyperpolarized Xenon Nuclear Magnetic Resonance (NMR) of Building Stone Materials

We have investigated several building stone materials, including minerals and rocks, using continuous flow hyperpolarized xenon (CF-HP) NMR spectroscopy to probe the surface composition and porosity. Chemical shift and line width values are consistent with petrographic information. Rare upfield shifts were measured and attributed to the presence of transition metal cations on the surface. The evolution of freshly cleaved rocks exposed to the atmosphere was also characterized. The CF-HP ¹²⁹Xe NMR technique is non-destructive and it could complement currently used techniques, like porosimetry and microscopy, providing additional information on the chemical nature of the rock surface and its evolution.