Nitrogen sorption measurements were carried out by a Belsorp-mini II gas analyzer at 77 K. The specific surface area (SBET) was determined by the BET equation (p/p0 = 0.05-0.15). The pore size distribution was determined from the desorption branch of the isotherm using the Bar — rett-Joyner-Halenda (BJH) theory. The samples were pretreated at 90 °C while degassing (~0.1 Pa). X-ray diffraction (XRD) measurements were conducted with an ARL X’tra X-ray diffractometer of Thermo Scientific (Waltham, MA, USA) equipped with a Cu Ka1 tube and a Peltier cooled lithium drifted silicon solid stage detector. Raman spectra are recorded using a Raman type FRA106/S spectrometer of Bruker (Karlsruhe, Ger­many), equipped with a Nd-YAG laser (X = 1064 nm).

7.4 CONCLUSIONS

Periodic Mesoporous Organosilica functionalized with sulfonic acid groups has been successfully synthesized and characterized. An ethenylene bridged PMO material was chosen as starting material and this was further post-modified in several steps. A bromination and subsequent substitution reaction was used followed by an oxidation turning the material into a sol­id acid catalyst. This material has been investigated for the acetylation of glycerol. The material showed an equal activity as Amberlyst-15; the lat­ter being usually considered as the reference most-efficient catalyst mate­rial for such kind of reactions. Recyclability experiments showed that the sulfonated Periodic Mesoporous Organosilica is reusable and showed the same total acetylation yield after three runs. Homogeneous tests showed that the acetylation of glycerol indeed occurs heterogeneously, suggesting the absence of leaching, e. g., of sulfonate species, in the medium, and thus the high stability of our material under working conditions.