Mechanical and Hydrothermal Stabilities of Aged Periodic Mesoporous Organosilicas

Abstract

Methylene-, ethylene-, and phenylene-bridged periodic mesoporous organosilicas (PMOs) synthesized with nonionic alkylethylene oxide templates exhibited significantly better mechanical and hydrothermal stabilities than periodic mesoporous silica. Synthesis of PMOs utilized the acid-catalyzed hydrolysis and condensation of bis(triethoxysilyl) precursors around supramolecular polyoxyethylene(10) stearyl ether (Brij 76) templates. Nitrogen gas sorption, thermogravimetry, and X-ray diffraction have been used to characterize the effects of aging, mechanical compression, and hydrothermal treatment on these materials. Both as-synthesized composites containing surfactant templates and extracted PMOs showed no degradation after 10 months. The enhanced stability of these nanoporous organosilicas relative to meoporous silica makes them potential candidates for use in advanced catalysis and adsorption applications.

Catalytic Upgrading of Bio-Oil by Reacting with Olefi ns and Alcohols over Solid Acids: Reaction Paths via Model Compound Studies

“…The materials retain porosity and ordering after three consecutive reactions as can be seen from the nitrogen sorption and XRD data. These results also confirm the reported stability of Periodic Mesoporous Organosilicas [20,23]. Table 2 presents an overview of the chemical characterization of the solids after the different synthetic procedures.…”

Highly ordered periodic mesoporous ethanesilica synthesized under neutral conditions

“…16 Small signals at 29.8 ppm and 70.6 ppm arise from the surfactant residue. 7 Solid-state 29 Si MAS NMR results for this sample show overlapped peaks in the range of 250 ppm to 275 ppm, corresponding to T n silicon atoms [SiC(OH) n (OSi) 32n ] (Fig. 8b).…”

Synthesis, characterization, and catalytic activity of sulfonic acid-functionalized periodic mesoporous organosilicas

“…It was found that the sulfonic acid-functionalized mesoporous organosilicas synthesized in this work show high catalytic activity and stability. It was shown by others [17,18] that PMOs exhibit very good mechanical and hydrothermal stability. These new materials could serve as solid acid catalysts with potential in many acid-catalyzed reactions.…”